Scaffold Fabrication Techniques of Biomaterials for Bone Tissue Engineering: A Critical Review

Recent progress in alginate-based nanocomposites for bone tissue engineering applications

Approximately 5-10 % of fractures are associated with non-union, posing a significant challenge in orthopedic applications. Addressing this issue, innovative approaches beyond traditional grafting techniques like bone tissue engineering (BTE) are required. Biomaterials, combined with cells and bioactive molecules in BTE, are critical in managing non-union. Alginate, a natural polysaccharide, has gained widespread recognition in bone regeneration due to its bioavailability, its ability to form gels through crosslinking with divalent cations, and its cost-effectiveness. However, its inherent mechanical weaknesses necessitate a combinatorial approach with other biomaterials. In recent years, nanoscale biomaterials have gained prominence for bone regeneration due to their structural and compositional resemblance to natural bone, offering a supportive environment that regulates cell proliferation and differentiation for new bone formation. In this review, we briefly outline the synthesis of alginate-based nanocomposites using different fabrication techniques, such as hydrogels, 3D-printed scaffolds, fibers, and surface coatings with polymer, ceramic, carbon, metal, or lipid-based nanoparticles. These alginate-based nanocomposites elicit angiogenic, antibacterial, and immunomodulatory properties, thereby enhancing the osteogenic potential as an insightful measure for treating non-union. Despite the existence of similar literature, this work delivers a recent and focused examination of the latest advancements and insights on the potential of alginate-based nanocomposites for BTE applications. This review also underscores the obstacles that alginate-based nanocomposites must overcome to successfully transition into clinical applications.

Nano-Hydroxyapatite/Poly(methyl methacrylate) Composite Bone Scaffold: Surfactant Surface Effects

In this study, poly(methyl methacrylate) (PMMA) nanofiber scaffolds reinforced with synthesized nano-hydroxyapatite (n-HA) were fabricated through electrospinning to enhance their potential for applications in bone tissue engineering. Sodium tripolyphosphate (STTP) was utilized as a surfactant to achieve a uniform distribution of particles and improve the structural integrity of the scaffolds. PMMA solutions were prepared at concentrations of the addition of STTP effectively stabilized n-HA dispersion, leading to enhanced fiber morphology, as confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The PMMA_10_HA_S nanofibers demonstrated a homogeneous fiber distribution with an average diameter of 345.40 ± 53.55 nm and a calcium content of 7.1%. Mechanical testing revealed that adding STTP enhanced the mechanical properties, with the n-HA-reinforced 10 wt.% PMMA nanofibers achieving a maximum tensile stress of 4.16 ± 2.13 MPa and an elongation of 7.1 ± 1.95%. Furthermore, cell cytotoxicity assays of different concentrations (25, 50, 75, and 100 mg/mL) using L929 fibroblast cells demonstrated no cytotoxic effect of PMMA_10_HA_S nanofibers. These findings, reinforced by STTP and n-HA, highlight the potential of PMMA_10_HA_S nanofiber scaffolds as promising candidates for bone tissue applications.

Application of Hydroxyapatite Composites in Bone Tissue Engineering: A Review

The treatment of bone defects is complicated by clinical conditions, such as trauma, tumor resection, and infection, which result in defects and impair the bone's regenerative capacity. Hydroxyapatite (HAp), the primary inorganic component of bone, possesses good biocompatibility and osteoconductivity. However, it has poor mechanical properties, a slow degradation rate, and limited functionality, necessitating combination with other materials to broaden its application scope. This paper summarizes the importance and properties of HAp composites and provides a categorized review of current research on HAp composites in bone tissue engineering. These composite scaffolds not only offer excellent mechanical support for cell growth and tissue regeneration but also facilitate new bone formation and vascularization. Additionally, the challenges faced by HAp composites, such as material property optimization and improvement of preparation techniques, are discussed. The paper also summarizes the applications of HAp composites in bone defect repair, dental implants, spinal fusion, and other fields.

Asiaticoside-Loaded Multifunctional Bioscaffolds for Enhanced Hyperglycemic Wound Healing

The review explores the potential of asiaticoside-loaded bioscaffolds to improve the management of hyperglycemic wounds, particularly diabetic foot ulcers (DFUs). Asiaticoside, sourced from Centella asiatica, possesses properties that address DFUs' healing challenges: insufficient angiogenesis, persistent inflammation, and delayed tissue regeneration. By incorporating asiaticoside into bioscaffold 3D designs including hydrogels, microneedle arrays, and nanofibrous meshes, therapeutic efficacy is optimized. This review examines the mechanisms of asiaticoside in wound healing (collagen production, angiogenesis modulation, inflammation reduction, and cell migration and proliferation) based on in vitro and in vivo studies. Asiaticoside also demonstrates synergistic abilities with other biomaterials, creating the possibility of more effective therapies. While preclinical research is promising, clinical trials are crucial to evaluate the efficacy and safety of asiaticoside-loaded bioscaffolds in patients with DFUs. Asiaticoside-loaded bioscaffolds are a significant development in wound healing and may aid in treating hyperglycemic wound complications. Their ability to offer individualized treatment plans has the potential to enhance the quality of life of those who suffer from diabetes. This review is based on a thorough literature search (2019-2024) across multiple databases, excluding secondary literature and non-English articles.

Advances in additive manufacturing for bone tissue engineering: materials, design strategies, and applications

The growing annual demand for bone grafts and artificial implants emphasizes the need for effective solutions to repair or replace injured bones. Additive manufacturing technology offers unique merits for advancing bone tissue engineering (BTE), enabling the creation of scaffolds and implants with customized shapes and designs, interconnected architecture, controlled mechanical properties and compositions, and broadening its range of applications. It overcomes the limitations of traditional manufacturing methods such as electrospinning, salt leaching, freeze drying, solvent casting etc. This review highlights additive manufacturing technologies and their applications in BTE, as well as materials and scaffold architectures to widen the potential of the biomedical sector. The selection of optimal printing methods for BTE requires careful consideration of the advantages and disadvantages against the needs for degradation, strength, and biocompatibility. Material extrusion and powder bed fusion techniques are the most widely used additive manufacturing processes in BTE. The comprehensive review also revealed that parametric designs such as triply periodic minimal surface (TPMS) and Voronoi hold better characteristics for their application in BTE. Voronoi designs exhibit exceptional randomness whereas TPMS structures feature high permeability with continuous surfaces. Topology optimized and gradient models exhibited superior physical and mechanical properties compared to uniform lattices. Future research should focus on the development of novel biomaterials, multi-material printing, assessing long-term impacts, and enhancing 3D printing technologies.

Integrating Physical and Biochemical Cues for Muscle Engineering: Scaffolds and Graft Durability

Muscle stem cells (MuSCs) are essential for skeletal muscle regeneration, influenced by a complex interplay of mechanical, biochemical, and molecular cues. Properties of the extracellular matrix (ECM) such as stiffness and alignment guide stem cell fate through mechanosensitive pathways, where forces like shear stress translate into biochemical signals, affecting cell behavior. Aging introduces senescence which disrupts the MuSC niche, leading to reduced regenerative capacity via epigenetic alterations and metabolic shifts. Transplantation further challenges MuSC viability, often resulting in fibrosis driven by dysregulated fibro-adipogenic progenitors (FAPs). Addressing these issues, scaffold designs integrated with pharmacotherapy emulate ECM environments, providing cues that enhance graft functionality and endurance. These scaffolds facilitate the synergy between mechanotransduction and intracellular signaling, optimizing MuSC proliferation and differentiation. Innovations utilizing human pluripotent stem cell-derived myogenic progenitors and exosome-mediated delivery exploit bioactive properties for targeted repair. Additionally, 3D-printed and electrospun scaffolds with adjustable biomechanical traits tackle scalability in treating volumetric muscle loss. Advanced techniques like single-cell RNA sequencing and high-resolution imaging unravel muscle repair mechanisms, offering precise mapping of cellular interactions. Collectively, this interdisciplinary approach fortifies tissue graft durability and MuSC maintenance, propelling therapeutic strategies for muscle injuries and degenerative diseases.

Quercetin-based biomaterials for enhanced bone regeneration and tissue engineering

Quercetin, a natural flavonoid, has been extensively researched for its potential in promoting bone regeneration and tissue engineering. This review aimed to provide a comprehensive overview of the applications of quercetin-based biomaterials in bone regeneration and tissue engineering. The review discusses several studies that have integrated quercetin into biomaterials such as electrospun fibers, hydrogels, microspheres, and nanoparticles. These biomaterials are engineered to imitate the natural extracellular matrix of bone, creating an environment conducive to cell attachment, growth, and differentiation. The investigations presented emphasize the potential of quercetin-derived biomaterials in improving bone regeneration, decreasing oxidative stress and inflammation, and facilitating bone tissue restoration. These biomaterials have demonstrated the ability to facilitate cell encapsulation, maintain consistent quercetin release patterns, and have been applied in a range of uses such as bone grafts, implants, and tissue engineering scaffolds. Biomaterials derived from quercetin are utilized in the treatment of bone-related disorders, including osteoporosis and bone defects. These materials enhance bone regeneration by providing a scaffold for new bone growth, promoting the development of new bone tissue, and improving the mechanical properties of bone tissue.

Decellularization of fish tissues for tissue engineering and regenerative medicine applications

Decellularization is the process of obtaining acellular tissues with low immunogenic cellular components from animals or plants while maximizing the retention of the native extracellular matrix structure, mechanical integrity and bioactivity. The decellularized tissue obtained through the tissue decellularization technique retains the structure and bioactive components of its native tissue; it not only exhibits comparatively strong mechanical properties, low immunogenicity and good biocompatibility but also stimulates in situ neovascularization at the implantation site and regulates the polarization process of recruited macrophages, thereby promoting the regeneration of damaged tissue. Consequently, many commercial products have been developed as promising therapeutic strategies for the treatment of different tissue defects and lesions, such as wounds, dura, bone and cartilage defects, nerve injuries, myocardial infarction, urethral strictures, corneal blindness and other orthopedic applications. Recently, there has been a growing interest in the decellularization of fish tissues because of the abundance of sources, less religious constraints and risks of zoonosis transmission between mammals. In this review, we provide a complete overview of the state-of-the-art decellularization of fish tissues, including the organs and methods used to prepare acellular tissues. We enumerated common decellularized fish tissues from various fish organs, such as skin, scale, bladder, cartilage, heart and brain, and elaborated their different processing methods and tissue engineering applications. Furthermore, we presented the perspectives of (i) the future development direction of fish tissue decellularization technology, (ii) expanding the sources of decellularized tissue and (iii) innovating decellularized tissue bio-inks for 3D bioprinting to unleash the great potential of decellularized tissue in tissue engineering and regenerative medicine applications.

Highly porous polycaprolactone microspheres for skeletal repair promote a mature bone cell phenotype in vitro

Improving our ability to treat skeletal defects is a critical medical challenge that necessitates the development of new biomaterials. One promising approach involves the use of degradable polymer microparticles with an interconnected internal porosity. Here, we employed a double emulsion to generate such round microparticles (also known as microspheres) from a polycaprolactone-based polymerised high internal phase emulsion (polyHIPE). These microspheres effectively supported the growth of mesenchymal progenitors over a 30-day period, and when maintained in osteogenic media, cells deposited a bone-like extracellular matrix, as determined by histological staining for calcium and collagen. Interestingly, cells with an osteocyte-like morphology were observed within the core of the microspheres indicating the role of a physical environment comparable to native bone for this phenotype to occur. At later timepoints, these cultures had significantly increased mRNA expression of the osteocyte-specific markers dentin matrix phosphoprotein-1 (Dmp-1) and sclerostin, with sclerostin also observed at the protein level. Cells pre-cultured on porous microspheres exhibited enhanced survival rates compared to those pre-cultured on non-porous counterparts when injected. Cells precultured on both porous and non-porous microspheres promoted angiogenesis in a chorioallantoic membrane (CAM) assay. In summary, the polycaprolactone polyHIPE microspheres developed in this study exhibit significant promise as an alternative to traditional synthetic bone graft substitutes, offering a conducive environment for cell growth and differentiation, with the potential for better clinical outcomes in bone repair and regeneration.

Mechanical Characterization of Polylactic Acid Composite Scaffolds Formed in Different Lattice Structures by Fused Deposition Modeling-Based 3D Printing

Scaffolds' designs and physical properties have an important place in tissue engineering. Using different biomaterials, scaffolds with other structures can be developed. The thermal and mechanical properties of biomaterials used in producing scaffolds with the fused deposition modeling method are significant for the application's success. The material must be suitable for both the production method and to be used as a scaffold. Therefore, this study designed three different scaffolds made of the same polylactic acid (PLA) material, but with different lattice structures. To determine the mechanical properties of PLA scaffolds formed, 800 N axial compression load at a 20 mm/min velocity was applied to the samples, with n = 3 in each group. To determine the stiffness of scaffolds, the stress-strain values were calculated by measuring the maximum displacement data under load in each group. Also, finite element analysis was performed on PLA scaffold models. At the same time, scanning electron microscope, differential thermal analysis-thermogravimetric analysis, differential scanning calorimetry, and X-ray powder diffraction pattern analyses were carried out. As a result, it has been concluded that the design significantly affects mechanical properties. Besides the material, the scaffold design is the most important parameter in tissue engineering studies.

An Up-to-Date Review of Materials Science Advances in Bone Grafting for Oral and Maxillofacial Pathology

Bone grafting in oral and maxillofacial surgery has evolved significantly due to developments in materials science, offering innovative alternatives for the repair of bone defects. A few grafts are currently used in clinical settings, including autografts, xenografts, and allografts. However, despite their benefits, they have some challenges, such as limited availability, the possibility of disease transmission, and lack of personalization for the defect. Synthetic bone grafts have gained attention since they have the potential to overcome these limitations. Moreover, new technologies like nanotechnology, 3D printing, and 3D bioprinting have allowed the incorporation of molecules or substances within grafts to aid in bone repair. The addition of different moieties, such as growth factors, stem cells, and nanomaterials, has been reported to help mimic the natural bone healing process more closely, promoting faster and more complete regeneration. In this regard, this review explores the currently available bone grafts, the possibility of incorporating substances and molecules into their composition to accelerate and improve bone regeneration, and advanced graft manufacturing techniques. Furthermore, the presented current clinical applications and success stories for novel bone grafts emphasize the future potential of synthetic grafts and biomaterial innovations in improving patient outcomes in oral and maxillofacial surgery.

Fatigue Performance of 3D-Printed Poly-Lactic-Acid Bone Scaffolds with Triply Periodic Minimal Surface and Voronoi Pore Structures

Bone scaffolds serve a crucial role in tissue engineering, particularly in facilitating bone regeneration where natural repair is insufficient. Despite advancements in the fabrication of polymeric bone scaffolds, the challenge remains to optimize their mechanical resilience. Specifically, research on the fatigue behaviour of polymeric bone scaffolds is scarce. This study investigates the influence of pore architecture on the mechanical performance of poly-lactic-acid (PLA) scaffolds under quasi-static and cyclic compression. PLA scaffolds with a 60% porosity were fabricated using extrusion-based 3D printing in various designs: Gyroid, Lidinoid, Fischer-Koch, IWP, and Voronoi. Results demonstrated that Gyroid scaffolds had the highest compressive strength (6.6 MPa), followed by Lidinoid, Fischer-Koch, IWP, and Voronoi designs. Increased strut thickness was linked to higher compressive strength. However, normalized fatigue resistance showed a different pattern. While scaffolds resisted fatigue cycles at low strain amplitudes, fatigue damage was observed at higher strains. Voronoi structures exhibited the highest normalized fatigue performance, enduring around 58,000 cycles at 85% strain amplitude, followed by Gyroid, Fischer-Koch, Lidinoid, and IWP structures. Enhanced fatigue performance in different topologies correlated with the minimum cross-sectional area of scaffolds. Given the importance of both static and fatigue strength, the Gyroid topology emerges as the superior choice overall.

Development and Applications of PLGA Hydrogels for Sustained Delivery of Therapeutic Agents

Poly(lactic-co-glycolic acid) (PLGA) hydrogels are highly utilized in biomedical research due to their biocompatibility, biodegradability, and other versatile properties. This review comprehensively explores their synthesis, properties, sustained release mechanisms, and applications in drug delivery. The introduction underscores the significance of PLGA hydrogels in addressing challenges like short half-lives and systemic toxicity in conventional drug formulations. Synthesis methods, including emulsion solvent evaporation, solvent casting, electrospinning, thermal gelation, and photopolymerization, are described in detail and their role in tailoring hydrogel properties for specific applications is highlighted. Sustained release mechanisms-such as diffusion-controlled, degradation-controlled, swelling-controlled, and combined systems-are analyzed alongside key kinetic models (zero-order, first-order, Higuchi, and Peppas models) for designing controlled drug delivery systems. Applications of PLGA hydrogels in drug delivery are discussed, highlighting their effectiveness in localized and sustained chemotherapy for cancer, as well as in the delivery of antibiotics and antimicrobials to combat infections. Challenges and future prospects in PLGA hydrogel research are discussed, with a focus on improving drug loading efficiency, improving release control mechanisms, and promoting clinical translation. In summary, PLGA hydrogels provide a promising platform for the sustained delivery of therapeutic agents and meet diverse biomedical requirements. Future advancements in materials science and biomedical engineering are anticipated to further optimize their efficacy and applicability in clinical settings. This review consolidates the current understanding and outlines future research directions for PLGA hydrogels, emphasizing their potential to revolutionize therapeutic delivery and improve patient outcomes.

Scaffold-Mediated Drug Delivery for Enhanced Wound Healing: A Review

Wound healing is a complex physiological process involving coordinated cellular and molecular events aimed at restoring tissue integrity. Acute wounds typically progress through the sequential phases of hemostasis, inflammation, proliferation, and remodeling, while chronic wounds, such as venous leg ulcers and diabetic foot ulcers, often exhibit prolonged inflammation and impaired healing. Traditional wound dressings, while widely used, have limitations such poor moisture retention and biocompatibility. To address these challenges and improve patient outcomes, scaffold-mediated delivery systems have emerged as innovative approaches. They offer advantages in creating a conducive environment for wound healing by facilitating controlled and localized drug delivery. The manuscript explores scaffold-mediated delivery systems for wound healing applications, detailing the use of natural and synthetic polymers in scaffold fabrication. Additionally, various fabrication techniques are discussed for their potential in creating scaffolds with controlled drug release kinetics. Through a synthesis of experimental findings and current literature, this manuscript elucidates the promising potential of scaffold-mediated drug delivery in improving therapeutic outcomes and advancing wound care practices.

3D-Printed Polycaprolactone-Based Containing Calcium Zirconium Silicate: Bioactive Scaffold for Accelerating Bone Regeneration

There is an essential clinical need to develop rapid process scaffolds to repair bone defects. The current research presented the development of calcium zirconium silicate/polycaprolactone for bone tissue engineering utilising melt extrusion-based 3D printing. Calcium zirconium silicate (CZS) nanoparticles were added to polycaprolactone (PCL) porous scaffolds to enhance their biological and mechanical properties, while the resulting properties were studied extensively. No significant difference was found in the melting point of the samples, while the crystallisation temperature points of the samples containing bioceramic increased from 36.1 to 40.2 °C. Thermal degradation commenced around 350 °C for all materials. According to our results, increasing the CZS content from 0 to 40 wt.% (PC40) in porous scaffolds (porosity about 55-62%) improved the compressive strength from 2.8 to 10.9 MPa. Furthermore, apatite formation ability in SBF solution increased significantly by enhancing the CZS percentage. According to MTT test results, the viability of MG63 cells improved remarkably (~29%) in PC40 compared to pure PCL. These findings suggest that a 3D-printed PCL/CZS composite scaffold can be fabricated successfully and shows great potential as an implantable material for bone tissue engineering applications.

Development of Biphasic Injectable Hydrogels for Meniscus Scaffold from Photocrosslinked Glycidyl Methacrylate-Modified Poly(Vinyl Alcohol)/Glycidyl Methacrylate-Modified Silk Fibroin

The development of a hydrogel material with a modified chemical structure of poly(vinyl alcohol) (PVA) and silk fibroin (SF) using glycidyl methacrylate (GMA) (denoted as PVA-g-GMA and SF-g-GMA) is an innovative approach in the field of biomaterials and meniscus tissue engineering in this study. The PVA-g-GMA/SF-g-GMA hydrogel was fabricated using different ratios of PVA-g-GMA to SF-g-GMA: 100/0, 75/25, 50/50, 25/75, and 0/100 (w/w of dry substances), using lithium phenyl (2,4,6-trimethylbenzoyl)phosphinate (LAP) as a free radical photoinitiator, for 10 min at a low ultraviolet (UV) intensity (365 nm, 6 mW/cm2). The mechanical properties, morphology, pore size, and biodegradability of the PVA-g-GMA/SF-g-GMA hydrogel were investigated. Finally, for clinical application, human chondrocyte cell lines (HCPCs) were mixed into PVA-g-GMA/SF-g-GMA solutions and fabricated into hydrogel to study the viability of live and dead cells and gene expression. The results indicate that as the SF-g-GMA content increased, the compressive modulus of the PVA-g-GMA/SF-g-GMA hydrogel dropped from approximately 173 to 11 kPa. The degradation rates of PVA-g-GMA/SF-g-GMA 100/0, 75/25, and 50/50 reached up to 15.61%, 17.23%, and 18.93% in 4 months, respectively. In all PVA-g-GMA/SF-g-GMA conditions on day 7, chondrocyte cell vitality exceeded 80%. The PVA-g-GMA/SF-g-GMA 75:25 and 50:50 hydrogels hold promise as a biomimetic biphasic injectable hydrogel for encapsulated augmentation, offering advantages in terms of rapid photocurability, tunable mechanical properties, favorable biological responses, and controlled degradation.

Current approaches in tissue engineering-based nanotherapeutics for osteosarcoma treatment

Osteosarcoma (OS) is a malignant bone neoplasm plagued by poor prognosis. Major treatment strategies include chemotherapy, radiotherapy, and surgery. Chemotherapy to treat OS has severe adverse effects due to systemic toxicity to healthy cells. A possible way to overcome the limitation is to utilize nanotechnology. Nanotherapeutics is an emerging approach in treating OS using nanoparticulate drug delivery systems. Surgical resection of OS leaves a critical bone defect requiring medical intervention. Recently, tissue engineered scaffolds have been reported to provide physical support to bone defects and aid multimodal treatment of OS. These scaffolds loaded with nanoparticulate delivery systems could also actively repress tumor growth and aid new bone formation. The rapid developments in nanotherapeutics and bone tissue engineering have paved the way for improved treatment efficacy for OS-related bone defects. This review focuses on current bifunctional nanomaterials-based tissue engineered (NTE) scaffolds that use novel approaches such as magnetic hyperthermia, photodynamic therapy, photothermal therapy, bioceramic and polymeric nanotherapeutics against OS. With further optimization and screening, NTE scaffolds could meet clinical applications for treating OS patients.

Harnessing the Potential of PLGA Nanoparticles for Enhanced Bone Regeneration

Recently, nanotechnologies have become increasingly prominent in the field of bone tissue engineering (BTE), offering substantial potential to advance the field forward. These advancements manifest in two primary ways: the localized application of nanoengineered materials to enhance bone regeneration and their use as nanovehicles for delivering bioactive compounds. Despite significant progress in the development of bone substitutes over the past few decades, it is worth noting that the quest to identify the optimal biomaterial for bone regeneration remains a subject of intense debate. Ever since its initial discovery, poly(lactic-co-glycolic acid) (PLGA) has found widespread use in BTE due to its favorable biocompatibility and customizable biodegradability. This review provides an overview of contemporary advancements in the development of bone regeneration materials using PLGA polymers. The review covers some of the properties of PLGA, with a special focus on modifications of these properties towards bone regeneration. Furthermore, we delve into the techniques for synthesizing PLGA nanoparticles (NPs), the diverse forms in which these NPs can be fabricated, and the bioactive molecules that exhibit therapeutic potential for promoting bone regeneration. Additionally, we addressed some of the current concerns regarding the safety of PLGA NPs and PLGA-based products available on the market. Finally, we briefly discussed some of the current challenges and proposed some strategies to functionally enhance the fabrication of PLGA NPs towards BTE. We envisage that the utilization of PLGA NP holds significant potential as a potent tool in advancing therapies for intractable bone diseases.

Silver-doped hydroxyapatite laden chitosan-gelatin nanocomposite scaffolds for bone tissue engineering: an in-vitro and in-ovo evaluation

Despite the advancements in bone tissue engineering, the majority of implant failures are caused due to microbial contamination. So, efforts are being made to develop biomaterial with antimicrobial property enhancing the regeneration of damaged bone tissue. In the present study, chitosan-gelatin (CG) scaffolds containing silver-doped hydroxyapatite (AgHAP) nanoparticles at 0.5%, 1.0% and 1.5% (w/v) were fabricated by lyophilization technique. The results confirmed the synthesis of AgHAP nanoparticles and showed interconnected porous structure of the nanocomposite scaffolds with 89%-75% porosity. Similarly, the swelling percentage, degradation behavior and compressive modulus of CG-AgHAP nanocomposite scaffolds were 1666%, 40% and 0.7 MPa, respectively. The developed nanocomposite scaffolds revealed better antimicrobial properties and bioactivity. The cell culture studies showed favorable viability of Wharton's jelly stem cells on CG-AgHAP nanocomposite scaffolds. CAM (chorioallantoic membrane) assay determined the angiogenic potential with better visualization of blood vessels in the CAM area. Hence, the obtained results confirmed that CG-AgHAP3 nanocomposite scaffold was the most suitable for bone tissue engineering applications among all scaffolds.

Resorbable GBR Scaffolds in Oral and Maxillofacial Tissue Engineering: Design, Fabrication, and Applications

Guided bone regeneration (GBR) is a promising technique in bone tissue engineering that aims to replace lost or injured bone using resorbable scaffolds. The promotion of osteoblast adhesion, migration, and proliferation is greatly aided by GBR materials, and surface changes are critical in imitating the natural bone structure to improve cellular responses. Moreover, the interactions between bioresponsive scaffolds, growth factors (GFs), immune cells, and stromal progenitor cells are essential in promoting bone regeneration. This literature review comprehensively discusses various aspects of resorbable scaffolds in bone tissue engineering, encompassing scaffold design, materials, fabrication techniques, and advanced manufacturing methods, including three-dimensional printing. In addition, this review explores surface modifications to replicate native bone structures and their impact on cellular responses. Moreover, the mechanisms of bone regeneration are described, providing information on how immune cells, GFs, and bioresponsive scaffolds orchestrate tissue healing. Practical applications in clinical settings are presented to underscore the importance of these principles in promoting tissue integration, healing, and regeneration. Furthermore, this literature review delves into emerging areas of metamaterials and artificial intelligence applications in tissue engineering and regenerative medicine. These interdisciplinary approaches hold immense promise for furthering bone tissue engineering and improving therapeutic outcomes, leading to enhanced patient well-being. The potential of combining material science, advanced manufacturing, and cellular biology is showcased as a pathway to advance bone tissue engineering, addressing a variety of clinical needs and challenges. By providing this comprehensive narrative, a detailed, up-to-date account of resorbable scaffolds' role in bone tissue engineering and their transformative potential is offered.

Novel scaffold platforms for simultaneous induction osteogenesis and angiogenesis in bone tissue engineering: a cutting-edge approach

Despite the recent advances in the development of bone graft substitutes, treatment of critical size bone defects continues to be a significant challenge, especially in the elderly population. A current approach to overcome this challenge involves the creation of bone-mimicking scaffolds that can simultaneously promote osteogenesis and angiogenesis. In this context, incorporating multiple bioactive agents like growth factors, genes, and small molecules into these scaffolds has emerged as a promising strategy. To incorporate such agents, researchers have developed scaffolds incorporating nanoparticles, including nanoparticulate carriers, inorganic nanoparticles, and exosomes. Current paper provides a summary of the latest advancements in using various bioactive agents, drugs, and cells to synergistically promote osteogenesis and angiogenesis in bone-mimetic scaffolds. It also discusses scaffold design properties aimed at maximizing the synergistic effects of osteogenesis and angiogenesis, various innovative fabrication strategies, and ongoing clinical studies.

Biomimetic Bilayered Scaffolds for Tissue Engineering: From Current Design Strategies to Medical Applications

Tissue damage due to cancer, congenital anomalies, and injuries needs new efficient treatments that allow tissue regeneration. In this context, tissue engineering shows a great potential to restore the native architecture and function of damaged tissues, by combining cells with specific scaffolds. Scaffolds made of natural and/or synthetic polymers and sometimes ceramics play a key role in guiding cell growth and formation of the new tissues. Monolayered scaffolds, which consist of uniform material structure, are reported as not being sufficient to mimic complex biological environment of the tissues. Osteochondral, cutaneous, vascular, and many other tissues all have multilayered structures, therefore multilayered scaffolds seem more advantageous to regenerate these tissues. In this review, recent advances in bilayered scaffolds design applied to regeneration of vascular, bone, cartilage, skin, periodontal, urinary bladder, and tracheal tissues are focused on. After a short introduction on tissue anatomy, composition and fabrication techniques of bilayered scaffolds are explained. Then, experimental results obtained in vitro and in vivo are described, and their limitations are given. Finally, difficulties in scaling up production of bilayer scaffolds and reaching the stage of clinical studies are discussed when multiple scaffold components are used.

Tissue Engineering Strategies Applied in Bone Regeneration and Bone Repair

Bone regeneration and repair present significant challenges in the field of regenerative medicine [...].

Graphene Oxide/RhPTH(1-34)/Polylactide Composite Nanofibrous Scaffold for Bone Tissue Engineering

Polylactide (PLA) is one of the most promising polymers that has been widely used for the repair of damaged tissues due to its biocompatibility and biodegradability. PLA composites with multiple properties, such as mechanical properties and osteogenesis, have been widely investigated. Herein, PLA/graphene oxide (GO)/parathyroid hormone (rhPTH(1-34)) nanofiber membranes were prepared using a solution electrospinning method. The tensile strength of the PLA/GO/rhPTH(1-34) membranes was 2.64 MPa, nearly 110% higher than that of a pure PLA sample (1.26 MPa). The biocompatibility and osteogenic differentiation test demonstrated that the addition of GO did not markedly affect the biocompatibility of PLA, and the alkaline phosphatase activity of PLA/GO/rhPTH(1-34) membranes was about 2.3-times that of PLA. These results imply that the PLA/GO/rhPTH(1-34) composite membrane may be a candidate material for bone tissue engineering.

Titanium Lattice Structures Produced via Additive Manufacturing for a Bone Scaffold: A Review

The progress in additive manufacturing has remarkably increased the application of lattice materials in the biomedical field for the fabrication of scaffolds used as bone substitutes. Ti6Al4V alloy is widely adopted for bone implant application as it combines both biological and mechanical properties. Recent breakthroughs in biomaterials and tissue engineering have allowed the regeneration of massive bone defects, which require external intervention to be bridged. However, the repair of such critical bone defects remains a challenge. The present review collected the most significant findings in the literature of the last ten years on Ti6Al4V porous scaffolds to provide a comprehensive summary of the mechanical and morphological requirements for the osteointegration process. Particular attention was given on the effects of pore size, surface roughness and the elastic modulus on bone scaffold performances. The application of the Gibson–Ashby model allowed for a comparison of the mechanical performance of the lattice materials with that of human bone. This allows for an evaluation of the suitability of different lattice materials for biomedical applications.