Biofabrication

Genetically modified cell membrane proteins can effectively regulate cell proliferation and differentiation, while also integrating novel biomaterials. As a promising biomedical tool, this technology has broad applications in tissue engineering and regenerative medicine. Both viral and non-viral gene transfection methods have been employed to create genetically modified cell membrane proteins. Numerous studies have demonstrated the significant efficacy of genetically modified cell membrane proteins in promoting bone regeneration, treating cardiovascular diseases, aiding lung injury recovery, advancing immunotherapy, and in applications involving engineered cell membrane sheets and cell spheroids. However, this technology faces several limitations, including biosafety and ethical concerns associated with genetic modification. This article summarizes recent advances in genetically modified cell membrane proteins, detailing their preparation, applications, limitations, and future directions.

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the head and neck. Due to low bioavailability and passive targetability of anticancer drugs show great limitations in cancer therapy, the treatment of OSCC faces major challenges. Folic acid (FA) targeting can deliver anticancer drugs efficiently into the tumor environment, further enhance the anti-cancer efficacy. Herein, the nanoplatform based on UiO-66 that encapsulated with an effective FA targeting ligands and the pH-responsive polyethylene glycol (PEG) layer for the targeted delivery of berberine (Ber) is constructed for fighting against OSCC. The FA modification and controlled pH-responsiveness enable the targeted delivery of UiO-66/PEG-FA, which promotes the release of Ber and increases the cumulative intracellular Ber concentration, which both promote consumption of glutathione (GSH) and induced generation of reactive oxygen species (ROS), further stimulate the secretion of inflammatory factors (TNF-α and IL-1β). A comprehensive evaluation of in vitro and in vivo experiments show that UiO-66@Ber/PEG-FA promote autophagy and apoptosis of tumor cells by regulating the expression of Beclin-1, ATG13, BAX and Bcl-2, and effectively inhibit tumor growth. Overall, UiO-66@Ber/PEG-FA exhibit superior pH-responsiveness and targeted therapeutic efficiencies in vitro and vivo, it can serve as an approach for OSCC therapy.

Engineering functional smooth muscle tissues requires precise control of cellular alignment, particularly in complex anatomical regions such as the gastroesophageal junction (GEJ). We present a scalable wet-spinning approach for generating pre-aligned microtissues (PAMs) from immortalized human esophageal smooth muscle cells embedded in a collagen-alginate core-shell fiber. After maturation, fibers were sectioned into uniform PAMs with preserved alignment and high cell viability. Immunofluorescence and gene expression analyses confirmed the expression of key contractile markers. PAMs were incorporated into a gelatin-methacryloyl bioink and 3D bioprinted to demonstrate alignment along the extrusion path. This method does not require specialized culture platforms and enables efficient production of aligned microtissues for bioprinting. It offers a promising strategy for fabricating anisotropic tissues and may facilitate the reconstruction of complex muscle structures such as the GEJ.

Polyetheretherketone (PEEK) is increasingly applied in bone defect repair due to its excellent biocompatibility and absence of artifact formation. However, the bio-inertness and inadequate mechanical properties of untreated PEEK remain significant challenges for PEEK-based implants. Hence, this study prepares a series of silicon nitride (Si3N4) fiber-reinforced PEEK composite porous scaffolds using twin-screw melt mixing-extrusion and material extrusion 3D printing. Comprehensive evaluations assess the mechanical properties, biocompatibility, osteogenic differentiation, angiogenesis activities, and antibacterial performances of various composites. Characterization results show that Si3N4 fiber-reinforced PEEK composites exhibit excellent printability, with well-oriented Si3N4 fibers uniformly distributed throughout the matrix. Furthermore, compared to non-reinforced PEEK, the addition of 8% Si₃N₄ fibers enhanced Young's modulus by 52.2% (6.36 GPa). Additionally, both in vitro and in vivo results indicate that all composite scaffolds exhibit excellent biocompatibility. Notably, the 8% Si₃N₄ fiber-reinforced PEEK composite demonstrated optimal multifunctional performance in osteogenic induction, angiogenic capacity, and antibacterial efficacy, significantly outperforming other experimental groups. In conclusion, this study offers a solution for enhancing the mechanical, anti-infective, and osseointegrative properties of PEEK, demonstrating its great potential for expanding the application of non-metallic orthopedic implants in bone defect repair.

Studying bone metastasis in in vitro models is essential for understanding the mechanisms driving this process, developing effective therapeutic strategies, and evaluating potential treatments for metastatic cancer patients. To this end, traditional two-dimensional (2D) cell culture models fail to replicate the native three-dimensional (3D) tissue microenvironment, resulting in significant disparities in biologically relevant behaviors and drug responses. The shift from 2D to 3D cell culture techniques represents an important step toward creating more biomimetic bone metastasis models. These systems more effectively emulate and replicate the complex interactions between cancer cells and bone tissue, including essential cell-cell and cell-extracellular matrix interactions, as well as in vivo biomechanical cues. The development and application of microfluidic-based 3D cancer models, incorporating diverse shapes, architectures, and modular structures such as organ-on-chip platforms, enable comprehensive screening and exploration of cellular interplay, the dissection of signaling pathways, and the resolution of limitations associated with traditional models. This review highlights recent advancements in microfluidic-based 3D bone metastasis models and examines innovative applications of this technology. These include hydrogel-based spherical and filaments biofabrication approaches, 2D and 3D tumor on-a- chips, and drug screening techniques such as concentration gradient generator-based, microdroplet-based, and microarray-based chips, as well as tumor tissue chips. Additionally, we discuss the benefits and limitations of these approaches in treating bone metastases and propose future directions for advancing microfluidic platforms in drug discovery and this research field.

Advanced tissue engineering strategies are vital to address challenging musculoskeletal conditions, such as volumetric muscle loss. These disorders impose a considerable economic burden and affect individuals' quality of life, highlighting the need for innovative treatments, such as tissue engineering, to address these challenges. Here, we examine how scaffold fibre orientation influences mechanical properties and cellular behaviour by utilising Melt Electrowriting (MEW) as a high-resolution 3D printing technique that combines aspects of electrospinning and melt based polymer deposition. In this work, we investigated the effects of fibre orientation in MEW scaffolds, and its effect on the scaffold mechanical properties as well as cell orientation and alignment. MEW scaffolds were mechanically characterized through uniaxial strain testing to determine critical parameters, including strain at failure (SAF), ultimate tensile strength (UTS), Young's modulus (E), fatigue rate, recovery time, and yield strain. These mechanical properties were analysed to define an optimal strain regime for transitioning from static to dynamic culture conditions under muscle-like cyclic loading, relevant to muscle’s viscoelastic behaviour. In parallel, static cultures of human skeletal myotubes and normal human dermal fibroblasts were grown on MEW scaffolds, with varying architectures, to study the effects of fibre aspect ratio on cell alignment. Cell alignment was visualized using DAPI/phalloidin staining and quantified with the ImageJ directionality plugin, enabling a systematic comparison of scaffold designs. This approach evaluates the potential of supportive scaffold architectures to promote aligned cell growth, offering insights into designing effective scaffolds for tissue regeneration.

Existing animal and human cell models have limitations in terms of heterogeneous differences or difficulties in sufficiently reproducing arterial structures and complex cell–cell interactions. The discovery of exosome-derived biomarkers using a 3D bioprinted atherosclerosis model provides a noninvasive and stable detection method and is expected to contribute to the development of early diagnosis and personalized treatment. To contribute to the discovery of exosome-derived biomarkers related to the early diagnosis and prognosis of cardiovascular diseases using a 3D bioprinted atherosclerosis model, we reproduced an arterial environment using 3D bioprinting composed of a biocompatible extracellular matrix (bioink) and various human cells in vitro. The 3D bioprintedatherosclerosis model composed of inflammatory macrophages, coronary artery smooth muscle cells, coronary artery endothelial cells, and collagen methacryloyl (ColMA) hydrogel was treated with LDL to induce atherosclerosis, and the atherosclerosis model was classified into Baseline (BL), Early Atherosclerosis (EA; Early Athero), and Late Atherosclerosis (LA; Late Athero) groups. The secreted exosomes were isolated according to the time period, and a characterization analysis was conducted to confirm the purity of the isolated exosomes. We evaluated the isolated exosomes qualitatively and quantitatively. Isolated exosomes were analyzed using proteomics and miRNA sequencing to verify whether the bioprinted atherosclerosis model induced atherosclerosis, and a novel early atherosclerosis biomarker, SERPINA11, was discovered. In conclusion, we verified that the bioprinted atherosclerosis model induced atherosclerosis and that the novel biomarker set of exosomal miRNAs (hsa-miR-143-5p and hsa-miR-6879-5p) expressed in early atherosclerosis and proteins (SERPINA11, AHSG, and F2) might be clinically useful in early diagnosis and prognosis.

Ultra-tiny-scale technology representing engineered micro- and nano-scale materials has gained considerable attention for a wide range of applications, including hearing restoration. The advent of hearing loss and its recovery has been the topic of intense discussion since many decades. Although conventional treatments partially support hearing recovery, they present certain limitations such as subsequent immune response and donor site morbidity leading to even worsened sensory disturbances. Microscale- and nanoscale-based approaches such as tissue engineering, nanoparticle-assisted drug delivery systems, and micro/nanofabrication-aided auditory stimulations have been shown to play an efficient role in recovery from hearing disorders. In particular, the introduction of different biomaterials and biopolymers (natural and synthetic) with influential topographical cues and excellent biocompatibility has been found to conveniently bypass previous challenges posed by rigid human ear structures and provided a new path for improved and advanced hearing-recovery approaches. This review is focused on the development of micro/nanoengineering-based hearing recovery therapeutics and their significant impact on the future of hearing research. It discusses the physiological functions associated with the human ear and the mechanism underlying distinct hearing loss disorders as well as highlights various engineered ultra-tiny-scale-assisted strategies for developing advanced hearing therapeutics. Finally, we deliberate on commercialization aspect and future perspectives of implementing micro/nanotechnologies for hearing restoration platforms.

Foreign body reaction (FBR) and insufficient vascularization greatly hinder the integration of 3D-bioprinted tissue substitutes with host tissues. Previous studies have shown that these problems are exacerbated by the stiffness of the 3D-bioprinted constructions, which is highly associated with the abnormal polarization of macrophages. Therefore, we developed an engineering strategy using membrane extrusion to prepare macrophage-derived extracellular vesicle mimics (EVMs). The EVMs derived from M1 and M2 macrophages (M1-EVMs and M2-EVMs) were rich in functional proteins. In the 2D environment, M1-EVMs promoted the fibrotic phenotype of fibroblasts, vascularization, and the M1 polarization of macrophages. In contrast, M2-EVMs effectively avoided the fibrotic trend, showed stronger angiogenic capabilities, and prevented excessive M1 polarization, demonstrating their potential to inhibit FBR and promote neovascularization. After bioprinting the EVMs loaded by gelatin-alginate bioink, the basic physical properties of the bioink were not significantly affected, and the biological functions of EVMs remain stable, indicating their potential as bioink additives. In the subcutaneous implantation model, unlike the FBR-aggravating effects of M1-EVMs, 3D-bioprinted M2-EVMs successfully reduced the immune response, prevented fibrous capsule formation, and increased vascular density. When applied to skin wound treatment, 3D-bioprinted M2-EVMs not only inhibited inflammatory levels but also exhibited pleiotropic pro-regenerative effects, effectively promoting vascularization, re-epithelialization, and appendage regeneration. As an innovative additive for bioinks, M2-EVMs present a promising approach to enhance the survival of bioengineered tissues and can further serve as a targeted drug loading system, promoting the development of regenerative medicine and improving clinical outcomes.

Tissue function depends on the 3D spatial organization of cells, extracellular matrix components, as well as dynamic nutrient gradients and mechanical forces. Advances in biofabrication technologies have enabled the creation of increasingly sophisticated tissue models, but achieving native-like tissue maturation post-fabrication remains a challenge. The development of bioreactors and microfluidic systems capable of introducing dynamic culture platforms and controlled mechanical and biochemical stimulation for biofabricated tissue analogues is therefore imperative to address this. In this technical note, we introduce a multi-step pipeline to fabricate, seed and perfuse geometrically complex hydrogel constructs with quality control protocols through the computational analysis of confocal multispectral 3D imaging data for each step of the process. Employing ultra-fast volumetric bioprinting, chips with tunable channel architectures were fabricated. Furthermore, an autoclavable and transparent perfusion bioreactor inspired by open-source designs was developed to enable controlled, long-term perfusion (up to 28 days) and real-time monitoring of cell behavior. As proof-of-concept, employing this pipeline, we fabricated a human mammary ductal model and an endothelialized vessel on-a-chip, demonstrating the compatibility of the platform with epithelial and endothelial cell lines, and investigated the effect of dynamic culture on tissue-specific cell organization. Dynamic perfusion underlined the influence of mechanical stimulation on cell organization and maturation. Various chip architectures, capable of recapitulating tissue-specific features (i.e. lobules) were printed, enabling the mono- and co-culture of human mammary epithelial and endothelial cells. Our pipeline, with the accompanying protocols and analysis scripts presented here, provide the potential to be applied for the dynamic culture of a wide range of tissues.

Since the first tissue engineered blood vessel (TEBV) was developed, different approaches, biomaterial scaffolds and cell sources have been used to obtain an engineered vessel as much similar as native vessels in terms of structure, functionality and mechanical properties. At the same time, diverse needs to obtain a functional TEBV have emerged, such as for blood vessel replacement for cardiovascular diseases to be used as artery bypass, to vascularize tissue engineered constructs, or even to model vascular diseases or drug testing. In this review, after briefly describing the native structure and function of arteries, we will give an overview of different biomaterials, cells and methods that have been used during the last years for the development of small TEBVs (1-6 mm diameter). The importance of perfusing the TEBVs in order to acquire functionality and maturation will be also discussed. Finally, we will center the review on TEBV applications beyond their use as vascular graft for cardiovascular diseases.

Cardiac tissue engineering is a rapidly growing field that holds great promise for the development of new therapies for heart disease. While significant progress has been made in the field over the past two decades, engineering functional myocardium of clinically relevant size and thickness remains an unmet challenge. A major roadblock in this respect is the current difficulty in incorporating efficient vascularization into engineered constructs. One potential solution involves the use of microvascular fragments from adipose tissue, which have demonstrated encouraging results in improving vascularization and graft survival following transplantation. However, this method lacks precise control over the vascular architecture within the constructs. Here, we set out to investigate the use of 3D bioprinting for the fabrication of human cardiac tissue constructs composed of human induced pluripotent stem cell (hiPSC) derivatives, while allowing for the precise control of the distribution and density of microvessel fragments within the bioprinted constructs. We carefully selected and optimized bioink compositions based on their printability, biocompatibility, and construct stability. Following transplantation into immunodeficient mice, 3D bioprinted cardiac constructs containing microvessel fragments exhibited rapid and efficient vascularization, resulting in prolonged graft survival. Overall, our studies underscore the advantages of employing engineering design and self-assembly across different scales to address current limitations of tissue engineering, and highlight the usefulness of 3D bioprinting in this context.

Mixed microbial communities are essential for various ecosystems, with bacteria often exhibiting unique behaviors in structured environments. However, replicating these interactions in vitro remains challenging, as traditional microbiology techniques based on well-mixed cultures fail to capture the spatial organization of natural communities. Chaotic 3D printing offers a versatile, high-throughput method for fabricating hydrogel constructs with multilayered microstructure in which different bacterial strains can coexist, closely mimicking the partial segregation seen in natural microbial ecosystems. Using a Kenics static mixer (KSM) printing nozzle, we bioprinted a bacterial consortium consisting of Lactobacillus rhamnosus, Bifidobacterium bifidum, and Escherichia coli as a simplified model for human gut microbiota. Chaotic bioprinting enabled the creation of microstructured cocultures with distinct niches, allowing all bacterial strains to coexist (without being scrambled) and reach a population equilibrium. We characterized the cocultures through fluorescence microscopy, colony counting, and quantitative polymerase chain reactions (qPCR). Our results demonstrate that the microarchitecture of the printed fibers significantly influences bacterial growth dynamics. Stratified arrangements enhanced coculture viability and balance over 72 hours compared to well-mixed and suspension conditions. Chaotic printing also allows the rational arrangement of strict anaerobic bacteria, such as B. bifidum, by positioning them in construct layers that are more susceptible to hypoxia. Chaotic bioprinting presents a powerful tool for engineering microbial ecosystems with precise spatial control. This approach holds promise for advancing our understanding of microbial interactions and has potential biomedical applications in antibiotic testing, microbiota research, bioremediation, and synthetic biology.

Tissue engineering aims to develop tissue constructs as models or substitutes for native tissues. For organ-level biological studies and regenerative medicine applications, it is essential to fabricate tissue constructs with physiologically relevant cell densities (on the order of 10 million to 1 billion cells·mL ⁻¹ , large size (centimeter scale and larger), and a controllable geometry to guide tissue maturation. State-of-the-art biofabrication methods, however, struggle to simultaneously meet all of these demands. The recently proposed acoustic holographic assembly (AHA) method shows promise, as it is compatible with culture media and enables the contactless, label-free, and volumetric assembly of biological cells in a predefined geometry within few minutes. Here we present an AHA biofabrication scheme designated for fabricating cell-dense, centimeter-scale, and arbitrarily-shaped tissue constructs using a compact benchtop instrument compatible with a biolab environment. We demonstrate the assembly of C2C12 myoblasts in gelatin methacryloyl (GelMA) into large and asymmetric branch-shaped constructs, which are rapidly formed with an average cell density of 40 million cells·mL ⁻¹ and a local density of up to 260 million cells·mL ⁻¹ . Featuring a high viability of 90.5%±4.3%, the assembled cell constructs are observed to grow within the GelMA hydrogel under perfusion over five days. Further, we show how AHA can --- in a single step --- assemble cells into layered and three-dimensional geometries inside standard cell culture labware. It can therefore help obtain engineered tissue constructs with structural and functional characteristics seen in more complex native tissues.

Organs-on-Chips (OoCs) are 3D models aiming to faithfully replicate in vitro specific functions of human organs or tissues. While promising as an alternative to traditional 2D cell culture and animal models in drug development, controlled realization of complex microvasculature within OoC remains a significant challenge. Here, we demonstrate how femtosecond laser patterning allows to produce hollow microvascular-like channels inside a collagen-based matrix directly within a microfluidic chip. The hydrogel preparation protocol was optimized to maintain structural stability, facilitating successful endothelialization of produced channels. The resulting microvascular structures exhibit notable physiological relevance, as evidenced by the expression of key endothelial markers (ZO-1, and VE-cadherin) and the successful reproduction of the barrier function. Furthermore, tumor necrosis factor-alpha (TNF-α) exposure induces a concentration-dependent increase in vascular permeability and inflammatory marker expression (ICAM-1). The proposed method holds the potential to control and faithfully reproduce the vascularization process in OoC platforms, in both physiological and inflammatory conditions.

One hallmark of healthy tendon tissue is the high confinement of tenocytes between tightly packed, highly aligned collagen fibers. During tendinopathy, this organization becomes dysregulated, leading to cells with round-shaped morphology and collagen fibers which exhibit crimping and misalignment. The elongated nuclei in healthy tendons are linked to matrix homeostasis through distinct mechanotransduction pathways, and it is believed that the loss of nuclear confinement could upregulate genes associated with abnormal matrix remodeling. Replicating the cell and nuclear morphology of healthy and diseased states of tendon, however, remains a significant challenge for engineered in vitro tendon models. Here we report on a high throughput biofabrication of mini-tendons that mimick the tendon core compartment based on the filamented light (FLight) approach. Each mini-tendon, with a length of 4 mm, was composed of parallel hydrogel microfilaments (2–5 µm diameter) and microchannels (2–10 µm diameter) that confined the cells. We generated four distinct matrices with varying stiffness (7–40 kPa) and microchannel dimensions. After 14 d of culture, 29% of tenocytes in the softest matrix with the largest microchannel diameter were aligned, exhibiting an average nuclear aspect ratio (nAR) of 2.1. In contrast, 84% of tenocytes in the stiffest matrix with the smallest microchannel diameter were highly aligned, with a mean nAR of 3.4. When tenocytes were cultured on the FLight hydrogels (2D) as opposed to within the hydrogels three-dimensional (3D), the mean nAR was less than 1.9, indicating that nuclear morphology is significantly more confined in 3D environments. By tuning the stiffness and microarchitecture of the FLight matrix, we demonstrated that mechanical confinement can be modulated to exert control over the extent of nuclear confinement. This high-throughput, tunable platform offers a promising approach for studying the mechanobiology of healthy and diseased tendons and for eventual testing of drug compounds against tendinopathy.

Big mechanically-active culture systems (BigMACS) are promising to stimulate, control, and pattern cell and tissue behaviours with less soluble factor requirements. However, it remains challenging to predict if and how distributed mechanical forces impact single-cell behaviours to pattern tissue. In this study, we introduce a tissue-scale finite element analysis framework able to correlate sub-cellular quantitative histology with centimetre-scale biomechanics. Our framework is relevant to diverse BigMACS, including media perfusion, tensile-stress, magnetic, and pneumatic tissue culture platforms. We apply our framework to understand how the design and operation of a multi-axial soft robotic bioreactor can spatially control mesenchymal stem cell (MSC) proliferation, orientation, differentiation to smooth muscle, and extracellular vascular matrix deposition. We find MSC proliferation and matrix deposition to positively correlate with mechanical stimulation but cannot be locally patterned by soft robot mechanical stimulation within a centimetre scale tissue. In contrast, local stress distribution was able to locally pattern MSC orientation and differentiation to smooth muscle phenotypes, where MSCs aligned perpendicular to principal stress direction and expressed increased α-SMA with increasing 3D Von Mises Stresses from 0 to 15 kPa. Altogether, our new biomechanical-histological simulation framework is a promising technique to derive the future mechanical design equations to control cell behaviours and engineer patterned tissue.

Despite the development of three-dimensional (3D) tissues that promises remarkable advances in myocardial therapies and pharmaceutical research, vascularization is required for the repair of damaged hearts using cardiac tissue engineering. In this study, we developed a method for rapid generation of a 3D cardiac tissue, with extremely high engraftment efficiency, by stacking cardiomyocyte sheets using fibrin as an adhesive. Cell sheets were created by peeling off confluent cultured cells from a culture dish grafted with a polymer that induced surface hydrophilicity in response to low temperatures. The high engraftment rate was attributed to the retention of the adhesive protein. The multistacked vascularized cell sheets prepared using fibrin, when transplanted into the subcutaneous tissue and at myocardial infarction site in rats, yielded a transplanted 3D myocardial tissue. Furthermore, multilayered cardiomyocyte sheets were transplanted twice at 1 week intervals to create a 3D myocardial tissue. Our data suggest that fibrin-based rapidly layered cell sheets can advance tissue-engineered transplantation therapy and should aid the development of next-generation tissue-engineered products in the fields of regenerative medicine and drug screening.

Injectable microgels, made from both natural and synthetic materials, are promising platforms for the encapsulation of cells or bioactive agents, such as drugs and growth factors, for delivery to injury sites. They can also serve as effective micro-scaffolds in bone tissue engineering (BTE), offering a supportive environment for cell proliferation or differentiation into osteoblasts. Microgels can be injected in the injury sites individually or in the form of aggregated/jammed ones named micro-granular hydrogels. This review focuses on common materials and fabrication techniques for preparing injectable microgels, as well as their characteristics and applications in BTE. These applications include their use as cell carriers, delivery systems for bioactive molecules, micro-granular hydrogels, bio-inks for bioprinting, three-dimensional microarrays, and the formation of microtissues. Furthermore, we discuss the current and potential future applications of microgels in bone tissue regeneration.

Osteochondral defects (OCD) refer to localized injuries affecting both the avascular cartilage and subchondral bone. Current treatments, such as transplantation or microfracture surgery, are hindered by limitations like donor availability and the formation of small, rigid fibrocartilage. Tissue engineering presents a promising alternative, yet challenges arise from limited oxygen and nutrient supply when fabricating human-scale tissue constructs. To address this, we propose assembling engineered micro-scale tissue constructs as building blocks for human-scale constructs. In this study, we aimed to develop bone and cartilage microtissues as building blocks for osteochondral tissue engineering. We fabricated placental stem cell (PSC)-laden microgels, inducing differentiation into osteogenic and chondrogenic microtissues. Utilizing a microfluidics chip platform, these microgels comprised a cell-laden core containing bone-specific and cartilage-specific growth factor-mimetic peptides, respectively, along with an acellular hydrogel shell. Additionally, we investigated the effect of culture conditions on microtissue formation, testing dynamic and static conditions. Results revealed over 85% cell viability within the microgels over 7 d of continuous growth. Under static conditions, approximately 60% of cells migrated from the core to the periphery, while dynamic conditions exhibited evenly distributed cells. Within 4 weeks of differentiation, growth factor-mimetic peptides accelerated PSC differentiation into bone and cartilage microtissues. These findings suggest the potential clinical applicability of our approach in treating OCD.

Biomaterials for orthopedic applications must have biocompatibility, bioactivity, and optimal mechanical performance. A suitable biomaterial formulation is critical for creating desired devices. Bioceramics with biopolymer composites and biomimetics with components similar to that of bone tissue, have been recognized as an area of research for orthopedic applications. The combination of bioceramics with biopolymers has the advantage of satisfying the need for robust mechanical support and extracellular matrices at the same time. Three-dimensional (3D) printing is a powerful method for restoring large bone defects and skeletal abnormalities owing to the favorable merits of preparing large, porous, patient-specific, and other intricate architectures. Bioceramic/biopolymer composites produced using 3D printing technology have several advantages, including desirable optimal architecture, enhanced tissue mimicry, and improved biological and physical properties. This review describes various 3D printing bioceramic/biopolymer composites for orthopedic applications. We hope that these technologies will inspire the future design and fabrication of 3D printing bioceramic/biopolymer composites for clinical and commercial applications.

Expanded polytetrafluoroethylene (ePTFE) grafts are Food and Drug Administration approved and effective for large vessel surgeries but face challenges in smaller vessels (Inner Diameter, ID ⩽ 6 mm) due to reduced blood flow and higher risks of thrombosis, stenosis, and infection. This study developed a vascular graft with an ID of 6 mm from decellularized human amniotic membrane (DAM graft) and compared its performance to ePTFE grafts in a porcine carotid artery model for one month. DAM grafts retained key extracellular matrix structures and mechanical properties post-decellularization, with customizable layers and stiffness to meet specific clinical needs. DAM grafts demonstrated successful carotid artery replacement, showing good surgical feasibility, patency, and post-operative recovery in all animals. In contrast to ePTFE grafts, which exhibited significant neointimal hyperplasia (NIH), poor endothelialization, and inflammation, DAM grafts displayed organized endothelial coverage, smooth muscle alignment, and reduced inflammation, minimizing NIH, thrombosis, and graft failure. These findings position DAM grafts as a promising alternative to synthetic grafts, especially for small-diameter applications. Future research should focus on improving endothelialization, exploring molecular mechanisms, and assessing long-term outcomes to further optimize DAM grafts for clinical use.

Primary hepatocytes are widely recognized for their ability to accurately represent the in vivo hepatocyte phenotype. However, traditional avascular primary hepatocyte culture models are limited by inadequate mass transfer, which leads to a rapid decline in hepatocyte function and survival. To address these challenges, vascularization of hepatic spheroids is crucial for enhancing oxygen and nutrient supply, thereby enabling the construction of larger and more complex hepatic tissues in vitro. In this study, we achieved vascularization of hepatic spheroids containing freshly isolated primary hepatocytes by incorporating fibroblasts as a source of paracrine factors to induce angiogenesis. Multicellular spheroids composed of primary hepatocytes and fibroblasts were formed in non-adhesive concave wells, and one of the spheroids was subsequently embedded in a fibrin–collagen hydrogel within a microfluidic device. Endothelial cells were then seeded onto adjacent microfluidic channels. They formed microvascular networks that extended toward and penetrated the hepatic spheroid. The vascularized hepatic spheroid closely mimicked hepatic sinusoids, with hepatocytes in close contact with microvessels. Moreover, the vascularized spheroid exhibited significantly enhanced hepatic function, specifically albumin secretion and urea synthesis. Our findings provide insights into the establishment of highly vascularized hepatic spheroids in vitro, which is crucial for constructing scalable hepatic tissues in the context of biofabrication.

Selective Laser Melting (SLM) has emerged as a transformative technology in bone tissue engineering, particularly for fabricating porous scaffolds from titanium alloys. These scaffolds offer a promising solution for treating critical-sized bone defects, providing mechanical support while promoting bone regeneration. A comprehensive review on recent advancements of SLM is provided by presenting a detailed analysis of cutting-edge research in the application of SLM for titanium alloy scaffold production. Key areas explored include structural designs like Triply Periodic Minimal Surfaces, material and process parameters optimization to enhance scaffold properties such as porosity, mechanical strength, and biocompatibility. Furthermore, the review emphasizes recent innovations in surface modification techniques which improve bioactivity and osseointegration to enable scaffolds to mimic the host tissues. In addition, this review provides essential insights in related to the potential of SLM to be adopted in producing personalized and high-performance medical implants. By synthesizing the latest trends and identifying key areas for future research, this paper aims to serve as a vital resource for the advancement and usage of SLM-fabricated scaffolds in clinical applications. The findings underscore the importance of continued innovation in this field, which has the potential to significantly improve patient outcomes in orthopaedics and beyond.

Regarding the approval of novel pharmaceuticals, the most common reason for failure is inadequate oral drug bioavailability. Owing to the complex physiological milieu of the human intestine, which is characterized by its varied composition, various functions, and one-of-a-kind dynamic conditions, it is difficult to reproduce the organ in vitro. Traditional monolayers in two dimensions, sophisticated three-dimensional systems, and developing fluid-dynamic platforms are examples of in-vitro intestinal models. Caco-2 cells have been the gold standard for studying drug permeability for over two decades, particularly for BCS Class II/III/IV drugs. Other intestinal in vitro models exist; however, pharmaceutical corporations and regulatory authorities use the Caco-2 cell line to predict human intestinal permeability. To predict oral drug absorption and study normal intestinal epithelial physiology, it is necessary to have advanced technologies capable of creating human intestinal epithelial cells (hIECs) with cellular variety and functions. There is a strong link between the permeability data obtained in vitro and the fractions absorbed by humans in complex multicellular models. However, although microphysiological systems accurately replicate physiological cues of the digestive tract, they still require standardization. We critically reviewed a step towards tissue-created 3D intestinal organoids and 3D heterocellular multicompartmental models without compromising cellular variety and function. To bridge the gap between 2D and 3D intestinal culture models, a physiologically appropriate hIEC model provides a novel platform for patient-specific testing and translational applications. A comprehensive understanding of numerous 3D in-vitro models of inflammatory bowel disease has been discussed. Additionally, this review will provide insights into the benefits and limitations of these models and their relevance in understanding intestinal physiology and accelerating drug discovery through high-throughput screening.