No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Strategies in Electrospun Polymer and Hybrid Scaffolds for Enhanced Cell Integration and Vascularization for Bone Tissue Engineering and Organoids
Abstract
Addressing the demand for bone substitutes, tissue engineering responds to the high prevalence of orthopedic surgeries worldwide and the limitations of conventional tissue reconstruction techniques. Materials, cells, and growth factors constitute the core elements in bone tissue engineering, influencing cellular behavior crucial for regenerative treatments. Scaffold design, including architectural features and porosity, significantly impacts cellular penetration, proliferation, differentiation, and vascularization. This review discusses the hierarchical structure of bone and the process of neovascularization in the context of biofabrication of scaffolds. We focus on the role of electrospinning and its modifications in scaffold fabrication to improve scaffold properties to enhance further tissue regeneration, for example, by boosting oxygen and nutrient delivery. We highlight how scaffold design impacts osteogenesis and the overall success of regenerative treatments by mimicking the extracellular matrix (ECM). Additionally, we explore the emerging field of bone organoids—self‐assembled, three‐dimensional (3D) structures derived from stem cells that replicate native bone tissue's architecture and functionality. While bone organoids hold immense potential for modeling bone diseases and facilitating regenerative treatments, their main limitation remains insufficient vascularization. Hence, we evaluate innovative strategies for pre‐vascularization and discuss the latest techniques for assessing and improving vascularization in both scaffolds and organoids presenting the most commonly used cell lines and biological models. Moreover, we analyze cutting‐edge techniques for assessing vascularization, evaluating their advantages and drawbacks to propose complex solutions. Finally, by integrating these approaches, we aim to advance the development of bioactive materials that promote successful bone regeneration.
... Several methods can be used to create bone tissue scaffolds with tridimensional structures, such as the foam replica method, electrospinning, air jet spinning, freeze-drying, gas foaming, solvent casting/particulate leaching, phase separation, and molecular selfassembly [15,[18][19][20]. These include the foam replica method, electrospinning, air jet spinning, freeze-drying, gas foaming, solvent casting/particulate leaching, phase separation, and molecular self-assembly [15]. ...
Objectives: This study aimed to synthesize polylactic acid (PLA) nanofibrillar scaffolds loaded with ibuprofen (IBU) using electrospinning (ES) and air-jet spinning (AJS). The scaffolds were evaluated for their physicochemical properties, drug release profiles, and biocompatibility to assess their potential for local analgesic applications. Methods: Solutions of 10% (w/v) PLA combined with IBU at concentrations of 10%, 20%, and 30% were processed into nanofibrillar membranes using ES and AJS. The scaffolds were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transformed infrared (FT-IR) spectroscopy. The drug release profile was assessed by ultraviolet-visible spectrophotometry (UV-Vis), and cell adhesion and viability were evaluated using fibroblast culture assays. Statistical analyses included qualitative analyses, t-tests, and Likelihood ratio tests. Results: SEM revealed randomly arranged nanofibers forming reticulated meshes, with more uniform dimensions observed in the AJS group. TGA and DSC analyses confirmed the thermody-namic stability of the scaffolds and enthalpy changes consistent with IBU incorporation, which FT-IR and UV-Vis validated. Drug release was sustained over 384 h, showing no significant differences between ES and AJS scaffolds (p > 0.05). Cytotoxicity and cell viability assays confirmed scaffold biocompatibility, with cellular responses proportional to drug concentration but within safe limits. Conclusions: PLA-IBU nanofibrillar scaffolds were successfully synthesized using ES and AJS. Both methods yielded biocompatible systems with stable properties and controlled drug release. Further, in vivo studies are necessary to confirm their clinical potential.
3D printing is a promising technique for producing bone implants, but there is still a need to adjust efficiency, facilitate production, and improve biocompatibility. Porous materials have a proven positive effect on the regeneration of bone tissue, but their production is associated with numerous limitations. In this work, we described a simple method of producing polymer or polymer-ceramic filaments for 3D-printing scaffolds by adding micrometer-scale porous structures on scaffold surfaces. Scaffolds included polycaprolactone (PCL) as the primary polymer, β-tricalcium phosphate (β-TCP) as the ceramic filler, and poly(ethylene glycol) (PEG) as a porogen. The pressurized filament extrusion gave flexible filaments composed of PCL, β-TCP, and PEG, which are ready to use in fused filament fabrication (FFF) 3D printers. Washing of 3D-printed scaffolds in ethanol solution removed PEG and revealed a microporous structure and ceramic particles on the scaffold’s surfaces. Furthermore, 3D-printed materials exhibit good printing precision, no cytotoxic properties, and highly impact MG63 cell alignment. Although combining PCL, PEG, and β-TCP is quite popular, the presented method allows the production of porous scaffolds with a well-organized structure without advanced equipment, and the produced filaments can be used to 3D print scaffolds on a simple commercially available 3D printer.
Building 3D electrospun macrostructures and monitoring the biological activities inside them are challenging. In this study, 3D fibrous polycaprolactone (PCL) macrostructures were successfully fabricated using in-house 3D electrospinning. The main factors supporting the 3D self-assembled nanofiber fabrication are the H3PO4 additives, flow rate, and initial distance. The effects of solution concentration, solvent, H3PO4 concentration, flow rate, initial distance, voltage, and nozzle speed on the 3D macrostructures were examined. The optimal conditions of 4 mL/h flow rate, 4 cm initial nozzle–collector distance, 14 kV voltage, and 1 mm/s nozzle speed provided a rapid buildup of cylinder macrostructures with 6 cm of diameter, reaching a final height of 16.18 ± 2.58 mm and a wall thickness of 3.98 ± 1.01 mm on one perimeter with uniform diameter across different sections (1.40 ± 1.10 μm average). Oxygen plasma treatment with 30–50 W for 5 min significantly improved the hydrophilicity of the PCL macrostructures, proving a suitable scaffold for in vitro cell cultures. Additionally, 3D images obtained by synchrotron radiation X-ray tomographic microscopy (SRXTM) presented cell penetration and cell growth within the scaffolds. This breakthrough in 3D electrospinning surpasses current scaffold fabrication limitations, opening new possibilities in various fields.
The in vitro evaluation of 3D scaffolds for bone tissue engineering in mono-cultures is a common practice; however, it does not represent the native complex nature of bone tissue. Co-cultures of osteoblasts and osteoclasts, without the addition of stimulating agents for monitoring cellular cross-talk, remains a challenge. In this study, a growth factor-free co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and human peripheral blood mononuclear cells (hPBMCs) has been established and used for the evaluation of 3D-printed scaffolds for bone tissue engineering. The scaffolds were produced from PLLA/PCL/PHBV polymeric blends, with two composite materials produced through the addition of 2.5% w/v nanohydroxyapatite (nHA) or strontium-substituted nanohydroxyapatite (Sr-nHA). Cell morphology data showed that hPBMCs remained undifferentiated in co-culture, while no obvious differences were observed in the mono- and co-cultures of hBM-MSCs. A significantly increased alkaline phosphatase (ALP) activity and osteogenic gene expression was observed in co-culture on Sr-nHA-containing scaffolds. Tartrate-resistant acid phosphatase (TRAP) activity and osteoclastogenic gene expression displayed significantly suppressed levels in co-culture on Sr-nHA-containing scaffolds. Interestingly, mono-cultures of hPBMCs on Sr-nHA-containing scaffolds indicated a delay in osteoclasts formation, as evidenced from TRAP activity and gene expression, demonstrating that strontium acts as an osteoclastogenesis inhibitor. This co-culture study presents an effective 3D model to evaluate the regenerative capacity of scaffolds for bone tissue engineering, thus minimizing time-consuming and costly in vivo experiments.
Bone fracture healing is a challenging process, due to insufficient and slow tissue repair. Sufferers from bone fractures struggle with one-third of nonunion, display graft rejection, high-costed implantation, or chronic pain. Novel advances in tissue engineering presented promising options for this strain. Biomaterials for bone repair allow accelerated regeneration, osteoblastic cell activation, and enhanced bone remodeling. There is a wide range of biomaterials that are biocompatible, bioresorbable, and biodegradable and used for bone tissue regeneration, promoting osteoconductive and osteoinductive properties. The main aim of bone tissue engineering is to generate rapid and optimal functional bone regeneration through a combination of biomaterials, growth factors, cells, and various agents. Recently bone tissue engineering has been attracted to the use of bioactive glass scaffolds incorporated with polymers and patient-specific fabrication of the bone healing material by 3D bioprinting. There are promising future outcomes that were reported by several research. The present review provides an outlook for recent most common biomaterials in bone tissue engineering suggesting bone tissue engineering practices should have been proceeded to clinical application.
The osteochondral defects (OCDs) resulting from the treatment of giant cell tumors of bone (GCTB) often present two challenges for clinicians: tumor residue leading to local recurrence and non-healing of OCDs. Therefore, this study focuses on developing a double-layer PGPC-PGPH scaffold using shell-core structure nanofibers to achieve “spatiotemporal control” for treating OCDs caused by GCTB. It addresses two key challenges: eliminating tumor residue after local excision and stimulating osteochondral regeneration in non-healing OCD cases. With a shell layer of protoporphyrin IX (PpIX)/gelatin (GT) and inner cores containing chondroitin sulfate (CS)/poly(lactic-co-glycolic acid) (PLGA) or hydroxyapatite (HA)/PLGA, coaxial electrospinning technology was used to create shell-core structured PpIX/GT-CS/PLGA and PpIX/GT-HA/PLGA nanofibers. These nanofibers were shattered into nano-scaled short fibers, and then combined with polyethylene oxide and hyaluronan to formulate distinct 3D printing inks. The upper layer consists of PpIX/GT-CS/PLGA ink, and the lower layer is made from PpIX/GT-HA/PLGA ink, allowing for the creation of a double-layer PGPC-PGPH scaffold using 3D printing technique. After GCTB lesion removal, the PGPC-PGPH scaffold is surgically implanted into the OCDs. The sonosensitizer PpIX in the shell layer undergoes sonodynamic therapy to selectively damage GCTB tissue, effectively eradicating residual tumors. Subsequently, the thermal effect of sonodynamic therapy accelerates the shell degradation and release of CS and HA within the core layer, promoting stem cell differentiation into cartilage and bone tissues at the OCD site in the correct anatomical position. This innovative scaffold provides temporal control for anti-tumor treatment followed by tissue repair and spatial control for precise osteochondral regeneration.
Regeneration of damaged urethral tissue remains a major challenge in the field of lower urinary tract reconstruction. To address this issue, various synthetic and natural biodegradable biomaterials are currently being explored for the fabrication of scaffolds that promote urethral regeneration and healing. In this study, we present an approach to fabricate a trilayer hybrid scaffold comprising a central layer of poly(lactic acid) (PLA) between two layers of chitosan. The chitosan/PLA/chitosan (CPC) scaffolds were fabricated by a sequential electrospinning process and their properties were evaluated for their suitability for urethral tissue engineering. The physical and biological properties of the CPC scaffolds were evaluated in comparison to electrospun PLA scaffolds and acellular dermis (Alloderm) as controls for a synthetic and a natural scaffold, respectively. Compared to the controls, the CPC scaffolds exhibited higher elastic modulus and ultimate tensile strength, while maintaining extensibility and suture retention strength appropriate for clinical use. The CPC scaffolds displayed significant hydrophilicity, which was associated with a higher water absorption capacity of the chitosan nanofibres. The degradation products of the CPC scaffolds did not exhibit cytotoxicity and promoted wound closure by fibroblasts in vitro. In addition, CPC scaffolds showed increased growth of smooth muscle cells, an essential component for functional regeneration of urethral tissue. Furthermore, in a chicken embryo-based assay, CPC scaffolds demonstrated significantly higher angiogenic potential, indicating their ability to promote vascularisation, a crucial aspect for successful urethral reconstruction. Overall, these results suggest that CPC hybrid scaffolds containing both natural and synthetic components offer significant advantages over conventional acellular or synthetic materials alone. CPC scaffolds show promise as potential candidates for further research into the reconstruction of the urethra in vivo.
With the continuous development of nanomaterials, nanofibers prepared by electrospinning have gradually occupied people’s vision because of their unique advantages, such as crisscross network and extracellular matrix-mimicking structure, high drug loading efficiency, and sustained release kinetics. Traditionally, electrospun fibers are mainly used as filter materials, wound dressings, and tissue engineering scaffolds, while their wide applications are limited to cancer nanomedicine applications due to their dense network structure. In recent years, two-dimensional fiber membranes have been transformed into short fibers that can be reconstructed to form fibrous rings or microspheres for cancer theranostics. Herein, this paper provides an overview of the recent advances in the design of electrospun short fibers that retain the advantages of nanofibers with good dispersibility for different nanomedicine applications, including cancer cell capture, cancer treatments, and cancer theranostics. The rational preparation of electrospun short fibers that are available to boost the development of nanomedicine is also discussed.
Bone defects stemming from tumorous growths, traumatic events, and diverse conditions present a profound conundrum in clinical practice and research. While bone has the inherent ability to regenerate, substantial bone anomalies require bone regeneration techniques. Bone organoids represent a new concept in this field, involving the 3D self‐assembly of bone‐associated stem cells guided in vitro with or without extracellular matrix material, resulting in a tissue that mimics the structural, functional, and genetic properties of native bone tissue. Within the scientific panorama, bone organoids ascend to an esteemed status, securing significant experimental endorsement. Through a synthesis of current literature and pioneering studies, this review offers a comprehensive survey of the bone organoid paradigm, delves into the quintessential architecture and ontogeny of bone, and highlights the latest progress in bone organoid fabrication. Further, existing challenges and prospective directions for future research are identified, advocating for interdisciplinary collaboration to fully harness the potential of this burgeoning domain. Conclusively, as bone organoid technology continues to mature, its implications for both clinical and research landscapes are poised to be profound.
3D printing and electrospinning are used to fabricate complex structures with improved properties. Combining 3D printing and electrospinning potentially creates composite structures with even superior properties for biomedical applications. However, there is limited research, use, and literature on this synergy. While 3D printing is used extensively in the biomedical and pharmaceutical industries, the 3D printed polymer strength can be limited due to the high cooling rate during the printing process, resulting in a lack of crystallinity. Additives such as crosslinkers and reinforcements such as particles, nanomaterials, and fibers are often incorporated into the polymer melt to improve its properties. One promising reinforcement is electrospun nanofibers, which have high aspect ratios, specific surface area, and porosity. However, electrospinning can result in variability in fiber size and morphology.
Further research is needed to optimize the technique and improve its reproducibility. This perspective provides an assessment of this synergistic technology. This study explores the potential for biomedical applications while offering opinions on the most recent research combining 3D printing and electrospinning. The fact that effective 3D printing and electrospinning integration can generate a powerful platform to develop nanomaterials with superstructures highlights the high significance of this perspective.
Human trabecular meshwork is a sieve-like tissue with large pores, which plays a vital role in aqueous humor outflow. Dysfunction of this tissue can occur, which leads to glaucoma and permanent vision loss. Replacement of trabecular meshwork with a tissue-engineered device is the ultimate objective. This study aimed to create a biomimetic structure of trabecular meshwork using electrospinning. Conventional electrospinning was compared to cryogenic electrospinning, the latter being an adaptation of conventional electrospinning whereby dry ice is incorporated in the fiber collector system. The dry ice causes ice crystals to form in-between the fibers, increasing the inter-fiber spacing, which is retained following sublimation. Structural characterization demonstrated cryo-scaffolds to have closer recapitulation of the trabecular meshwork, in terms of pore size, porosity, and thickness. The attachment of a healthy, human trabecular meshwork cell line (NTM5) to the scaffold was not influenced by the fabrication method. The main objective was to assess cell infiltration. Cryo-scaffolds supported cell penetration deep within their structure after seven days, whereas cells remained on the outer surface for conventional scaffolds. This study demonstrates the suitability of cryogenic electrospinning for the close recapitulation of trabecular meshwork and its potential as a 3D in vitro model and, in time, a tissue-engineered device.
Adipose-derived mesenchymal stem cells (ADSCs) show poor survival after transplantation, limiting their clinical application. In this study, a series of Poly(l-lactide-co-ε-caprolactone) (PLCL)/acellular dermal matrix (ADM) nanofiber scaffolds with different proportions were prepared by electrospinning. By studying their morphology, hydrophilicity, tensile mechanics, and biocompatibility, PLCL/ADM nanofiber scaffolds with the best composition ratio (PLCL:ADM = 7:3) were selected to prepare short nanofibers. And based on this, injectable Gelatin methacryloyl (GelMA) hydrogel loaded with PLCL/ADM short nanofibers (GelMA-Fibers) was constructed as a transplantation vector of ADSCs. ADSCs and GelMA-Fibers were co-cultured, and the optimal loading concentration of PLCL/ADM nanofibers was investigated by cell proliferation assay, live/dead cell staining, and cytoskeleton staining in vitro. In vivo investigations were also performed by H&E staining, Oil red O staining, and TUNEL staining, and the survival and apoptosis rates of ADSCs transplanted in vivo were analyzed. It was demonstrated that GelMA-Fibers could effectively promote the proliferation of ADSCs in vitro. Most importantly, GelMA-Fibers increased the survival rate of ADSCs transplantation and decreased their apoptosis rate within 14 days. In conclusion, the constructed GelMA-Fibers would provide new ideas and options for stem cell tissue engineering and stem cell-based clinical therapies.
The escalating prevalence of anterior cruciate ligament (ACL) injuries in sports necessitates innovative strategies for ACL reconstruction. In this study, we propose a multiphasic bone-ligament-bone (BLB) integrated scaffold as a potential solution. The BLB scaffold comprised two polylactic acid (PLA)/deferoxamine (DFO)@mesoporous hydroxyapatite (MHA) thermally induced phase separation (TIPS) scaffolds bridged by silk fibroin (SF)/connective tissue growth factor (CTGF)@Poly(l-lactide-co-ε-caprolactone) (PLCL) nanofiber yarn braided scaffold. This combination mimics the native architecture of the ACL tissue. The mechanical properties of the BLB scaffolds were determined to be compatible with the human ACL. In vitro experiments demonstrated that CTGF induced the expression of ligament-related genes, while TIPS scaffolds loaded with MHA and DFO enhanced the osteogenic-related gene expression of bone marrow stem cells (BMSCs) and promoted the migration and tubular formation of human umbilical vein endothelial cells (HUVECs). In rabbit models, the BLB scaffold efficiently facilitated ligamentization and graft-bone integration processes by providing bioactive substances. The double delivery of DFO and calcium ions by the BLB scaffold synergistically promoted bone regeneration, while CTGF improved collagen formation and ligament healing. Collectively, the findings indicate that the BLB scaffold exhibits substantial promise for ACL reconstruction. Additional investigation and advancement of this scaffold may yield enhanced results in the management of ACL injuries.
3D organoids have been widely used as tractable in vitro models capable of elucidating aspects of human development and disease. However, the manual and low throughput culture methods coupled with a low reproducibility and geometric heterogeneity restricts the scope and application of organoid research. Combining expertise from stem cell biology and bioengineering offers a promising approach to address some of these limitations. Here, we use melt electrospinning writing to generate tuneable grid scaffolds that can guide the self‐organization of pluripotent stem cells into patterned arrays of embryoid bodies. We show that grid geometry is a key determinant of stem cell self‐organization, guiding the position and size of emerging lumens via curvature‐controlled tissue growth. We report two distinct methods for culturing scaffold‐grown embryoid bodies into either interconnected or spatially discrete cerebral organoids. These scaffolds provide a high‐throughput method to generate, culture and analyse large numbers of organoids, substantially reducing the time investment and manual labour involved in conventional methods of organoid culture. We anticipate that this methodological development will open up new opportunities for guiding pluripotent stem cell culture, studying lumenogenesis, and generating large numbers of uniform organoids for high throughput screening.
This article is protected by copyright. All rights reserved
Current design strategies for biomedical tissue scaffolds are focused on multifunctionality to provide beneficial microenvironments to support tissue growth. We have developed a simple yet effective approach to create core-shell fibers of poly(3-hydroxybuty-rate-co-3-hydroxyvalerate) (PHBV), which are homogenously covered with titanium dioxide (TiO2) nanoparticles. Unlike the blend process, co-axial electrospinning enabled the uniform distribution of nanoparticles without the formation of large aggregates. We observed 5 orders of magnitude reduction in Escherichia coli survival after contact with electrospun scaffolds compared to the non-material control. In addition, our hybrid cores-shell structure supported significantly higher osteoblast proliferation after 7 days of cell culture and profound generation of 3D networked collagen fibers after 14 days. The organic-inorganic composite scaffold produced in this study demonstrates a unique combination of antibacterial properties and increased bone regeneration properties. In summary, the multifunctionality of the presented core-shell cPHBV+sTiO2 scaffolds shows great promise for biomedical applications.
Rapid advancements in traditional bone tissue engineering have led to innovation in bone repair models and the resolution of insurmountable clinical issues like graft scarcity. The pathophysiological process of treating bone disease, however, is a multidimensional and multimodal regenerative regulatory mechanism that includes numerous immune, inflammatory, or metabolic responses related to the graft or the organism itself. Based on a 3D in vitro cell culture system that is remarkably identical to the body's bone tissue, the bone organoid is a biomimicking bone organ environment. It can accurately mimic the actual repair and regeneration condition in vivo because it shares the same physiological function, structure, morphology, and metabolic process as endogenous bone tissue. As a disruptive regenerative medicine technology, it has wide application prospects in the fields of organ development, gene editing, disease modeling, and precision therapy. Herein, the development process and physiological basis of different cell‐based bone organoids are reviewed, the current status of the application of different materials, cells, and construction methods for building bone organoids is described, and the prospects and challenges for the development of bone organoids in future medical fields is discussed.
Bone is a highly vascularized organ that not only plays multiple roles in supporting the body and organs but also endows the microstructure, enabling distinct cell lineages to reciprocally interact. Recent studies have uncovered relevant roles of the bone vasculature in bone patterning, morphogenesis, homeostasis, and pathological bone destruction, including osteoporosis and tumor metastasis. This review provides an overview of current topics in the interactive molecular events between endothelial cells and bone cells during bone ontogeny and discusses the future direction of this research area to find novel ways to treat bone diseases.
Organoids are biomimetic tissue analogs that are generated via the self‐organization of stem cells or adult cells relying on developmental biology principles. They present tissue‐specific structures and functional complexity, bridging the gap between planar cell culture and animal models to accelerate the applications of drug testing, tissue engineering and regenerative medicine. However, the current organoids are still limited in long‐term culture, maturation, complexities and functionalities due largely to the lack of vascularization in the analogs. Herein, we give an overview of the latest development of vascularization in the organoid field. We first provide two typical strategies of self‐assembly and engineering to perform and realize the vascularization in engineering organoids, as well as the crucial factors affecting vasculogenesis. Then, we describe the representative applications using vascularized organoids in biomedical fields. Finally, we discuss the challenges and future perspectives in the development of advanced biomaterials and modified approaches toward building vascularized organoids with higher fidelity and functionality.
Bone is one of the key components of the musculoskeletal system. Bone and joint disease are the fourth most widespread disease, in addition to cardiovascular disease, cancer, and diabetes, which seriously affect people’s quality of life. Bone organoids seem to be a great model by which to promote the research method, which further could improve the treatment of bone and joint disease in the future. Here, we introduce the various bone and joint diseases and their biology, and the conditions of organoid culture, comparing the in vitro models among 2D, 3D, and organoids. We summarize the differing potential methods for culturing bone-related organoids from pluripotent stem cells, adult stem cells, or progenitor cells, and discuss the current and promising bone disease organoids for drug screening and precision medicine. Lastly, we discuss the challenges and difficulties encountered in the application of bone organoids and look to the future in order to present potential methods via which bone organoids might advance organoid construction and application.
Mechanical processing of cortical bone tissue is one of the most common surgical procedures. A critical issue accompanying this processing is the condition of the surface layer, which can stimulate tissue growth and serve as a drug carrier. A comparison of the surface condition before and after orthogonal and abrasive processing was conducted to validate the influence of bone tissue’s processing mechanism and orthotropic properties on the surface topography. A cutting tool with a defined geometry and a custom-made abrasive tool was used. The bone samples were cut in three directions, depending on the orientation of the osteons. The cutting forces, acoustic emission, and surface topography were measured. The level of isotropy and the topography of the grooves showed statistical differences relative to the anisotropy directions. After orthogonal processing, the surface topography parameter Ra was determined from 1.38 ± 0.17 μm to 2.82 ± 0.32. In the case of abrasive processing, no correlation was found between the orientation of osteons and topographical properties. The average groove density for abrasive machining was below 1004 ± 0.7, and for orthogonal, it was above 1156 ± 58. Due to the positive properties of the developed bone surface, it is advisable to cut in the transverse direction and parallel to the axis of the osteons.
Critical-sized bone defects are a challenging issue during bone regeneration. Bone tissue engineering is aimed to repair such defects using biomimicking scaffolds and stem cells. Electrospinning allows the fabrication of biocompatible, biodegradable, and strengthened scaffolds for bone regeneration. Natural and synthetic polymers, alone or in combination, have been employed to fabricate scaffolds with appropriate properties for the osteogenic differentiation of stem cells. Dental pulps are rich in stem cells, and dental pulp stem cells (DPSCs) have a high capacity for proliferation, differentiation, immunomodulation, and trophic factor expression. Researchers have tried to enhance osteogenesis through scaffold modification approaches, including incorporation or coating with mineral, inorganic materials, and herbal extract components. Among them, the incorporation of nanofibers with hyaluronic acid (HA) has been widely used to promote osteogenesis. In this review, the electrospun scaffolds and their modifications used in combination with DPSCs for bone regeneration are discussed.
Introduction
Hyperbaric oxygen therapy (HBOT) is one of the common clinical treatments, but adverse effects have hampered and limited the clinical application and promotion of hyperbaric oxygen therapy. A systematic review and meta-analysis of the adverse effects of hyperbaric oxygen therapy have conducted by our group to provide a theoretical basis for clinical treatment.
Methods
Three electronic databases (PubMed, Web of Science, and The Cochrane Library) were comprehensively searched for randomized clinical trials (RCTs) from March 2012 to October 2022. Two reviewers independently screened titles and abstracts for eligibility and assessed the quality of the included studies. The meta-analysis was performed using RevMan 5.3.
Results
A total of 24 RCTs involving 1,497 participants were identified. ① The HBOT group reported more adverse effects (30.11% vs. 10.43%, p < 0.05). ② The most frequent side effect of HBOT is ear discomfort (113 cases). ③ When the course of hyperbaric oxygen was >10 sessions, the incidence of adverse effects was higher than that of the control group; when the course of HBOT was ≤10 sessions, the adverse effects caused by hyperbaric oxygen were comparatively lower. ④ When the chamber pressure is above 2.0 ATA, the incidence of adverse effects is higher than that of the control group. While the chamber pressure is lower than 2.0 ATA, HBOT is relatively safe compared with the previous one.
Conclusion
Hyperbaric oxygen therapy (HBOT) is more likely to cause adverse reactions when the chamber pressure is above 2.0 ATA. More attention should be paid to the possible occurrence of related adverse effects if the treatment course is >10 sessions.
Systematic review registration
https://www.crd.york.ac.uk/PROSPERO/ , identifier CRD42022316605.
The application of mechanical stimulation on bone tissue engineering constructs aims to mimic the native dynamic nature of bone. Although many attempts have been made to evaluate the effect of applied mechanical stimuli on osteogenic differentiation, the conditions that govern this process have not yet been fully explored. In this study, pre-osteoblastic cells were seeded on PLLA/PCL/PHBV (90/5/5 wt.%) polymeric blend scaffolds. The constructs were subjected every day to cyclic uniaxial compression for 40 min at a displacement of 400 μm, using three frequency values, 0.5, 1, and 1.5 Hz, for up to 21 days, and their osteogenic response was compared to that of static cultures. Finite element simulation was performed to validate the scaffold design and the loading direction, and to assure that cells inside the scaffolds would be subjected to significant levels of strain during stimulation. None of the applied loading conditions negatively affected the cell viability. The alkaline phosphatase activity data indicated significantly higher values at all dynamic conditions compared to the static ones at day 7, with the highest response being observed at 0.5 Hz. Collagen and calcium production were significantly increased compared to static controls. These results indicate that all of the examined frequencies substantially promoted the osteogenic capacity.
This research aimed at designing and fabricating a smart thermosensitive injectable methylcellulose/ agarose hydrogel system loaded with short electrospun bioactive PLLA/laminin fibers as a scaffold for tissue engineering applications or 3D cell culture models. Considering ECM-mimicking morphology and chemical composition, such a scaffold is capable of ensuring a hospitable environment for cell adhesion, proliferation, and differentiation. Its viscoelastic properties are beneficial from the practical perspective of minimally invasive materials that are introduced to the body via injection. Viscosity studies showed the shear-thinning character of MC/AGR hydrogels enabling the potential injection ability of highly viscous materials. Injectability tests showed that by tuning the injection rate, even a high amount of short fibers loaded inside of hydrogel could be efficiently injected into the tissue. Biological studies showed the non-toxic character of composite material with excellent viability, attachment, spreading, and proliferation of fibroblasts and glioma cells. These findings indicate that MC/AGR hydrogel loaded with short PLLA/ laminin fibers is a promising biomaterial for both tissue engineering applications and 3D tumor culture models.
With increased diabetes incidence, diabetic wound healing is one of the most common diabetes complications and is characterized by easy infection, chronic inflammation, and reduced vascularization. To address these issues, biomaterials with multifunctional antibacterial, immunomodulatory, and angiogenic properties must be developed to improve overall diabetic wound healing for patients. In our study, we prepared porous poly (L-lactic acid) (PLA) nanofiber membranes using electrospinning and solvent evaporation methods. Then, sulfated chitosan (SCS) combined with polydopamine-gentamicin (PDA-GS) was stepwise modified onto porous PLA nanofiber membrane surfaces. Controlled GS release was facilitated via dopamine self-polymerization to prevent early stage infection. PDA was also applied to PLA nanofiber membranes to suppress inflammation. In vitro cell tests results showed that PLA/SCS/PDA-GS nanofiber membranes immuomodulated macrophage toward the M2 phenotype and increased endogenous vascular endothelial growth factor secretion to induce vascularization. Moreover, SCS-contained PLA nanofiber membranes also showed good potential in enhancing macrophage trans-differentiation to fibroblasts, thereby improving wound healing processes. Furthermore, our in vitro antibacterial studies against Staphylococcus aureus indicated the effective antibacterial properties of the PLA/SCS/PDA-GS nanofiber membranes. In summary, our novel porous PLA/SCS/PDA-GS nanofiber membranes possessing enhanced antibacterial, anti-inflammatory, and angiogenic properties demonstrate promising potential in diabetic wound healing processes.
Prior research establishing that bone interacts in coordination with the bone marrow microenvironment (BMME) to regulate hematopoietic homeostasis was largely based on analyses of individual bone-associated cell populations. Recent advances in intravital imaging has suggested that the expansion of hematopoietic stem cells (HSCs) and acute myeloid leukemia cells is restricted to bone marrow microdomains during a distinct stage of bone remodeling. These findings indicate that dynamic bone remodeling likely imposes additional heterogeneity within the BMME to yield differential clonal responses. A holistic understanding of the role of bone remodeling in regulating the stem cell niche and how these interactions are altered in age-related hematological malignancies will be critical to the development of novel interventions. To advance this understanding, herein, we provide a synopsis of the cellular and molecular constituents that participate in bone turnover and their known connections to the hematopoietic compartment. Specifically, we elaborate on the coupling between bone remodeling and the BMME in homeostasis and age-related hematological malignancies and after treatment with bone-targeting approaches. We then discuss unresolved questions and ambiguities that remain in the field.
With a history of more than 100 years of different applications in various scientific fields, the chicken chorioallantoic membrane (CAM) assay has proven itself to be an exceptional scientific model that meets the requirements of the replacement, reduction, and refinement principle (3R principle). As one of three extraembryonic avian membranes, the CAM is responsible for fetal respiration, metabolism, and protection. The model provides a unique constellation of immunological, vascular, and extracellular properties while being affordable and reliable at the same time. It can be utilized for research purposes in cancer biology, angiogenesis, virology, and toxicology and has recently been used for biochemistry, pharmaceutical research, and stem cell biology. Stem cells and, in particular, mesenchymal stem cells derived from adipose tissue (ADSCs) are emerging subjects for novel therapeutic strategies in the fields of tissue regeneration and personalized medicine. Because of their easy accessibility, differentiation profile, immunomodulatory properties, and cytokine repertoire, ADSCs have already been established for different preclinical applications in the files mentioned above. In this review, we aim to highlight and identify some of the cross-sections for the potential utilization of the CAM model for ADSC studies with a focus on wound healing and tissue engineering, as well as oncological research, e.g., sarcomas. Hereby, the focus lies on the combination of existing evidence and experience of such intersections with a potential utilization of the CAM model for further research on ADSCs.
Citation: Abdelaziz, A.G.; Nageh, H.; Abdo, S.M.; Abdalla, M.S.; Amer, A.A.; Abdal-hay, A.; Barhoum, A. A
Abstract: Over the last few years, biopolymers have attracted great interest in tissue engineering and regenerative medicine due to the great diversity of their chemical, mechanical, and physical properties for the fabrication of 3D scaffolds. This review is devoted to recent advances in synthetic and natural polymeric 3D scaffolds for bone tissue engineering (BTE) and regenerative therapies. The review comprehensively discusses the implications of biological macromolecules, structure, and composition of polymeric scaffolds used in BTE. Various approaches to fabricating 3D BTE scaffolds are discussed, including solvent casting and particle leaching, freeze-drying, thermally induced phase separation, gas foaming, electrospinning, and sol-gel techniques. Rapid prototyping technologies such as stereolithography, fused deposition modeling, selective laser sintering, and 3D bioprinting are also covered. The immunomodulatory roles of polymeric scaffolds utilized for BTE applications are discussed. In addition, the features and challenges of 3D polymer scaffolds fabricated using advanced additive manufacturing technologies (rapid prototyping) are addressed and compared to conventional subtractive manufacturing techniques. Finally, the challenges of applying scaffold-based BTE treatments in practice are discussed in-depth.
Tissue organoids hold enormous potential as tools for a variety of applications, including disease modeling and drug screening. To effectively mimic the native tissue environment, it is critical to integrate a microvasculature with the parenchyma and stroma. In addition to providing a means to physiologically perfuse the organoids, the microvasculature also contributes to the cellular dynamics of the tissue model via the cells of the perivascular niche, thereby further modulating tissue function. In this review, we discuss current and developing strategies for vascularizing organoids, consider tissue-specific vascularization approaches, discuss the importance of perfusion, and provide perspectives on the state of the field.
Electrospinning is a promising approach for the development of fibrous tissue engineering (TE) scaffolds suitable for hard and soft tissues. Apart from physicomechanical properties, electrospun fibers are required to incorporate bioactive cues to control cellular functions, including facilitating biomineralization and osteogenic differentiation in case of bone TE, as well as vascularization, to support successful tissue regeneration. In recent years, bioactive glass (BG) addition to electrospun biopolymer fibers has shown promising results in enhancing the properties of fibers, including the improvement of biological performance. In this article, a comprehensive overview of BG‐containing electrospun polymer composite fibers is presented, identifying the parameters that affect the mechanical properties as well as the biological response in vivo and in vitro. Subsequently, the effects of BG addition on the properties of the scaffolds are discussed. Recent developments in the fields of bone regeneration, wound healing, and drug delivery using BG‐containing electrospun fibrous scaffolds are described in detail. Essential aspects related to BG‐polymer composite fibers for translational research in TE are highlighted for future research in this field.
Human organoid model systems have changed the landscape of developmental biology and basic science. They serve as a great tool for human specific interrogation. In order to advance our organoid technology, we aimed to test the compatibility of a piezoelectric material with organoid generation, because it will create a new platform with the potential for sensing and actuating organoids in physiologically relevant ways. We differentiated human pluripotent stem cells into spheroids following the traditional human intestinal organoid (HIO) protocol atop a piezoelectric nanofiber scaffold. We observed that exposure to the biocompatible piezoelectric nanofibers promoted spheroid morphology three days sooner than with the conventional methodology. At day 28 of culture, HIOs grown on the scaffold appeared similar. Both groups were readily transplantable and developed well-organized laminated structures. Graft sizes between groups were similar. Upon characterizing the tissue further, we found no detrimental effects of the piezoelectric nanofibers on intestinal patterning or maturation. Furthermore, to test the practical feasibility of the material, HIOs were also matured on the nanofiber scaffolds and treated with ultrasound, which lead to increased cellular proliferation which is critical for organoid development and tissue maintenance. This study establishes a proof of concept for integrating piezoelectric materials as a customizable platform for on-demand electrical stimulation of cells using remote ultrasonic waveforms in regenerative medicine.
Electrospinning technology has recently attracted increased attention in the biomedical field, and preparing various cellulose nanofibril membranes for periodontal tissue regeneration has unique advantages. However, the characteristics of using a single material tend to make it challenging to satisfy the requirements for a periodontal barrier film, and the production of composite fibrous membranes frequently impacts the quality of the final fiber membrane due to the influence of miscibility between different materials. In this study, nanofibrous membranes composed of polylactic acid (PLA) and polycaprolactone (PCL) fibers were fabricated using side-by-side electrospinning. Different concentrations of gelatin were added to the fiber membranes to improve their hydrophilic properties. The morphological structure of the different films as well as their composition, wettability and mechanical characteristics were examined. The results show that PCL/PLA dual-fibrous composite membranes with an appropriate amount of gelatin ensures sufficient mechanical strength while obtaining improved hydrophilic properties. The viability of L929 fibroblasts was evaluated using CCK-8 assays, and cell adhesion on the scaffolds was confirmed by scanning electron microscopy and by immunofluorescence assays. The results demonstrated that none of the fibrous membranes were toxic to cells and the addition of gelatin improved cell adhesion to those membranes. Based on our findings, adding 30% gelatin to the membrane may be the most appropriate content for periodontal tissue regeneration, considering the scaffold’s mechanical qualities, hydrophilic properties and biocompatibility. In addition, the PCL-gelatin/PLA-gelatin dual-fibrous membranes prepared using side-by-side electrospinning technology have potential applications for tissue engineering.
Core–shell structure is a concentric circle structure found in nature. The rapid development of electrospinning technology provides more approaches for the production of core–shell nanofibers. The nanoscale effects and expansive specific surface area of core–shell nanofibers can facilitate the dissolution of drugs. By employing ingenious structural designs and judicious polymer selection, specialized nanofiber drug delivery systems can be prepared to achieve controlled drug release. The synergistic combination of core–shell structure and materials exhibits a strong strategy for enhancing the drug utilization efficiency and customizing the release profile of drugs. Consequently, multi‐chamber core–shell nanofibers hold great promise for highly efficient disease treatment. However, little attention concentration is focused on the effect of multi‐chamber core–shell nanofibers on controlled release of drugs. In this review, we introduced different fabrication techniques for multi‐chamber core–shell nanostructures, including advanced electrospinning technologies and surface functionalization. Subsequently, we reviewed the different controlled drug release behaviors of multi‐chamber core–shell nanofibers and their potential needs for disease treatment. The comprehensive elucidation of controlled release behaviors based on electrospun multi‐chamber core–shell nanostructures could inspire the exploration of novel controlled delivery systems. Furthermore, once these fibers with customizable drug release profiles move toward industrial mass production, they will potentially promote the development of pharmacy and the treatment of various diseases.
This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies
This study aims to develop, characterize, and evaluate the best statin‐loaded Collagen Silver nanoparticle‐coated polycaprolactone nanofibers by electrospinning technique. The characterization and evaluation results reveal that nanofibers had shown an aligned Collagen Silver nanoparticle‐coated polycaprolactone nanofibers distribution of fibers and aliment of collagen and silver nanoparticle coating material on the surface of the nanofibers. Furthermore, the electrospun nanofibers have shown no interaction between the drug and collagen and PCL polymeric material and have demonstrated controlled drug release for 360 h and significant degradation for 60 days of the study. In vitro, among the nanofiber treatment groups and the control groups, Pravastatin Collagen Silver nanoparticle‐coated polycaprolactone nanofibers have shown cell proliferation and migration of NHDF cells and blood vessel development in the CAM assay and potential anti‐bacterial activity against S. aureus and E. coli . In vivo, the Pravastatin Collagen Silver nanoparticle‐coated polycaprolactone nanofibers have demonstrated improved wound recovery, re‐epithelization, fibroblast cell proliferation, angiogenesis, and ECM remodeling and enhanced VEGF‐sprouting in the excised tissues of streptozotocin‐induced diabetic rats for 7, 14, and 21 days of the study. Therefore, the developed Pravastatin Collagen Silver nanoparticle‐coated polycaprolactone nanofibers could be a promising wound‐dressing platform for effectively treating and managing diabetic wounds.
Highlights
Nanofiber wound dressings provide numerous structural features in biomaterials.
Polycaprolactone can release the repurposed statin molecules into the wound site in a controlled manner.
In diabetic wounds, ECM tissue remodeling stimulates repair and vessel growth.
Pravastatin has been demonstrated to improve angiogenesis and ECM secretion for wound healing in diabetic conditions.
Aim:
Silk fibroin/chitosan/ZnO/Astragalus arbusculinus (Ast) gum fibrous scaffolds along with adipose-derived mesenchymal stem cells (ADSCs) were investigated for accelerating diabetic wound healing.
Methods:
Scaffolds with a core-shell structure and different compositions were synthesized using the electrospinning method. Biological in vitro investigations included antibacterial testing, cell viability analysis and cell attachment evaluation. In vivo experiments, including the chicken chorioallantoic membrane (CAM) test, were conducted to assess wound-healing efficacy and histopathological changes.
Results:
The incorporation of Ast to the silk fibroin@ chitosan/ZnO scaffold improved wound healing in diabetic mice. In addition, seeding of ADSCs on the scaffold accelerated wound healing.
Conclusion:
These findings suggest that the designed scaffold can be useful for skin regeneration applications.
Nanofiber membranes (NFMs), which have an extracellular matrix (ECM)‐mimicking structure and unique physical properties, have garnered great attention as biomimetic materials for developing physiologically relevant in vitro organ/tissue models. Recent progress in NFM fabrication techniques immensely contributed to the development of NFM‐based cell culture platforms for constructing physiological organ/tissue models. However, despite the significance of the NFM fabrication technique, an in‐depth discussion of the fabrication technique and its future aspect was insufficient. This review provides an overview of the current state‐of‐the‐art of NFM fabrication techniques from electrospinning techniques to post‐processing techniques for the fabrication of various types of NFM‐based cell culture platforms. Moreover, the advantages of the NFM‐based culture platforms in the construction of organ/tissue models are discussed especially for tissue barrier models, spheroids/organoids, and biomimetic organ/tissue constructs. Finally, the review concludes with perspectives on challenges and future directions for fabrication and utilization of NFMs.
This article is protected by copyright. All rights reserved
Successful regeneration of critical-size defects remains one of the significant challenges in regenerative engineering. These large-scale bone defects are difficult to regenerate and are often reconstructed with matrices that do not provide adequate oxygen levels to stem cells involved in the regeneration process. Hypoxia-induced necrosis predominantly occurs in the center of large matrices since the host tissue's local vasculature fails to provide sufficient nutrients and oxygen. Indeed, utilizing oxygen-generating materials can overcome the central hypoxic region, induce tissue in-growth, and increase the quality of life for patients with extensive tissue damage. This article reviews recent advances in oxygen-generating biomaterials for translational bone regenerative engineering. We discussed different oxygen-releasing and delivery methods, fabrication methods for oxygen-releasing matrices, biology, oxygen's role in bone regeneration, and emerging new oxygen delivery methods that could potentially be used for bone regenerative engineering.
Human Adipose‐Derived Mesenchymal Stem/Stromal Cells (hAD‐MSCs) have great potential for tissue regeneration. Since transplanted hAD‐MSCs are likely to be placed in a hypoxic environment, culturing the cells under hypoxic conditions might improve their post‐transplantation survival and regenerative performance. The combination of hAD‐MSCs and PCL‐nHA nanofibers synergically improves the contribution of both components for osteoblast differentiation. In this work, we hypothesized that this biomaterial constitutes a hypoxic environment for hAD‐MSCs. We studied the cellular re‐arrangement and the subcellular ultrastructure by Transmission Electron Microscopy (TEM of hAD‐MSCs grown into PCL‐nHA nanofibers, and we compared them with the same cells grown in 2D cultures, over tissue culture‐treated plastic, or glass coverslips. Among the most evident changes, PCL‐nHA grown cells showed enlarged mitochondria, and accumulation of glycogen granules, consistent with a hypoxic environment. We observed a 3,5 upregulation (p = 0.0379) of Hypoxia Inducible Factor (HIF‐1A gene expression in PCL‐nHA grown cells. This work evidences for the first time intra‐cellular changes in 3D compared to 2D cultures, which are adaptive responses of the cells to an environment more closely resembling that of the in vivo niche after transplantation, thus PCL‐nHA nanofibers are adequate for hAD‐MSCs pre‐conditioning. This article is protected by copyright. All rights reserved