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3D Bioprinting for Engineering Complex Tissues
... LAB printing does not require a printhead, so the pressure on the cells is reduced by mechanical stress. Laser-assisted printing has high resolution and high cell deposition density, but it has high requirements for cross-linking and high price, and the effect of laser on cells is still unclear [13,28]. ...
... BioMedical Engineering OnLine (2025) 24:14 produces discontinuous ink droplets, while extrusion printing produces continuous materials [13]. Although the accuracy of extrusion printing is not as high as inkjet printing, it can print a wider range of materials, and it can print a wider range of material viscosity, while inkjet printing cannot print materials with high viscosity [28]. Murphy et al. [29] have shown that the mechanical stress of extrusion printing can affect cells. ...
Currently, bone tissue engineering is a research hotspot in the treatment of orthopedic diseases, and many problems in orthopedics can be solved through bone tissue engineering, which can be used to treat fractures, bone defects, arthritis, etc. More importantly, it can provide an alternative to traditional bone grafting and solve the problems of insufficient autologous bone grafting, poor histocompatibility of grafts, and insufficient induced bone regeneration. Growth factors are key factors in bone tissue engineering by promoting osteoblast proliferation and differentiation, which in turn increases the efficiency of osteogenesis and bone regeneration. 3D printing technology can provide carriers with better pore structure for growth factors to improve the stability of growth factors and precisely control their release. Studies have shown that 3D-printed scaffolds containing growth factors provide a better choice for personalized treatment, bone defect repair, and bone regeneration in orthopedics, which are important for the treatment of orthopedic diseases and have potential research value in orthopedic applications. This paper aims to summarize the research progress of 3D printed scaffolds containing growth factors in orthopedics in recent years and summarize the use of different growth factors in 3D scaffolds, including bone morphogenetic proteins, platelet-derived growth factors, transforming growth factors, vascular endothelial growth factors, etc. Optimization of material selection and the way of combining growth factors with scaffolds are also discussed.
... The most common 3D printing technologies are extrusion bioprinting, laser-assisted bioprinting (LAB), and inkjet bioprinting (Fig. 6A) [119]. Among these, only extrusion bioprinting and inkjet bioprinting can easily create a variety of compositional gradients. ...
... 3D printing utilizes multiple print heads to integrate various materials, including hydrogels, easily extrudable synthetic polymers, and ceramics. Additionally, 3D bioprinting facilitates the rapid and on-demand biomimetic design of complex soft and hard tissue interface structures [116,119]. Copyright 2015, Elsevier and Copyright 2018, Elsevier; (B) Dual gradient scaffolds with porosity and HA content prepared by a multi material extrusion 3D printing system [122]. ...
Bone and soft tissues are connected by a complex interface that is crucial for the smooth transfer of mechanical stress. Effective repair of this interface requires bio-scaffolds specifically designed to support the regeneration of diverse cell types and signalling molecules. With advances in micro- and nanotechnologies, gradient biomaterial scaffolds have demonstrated significant potential in interface tissue regeneration. This paper reviews the structure of the bone-soft tissue interface, the various gradient scaffold types, and construction methods. It also discusses the recent developments and future directions in interface tissue engineering, emphasizing the potential of gradient scaffolds to restore the natural structure and function of bone-soft tissue interfaces. Overall, this paper provides valuable insights into the application of gradient scaffolds for bone-soft tissue interface engineering, offering inspiration for biomimetic approaches to soft-hard interface repair in future medical engineering.
The Translational Potential of this Article
First, the emphasis on gradient scaffolds could significantly impact clinical practices related to bone-soft tissue integration, ultimately improving patient outcomes and quality of life. Second, it also aligns with the growing trend of biomimetic approaches in medical engineering, potentially inspiring new innovations in bone-soft tissue repair strategies.
... • Case Study: Mandrycky et al. (2020) [8] reported a case involving a 35-year-old male with a critical-sized femoral defect resulting from a motorcycle accident. The patient was treated with a bioprinted scaffold composed of hydroxyapatite and polylactic acid, seeded with autologous mesenchymal stem cells. ...
... Over a follow-up period of 12 months, the defect showed complete osseointegration and restoration of mechanical strength, confirmed by radiographic and biomechanical testing. • Outcome: The study demonstrated an 85% reduction in recovery time compared to traditional bone grafting methods, with no complications such as infection or graft rejection (Mandrycky et al., 2020) [8] . ...
The advent of 3D bioprinting has emerged as a transformative technology in orthopedic medicine, bridging the gap between regenerative medicine and personalized healthcare. By utilizing bioinks-combinations of living cells and biocompatible materials-this technology allows the fabrication of anatomically precise scaffolds and implants that closely mimic native bone, cartilage, and musculoskeletal structures. Recent advancements have demonstrated remarkable clinical successes. For instance, bioprinted bone scaffolds infused with osteogenic factors have shown an 80% increase in bone regeneration rates in preclinical models, while cartilage repair using bioprinted constructs has led to functional recovery in over 70% of patients within one year of treatment. The global market for 3D bioprinting in orthopedics is projected to grow at a compound annual growth rate (CAGR) of 18.7%, expected to reach $4.4 billion by 2028, reflecting the increasing demand for precision medicine and customized implants. Clinical applications span from treating critical-sized bone defects and osteochondral injuries to personalized joint reconstructions and spinal implants. Moreover, bioprinted scaffolds have reduced revision surgery rates by 25%, highlighting their long-term benefits. Despite these advancements, challenges such as vascularization, high production costs, and regulatory hurdles remain significant barriers to widespread adoption. Nevertheless, emerging technologies like AI-driven modeling and 4D bioprinting hold promise for overcoming these limitations. This review explores the materials, methodologies, clinical applications, and future directions of 3D bioprinting in orthopedics, emphasizing its potential to redefine the standard of care and improve patient outcomes.
... The key to bioprinting lies in the selection of printing materials and the control of the printing process. The biomaterials need to have the ability to grow and differentiate cells to ensure that the printed tissues can work properly in the body [3]. The bioprinting process requires precise control of factors such as the plasticity of the material, the temperature, and the shape of the desired scaffold to ensure that the printed structure has the desired physiological and mechanical properties. ...
... Currently, there are many patients waiting for organ donation worldwide [5]. Bioprinting technology can make up for the shortage of organs by printing living tissues, providing an alternative choice for patients waiting for organ transplants [3]. However, bioprinting technology faces a number of challenges and constraints. ...
3D bioprinting technology plays an important role in all aspects of medicine, including bioengineering, tissue repair, scaffolds, and biomedical devices. However, 3D bioprinting technologies that currently exist still face significant challenges in terms of materials and the establishment of supply chains. Therefore, the need to consider the specific application requirements when selecting an appropriate bioprinting method is crucial. The purpose of this paper is to outline the advantages and disadvantages of 3D bioprinting various printing devices and explore the methods of 3D bioprinting in terms of material selection. We believe that 3D printing technology will be widely used in the future and become a dazzling presence in various fields.
... During inkjet printing, a bioink comprised of a hydrogel prepolymer solution with cells is stored in the ink cartridge, which serves as the controlled source for droplet generation. Droplets of adjustable sizes are created when the printer heads are deformed by a piezoelectric or thermal actuator [38]. Laser-assisted bioprinting consists of a donor slide made of transparent glass where the bioink is transferred to the receiver slide when the metal layer beneath the hydrogel is vaporized by a laser pulse [39]. ...
... Another positive aspect of 3D bioprinting is that it enables rapid production of scaffolds due to its automated nature. The ability to control the deposition of multiple bioinks containing different cell types is another advantage of 3D bioprinting that allows for control over the printing patterns of cells and materials [38]. ...
Osteoarthritis (OA) is a prevalent joint disorder that is characterized by the degeneration of articular cartilage in synovial joints. Most of the current treatment options for this disorder tend to focus on symptom management rather than addressing the underlying progression of the disease. Cartilage tissue engineering has emerged as a promising approach to address the limitations of current OA treatments, aiming to regenerate cartilage and restore the natural function of affected joints. Like any other tissue engineering field, cartilage tissue engineering uses different fabrication techniques and biomaterials to develop the constructs. Numerous studies over the last few years have demonstrated the preclinical efficacy of tissue‐engineered constructs in promoting cartilage regeneration and highlight the potential of tissue‐engineered constructs as a viable therapeutic approach for OA. This paper aims to provide a focused review of advancements in tissue‐engineered constructs over the past decade. Specifically, we highlight the constructs based on natural, synthetic, and composite biomaterials and the varying conventional and advanced fabrication techniques. We also highlight the challenges in state‐of‐the‐art cartilage tissue engineering that must be overcome in the upcoming years to fully replicate the complex anatomy of the native cartilage. We believe that continued collaborative research efforts among researchers from various facets of engineering and clinicians are required to advance the field of cartilage tissue engineering and become a viable OA therapy.
... 3D bioprinting is an advanced technology that mimics the complexity of natural tissue. Bioprinting can precisely and delicately control the deposition of cells and biomaterials to construct structures that closely resemble the microenvironment of natural tissue [74,75]. 3D bioprinting has the potential to support the regeneration of damaged tissue and halt the progression of disease by replicating the complex structure of the affected site of injury [76,77]. ...
Bone marrow mesenchymal stem cells (BMSCs) tissue engineering has been an emerging field of research in recent years. Given the increasing global interest, we utilized a bibliometric analysis and visualization of studies on BMSCs in the field of tissue engineering published from 2004 to 2023 to explore research progress and identify future research directions. Data was collected from the Web of Science Core Collection (WoSCC), and in-depth analysis was conducted using various bibliometric tools, including CiteSpace, VOSviewer, and R-Bibliometrix. Our study revealed the historical development and evolution of active topics in BMSCs in terms of temporal dynamics, covering 2967 publications, 65 countries, 2454 academic institutions, and 605 journals, with significant growth observed over the last 20 years. China and the United States dominate the global research landscape. Shanghai Jiao Tong University is one of the most significant contributors to the field. In terms of co-citation analysis, Biomaterials was identified as a key journal. Our analysis also revealed current trends such as extracellular vesicles, exosomes, 3D printing, hydrogels, and nanomaterials. These findings provide a clear perspective for future research on the tissue engineering of BMSCs. This study fills a gap in the field of bibliometrics, enabling researchers to identify popular research areas and providing a comprehensive perspective and broad outlook on this emerging field of research.
... Three-dimensional (3D) bioprinting technology provides significant advantages for biomedical engineering applications, particularly in the development of personalized tissue models, organ prototypes, and patient-specific implants [5]. Its ability to fabricate complex tissue structures with high precision allows for better replication of native tissues, which is crucial for applications such as tissue engineering and precision medicine [6]. ...
Three-dimensional bioprinting has emerged as a promising strategy in tissue engineering, aiming to fabricate functional tissue constructs for organ regeneration. A critical challenge in this field is the development of organ-specific bioinks that can provide a microenvironment conducive to cellular growth and differentiation. In this study, we successfully developed a photocrosslinkable bioink by methacrylating decellularized porcine kidney extracellular matrix. The decellularization process effectively removed all cellular components while preserving the native kidney extracellular matrix composition. The resulting methacrylated decellularized extracellular matrix bioink exhibited optimal rheological properties, making it well-suited for digital light processing based stereolithography and piston-driven extrusion bioprinting. Human embryonic kidney cells encapsulated in the bioink showed high viability and a strong proliferative capacity, indicating potential for tissue-specific maturation over time. This work demonstrates the feasibility of utilizing kidney-specific decellularized extracellular matrix-based bioinks, providing a platform for engineering renal tissue constructs for therapeutic applications.
... Interestingly, PVA can also undergo supramolecular interactions (Hbonding) with GelMA chains, which contributes to the higher structural stability of the P-Gel-5% inserts. Reports suggest that the interpenetrating network hydrogels align with the requirements of extrusion-based 3D printing [40][41][42]. However, vat polymerizationbased techniques offer higher geometrical complexity and higher shape fidelity [27]. ...
Purpose: To fabricate 3D-printed, biodegradable conjunctival gelatin methacrylate (GelMA) inserts that can release polyvinyl alcohol (PVA) when exposed to an ocular surface enzyme. Method: In this work, biodegradable conjunctival inserts were 3D-printed using a stereolithography-based technique. The release of PVA from these insert formulations (containing 10% GelMA and 5% PVA (P-Gel-5%)) was assessed along with different mathematical models of drug release. The biodegradation rates of these inserts were studied in the presence of a tear-film enzyme (matrix metalloproteinase-9; MMP9). The morphology of the inserts before and after enzymatic degradation was monitored using scanning electron microscopy. Results: The 3D-printed P-Gel-5% inserts formed a semi-interpenetrating network, which was mechanically stronger than GelMA inserts. The PVA release graphs demonstrate that at the end of 24 h, 222.7 ± 20.3 µg, 265.5 ± 27.1 µg, and 242.7 ± 30.4 µg of PVA were released when exposed to 25, 50, and 100 µg/mL of MMP9, respectively. The release profiles of the P-Gel-5% containing hydrogels in the presence of different concentrations of MMP9 showed the highest linearity with the Korsmeyer–Peppas model. The results suggest that the degradation rate over 24 h is a function of MMP9 enzyme concentration. Over 80% of P-Gel-5% inserts were degraded at the end of 8 h, 12 h, and 24 h in the presence of 100, 50, and 25 µg/mL MMP9 enzyme solutions, respectively. Conclusions: These results demonstrate the potential for 3D printing of GelMA for use as conjunctival inserts. These inserts could be used to deliver PVA, which is a well-known therapeutic agent for dry eye disease. PVA release is influenced by multiple mechanisms, including diffusion and enzymatic degradation, which is supported by morphological studies and biodegradation results.
... Using bioink with improper viscosity can cause nozzle blockage. Therefore, bioinks suitable for inkjet bioprinting should have a low cell density to maintain a suitable viscosity [107]. (4) Possible cell sedimentation. ...
The emergence of tissue engineering (TE) has provided new vital means for human body tissue/organ repair. TE scaffolds can provide temporary structural support for cell attachment, growth, and proliferation, until the body restores the mechanical and biological properties of the host tissues. Since native tissues are inhomogeneous and in many situations are graded structures for performing their unique functions, graded scaffolds have become increasingly attractive for regenerating particular types of tissues, which aim to offer a more accurate replication of native interactions and functions. Importantly, the advances introduced by additive manufacturing (AM) have now enabled more design freedom and are capable of tailoring both structural and compositional gradients within a single scaffold. In this context, graded TE scaffolds fabricated by AM technologies have been attracting increasing attention. In this review, we start with an introduction of common graded structures in the human body and analyse the advantages and strengths of AM-formed graded scaffolds. Various AM technologies that can be leveraged to produce graded scaffolds are then reviewed based on non-cellular 3D printing and cell-laden 3D bioprinting. The comparisons among various AM technologies for fabricating graded scaffolds are presented. Subsequently, we propose several types of gradients, structural, material, biomolecular and multi-gradients for scaffolds, and highlight the design methods, resulting mechanical properties and biological responses. Finally, current status, challenges and perspectives for AM in developing graded scaffolds are exhibited and discussed.
... The 3D-bioprinted structure can be used to simulate the TME. Different cell layers can be produced using bioprinting, including normal tissue-specific cells, connective tissue and cancer cells (108). This technology can accurately replicate the complex structure and microenvironment of cancer cells, creating organoid models that are more similar to the real-world situation of the tumor (109). ...
... Yuan et al. (2021) used photo-crosslinked methacrylated gelatin in combination with silica nanoparticles to achieve rapid diffusion of internal stem cells and improve the osteogenic efficiency of stem cells. With the rapid development of the additive manufacturing industry, the high resolution of bioprinting has led to it becoming the dominant manufacturing technology in the medical field (Mandrycky et al., 2016). This technique is extensively utilized in bone tissue engineering, regenerative medicine, and medical device applications (Wan et al., 2020). ...
Background
The application of bioprinted hydrogels in the field of bone regeneration is garnering increasing attention. The objective of this study is to provide a comprehensive overview of the current research status, hotspots and research directions in this field through bibliometric methods, and to predict the development trend of this field.
Methods
A search was conducted on 27 December 2024, for papers published on the Web of Science from 2010 to 2025. We used the bibliometrix package in the software program R to analyze the retrieved data and VOSviewer and CiteSpace to visualize hotspots and research trends in bioprinted hydrogels for bone regeneration.
Results
We identified and reviewed 684 articles published in this field between 2010 and 2025. A total of 811 institutions and 1,166 researchers from 41 countries/regions contributed to these publications. Among them, China led in terms of the number of articles published, single-country publications (SCP), and multi-country publications (MCP). Our bibliometric-based visualization analysis revealed that the mechanical properties and osteogenic differentiation capacity of biomaterials have been a focal research topic over the past decade, while emerging research has also concentrated on the in vitro fabrication of stem cells for bone regeneration and osteogenic differentiation, particularly the precise application of in situ stem cell-loaded bioprinted organoids.
Conclusion
This study provides an in-depth analysis of the research trajectory in the application of bioprinted hydrogels for bone regeneration. The number of research papers in this field is increasing annually, and the main research hotspots include bone regeneration, 3D printing, scaffolds, and hydrogels. Future research directions may focus on gelatin, additive manufacturing, and growth factors. Additionally, international collaboration is essential to enhance the effectiveness of bioprinted hydrogels in bone regeneration applications.
... 3D bioprinting is an additive manufacturing technology in which bioartificial organs are created by layer-by-layer deposition of bioink composed of cells and biomaterials guided by a computer-aided design (CAD) model . The various advantages of 3D bioprinting include control over cell distribution, high resolution of cell deposition, scalability, and cost-effectiveness (Mandrycky et al., 2016). In addition to cells, other tissue constituents like the extracellular matrix (ECM), growth factors, and other biomolecules can be included in the bioink and, ultimately, in the developed construct . ...
A drug to be successfully launched in the market requires a significant amount of capital, resources and time, where the unsuccessful results in the last stages lead to catastrophic failure for discovering drugs. This is the very reason which calls for the invention of innovative models that can closely mimic the human in vivo model for producing reliable results. Throughout the innovation line, there has been improvement in the rationale in silico designing but yet there is requirement for in vitro-in vivo correlations. During the evolving of the drug testing models, the 3D models produced by different methods have been proven to produce better results than the traditional 2D models. However, the in vitro fabrications of live tissues are still bottleneck in realizing their complete potential. There is an urgent need for the development of single, standard and simplified in vitro 3D tissue models that can be reliable for investigating the biological and pathological aspects of drug discovery, which is yet to be achieved. The existing pre-clinical models have considerable drawbacks despite being the gold standard in pre-clinical research. The major drawback being the interspecies differences and low reliability on the generated results. This gap could be overcome by the fabrication of bioengineered human disease models for drug screening. The advancement in the fabrication of 3D models will provide a valuable tool in screening drugs at different stages as they are one step closer to bio-mimic human tissues. In this review, we have discussed on the evolution of preclinical studies, and different models, including mini tissues, spheroids, organoids, bioengineered three dimensional models and organs on chips. Furthermore, we provide details of different disease models fabricated across various organs and their applications. In addition to this, the review also focuses on the limitations and the current prospects of the role of three dimensionally bioprinted models in drug screening and development.
... This technique categories include laser direct writing (LDW), laser-induced forward transfer (LIFT), and matrix-assisted pulsed laser evaporation (MAPLE). Its advantages contain nozzle absence of this bioprinter, preventing direct contact from the bioink and thereafter minimizing mechanical stress [26]; it also achieves an extremely high survival rate (about >95%) of cells and minimal impact on cell proliferation and apoptosis [19,[27][28][29]. The disadvantages are the complexity of printing system, high cost of the equipment, and limited alternatives of printable materials [19], indicating why it is less frequently applied in 3D bioprinting. ...
Three-dimensional (3D) bioprinting, an additive manufacturing technology, fabricates biomimetic tissues that possess natural structure and function. It involves precise deposition of bioinks, including cells, and bioactive factors, on basis of computer-aided 3D models. Articular cartilage injuries, a common orthopedic issue. Current repair methods, for instance microfracture procedure (MF), autologous chondrocyte implantation (ACI), and osteochondral autologous transfer surgery have been applied in clinical practice. However, each procedure has inherent limitation. For instance, MF surgery associates with increased subchondral cyst formation and brittle subchondral bone. ACI procedure involves two surgeries, and associate with potential risks infection and delamination of the regenerated cartilage. In addition, chondrocyte implantation’s efficacy depends on the patient’s weight, joint pathology, gender-related histological changes of cartilage, and hormonal influences that affect treatment and prognosis. So far, it is a still a grand challenge for achieving a clinical satisfactory in repairing and regeneration of cartilage defects using conditional strategies. 3D biofabrication provide a potential to fabricate biomimetic articular cartilage construct that has shown promise in specific cartilage repair and regeneration of patients. This review reported the techniques of 3D bioprinting applied for cartilage repair, and analyzed their respective merits and demerits, and limitations in clinical application. A summary of commonly used bioinks has been provided, along with an outlook on the challenges and prospects faced by 3D bioprinting in the application of cartilage tissue repair. It provided an overall review of current development and promising application of 3D biofabrication technology in articular cartilage repair.
... The laser-assisted bioprinting method employs five crucial components: a pulsed laser beam, a focusing system, a donor layer with an energy-absorbing layer, a liquid bioink solution, and a substrate for patterning and crosslinking bioink [64]. This method ensures high cell viability by eliminating direct contact between the bioink and the dispenser [65]. Additionally, laser-assisted bioprinting is compatible with various bioink compositions and inherent viscosities [59]. ...
Regeneration of the multiple tissues and interfaces in the periodontal complex necessitates multidisciplinary evaluation to establish structure/function relationships. This article, an initiative of the Academy of Dental Materials, provides guidance for performing chemical, structural, and mechanical characterization of materials for periodontal tissue regeneration, and outlines important recommendations on methods of testing bioactivity, biocompatibility, and antimicrobial properties of biomaterials/scaffolds for periodontal tissue engineering. First, we briefly summarize periodontal tissue engineering fabrication methods. We then highlight critical variables to consider when evaluating a material for periodontal tissue regeneration, and the fundamental tests used to investigate them. The recommended tests and designs incorporate relevant international standards and provide a framework for characterizing newly developed materials focusing on the applicability of those tests for peri- odontal tissue regeneration. The most common methods of biofabrication (electrospinning, injectable hydrogels, fused deposition modelling, melt electrowriting, and bioprinting) and their specific applications in periodontal tissue engineering are reviewed. The critical techniques for morphological, chemical, and mechanical charac- terization of different classes of materials used in periodontal regeneration are then described. The major ad- vantages and drawbacks of each assay, sample sizes, and guidelines on specimen preparation are also highlighted. From a biological standpoint, fundamental methods for testing bioactivity, the biocompatibility of materials, and the experimental models for testing the antimicrobial potential are included in this guidance. In conclusion, researchers performing studies on periodontal tissue regeneration will have this guidance as a tool to assess essential properties and characteristics of their materials/scaffold-based strategies.
... CC BY 4.0. Reprinted from [79], © 2015 Elsevier Inc. All rights reserved. ...
Brain, the material foundation of human intelligence, is the most complex tissue in the human body. Brain diseases are among the leading threats to human life, yet our understanding of their pathogenic mechanisms and drug development remains limited, largely due to the lack of accurate brain-like tissue models that replicate its complex structure and functions. Therefore, constructing brain-like models—both in morphology and function—possesses significant scientific value for advancing brain science and pathological pharmacology research, representing the frontiers in the biomanufacturing field. This review outlines the primary requirements and challenges in biomanufacturing brain-like tissue, addressing its complex structures, functions, and environments. Also, the existing biomanufacturing technologies, strategies, and characteristics for brain-like models are depicted, and cutting-edge developments in biomanufacturing central neural repair prosthetics, brain development models, brain disease models, and brain-inspired biocomputing models are systematically reviewed. Finally, the paper concludes with future perspectives on the biomanufacturing of brain-like tissue transitioning from structural manufacturing to intelligent functioning.
... Accurate assessment of wound area is crucial for clinical treatment, particularly in burn cases where incorrect area evaluation can lead to improper fluid resuscitation, increasing the risks of fluid overload, shock, renal failure, and compartment syndrome [38]. High-quality imaging is the basis of wound measurement [31]. ...
Skin injuries caused by physical, pathological, and chemical factors not only compromise appearance and barrier function but can also lead to life-threatening microbial infections, posing significant challenges for patients and healthcare systems. Artificial intelligence (AI) technology has demonstrated substantial advantages in processing and analyzing image information. Recently, AI-based methods and algorithms, including machine learning, deep learning, and neural networks, have been extensively explored in wound care and research, providing effective clinical decision support for wound diagnosis, treatment, prognosis, and rehabilitation. However, challenges remain in achieving a closed-loop care system for the comprehensive application of AI in wound management, encompassing wound diagnosis, monitoring, and treatment. This review comprehensively summarizes recent advancements in AI applications in wound repair. Specifically, it discusses AI's role in injury type classification, wound measurement (including area and depth), wound tissue type classification, wound monitoring and prediction, and personalized treatment. Additionally, the review addresses the challenges and limitations AI faces in wound management. Finally, recommendations for the application of AI in wound repair are proposed, along with an outlook on future research directions, aiming to provide scientific evidence and technological support for further advancements in AI-driven wound repair theranostics.
... Photo-initiators are generally toxic, which may lead to unintended cellular harm [127]. • The impact of continuous and prolonged laser exposure on cells has not been fully determined [129]. ...
Cardiovascular disease is one of the leading causes of death and serious illness in Europe and worldwide. Conventional treatment—replacing the damaged blood vessel with an autologous graft—is not always affordable for the patient, so alternative approaches are being sought. One such approach is patient-specific tissue bioprinting, which allows for precise distribution of cells, material, and biochemical signals. With further developmental support, a functional replacement tissue or vessel can be created. This review provides an overview of the current state of bioprinting for vascular graft manufacturing and summarizes the hydrogels used as bioinks, the material of carriers, and the current methods of fabrication used, especially for vessels smaller than 6 mm, which are the most challenging for cardiovascular replacements. The fabrication methods are divided into several sections—self-supporting grafts based on simple 3D bioprinting and bioprinting of bioinks on scaffolds made of decellularized or nanofibrous material.
... Преимуществами являются высокие скорость обработки и разрешение, низкая стоимость, простота эксплуатации и возможность коррекции параметров печати. Однако такой метод требует относительно низкой вязкости биоматериала (3,5-12 мПа/с), ограничен концентрацией клеточного компонента (<5 ×10 6 клеток/мл), а также лишен возможности создания целостных структур ввиду низкой вязкости биоматериала [33]. ...
An urgent problem of modern implantology remains the development of means and methods for restoring the integrity of bone tissue when defects occur. An important aspect of the problem remains the validity of the choice of osteoplastic material. Despite the fairly successful use of various types of osteoplastic materials in clinical implantology for the closure of small bone defects, the treatment of large diastases remains a subject of debate and requires further search and testing of various osteoplastic materials. Aim of the study: to analyze specialized scientific literature and describe the characteristics of the most common osteoplastic materials for replacing bone tissue defects. Methodology. This literature review was based on 63 sources from the following databases: PubMed, PubMed Central, Scopus, Medscape, Elibrary, ResearchGate, Google Scholar. Results. A description of osteoinductive materials used to replace bone defects in modern clinical practice is presented: ceramics, biocomposites based on them, corals, synthetic bones, mesenchymal stem cell cultures, 3D printing, etc. Emphasis is placed on the advantages and disadvantages of these methods. Conclusions. Based on the analysis of the literature, we can conclude that the problem of developing and introducing osteoplastic materials into clinical practice is a complex and multi-level area of joint activity of specialists in various fields. The most promising areas for further research are modifications of ceramic-based osteoplastic structures to increase their density, as well as additional cultivation of mesenchymal cells and 3D printing. However, these methods for replacing extensive bone tissue defects also need to be improved and new research conducted.
... This review aims to explore the current state of 3D printing technologies in wound care, highlight recent advances in 3D-printed scaffolds and skin substitutes, and discuss the future potential of this revolutionary technology. By examining the integration of 3D printing in wound healing, this paper seeks to provide insights into how personalized medicine and regenerative therapies can reshape wound care practices [10,11]. ...
The field of wound healing faces significant challenges, particularly in the treatment of chronic wounds, which often result in prolonged healing times and complications. Recent advancements in 3D printing technology have provided innovative solutions to these challenges, offering tailored and precise approaches to wound care. This review highlights the role of 3D printing in enhancing wound healing, focusing on its application in creating biocompatible scaffolds, custom wound dressings, and drug delivery systems. By mimicking the extracellular matrix (ECM) and facilitating cell proliferation, 3D-printed biomaterials have the potential to significantly accelerate the healing process. In addition, 3D bioprinting enables the production of functional skin substitutes that can be customized for individual patients. Despite the promise of these technologies, several challenges remain, including the need for improved vascularization, cost concerns, and regulatory hurdles. The future of wound healing lies in the continued integration of 3D printing with emerging technologies such as 4D printing and bioelectronics, providing opportunities for personalized and on-demand therapies. This review explores the current state of 3D printing in wound care, its challenges, and the future potential of these innovative technologies.
... Looking toward the future, one technology that will revolutionize the world of 3D printing will be bioprinting, that is, the ability to print and recreate damaged tissues or even organs using 3D printers. This, in our opinion, must be the new research front to which we pay more attention and interest, driven especially by the need to replace organs and regenerate tissues [50,51]. ...
Citation: Michelutti, L.; Tel, A.; Robiony, M.; Sembronio, S.; Nocini, R.; Agosti, E.; Ius, T.; Gagliano, C.; Zeppieri, M. Progress in 3D Printing Applications for the Management of Orbital Disorders: A Systematic Review. Abstract: Introduction: 3D printing technology has gained considerable interest in the domain of orbital illnesses owing to its capacity to transform diagnosis, surgery planning, and treatment. This systematic review seeks to deliver a thorough examination of the contemporary applications of 3D printing in the treatment of ocular problems, encompassing tumors, injuries, and congenital defects. This systematic review of recent studies has examined the application of patient-specific 3D-printed models for preoperative planning, personalized implants, and prosthetics. Methods: This systematic review was conducted according to the PRISMA guidelines. The PICOS is "What are the current advances and applications of 3D printing for the management of orbital pathology?" The databases analyzed for the research phase are MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, ScienceDirect, Scopus, CINAHL, and Web of Science. Results: Out of 314 studies found in the literature, only 12 met the inclusion and exclusion criteria. From the included studies, it is evident that 3D printing can be a useful technology for the management of trauma and oncological pathologies of the orbital region. Discussion: 3D printing proves to be very useful mainly for the purpose of improving the preoperative planning of a surgical procedure, allowing for better preparation by the surgical team and a reduction in operative time and complications. Conclusions: 3D printing has proven to be an outstanding tool in the management of orbit pathology. Comparing the advantages and disadvantages of such technology, the former far outweigh the latter.
It has been more than two decades since laser‐induced forward transfer (LIFT) was studied on a laboratory scale for its ability to print biomaterials. Most of the published works in this field are focused on the use of nanosecond lasers. Our final objective is to use the LIFT technique in a picosecond regime to create in vitro biomodels for tissue engineering and regenerative medicine applications. But in a first approach, the work presented here focuses on hydrodynamics and rheological studies for the optimization of the process for bioapplications. In order to precisely control the amount and position of the deposited material, it is necessary to carefully investigate the jetting dynamics as a function of various parameters, including the laser fluence and the rheological properties of the bioink. In this study, time‐resolved fast imaging is used to investigate the hydrodynamics of the transfer of successive jets at a high pulse repetition rate. Different conditions have been determined (bioink viscosity, specific jetting dynamic associated with a precise distance for printing, and laser parameters) for precise control of the quantity of ink and number of cells deposited per droplet associated with high accuracy on their location and good reproducibility of the printing process.
Natural biomolecules with excellent biocompatibility, degradability, and the ability to guide effective tissue regeneration are considered ideal materials for constructing tissue engineering hydrogel scaffolds. The employing of 3D printing technology facilitates the preparation of natural biomolecular‐based scaffold for specific morphological requirements for tissue engineering. However, there are significant limitations in the precise manufacturing of such scaffolds using extrusion‐based 3D printing technology. In this review, we put forward the challenges encountered in the 3D printing process using natural biomolecular inks. Building upon this, we summarize and discuss strategies commonly employed to enhance the printing performance of natural biomolecular inks, including inducing rapid ink cross‐linking, improving ink rheological properties, incorporating auxiliary inks for shaping, flexibly controlling ink extrusion, and optimizing printing equipment. Furthermore, this review offers a perspective on the future design and development of printing technologies based on natural biomolecular inks.
The paper is related to engineering hydroponic farming systems using household waste material for cultivating home-based plants. It is based on a project model made for a science exhibition. Various waste materials, such as plastic bottles, plastic glasses, coconut fibers, etc., are reutilized to fabricate the project. Finally, it is concluded that we can utilize household waste material to effectively develop such a hydroponic system for cultivating home-based plants such as spinach, coriander, chili, etc. This project supports soil-free farming techniques for better human health
The application of three-dimensional (3D) printing/bioprinting technologies and cell therapies has garnered significant attention due to their potential in the field of regenerative medicine. This paper aims to provide a comprehensive overview of 3D printing/bioprinting technology and cell therapies, highlighting their results in diverse medical applications, while also discussing the capabilities and limitations of their combined use. The synergistic combination of 3D printing and cellular therapies has been recognised as a promising and innovative approach, and it is expected that these technologies will progressively assume a crucial role in the treatment of various diseases and conditions in the foreseeable future. This review concludes with a forward-looking perspective on the future impact of these technologies, highlighting their potential to revolutionize regenerative medicine through enhanced tissue repair and organ replacement strategies.
Wound care challenges healthcare systems worldwide as traditional dressings often fall short in addressing the diverse and complex nature of wound healing. Given conventional treatments limitations, innovative alternatives are urgent. Additive manufacturing (AM) has emerged as a distinct and transformative approach for developing advanced wound dressings, offering unprecedented functionality and customization. Besides exploring the AM processes state‐of‐the‐art, this review comprehensively examines the application of AM to produce cellular‐compatible and bioactive, therapeutic agent delivery, patient‐centric, and responsive dressings. This review distinguishes itself from the published literature by covering a variety of wound types and by summarizing important data, including used materials, process/technology, printing parameters, and findings from in vitro, ex vivo, and in vivo studies. The prospects of AM in enhancing wound healing outcomes are also analyzed in a translational and cost‐effective manner.
Acne vulgaris is a widespread chronic inflammatory skin illness that is primarily caused by inflammation, irregular skin cell turnover inside hair follicles, increased sebum production, and Propionibacterium acnes bacterial overgrowth. This comprehensive overview examines the intricate causes of acne vulgaris. The paper highlights the significant role of genetic predisposition, hormonal fluctuations, and environmental factors in acne development. Various in vivo and in vitro models, including mouse ear edema, rat models, and advanced techniques like 3D bioprinting and organ-on-a-chip systems, are discussed for their utility in studying acne pathogenesis and testing therapeutic interventions. The review underscores the importance of integrating diverse models to enhance understanding of acne mechanisms and improve treatment strategies, while also acknowledging the limitations of current models in replicating the complexity of human skin. Future research should focus on refining these models to better capture the multifactorial nature of acne and facilitate the development of effective, targeted therapies.
The technique of 3D printing is emerging. To fulfill the demands of various patients, it can swiftly and precisely produce scaffolds for bone tissue engineering using customized forms and designs. It also builds rigid structures by stacking substances layer by layer. The utilization of 3D printing for developing prosthetics, tailored implants, drug delivery systems, and 3D scaffolds for tissue engineering and regenerative therapies has advanced rapidly.
In the treatment of bones, teeth, and organs, tissue engineering has emerged as an attractive replacement technique. Eventually, 3D printed tissue parts may help the pharmaceutical industry simplify their research and development processes by overcoming a number of obstacles. Over time, it may also help bring down costs and improve accessibility to and effectiveness of drugs. This article provides a review of the state of the art in terms of 3D biomaterial scaffold research and its utilization in bone tissue engineering. Additionally, challenges in the field of bioprinting for the search for bioinks, difficulties in bioprinting while utilizing different techniques, production of patient-specific bone tissue scaffolds, etc. are discussed. Further growth developments related to the area have been projected for the future.
Three-dimensional bioprinting is getting enormous attention among the scientific community for its application in complex regenerative tissue engineering applications. One of the focus areas of 3-D bioprinting is Skin tissue engineering. Skin is the largest external organ and also the outer protective layer is prone to injuries due to accidents, burns, pathologic diseases like diabetes, and immobilization of patients due to other health conditions, etc. The demand for skin tissue and the need for an off-the-shelf skin construct to treat patients is increasing on an alarming basis. Conventional approaches like skin grafting increase morbidity. Other approaches include acellular grafts, where integration with the host tissue is a major concern. The emerging technology of the future is 3D bioprinting, where different biopolymers or hybrid polymers together provide the properties of extracellular matrix (ECM) and tissue microenvironment needed for cellular growth and proliferation. This raises the hope for the possibility of a shelf skin construct, which can be used on demand or even skin can be printed directly on the wound site (in-situ printing) based on the depth and complex structure of the wound site. In the present review article, we have tried to provide an overview of Skin tissue engineering, Conventional advancement in technology, 3D bioprinting and bioprinters for skin 3D printing, different biomaterials for skin 3D bioprinting applications, desirable properties of biomaterials and future challenges.
The creation of self-organizing liver organoids represents a significant, although modest, step toward addressing the ongoing organ shortage crisis in allogeneic liver transplantation. However, researchers have recognized that achieving a fully functional whole liver remains a distant goal, and the original ambition of organoid-based liver generation has been temporarily put on hold. Instead, liver organoids have revolutionized the field of hepatology, extending their influence into various domains of precision and molecular medicine. These 3D cultures, capable of replicating key features of human liver function and pathology, have opened new avenues for human-relevant disease modeling, CRISPR gene editing, and high-throughput drug screening that animal models cannot accomplish. Moreover, advancements in creating more complex systems have led to the development of multicellular assembloids, dynamic organoid-on-chip systems, and 3D bioprinting technologies. These innovations enable detailed modeling of liver microenvironments and complex tissue interactions. Progress in regenerative medicine and transplantation applications continues to evolve and strives to overcome the obstacles of biocompatibility and tumorigenecity. In this review, we examine the current state of liver organoid research by offering insights into where the field currently stands, and the pivotal developments that are driving its shaping its future.
Background:
Oral squamous cell carcinoma (OSCC) presents significant challenges due to its complex microenvironment and invasive characteristics. Traditional two-dimensional (2D) culture systems are inadequate for modelling the intricate features of OSCC, necessitating advanced techniques for better in vitro modelling.
Objective:
This review aims to explore the applications of 3D bioprinting in modelling the OSCC microenvironment, highlighting the advantages over conventional methods and discussing recent advancements in the field.
Methods:
The review synthesizes recent literature on 3D bioprinting technologies, focusing on their application in replicating OSCC's microenvironment. Key areas include the integration of various cell types within a biomimetic extracellular matrix, the use of microfluidic systems to study tumor-stromal interactions, and the incorporation of advanced imaging modalities.
Results:
3D bioprinting allows for the precise fabrication of complex OSCC tumor architectures, incorporating cancer cells, stromal cells, and immune cells. The integration of microfluidic systems facilitates the study of tumor invasion, metastasis, and drug response. Recent advancements in bioink development, particularly the use of patient-derived cells and biomolecules, enhance the physiological relevance of these models. Emerging imaging technologies provide unprecedented insights into the dynamics of OSCC progression within these constructs.
Conclusion:
3D bioprinting shows immense potential for advancing the understanding of OSCC pathobiology and developing personalized therapeutic strategies. However, challenges such as standardizing bioink formulations and scaling fabrication techniques must be addressed to effectively translate these innovations into clinical practice.
Nanocellulose is a versatile material which is now finding applications in biomaterials science, and as a sustainable resource it is particularly attractive to the industrial and research communities.
Drawing on a global authorship, this book explains how the antimicrobial and immunological properties of nanocellulose make it an ideal material for applications in tissue engineering, whether in hydrogels, scaffolds, or polymer composites. Readers will discover how to extract and characterise nanocellulose and fabricate it in a wide variety of tissue engineering scenarios. Opportunities for 3D printing are considered among a wealth of approaches. With regulatory frameworks in mind, toxicological evaluations and life-cycle assessment of materials are discussed, ensuring that this is a comprehensive source of information for anyone seeking a more sustainable approach to tissue engineering and biomaterials.
In recent decades, 3D bioprinting has garnered significant research attention due to its ability to manipulate biomaterials and cells to create complex structures precisely. However, due to technological and cost constraints, the clinical translation of 3D bioprinted products (BPPs) from bench to bedside has been hindered by challenges in terms of personalization of design and scaling up of production. Recently, the emerging applications of artificial intelligence (AI) technologies have significantly improved the performance of 3D bioprinting. However, the existing literature remains deficient in a methodological exploration of AI technologies' potential to overcome these challenges in advancing 3D bioprinting toward clinical application. This paper aims to present a systematic methodology for AI-driven 3D bioprinting, structured within the theoretical framework of Quality by Design (QbD). This paper commences by introducing the QbD theory into 3D bioprinting, followed by summarizing the technology roadmap of AI integration in 3D bioprinting, including multi-scale and multi-modal sensing, data-driven design, and in-line process control. This paper further describes specific AI applications in 3D bioprinting's key elements, including bioink formulation, model structure, printing process, and function regulation. Finally, the paper discusses current prospects and challenges associated with AI technologies to further advance the clinical translation of 3D bioprinting.
Organoids, with their capacity to mimic the structures and functions of human organs, have gained significant attention for simulating human pathophysiology and have been extensively investigated in the recent past. Additionally, 3D bioprinting, as an emerging bio‐additive manufacturing technology, offers the potential for constructing heterogeneous cellular microenvironments, thereby promoting advancements in organoid research. In this review, the latest developments in 3D bioprinting technologies aimed at enhancing organoid engineering are introduced. The commonly used bioprinting methods and materials for organoids, with a particular emphasis on the potential advantages of combining 3D bioprinting with organoids are summarized. These advantages include achieving high cell concentrations to form large cellular aggregates, precise deposition of building blocks to create organoids with complex structures and functions, and automation and high throughput to ensure reproducibility and standardization in organoid culture. Furthermore, this review provides an overview of relevant studies from recent years and discusses the current limitations and prospects for future development.
Bio-printing is a trending technology in the field of tissue
engineering and regenerative medicine is created the complex
three dimensional structure. The advancement in bio printing,
steps and materials used in bio printer has been highlighted. The
various Bio printing technique such as Micro extrusion, inkjet
printing and laser based approaches. The roles of biomaterials
and it's important in bioprinting. The biomaterials characters
such as cell viability, adhesion, differentiation, biodegradable
and biocompatibility. It creates the evolution in the medical field.
Bioprinting is a rapidly developing technique for biofabrication. Because of its high resolution and the ability to print living cells, bioprinting has been widely used in artificial tissue and organ generation as well as microscale living cell deposition. In this paper, we present a low-cost stereolithography-based bioprinting system that uses visible light crosslinkable bioinks. This low-cost stereolithography system was built around a commercial projector with a simple water filter to prevent harmful infrared radiation from the projector. The visible light crosslinking was achieved by using a mixture of polyethylene glycol diacrylate (PEGDA) and gelatin methacrylate (GelMA) hydrogel with eosin Y based photoinitiator. Three different concentrations of hydrogel mixtures (10% PEG, 5% PEG + 5% GelMA, and 2.5% PEG + 7.5% GelMA, all w/v) were studied with the presented systems. The mechanical properties and microstructure of the developed bioink were measured and discussed in detail. Several cell-free hydrogel patterns were generated to demonstrate the resolution of the solution. Experimental results with NIH 3T3 fibroblast cells show that this system can produce a highly vertical 3D structure with 50 μm resolution and 85% cell viability for at least five days. The developed system provides a low-cost visible light stereolithography solution and has the potential to be widely used in tissue engineering and bioengineering for microscale cell patterning.
We demonstrate the additive manufacturing of complex three-dimensional (3D) biological structures using soft protein and polysaccharide hydrogels that are challenging or impossible to create using traditional fabrication approaches. These structures are built by embedding the printed hydrogel within a secondary hydrogel that serves as a temporary, thermoreversible, and biocompatible support. This process, termed freeform reversible embedding of suspended hydrogels, enables 3D printing of hydrated materials with an elastic modulus <500 kPa including alginate, collagen, and fibrin. Computer-aided design models of 3D optical, computed tomography, and magnetic resonance imaging data were 3D printed at a resolution of ~200 μm and at low cost by leveraging open-source hardware and software tools. Proof-of-concept structures based on femurs, branched coronary arteries, trabeculated embryonic hearts, and human brains were mechanically robust and recreated complex 3D internal and external anatomical architectures.
Developments in micro- and nanofluidic technologies have led to new kinds of cell culture and screening systems that are collectively termed organ-on-a-chip systems. Organ-on-a-chip systems are in vitro microfabricated devices that mimic dynamic interactions of in vivo microenvironments. In addition to existing two-dimensional and three-dimensional tissues, organ-on-a-chip systems can mimic the biomechanical and biochemical microenvironments of in vivo tissues as well as the interactional effects of the microenvironments on cell and tissue functions. Owing to those features, organ-ona-chip systems have become excellent platforms for drug screening and delivery tests. In this review, specific examples of organ-on-a-chip devices and their applications in tissue engineering and drug delivery tests are presented. The utility and performance of stateof-the-art organ-on-a-chip systems, including lung-on-a-chip, heart-on-a-chip, vessel-ona-chip, liver-on-a-chip, and tumor-on-a-chip, are also covered in this review. Limitations of conventional systems, basic fabrication processes for organ-on-a-chip devices, and future prospects of organ-on-a-chip systems are discussed.
Management of large structural defects of the ankle and hindfoot is challenging with modest outcomes in the literature. Tibiotalocalcaneal (TTC) arthrodesis using a retrograde intramedullary nail has been used for the treatment of talar avascular necrosis, severe tibial plafond fractures, ankle and hindfoot nonunions, Charcot arthropathy, and failed total ankle arthroplasty. External fixators and spatial frames provide robust multiplanar correction of deformity, but little is known in the literature regarding the salvage treatment of persistent nonunion refractory to frame treatment. In this report, we present the case of an open tibial plafond fracture with nonunion despite 1 year of fixator and frame management that was successfully treated using a patient-specific 3-dimensional printed titanium truss cage in combination with a retrograde TTC nail. At most recent 1-year follow-up, the patient had minimal pain, no wound complications, and was able to ambulate and work independently without an assistive device for the first time in 2 years since his original injury. The case presented here serves as a proof of principle that requires future research to determine its long-term clinical benefits, cost-effectiveness, and complications.
Level V: Expert Opinion.
© 2015 The Author(s).
The purpose of this paper is to demonstrate that an inexpensive 3D printer can be used to manufacture patient‐specific bolus for external beam therapy, and to show we can accurately model this printed bolus in our treatment planning system for accurate treatment delivery. Percent depth‐dose measurements and tissue maximum ratios were used to determine the characteristics of the printing materials, acrylonitrile butadiene styrene and polylactic acid, as bolus material with physical density of 1.04 and 1.2 g/cm3, and electron density of 3.38×1023electrons/cm3 and 3.80×1023 electrons/cm3, respectively. Dose plane comparisons using Gafchromic EBT2 film and the RANDO phantom were used to verify accurate treatment planning. We accurately modeled a printing material in Eclipse treatment planning system, assigning it a Hounsfield unit of 260. We were also able to verify accurate treatment planning using gamma analysis for dose plane comparisons. With gamma criteria of 5% dose difference and 2 mm DTA, we were able to have 86.5% points passing, and with gamma criteria of 5% dose difference and 3 mm DTA, we were able to have 95% points passing. We were able to create a patient‐specific bolus using an inexpensive 3D printer and model it in our treatment planning system for accurate treatment delivery.
PACS numbers: 87.53.Jw, 87.53.Kn, 87.56.ng
Additive manufacturing or 3D printing is the process by which three dimensional data fields are translated into real-life physical representations. 3D printers create physical printouts using heated plastics in a layered fashion resulting in a three-dimensional object. We present a technique for creating customised, inexpensive 3D orbit models for use in orbital surgical training using 3D printing technology. These models allow trainee surgeons to perform ‘wet-lab’ orbital decompressions and simulate upcoming surgeries on orbital models that replicate a patient's bony anatomy. We believe this represents an innovative training tool for the next generation of orbital surgeons.
Three-dimensional integrated organ printing (IOP) technology seeks to fabricate tissue constructs that can mimic the structural and functional properties of native tissues. This technology is particularly useful for complex tissues such as those in the musculoskeletal system, which possess regional differences in cell types and mechanical properties. Here, we present the use of our IOP system for the processing and deposition of four different components for the fabrication of a single integrated muscle-tendon unit (MTU) construct. Thermoplastic polyurethane (PU) was co-printed with C2C12 cell-laden hydrogel-based bioink for elasticity and muscle development on one side, while poly(ϵ-caprolactone) (PCL) was co-printed with NIH/3T3 cell-laden hydrogel-based bioink for stiffness and tendon development on the other. The final construct was elastic on the PU-C2C12 muscle side (E = 0.39 ± 0.05 MPa), stiff on the PCL-NIH/3T3 tendon side (E = 46.67 ± 2.67 MPa) and intermediate in the interface region (E = 1.03 ± 0.14 MPa). These constructs exhibited >80% cell viability at 1 and 7 d after printing, as well as initial tissue development and differentiation. This study demonstrates the versatility of the IOP system to create integrated tissue constructs with region-specific biological and mechanical characteristics for MTU engineering.
The exceptional properties of graphene enable applications in electronics, optoelectronics, energy storage, and structural composites. Here we demonstrate a 3D printable graphene (3DG) composite consisting of majority graphene and minority polylactide-co-glycolide, a biocompatible elastomer, 3D printed from a liquid ink. This ink can be utilized under ambient conditions via extrusion-based 3D printing to create graphene structures with features as small as 100 µm comprised of as few as two layers (<300 µm thick object) or many hundreds of layers (>10 cm thick object). The resulting 3DG material is mechanically robust and flexible while retaining electrical conductivities greater than 800 S/m, an order of magnitude increase over previously reported 3D printed carbon materials. In vitro experiments in simple growth medium, in the absence of neurogenic stimuli, reveal that 3DG supports human mesenchymal stem cell (hMSC) adhesion, viability, proliferation, and neurogenic differentiation with significant upregulation of glial and neuronal genes. This coincides with hMSCs adopting highly elongated morphologies with features similar to axons and presynaptic terminals. In vivo experiments indicate that 3DG has promising biocompatibility over the course of at least 30 days. Surgical tests using a human cadaver nerve model also illustrate that 3DG has exceptional handling characteristics and can be intraoperatively manipulated and applied to fine surgical procedures. With this unique set of properties, combined with ease of fabrication, 3DG could be applied towards the design and fabrication of a wide range of functional electronic, biological, and bioelectronic medical and non-medical devices.
The peripheral nervous system has a limited innate capacity for self-repair following injury, and surgical intervention is often required. For injuries greater than a few millimeters autografting is standard practice although it is associated with donor site morbidity and is limited in its availability. Because of this, nerve guidance conduits (NGCs) can be viewed as an advantageous alternative, but currently have limited efficacy for short and large injury gaps in comparison to autograft. Current commercially available NGC designs rely on existing regulatory approved materials and traditional production methods, limiting improvement of their design. The aim of this study was to establish a novel method for NGC manufacture using a custom built laser-based microstereolithography (μSL) setup that incorporated a 405 nm laser source to produce 3D constructs with ∼50 μm resolution from a photocurable poly(ethylene glycol) resin. These were evaluated by SEM, in vitro neuronal, Schwann and dorsal root ganglion culture and in vivo using a thy-1-YFP-H mouse common fibular nerve injury model. NGCs with dimensions of 1 mm internal diameter × 5 mm length with a wall thickness of 250 μm were fabricated and capable of supporting re-innervation across a 3 mm injury gap after 21 days, with results close to that of an autograft control. The study provides a technology platform for the rapid microfabrication of biocompatible materials, a novel method for in vivo evaluation, and a benchmark for future development in more advanced NGC designs, biodegradable and larger device sizes, and longer-term implantation studies.
Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
This study evaluated the structural, mechanical, and cytocompatibility changes of three dimensional (3D) printed porous polymer scaffolds during degradation. Three porous scaffold designs were fabricated from a poly(propylene fumarate) (PPF) resin. PPF is a hydrolytically degradable polymer that has been well characterized for applications in bone tissue engineering. Over a 224 day period, scaffolds were hydrolytically degraded and changes in scaffold parameters, such as porosity and pore size, were measured nondestructively using micro-computed tomography. In addition, changes in scaffold mechanical properties were also measured during degradation. Scaffold degradation was verified through decreasing pH and increasing mass loss as well as the formation of micropores and surface channels. Current methods to evaluate polymer cytotoxicity have been well established, however, the ability to evaluate toxicity of an absorbable polymer as it degrades has not been well explored. This study therefore also proposes a novel method to evaluate the cytotoxicity of the absorbable scaffolds using a combination of degradation extract, phosphate buffered saline, and cell culture media. Fibroblasts were incubated with this combination media and cytotoxicity was evaluated using XTT assay and fluorescence imaging. Cell culture testing demonstrated that the 3D printed scaffold extracts did not induce significant cell death. Additionally, results showed that over a 224 day time period, porous PPF scaffolds provided mechanical stability while degrading. Overall, these results show that degradable, 3D printed PPF scaffolds are suitable for bone tissue engineering through the use of a novel toxicity during degradation assay.
Most current drug screening assays used to identify new drug candidates are 2D cell-based systems, even though such in vitro assays do not adequately re-create the in vivo complexity of 3D tissues. Inadequate representation of the human tissue environment during a preclinical test can result in inaccurate predictions of compound effects on overall tissue functionality. Screening for compound efficacy by focusing on a single pathway or protein target, coupled with difficulties in maintaining long-term 2D monolayers, can serve to exacerbate these issues when using such simplistic model systems for physiological drug screening applications. Numerous studies have shown that cell responses to drugs in 3D culture are improved from those in 2D, with respect to modeling in vivo tissue functionality, which highlights the advantages of using 3D-based models for preclinical drug screens. In this review, we discuss the development of microengineered 3D tissue models that accurately mimic the physiological properties of native tissue samples and highlight the advantages of using such 3D microtissue models over conventional cell-based assays for future drug screening applications. We also discuss biomimetic 3D environments, based on engineered tissues as potential preclinical models for the development of more predictive drug screening assays for specific disease models.
Adaptations of mass-market consumer electronics are increasingly used to aid experimentation in engineering, life sciences, and education. Inspired by recent bioprinting and imaging research, we have developed a low-cost, networkable, scalable bioprinter with integrated imaging that enables automated fluid deposition with monitoring biological materials over a large area that can interface with standard plasticware. We re-engineered a desktop printer and scanner with mechanical workarounds (rather than software) to leverage the unmodified software, creating a complete system for $700. We found that the resulting print accuracy and precision of this system were close to those of the unmodified printer and scanner. We demonstrate the reach of this system by printing multiple strains of Escherichia coli, performing quantitative time-lapse recordings of bacterial growth, and then separating different fluorescent strains according to color. A fluid-deposition and imaging platform, like the one developed here, could be integrated for do-it-yourself research, remote experimentation, and (on-line) education.
Additive manufacturing, otherwise known as three-dimensional (3D) printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education and medicine. Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D-bioprinted tissue models for research, drug discovery and toxicology.
The ability to print and pattern all the components that make up a tissue (cells and matrix materials) in three dimensions to generate structures similar to tissues is an exciting prospect of bioprinting. However, the majority of the matrix materials used so far for bioprinting cannot represent the complexity of natural extracellular matrix (ECM) and thus are unable to reconstitute the intrinsic cellular morphologies and functions. Here, we develop a method for the bioprinting of cell-laden constructs with novel decellularized extracellular matrix (dECM) bioink capable of providing an optimized microenvironment conducive to the growth of three-dimensional structured tissue. We show the versatility and flexibility of the developed bioprinting process using tissue-specific dECM bioinks, including adipose, cartilage and heart tissues, capable of providing crucial cues for cells engraftment, survival and long-term function. We achieve high cell viability and functionality of the printed dECM structures using our bioprinting method.
The ability of the living body to heal and regenerate itself following trauma is astonishing. Numerous events of repair and regeneration occur during our lifetime, most of which we are never aware of. Unfortunately, in some cases, the injury or defect cannot be adequately repaired solely by nature and medical intervention is required.
Eung-Sam Kim,1,2 Eun Hyun Ahn,3,4 Tal Dvir,5,6 Deok-Ho Kim1,4,71Department of Bioengineering, University of Washington, Seattle, WA, USA; 2Department of Biological Sciences, Chonnam National University, Gwangju, Korea; 3Department of Pathology, 4Institute of Stem Cell and Regenerative Medicine, School of Medicine, University of Washington, Seattle, WA, USA; 5Department of Molecular Microbiology and Biotechnology, 6Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel; 7Center for Cardiovascular Biology, University of Washington, Seattle, WA, USAThe history of human kind suggests that there has been a correlation between global population growth and major events in science and technology over the last three centuries. Sharp increases in the world’s population have been triggered by the industrial revolution and scientific and technological breakthroughs including: the advent of the railways, discovery of penicillin and deoxyribonucleic acid (DNA), and the invention of the computer.1 Since the 20th century, interdisciplinary areas in the physical and biological sciences have accelerated the progress of biomedical applications. The recent integration of emerging nanotechnology into biology and biomedicine has resulted in a range of innovative nanoengineering efforts for the repair and regeneration of tissues and organs.2 Thus, it is expected that nanoengineering approaches to biomedical applications can contribute to addressing the present issue of personal and global health care and its economic burden for more than 7 billion people.Why are we paying attention to nanoengineering for biomedical applications? The size of most biomolecules ranges from 0.2 nm to 200 nm (Figure 1). Research has focused on control of the interaction and localization of biomolecules even at the single-molecule level using ever-evolving nanotechnology.3 The evidence indicates that cells can respond to nanoscale changes in the dynamic extracellular matrix and vice versa. Biomimetic nanopatterns alone can direct the differentiation of stem cells without involvement of exogenous soluble biochemical factors.4,5 This regulation of cellular behavior by nanotechnology is one of many examples demonstrating the significant applications of nanoengineering in biomedicine. This special issue includes four review papers and seven research articles that provide an insight into current nanoengineering approaches to the repair or regeneration of tissues and organs.
Vascularization remains a critical challenge in tissue engineering. The development of vascular networks within densely populated and metabolically functional tissues facilitate transport of nutrients and removal of waste products, thus preserving cellular viability over a long period of time. Despite tremendous progress in fabricating complex tissue constructs in the past few years, approaches for controlled vascularization within hydrogel based engineered tissue constructs have remained limited. Here, we report a three dimensional (3D) micromolding technique utilizing bioprinted agarose template fibers to fabricate microchannel networks with various architectural features within photocrosslinkable hydrogel constructs. Using the proposed approach, we were able to successfully embed functional and perfusable microchannels inside methacrylated gelatin (GelMA), star poly(ethylene glycol-co-lactide) acrylate (SPELA), poly(ethylene glycol) dimethacrylate (PEGDMA) and poly(ethylene glycol) diacrylate (PEGDA) hydrogels at different concentrations. In particular, GelMA hydrogels were used as a model to demonstrate the functionality of the fabricated vascular networks in improving mass transport, cellular viability and differentiation within the cell-laden tissue constructs. In addition, successful formation of endothelial monolayers within the fabricated channels was confirmed. Overall, our proposed strategy represents an effective technique for vascularization of hydrogel constructs with useful applications in tissue engineering and organs on a chip.
Rationally designed nanoparticles that can bind toxins show great promise for detoxification. However, the conventional intravenous administration of nanoparticles for detoxification often leads to nanoparticle accumulation in the liver, posing a risk of secondary poisoning especially in liver-failure patients. Here we present a liver-inspired three-dimensional (3D) detoxification device. This device is created by 3D printing of designer hydrogels with functional polydiacetylene nanoparticles installed in the hydrogel matrix. The nanoparticles can attract, capture and sense toxins, while the 3D matrix with a modified liver lobule microstructure allows toxins to be trapped efficiently. Our results show that the toxin solution completely loses its virulence after treatment using this biomimetic detoxification device. This work provides a proof-of-concept of detoxification by a 3D-printed biomimetic nanocomposite construct in hydrogel, and could lead to the development of alternative detoxification platforms.
Cellular particle dynamics (CPD) is an effective computational method to describe the shape evolution and biomechanical relaxation processes in systems composed of micro tissues such as multicellular aggregates. Therefore, CPD is a useful tool to predict the outcome of postprinting structure formation in bioprinting. The predictive power of CPD has been demonstrated for multicellular systems composed of identical volume-conserving spherical and cylindrical bioink units. Experiments and computer simulations were related through an independently developed theoretical formalism based on continuum mechanics. Here we generalize the CPD formalism to (i) include non-identical bioink particles often used in specific bioprinting applications, (ii) describe the more realistic experimental situation in which during the post-printing structure formation via the fusion of spherical bioink units the volume of the system decreases, and (iii) directly connect CPD simulations to the corresponding experiments without the need of the intermediate continuum theory inherently based on simplifying assumptions.
Work supported by NSF [PHY-0957914]. The computations were performed on the HPC resources at the University of Missouri Bioinformatics Consortium (UMBC).
Advances in three-dimensional (3D) printing have enabled the direct assembly of cells and extracellular matrix materials to form in vitro cellular models for 3D biology, the study of disease pathogenesis and new drug discovery. In this study, we report a method of 3D printing for Hela cells and gelatin/alginate/fibrinogen hydrogels to construct in vitro cervical tumor models. Cell proliferation, matrix metalloproteinase (MMP) protein expression and chemoresistance were measured in the printed 3D cervical tumor models and compared with conventional 2D planar culture models. Over 90% cell viability was observed using the defined printing process. Comparisons of 3D and 2D results revealed that Hela cells showed a higher proliferation rate in the printed 3D environment and tended to form cellular spheroids, but formed monolayer cell sheets in 2D culture. Hela cells in 3D printed models also showed higher MMP protein expression and higher chemoresistance than those in 2D culture. These new biological characteristics from the printed 3D tumor models in vitro as well as the novel 3D cell printing technology may help the evolution of 3D cancer study.
Although synthetic polymers are desirable in tissue engineering applications for the reproducibility and tunability of their properties, synthetic small diameter vascular grafts lack the capability to endothelialize in vivo. Thus, synthetically fabricated biodegradable tissue scaffolds that reproduce important aspects of the extracellular environment are required to meet the urgent need for improved vascular grafting materials. In this study, we have successfully fabricated well-defined nanopatterned cell culture substrates made of a biodegradable composite hydrogel consisting of poly(ethylene glycol) dimethacrylate (PEGDMA) and gelatin methacrylate (GelMA) by using UV-assisted capillary force lithography. The elasticity and degradation rate of the composite PEG–GelMA nanostructures were tuned by varying the ratios of PEGDMA and GelMA. Human umbilical vein endothelial cells (HUVECs) cultured on nanopatterned PEG–GelMA substrates exhibited enhanced cell attachment compared with those cultured on unpatterned PEG–GelMA substrates. Additionally, HUVECs cultured on nanopatterned PEG-GelM substrates displayed well-aligned, elongated morphology similar to that of native vascular endothelial cells and demonstrated rapid and directionally persistent migration. The ability to alter both substrate stiffness and degradation rate and culture endothelial cells with increased elongation and alignment is a promising next step in recapitulating the properties of native human vascular tissue for tissue engineering applications.
Fabrication of three dimensional (3D) organoids with controlled microarchitectures has been shown to enhance tissue functionality. Bioprinting can be used to precisely position cells and cell-laden materials to generate controlled tissue architecture. Therefore, it represents an exciting alternative for organ fabrication. Despite the rapid progress in the field, the development of printing processes that can be used to fabricate macroscale tissue constructs from ECM-derived hydrogels has remained a challenge. Here we report a strategy for bioprinting of photolabile cell-laden methacrylated gelatin (GelMA) hydrogels. We bioprinted cell-laden GelMA at concentrations ranging from 7 to 15% with varying cell densities and found a direct correlation between printability and the hydrogel mechanical properties. Furthermore, encapsulated HepG2 cells preserved cell viability for at least eight days following the bioprinting process. In summary, this work presents a strategy for direct-write bioprinting of a cell-laden photolabile ECM-derived hydrogel, which may find widespread application for tissue engineering, organ printing and the development of 3D drug discovery platforms.
Vascularization of thick engineered tissue and organ constructs like the heart, liver, pancreas or kidney remains a major challenge in tissue engineering. Vascularization is needed to supply oxygen and nutrients and remove waste in living tissues and organs through a network that should possess high perfusion ability and significant mechanical strength and elasticity. In this paper, we introduce a fabrication process to print vascular conduits directly, where conduits were reinforced with carbon nanotubes (CNTs) to enhance their mechanical properties and bioprintability. In vitro evaluation of printed conduits encapsulated in human coronary artery smooth muscle cells was performed to characterize the effects of CNT reinforcement on the mechanical, perfusion and biological performance of the conduits. Perfusion and permeability, cell viability, extracellular matrix formation and tissue histology were assessed and discussed, and it was concluded that CNT-reinforced vascular conduits provided a foundation for mechanically appealing constructs where CNTs could be replaced with natural protein nanofibers for further integration of these conduits in large-scale tissue fabrication.
Developing stimulus-responsive biomaterials with easy-to-tailor properties is a highly desired goal of the tissue engineering community. A novel type of electroactive biomaterial, the conductive polymer, promises to become one such material. Conductive polymers are already used in fuel cells, computer displays and microsurgical tools, and are now finding applications in the field of biomaterials. These versatile polymers can be synthesised alone, as hydrogels, combined into composites or electrospun into microfibres. They can be created to be biocompatible and biodegradable. Their physical properties can easily be optimized for a specific application through binding biologically important molecules into the polymer using one of the many available methods for their functionalization. Their conductive nature allows cells or tissue cultured upon them to be stimulated, the polymers' own physical properties to be influenced post-synthesis and the drugs bound in them released, through the application of an electrical signal. It is thus little wonder that these polymers are becoming very important materials for biosensors, neural implants, drug delivery devices and tissue engineering scaffolds. Focusing mainly on polypyrrole, polyaniline and poly(3,4-ethylenedioxythiophene), we review conductive polymers from the perspective of tissue engineering. The basic properties of conductive polymers, their chemical and electrochemical synthesis, the phenomena underlying their conductivity and the ways to tailor their properties (functionalization, composites, etc.) are discussed. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).
In the ear reconstruction field, tissue engineering enabling the regeneration of the ear's own tissue has been considered to be a promising technology. However, the ear is known to be difficult to regenerate using traditional methods due to its complex shape and composition. In this study, we used three-dimensional (3D) printing technology including a sacrificial layer process to regenerate both the auricular cartilage and fat tissue. The main part was printed with poly-caprolactone (PCL) and cell-laden hydrogel. At the same time, poly-ethylene-glycol (PEG) was also deposited as a sacrificial layer to support the main structure. After complete fabrication, PEG can be easily removed in aqueous solutions, and the procedure for removing PEG has no effect on the cell viability. For fabricating composite tissue, chondrocytes and adipocytes differentiated from adipose-derived stromal cells were encapsulated in hydrogel to dispense into the cartilage and fat regions, respectively, of ear-shaped structures. Finally, we fabricated the composite structure for feasibility testing, satisfying expectations for both the geometry and anatomy of the native ear. We also carried out in vitro assays for evaluating the chondrogenesis and adipogenesis of the cell-printed structure. As a result, the possibility of ear regeneration using 3D printing technology which allowed tissue formation from the separately printed chondrocytes and adipocytes was demonstrated.
We have investigated whether inkjet printing technology can be extended to print cells of the adult rat central nervous system (CNS), retinal ganglion cells (RGC) and glia, and the effects on survival and growth of these cells in culture, which is an important step in the development of tissue grafts for regenerative medicine, and may aid in the cure of blindness. We observed that RGC and glia can be successfully printed using a piezoelectric printer. Whilst inkjet printing reduced the cell population due to sedimentation within the printing system, imaging of the printhead nozzle, which is the area where the cells experience the greatest shear stress and rate, confirmed that there was no evidence of destruction or even significant distortion of the cells during jet ejection and drop formation. Importantly, the viability of the cells was not affected by the printing process. When we cultured the same number of printed and non-printed RGC/glial cells, there was no significant difference in cell survival and RGC neurite outgrowth. In addition, use of a glial substrate significantly increased RGC neurite outgrowth, and this effect was retained when the cells had been printed. In conclusion, printing of RGC and glia using a piezoelectric printhead does not adversely affect viability and survival/growth of the cells in culture. Importantly, printed glial cells retain their growth-promoting properties when used as a substrate, opening new avenues for printed CNS grafts in regenerative medicine.
Recent development in bioprinting technology enables the fabrication of complex, precisely controlled cell-encapsulated tissue constructs. Bioprinted tissue constructs have potential in both therapeutic applications and nontherapeutic applications such as drug discovery and screening, disease modelling and basic biological studies such as in vitro tissue modelling. The mechanical properties of bioprinted in vitro tissue models play an important role in mimicking in vivo the mechanochemical microenvironment. In this study, we have constructed three-dimensional in vitro soft tissue models with varying structure and porosity based on the 3D cell-assembly technique. Gelatin/alginate hybrid materials were used as the matrix material and cells were embedded. The mechanical properties of these models were assessed via compression tests at various culture times, and applicability of three material constitutive models was examined for fitting the experimental data. An assessment of cell bioactivity in these models was also carried out. The results show that the mechanical properties can be improved through structure design, and the compression modulus and strength decrease with respect to time during the first week of culture. In addition, the experimental data fit well with the Ogden model and experiential function. These results provide a foundation to further study the mechanical properties, structural and combined effects in the design and the fabrication of in vitro soft tissue models.
Rupture of a nerve is a debilitating injury with devastating consequences for the individual's quality of life. The gold standard of repair is the use of an autologous graft to bridge the severed nerve ends. Such repair however involves risks due to secondary surgery at the donor site and may result in morbidity and infection. Thus the clinical approach to repair often involves non-cellular solutions, grafts composed of synthetic or natural materials. Here we report on a novel approach to biofabricate fully biological grafts composed exclusively of cells and cell secreted material. To reproducibly and reliably build such grafts of composite geometry we use bioprinting. We test our grafts in a rat sciatic nerve injury model for both motor and sensory function. In particular we compare the regenerative capacity of the biofabricated grafts with that of autologous grafts and grafts made of hollow collagen tubes by measuring the compound action potential (for motor function) and the change in mean arterial blood pressure as consequence of electrically eliciting the somatic pressor reflex. Our results provide evidence that bioprinting is a promising approach to nerve graft fabrication and as a consequence to nerve regeneration.
To understand the physical behavior and migration of cancer cells, a 3D in vitro micro-chip in hydrogel was created using 3D projection printing. The micro-chip has a honeycomb branched structure, aiming to mimic 3D vascular morphology to test, monitor, and analyze differences in the behavior of cancer cells (i.e. HeLa) vs. non-cancerous cell lines (i.e. 10 T1/2). The 3D Projection Printing system can fabricate complex structures in seconds from user-created designs. The fabricated microstructures have three different channel widths of 25, 45, and 120 microns wide to reflect a range of blood vessel diameters. HeLa and 10 T1/2 cells seeded within the micro-chip were then analyzed for morphology and cell migration speed. 10 T1/2 cells exhibited greater changes in morphology due to channel size width than HeLa cells; however, channel width had a limited effect on 10 T1/2 cell migration while HeLa cancer cell migration increased as channel width decreased. This physiologically relevant 3D cancer tissue model has the potential to be a powerful tool for future drug discoveries and cancer migration studies.
The release profiles and anti-bacterial properties of gentamycin (GEN) incorporated into in situ forming hydrogels for application as an in situ forming wound or burn dressing was investigated. Hydrogels were prepared by mixing gentamycin (GEN) with either a solution of the oxidized alginate in 0.1 M borax or a solution of gelatin in water and combining the two solutions. The release of GEN from these gels was studied by varying the order of mixing the drug with either oxidized alginate or gelatin. The antibacterial property of these gels was evaluated using gram negative P. aeruginosa and gram positive S. aureus. The gelation reaction between periodate-oxidized alginate and gelatin through Schiff's base formation was swift enabling in situ formation of GEN-loaded hydrogels. Drug release was slow when GEN was first mixed with oxidized alginate due to conjugation of the drug to the polymer through Schiff's base while release was more rapid when it was first mixed with gelatin. Drug payload also controlled the release of drug from the hydrogel matrix. Release occurred with an initial burst effect, followed by a relatively constant release. GEN released from the hydrogels was bactericidal against both strains of bacteria used for testing.
Significance
The ability to continuously mix complex fluids at the microscale depends on their flow rate, rheology, and mixing rate. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of materials. Based on this understanding, active mixing printheads are designed and implemented for multimaterial printing of 3D architectures whose local composition and properties can be programmably tailored.
Articular cartilage is the load-bearing tissue found inside all articulating joints of the body. It vastly reduces friction and allows for smooth gliding between contacting surfaces. The structure of articular cartilage matrix and cellular composition is zonal and is important for its mechanical properties. When cartilage becomes injured through trauma or disease, it has poor intrinsic healing capabilities. The spectrum of cartilage injury ranges from isolated areas of the joint to diffuse breakdown and the clinical appearance of osteoarthritis. Current clinical treatment options remain limited in their ability to restore cartilage to its normal functional state. This review focuses on the evolution of biomaterial scaffolds that have been used for functional cartilage tissue engineering. In particular, we highlight recent developments in multi-scale biofabrication approaches attempting to recapitulate the complex 3D matrix of native articular cartilage tissue. Additionally, we focus on the application of these methods to engineering each zone of cartilage and engineering full thickness osteo-chondral tissues for improved clinical implantation. These methods have shown the potential to control individual cell-to-scaffold interactions and drive progenitor cell differentiation into a chondrocyte lineage. The use of these bioinspired nanoengineered scaffolds hold promise for recreation of structure and function on the whole tissue level and may represent exciting new developments for future clinical applications for cartilage injury and restoration.
Three-dimensional printing technology is rapidly changing the way we produce all sort of objects, having also included medical applications. We embarked in a pilot study to assess the value of patient-specific 3-D physical manufacturing of spleno-pancreatic anatomy in helping during patient's counseling and for preoperative planning.
Twelve patients scheduled for a laparoscopic splenectomy underwent contrast CT and subsequent post-processing to create virtual 3-D models of the target anatomy, and 3-D printing of the relative solid objects. The printing process, its cost and encountered problems were monitored and recorded. Patients were asked to rate the value of 3-D objects on a 1-5 scale in facilitating their understanding of the proposed procedure. Also 10 surgical residents were required to evaluate the perceived extra value of 3-D printing in the preoperative planning process.
The post-processing analysis required an average of 2; 20 h was needed to physically print each model and 4 additional hours to finalize each object. The cost for the material employed for each object was around 300 euros. Ten patients gave a score of 5, two a score of 4. Six residents gave a score of 5, four a score of 4.
Three-dimensional printing is helpful in understanding complex anatomy for educational purposes at all levels. Cost and working time to produce good quality objects are still considerable.
The introduction of 3D bioprinting is expected to revolutionize the field of tissue engineering and regenerative medicine. The 3D bioprinter is able to dispense materials while moving in X, Y and Z directions; enabling the engineering of complex structures from the bottom up. In this study a bioink that combines the outstanding shear thinning properties of nanofibrillated cellulose (NFC) with the fast crosslinking ability of alginate was formulated for the 3D bioprinting of living soft tissue with cells. Printability was evaluated with concern to printer parameters and shape fidelity. The shear thinning behavior of the tested bioinks enabled printing of both 2D gridlike structures as well as 3D constructs. Furthermore, anatomically shaped cartilage structures, such as a human ear and sheep meniscus, were 3D printed using MRI and CT images as blueprints. Human chondrocytes bioprinted in the non-cytotoxic, nanocellulose-based bioink exhibited a cell viability of 73% and 86% after 1 and 7 days of 3D culture, respectively. Based on these results we can conclude that the nanocellulose-based bioink is a suitable hydrogel for 3D bioprinting with living cells. This study demonstrates the potential use of nanocellulose for 3D bioprinting of living tissues and organs.
Additive manufacturing processes such as 3D printing use time-consuming, stepwise layer-by-layer approaches to object fabrication. We demonstrate the continuous generation of monolithic polymeric parts up to tens of centimeters in size with feature resolution below 100 micrometers. Continuous liquid interface production is achieved with an oxygen-permeable window below the ultraviolet image projection plane, which creates a "dead zone" (persistent liquid interface) where photopolymerization is inhibited between the window and the polymerizing part. We delineate critical control parameters and show that complex solid parts can be drawn out of the resin at rates of hundreds of millimeters per hour. These print speeds allow parts to be produced in minutes instead of hours.
Copyright © 2015, American Association for the Advancement of Science.
The study aims to investigate the techniques of design and construction of CT 3D reconstructional data-based polycaprolactone (PCL)-hydroxyapatite (HA) scaffold. Femoral and lumbar spinal specimens of eight male New Zealand white rabbits were performed CT and laser scanning data-based 3D printing scaffold processing using PCL-HA powder. Each group was performed eight scaffolds. The CAD-based 3D printed porous cylindrical stents were 16 piece × 3 groups, including the orthogonal scaffold, the Pozi-hole scaffold and the triangular hole scaffold. The gross forms, fiber scaffold diameters and porosities of the scaffolds were measured, and the mechanical testing was performed towards eight pieces of the three kinds of cylindrical scaffolds, respectively. The loading force, deformation, maximum-affordable pressure and deformation value were recorded. The pore-connection rate of each scaffold was 100 % within each group, there was no significant difference in the gross parameters and micro-structural parameters of each scaffold when compared with the design values (P > 0.05). There was no significant difference in the loading force, deformation and deformation value under the maximum-affordable pressure of the three different cylinder scaffolds when the load was above 320 N. The combination of CT and CAD reverse technology could accomplish the design and manufacturing of complex bone tissue engineering scaffolds, with no significant difference in the impacts of the microstructures towards the physical properties of different porous scaffolds under large load.
The development of advanced scaffolds that recapitulate the anisotropic mechanical behavior and biological functions of the extracellular matrix in leaflets would be transformative for heart valve tissue engineering. In this study, anisotropic mechanical properties were established in poly(ethylene glycol) (PEG) hydrogels by crosslinking stripes of 3.4kDa PEG diacrylate (PEGDA) within 20kDa PEGDA base hydrogels using a photolithographic patterning method. Varying the stripe width and spacing resulted in a tensile elastic modulus parallel to the stripes that was 4.1-6.8 times greater than that in the perpendicular direction, comparable to the degree of anisotropy between the circumferential and radial orientations in native valve leaflets. Biomimetic PEG-peptide hydrogels were prepared by tethering the cell-adhesive peptide RGDS and incorporating the collagenase-degradable peptide PQ (GGGPQG↓IWGQGK) into the polymer network. The specific amounts of RGDS and PEG-PQ within the resulting hydrogels influenced the elongation, de novo extracellular matrix deposition and hydrogel degradation behavior of encapsulated valvular interstitial cells (VICs). In addition, the morphology and activation of VICs grown atop PEG hydrogels could be modulated by controlling the concentration or micro-patterning profile of PEG-RGDS. These results are promising for the fabrication of PEG-based hydrogels using anatomically and biologically inspired scaffold design features for heart valve tissue engineering.
Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Bioprinting has emerged in recent years as an attractive method for creating 3-D tissues and organs in the laboratory, and therefore is a promising technology in a number of regenerative medicine applications. It has the potential to (i) create fully functional replacements for damaged tissues in patients, and (ii) rapidly fabricate small-sized human-based tissue models, or organoids, for diagnostics, pathology modeling, and drug development. A number of bioprinting modalities have been explored, including cellular inkjet printing, extrusion-based technologies, soft lithography, and laser-induced forward transfer. Despite the innovation of each of these technologies, successful implementation of bioprinting relies heavily on integration with compatible biomaterials that are responsible for supporting the cellular components during and after biofabrication, and that are compatible with the bioprinting device requirements. In this review, we will evaluate a variety of biomaterials, such as curable synthetic polymers, synthetic gels, and naturally derived hydrogels. Specifically we will describe how they are integrated with the bioprinting technologies above to generate bioprinted constructs with practical application in medicine.
A well-known osteogenic agent in the field of regenerative medicine is bone morphogenetic protein-2 (BMP-2). Non-viral delivery of a plasmid containing the gene encoding BMP-2 has shown to induce bone formation in vivo. In order to develop gene activated matrices into larger constructs, we created porosity in a hydrogel using bioprinting technology, thereby allowing better diffusion and blood vessel ingrowth. We were able to produce 3D constructs that were accurate and reproducible in size, shape and pore geometry. Constructs consisting of alginate supplemented with multipotent stromal cells (MSCs) and calcium phosphate particles were printed either in a porous or a non-porous/solid fashion. The plasmid DNA encoding BMP-2 was included in the constructs. Porous constructs were reproducibly bioprinted and remained intact for at least 14 days in culture. Cells were efficiently transfected by the plasmid DNA, and differentiated towards the osteogenic lineage as shown by elevated BMP-2 and ALP production. Porous constructs performed in the first week were better in producing BMP-2 than solid constructs. However, after implantation for six weeks subcutaneously in nude mice, no bone formation was seen, which calls for optimization of the biomaterials used. In conclusion, we show for the first time a model in which 3D printing and non-viral gene therapy can be combined.
Over the past several decades, there has been an ever-increasing demand for organ transplants. However, there is a severe shortage of donor organs, and as a result of the increasing demand, the gap between supply and demand continues to widen. A potential solution to this problem is to grow or fabricate organs using biomaterial scaffolds and a person's own cells. Although the realization of this solution has been limited, the development of new biofabrication approaches has made it more realistic. This review provides an overview of natural and synthetic biomaterials that have been used for organ/tissue development. It then discusses past and current biofabrication techniques, with a brief explanation of the state of the art. Finally, the review highlights the need for combining vascularization strategies with current biofabrication techniques. Given the multitude of applications of biofabrication technologies, from organ/tissue development to drug discovery/screening to development of complex in vitro models of human diseases, these manufacturing technologies can have a significant impact on the future of medicine and health care. Expected final online publication date for the Annual Review of Biomedical Engineering Volume 16 is July 01, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
J. A. Lewis and co-workers report on page 3124 a new bio-printing method for fabricating 3D tissue constructs replete with vasculature, multiple types of cells, and extracellular matrix. These intricate, heterogeneous structures are created by precisely co-printing multiple materials, known as bio-inks, in three dimensions. These 3D microengineered environments open new avenues for drug screening and tissue engineering. Cover image by Helena Sue Martin, David Kolesky, and Jennifer Lewis (Harvard University).
A method for interfacing an HP26 ink-jet cartridge to a computing resource is presented. A general purpose interface will allow new and custom application of ink-jet printing technology. Drive characteristics of the HP26 cartridge are captured and a driver board subsequently developed that permits direct control of nozzle firing timing and properties. Reproduction of the drive signal and satisfactory ink deposition is validated. The application of ink-jet printing technology to bioprinting research is targeted in this work.
Current tissue engineering methods lack the ability to properly recreate scaffold-free, cell dense tissues with physiological structures. Recent studies have shown that the use of nanoscale cues allows for precise control over large area 2D tissue structures without restricting cell growth or cell density. In this study, we developed a simple and versatile platform combining a thermoresponsive nanofabricated substratum (TNFS) incorporating nanotopographical cues and the gel casting method for the fabrication of scaffold-free 3D tissues. Our TNFS allows for the structural control of aligned cell monolayers, which can be spontaneously detached via a change in culture temperature. Utilizing our gel casting method, viable, aligned cell sheets can be transferred without loss of anisotropy or stacked with control over individual layer orientations. Transferred cell sheets and individual cell layers within multilayered tissues robustly retain structural anisotropy, allowing for the fabrication of scaffold-free, 3D tissues with hierarchal control of overall tissue structure.
Polyelectrolyte complexes (PECs) represent promising materials for drug delivery and tissue engineering applications. These substances are obtained in aqueous medium without the need for crosslinking agents. PECs can be produced through the combination of oppositely charged medical grade polymers, which include the stimuli responsive ones. In this work, three-dimensional porous scaffolds were produced through the lyophilisation of pH sensitive PECs made of chitosan (CS) and carrageenan (CRG). CS:CRG molar ratios of 1:1 (CSCRG1), 2:1 (CSCRG2) and 3:1 (CSCRG3) were used. The chemical compositions of the PECs, as well as their influence in the final structure of the scaffolds were meticulously studied. In addition, the pH responsiveness of the PECs in a range including the physiological pH values of 7.4 (simulating normal physiological conditions) and 4.5 (simulating inflammatory response) was assessed. Results showed that the PECs produced were stable at pH values of 7.4 and under but dissolved as the pH increased to non-physiological values of 9 and 11. However, after dissolution, the PEC could be reprecipitated by decreasing the pH to values close to 4.5. The scaffolds obtained presented large and interconnected pores, being equally sensitive to changes in the pH. CSCRG1 scaffolds appeared to have higher hydrophilicity and therefore higher water absorption capacity. The increase in the CS:CRG molar ratios improved the scaffold mechanical properties, with CSCRG3 presenting the higher compressive modulus under wet conditions. Overall, the PEC scaffolds appear promising for tissue engineering related applications that require the use of pH responsive materials stable at physiological conditions.
Alginate hydrogels functionalized with D-, or L-penicillamine (D-, L-PEN-Alg) are used as new 3D scaffolds for cell adhesion studies. The cells recognize and show different adhesion properties in the respective 3D hydrogel scaffolds. C-6-glioma and endothelial cells show higher affinity to the D-PEN than to the L-PEN functionalized 3D alginate hydrogel scaffold. The cultivated cells are harvested from the hydrogel and are reused, for example, for cell growth experiments on 2D surfaces to prove their viability as well.
The formation and structure properities of N-isopropyl base acrylamide (PNIPAm)gels with different synthetic temperatures, monomer concentrations and crosslinker concentrations were discussed, and the application of intelligent glass was researched. The results show: The synthesized PNIPAm gel is transparent and elastic, when the temperature is at 10 °C -20 °C, monomer concentration is 10%, crosslinker concentration is 5%. With the increasing of polymerization temperature, monomer concentration, and crosslinker concentration, the temperature of color change is both 32°C, leading to the decrease of transmittance ratio, the readuce of temperature sensitivity. Synthesized PNIPAm gel was put in the glass of interlayer, which plays a good shading result.
Fusion of cell tissues is an ubiquitous phenomenon and has important technological applications including tissue biofabrication. In this work we present experimental results of
aggregates fusion using adipose derived stem cells (ADSC) and a three dimensional computer simulation of the process using the cellular Potts model with aggregates reaching 10,000 cells. We consider fusion of round aggregates and monitor the dimensionless neck area of contact between the two aggregates to characterize the process, as done for the coalescence of liquid droplets and polymers. Both experiments and simulations show that the evolution of this quantity obeys a power law in time. We also study quantitatively individual cell motion with the simulation and it corresponds to an anomalous diffusion.