Poly(lactic-co-glycolic acid)-based composite bone-substitute materials

Enhancement of in vitro and in vivo bone repair performance of decalcified bone/gelma by desferrioxamine

Autologous and allogeneic bone grafting is currently the clinical gold standard for the treatment of bone defects; however, it is limited by the scarcity of autologous sources and the risk of secondary trauma, as well as the complications of disease transmission and immune rejection associated with allogeneic grafts. The clinical management of bone defects remains a significant challenge. In this study, we prepared a demineralized bone matrix/gelatin methacrylate composite hydrogel loaded with deferoxamine (GelMA/DBM/DFO) using a freeze-drying method and investigated its properties. Assessments using CCK-8, live-dead fluorescence staining, alkaline phosphatase staining, and Alizarin Red staining indicated that the GelMA/DBM/DFO composite hydrogel demonstrated superior biocompatibility and in vitro osteogenic differentiation capacity compared with the GelMA/DBM composite hydrogel. We established a cranial defect model in Sprague-Dawley (SD) rats and examined peripheral blood indices, micro-computed tomography (Micro-CT), hematoxylin and eosin (HE) staining, Masson's trichrome staining, and immunohistochemical staining for bone morphogenetic protein-2 (BMP-2) and collagen type I (COL-1). Both hydrogels exhibited good biosafety and the GelMA/DBM/DFO hydrogel showed more effective repair of cranial defects in SD rats. This study provides a novel material for bone-defect repair.

Recent Advances and Challenges for Biological Materials in Micro/Nanocarrier Synthesis for Bone Infection and Tissue Engineering

Roughly 1.71 billion people worldwide suffer from large bone abnormalities, which are the primary cause of disability. Traditional bone grafting procedures have several drawbacks that impair their therapeutic efficacy and restrict their use in clinical settings. A great deal of work has been done to create fresh, more potent strategies. Under these circumstances, a crucial technique for the regeneration of major lesions has emerged: bone tissue engineering (BTE). BTE involves the use of biomaterials that can imitate the natural design of bone. To yet, no biological material has been able to fully meet the parameters of the perfect implantable material, even though several varieties have been created and investigated for bone regeneration. Against this backdrop, researchers have focused a great deal of interest over the past few years on the subject of nanotechnology and the use of nanostructures in regenerative medicine. The ability to create nanoengineered particles that can overcome the current constraints in regenerative strategies─such as decreased cell proliferation and differentiation, insufficient mechanical strength in biological materials, and insufficient production of extrinsic factors required for effective osteogenesis has revolutionized the field of bone and tissue engineering. The effects of nanoparticles on cell characteristics and the application of biological materials for bone regeneration are the main topics of our review, which summarizes the most recent in vitro and in vivo research on the application of nanotechnology in the context of BTE.

Three-dimensional bio-derived materials for biomedical applications: challenges and opportunities

Three-dimensional (3D) bio-derived materials are emerging as a promising approach to enhance wound healing therapies. These innovative materials can be tailored to meet the specific needs of various wound types and patients, facilitating the controlled release of therapeutic agents such as growth factors and antibiotics, which promote cell growth and tissue regeneration. Despite their potential, significant challenges remain in achieving optimal biocompatibility, ensuring structural integrity, and maintaining precise release mechanisms. Additionally, issues such as scalability, cost-effectiveness, and regulatory compliance pose substantial barriers to widespread use. However, recent advances in materials science and interdisciplinary research offer new opportunities to overcome these challenges. This review provides a comprehensive analysis of the current state of 3D bio-derived materials in biomedical applications, highlighting the types of materials available, their advantages and limitations, and the progress made in their design and development. It also outlines new directions for future research aimed at bridging the gap between scientific discoveries and their practical applications in injury healing strategies. The findings of this review underscore the significant potential of 3D bio-derived materials in revolutionizing wound healing and advancing personalized therapeutic approaches.

Recent advances in fucoidan-based improved delivery systems: Structure, carrier types and biomedical applications

Consumer demand for nutritional supplements has fueled the rapid growth of the functional food market. However, ensuring the stability of functional factors in harsh environments remains a major challenge. The development of encapsulation systems is regarded as an effective method for enhancing the stability of functional factors, encapsulation carriers can offer protection for these functional factors. However, the selection of materials remains a significant constraint in the construction of delivery systems. Therefore, developing new encapsulation materials is crucial for advancing delivery systems, preserving the stability of functional factors, and ensuring public health. Fucoidan, a sulfated marine polysaccharide, has garnered significant attention in the field of encapsulation due to its notable advantages, including its remarkable bioactivity, biocompatibility, and targeted binding properties. Fucoidan-improved delivery systems provide new strategies for encapsulation of functional factors. This review first describes the structure of fucoidan, its modification and lists the applications of modified fucoidan, and assesses its feasibility for enhancing delivery systems. Second, it summarizes several common encapsulation technologies and methods, and outlines various carrier types based on fucoidan. Finally, it elucidates recent advances in the biomedical applications of fucoidan-improved delivery systems. Notably, it also presents the challenges and future prospects of this promising field.

Effects of Hydrogels on Mesenchymal Stem/Stromal Cells Paracrine Activity and Extracellular Vesicles Production

Mesenchymal stem/stromal cells (MSCs) are a valuable source of paracrine factors, as they have a remarkable secretory capacity, and there is a sizeable knowledge base to develop industrial and clinical production protocols. Promising cell-free approaches for tissue regeneration and immunomodulation are driving research towards secretome applications, among which extracellular vesicles (EVs) are steadily gaining attention. However, the manufacturing and application of EVs is limited by insufficient yields, knowledge gaps, and low standardization. Facing these limitations, hydrogels represent a versatile three-dimensional (3D) culture platform that can incorporate extracellular matrix (ECM) components to mimic the natural stem cell environment in vitro; via these niche-mimicking properties, hydrogels can regulate MSCs' morphology, adhesion, proliferation, differentiation and secretion capacities. However, the impact of the hydrogel's architectural, biochemical and biomechanical properties on the production of EVs remains poorly understood, as the field is still in its infancy and the interdependency of culture parameters compromises the comparability of the studies. Therefore, this review summarizes and discusses the reported effects of hydrogel encapsulation and culture on the secretion of MSC-EVs. Considering the effects of cell-material interactions on the overall paracrine activity of MSCs, we identify persistent challenges from low standardization and process control, and outline future paths of research, such as the synergic use of hydrogels and bioreactors to enhance MSC-EV generation.

Mechanically robust surface-degradable implant from fiber silk composites demonstrates regenerative potential

Through millions of years of evolution, bones have developed a complex and elegant hierarchical structure, utilizing tropocollagen and hydroxyapatite to attain an intricate balance between modulus, strength, and toughness. In this study, continuous fiber silk composites (CFSCs) of large size are prepared to mimic the hierarchical structure of natural bones, through the inheritance of the hierarchical structure of fiber silk and the integration with a polyester matrix. Due to the robust interface between the matrix and fiber silk, CFSCs show maintained stable long-term mechanical performance under wet conditions. During in vivo degradation, this material primarily undergoes host cell-mediated surface degradation, rather than bulk hydrolysis. We demonstrate significant capabilities of CFSCs in promoting vascularization and macrophage differentiation toward repair. A bone defect model further indicates the potential of CFSC for bone graft applications. Our belief is that the material family of CFSCs may promise a novel biomaterial strategy for yet to be achieved excellent regenerative implants.

Enhanced healing of critical-sized bone defects using degradable scaffolds with tailored composition through immunomodulation and angiogenesis

The impact of orthopedic scaffolds on bone defect healing, particularly the late-stage bone remodeling process, is pivotal for the therapeutic outcome. This study applies fadditively manufactured scaffolds composed of hydroxyapatite-doped poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (HA-PELGA) with varying properties to treat rat calvarial defects, elucidating their significant role in bone remodeling by modulating physiological responses. We engineered two scaffolds with different polylactic acid (PLA) to polyglycolic acid (PGA) ratio (9/1 and 18/1) to vary in hydrophobicity, degradation rate, mechanical properties, and structural stability. These variations influenced physiological responses, including osteogenesis, angiogenesis, and immune reactions, thereby guiding bone remodeling. Our findings show that the HA-PELGA(18/1) scaffold, with a slower degradation rate, supported bulk bone formation due to a stable microenvironment. Conversely, the HA-PELGA(9/1) scaffold, with a faster degradation rate and more active interfaces, facilitated the formation of a thin bone layer and higher bone infiltration. This study demonstrates these degradable scaffolds help to promote bone healing and reveals how scaffold properties influence the bone remodeling process, offering a potential strategy to optimize scaffold design aiming at late-stage bone defect healing.

Light Assisted Covalent Immobilization of Proteins for Biomedical Applications

The covalent immobilization of proteins attracts considerable interest in the biomedical field due to its potential applications in biosensors, recombinant protein purification, and the development of personalized therapeutic carriers. In response to the demand for more cost-effective, time-efficient, and simpler protocols, photo-immobilization emerges as a technique that circumvents the limitations of conventional methods. This approach offers enhanced precision at the nanoscale level and facilitates device reusability, thereby aligning with current sustainability concerns. Photo-immobilization is versatile, as it can be applied to both 2D and 3D substrates. While some methods involve complex protocols using genetically engineered photosensitive linkers, more straightforward techniques rely on amino acid bonds, such as disulfide bonds, for covalent protein bonding. Photo-immobilization can be achieved with both ultraviolet (UV) and visible light. This systematic review examines literature from Scopus, PubMed, and Web of Science, offering insights into relevant studies and considerations for covalent protein immobilization, and presents photochemical approaches applicable to major protein types.

β-ecdysone/PLGA composite scaffolds promote skull defect healing in diabetic rat

Introduction

Diabetes mellitus often leads to bone metabolism disorders, hindering bone regeneration and delaying the healing of bone defects. β-Ecdysone, a plant-derived hormone known for its wide range of physiological activities, possesses hypoglycemic effects and promotes osteogenic differentiation. This study developed a composite PLGA slow-release scaffold loaded with β-ecdysone to enhance its bioavailability through topical administration and to investigate its potential to heal diabetic bone defects.

Methods

The composite scaffolds were fabricated using solution casting/particle leaching and freeze-drying techniques. Then a series of characterizations were subjected to test the performance of composite scaffolds, and in vitro safety of the composite scaffolds was tested by CCK8 assay and live/dead cell staining. Further, micro-CT and histology to evaluate the effect of β-E/PLGA composite scaffolds on healing of skull defects in diabetic rats at 4 and 8 weeks after implantation. Simultaneously, the safety of the scaffolds in vivo was also evaluated.

Results

The material characterization results indicated that, in comparison to the single-pore size scaffold, the composite scaffold exhibited superior porosity, swelling ratio, drug loading capacity, and mechanical properties. Additionally, the composite scaffolds showed appropriate degradation performance and sustained drug release profiles. The CCK8 cytotoxicity assay and live/dead cell staining demonstrated that BMSCs survived and proliferated on the composite scaffold under both low-glucose and high-glucose conditions. Micro-CT and histological investigation demonstrated that β-E/PLGA composite scaffolds promoted new bone growth in the skull defect region of diabetic rats.

Conclusion

Overall, these findings suggest that the β-E/PLGA composite scaffolds promote the healing of bone defects in diabetic rats. The combination of β-ecdysone and tissue-engineered scaffolds presents a promising approach for treating diabetes-related bone defects.

Incorporating Hydrogel (with Low Polymeric Content) into 3D-Printed PLGA Scaffolds for Local and Sustained Release of BMP2 in Repairing Large Segmental Bone Defects

Treating large bone defects remains a considerable challenge for clinicians: bone repair requires scaffolds with mechanical properties and bioactivities. Herein, based on crosslinking o-phthalaldehyde (OPA) with amine groups, 4-arm polyethylene glycol (4armPEG)-OPA/Gelatin hydrogel loaded with bone morphogenetic protein 2 (BMP2) is prepared and a three dimensional (3D)-printed poly (lactic-co-glycolic acid) (PLGA) porous scaffold is filled with the hydrogel solution. The composite scaffold, with a compression modulus of 0.68 ± 0.097 GPa similar to the cancellous bone, has a porosity of 56.67 ± 4.72% and a pore size of about 380 µm, promoting bone growth. The hydrogel forms a porous network at low concentrations, aiding protein release and cell migration. The hydrogel degrades in approximately three weeks, and the scaffold takes five months, matching bone repair timelines. BMP2 release experiment shows a sustained BMP2 release with a 72.4 ± 0.53% release ratio. The ALP activity test and alizarin red staining shows effective osteogenic promotion, while RT-PCR confirms BMP2@Gel enhanced COL-1 and OPN expression. Animal experiments further validate the composite scaffold's bone repair efficacy. This study demonstrates the effectiveness of the hydrogel in releasing BMP2 and the mechanical support of the 3D-printed PLGA porous scaffold, providing a new treatment for bone defects.

3D Bioprinting Strategies for Melatonin‐Loaded Polymers in Bone Tissue Engineering

Bone pathologies are still among the most challenging issues for orthopedics. Over the past decade, different methods are developed for bone repair. In addition to advanced surgical and graft techniques, polymer‐based biomaterials, bioactive glass, chitosan, hydrogels, nanoparticles, and cell‐derived exosomes are used for bone healing strategies. Owing to their variation and promising advantages, most of these methods are not translated into clinical practice. Three dimensonal (3D) bioprinting is an additive manufacturing technique that has become a next‐generation biomaterial technique adapted for anatomic modeling, artificial tissue or organs, grafting, and bridging tissues. Polymer‐based biomaterials are mostly used for the controlled release of various drugs, therapeutic agents, mesenchymal stem cells, ions, and growth factors. Polymers are now among the most preferable materials for 3D bioprinting. Melatonin is a well‐known antioxidant with many osteoinductive properties and is one of the key hormones in the brain–bone axis. 3D bioprinted melatonin‐loaded polymers with unique lipophilic, anti‐inflammatory, antioxidant, and osteoinductive properties for filling large bone gaps following fractures or congenital bone deformities may be developed in the future. This study summarized the benefits of 3D bioprinted and polymeric materials integrated with melatonin for sustained release in bone regeneration approaches.

Biomimetic Natural Biomaterial Nanocomposite Scaffolds: A Rising Prospect for Bone Replacement

Biomimetic natural biomaterial (BNBM) nanocomposite scaffolds for bone replacement can reduce the rate of implant failure and the associated risks of post-surgical complications for patients. Traditional bone implants, like allografts, and autografts, have limitations, such as donor site morbidity and potential patient inflammation. Over two million bone transplant procedures are performed yearly, and success varies depending on the material used. This emphasizes the importance of developing new biomaterials for bone replacement. Innovative BNBM nanocomposites for modern bone fabrication can promote the colonization of the desired cellular components and provide the necessary mechanical properties. Recent studies have highlighted the advantages of BNBM nanocomposites for bone replacement; therefore, this review focuses on the application of cellulose, chitosan, alginates, collagen, hyaluronic acid, and synthetic polymers enhanced with nanoparticles for the fabrication of nanocomposite scaffolds used in bone regeneration and replacement. This work outlines the most up-to-date overview and perspectives of selected promising BNBM nanocomposites for bone replacement that could be used for scaffold fabrication and replace other biomorphic materials such as metallics, ceramics, and synthetic polymers in the future. In summary, the concluding remarks highlight the advantages and disadvantages of BNBM nanocomposites, prospects, and future directions for bone tissue regeneration and replacement.

Antisolvent 3D Printing of Gene-Activated Scaffolds for Bone Regeneration

The use of 3D-printed gene-activated bone grafts represents a highly promising approach in the fields of dentistry and orthopedics. Bioresorbable poly-lactic-co-glycolic acid (PLGA) scaffolds, infused with adenoviral constructs that carry osteoinductive factor genes, may provide an effective alternative to existing bone grafts for the reconstruction of extensive bone defects. This study aims to develop and investigate the properties of 3D scaffolds composed of PLGA and adenoviral constructs carrying the BMP2 gene (Ad-BMP2), both in vitro and in vivo. The elastic modulus of the disk-shaped PLGA scaffolds created using a specialized 3D printer was determined by compressive testing in both axial and radial directions. In vitro cytocompatibility was assessed using adipose-derived stem cells (ADSCs). The ability of Ad-BMP2 to transduce cells was evaluated. The osteoinductive and biocompatible properties of the scaffolds were also assessed in vivo. The Young's modulus of the 3D-printed PLGA scaffolds exhibited comparable values in both axial and radial compression directions, measuring 3.4 ± 0.7 MPa for axial and 3.17 ± 1.4 MPa for radial compression. The scaffolds promoted cell adhesion and had no cytotoxic effect on ADSCs. Ad-BMP2 successfully transduced the cells and induced osteogenic differentiation in vitro. In vivo studies demonstrated that the 3D-printed PLGA scaffolds had osteoinductive properties, promoting bone formation within the scaffold filaments as well as at the center of a critical calvarial bone defect.

Effect of nHA/CS/PLGA delivering adipose stem cell-derived exosomes and bone marrow stem cells on bone healing-in vitro and in vivo studies

Adipose stem cell-derived exosomes (ADSC-EXO) have been demonstrated to promote osteogenic differentiation of bone marrow stem cells (BMSCs) and facilitate bone regeneration. The present study aims to investigate the effect of ADSC-EXO-loaded nano-hydroxyapatite/chitosan/poly-lactide-co-glycolide (nHA/CS/PLGA) scaffolds on maxillofacial bone regeneration using tissue engineering. ADSC-EXO was isolated and co-cultured with BMSCs, and the osteogenic differentiation of BMSCs was assessed through the detection of mineralized nodule formation, alkaline phosphatase (ALP) activity, and mRNA expression of COL1A1 and runt-related transcription factor 2 (RUNX2). The nHA/CS/PLGA scaffolds were fabricated and loaded with ADSC-EXO and BMSCs, and these tissue engineering complexes were applied to the maxillofacial bone defect region of rabbits to elucidate their bone regeneration effect. The osteogenic differentiation of BMSCs was markedly enhanced when they were co-cultured with ADSC-EXO. This was evidenced by an increase in the formation of mineralized nodule formation, ALP activity, and mRNA expression of COL1A1 and runt-related transcription factor 2 (RUNX2). In vivo experiments demonstrated that the application of ADSC-EXO and BMSCs loaded nHA/CS/PLGA scaffolds effectively repaired maxillofacial bone defects in rabbits. ADSC-EXO has been demonstrated to promote the osteogenic differentiation of BMSCs. The ADSC-EXO and BMSCs loaded nHA/CS/PLGA scaffolds have been shown to facilitate the regeneration of maxillofacial bone defects. This may serve as a potential therapeutic strategy for large-scale bone defects.

Poly (lactic acid) electrospun nanofiber membranes: Advanced characterization for biomedical applications with drug loading performance studies

Traditional dressings have shortcomings such as poor moisture absorption and easy to adhere, making the development of new dressings crucial. In this work, a PLA/PVP crosslinked drug-loaded nanofiber membrane was prepared through electrospinning and ultraviolet crosslinking, with poly (lactic acid) (PLA), polyvinylpyrrolidone (PVP), and salicylic acid (SA) as starting materials. The results demonstrated that the inclusion of PVP notably boosted the viscosity and conductivity of the blend spinning solution. The roughness of the fabricated fiber was elevated, and the diameter of the fibers was more uniform. Additionally, the incorporation of PVP not only enhanced the porosity of the fiber membrane but also effectively decreased its contact angle. Notably, when the PVP content reached 40 %, the contact angle underwent a substantial reduction, decreasing significantly from 125.4° to 82.2°. The SA drug-loaded fiber membrane exhibited a notable bacteriostatic effect against Escherichia coli and Staphylococcus aureus, with its release behavior adhering to Fick's diffusion law. In the cell viability experiment, the cell proliferation rate increased from 94 % to 129 % after 3 days. This shows that the prepared membrane has good antibacterial effect and cell compatibility, which provides a theoretical basis for the construction of a new medical dressing.

Management of pediatric ankle fractures: comparison of biodegradable PLGA implants with traditional metal screws

Introduction

The relevance of biodegradable implants has gained more importance in modern clinical practice. The study aimed to evaluate the effects and outcomes of ankle fracture treatment with absorbable implants compared to metal screws. These implants are made from poly l-lactic-co-glycolic acid (PLGA), however, there are several other materials available on the market.

Methods

In a retrospective review, a total of 128 patients were under observation, with distal tibial fracture types ranging from Salter-Harris II-IV. In the absorbable group, patients were treated with the implants (n = 76). The metal group included patients treated with titanium or steel screws (n = 52). The extremities were placed in a cast for six weeks after surgery and were utilized for another 6-8 weeks. Patients were followed up for 12-30 months and were evaluated accordingly. The authors examined several aspects such as age, gender, open or closed repair, mechanism of injury, length of hospitalization, type of fracture, time of recovery, and complications.

Results

There were no statistically significant differences between the groups regarding demographic qualities, such as age, type of fracture, side of injury, and length of cast application (p > 0.05 in all cases). Out of 76 patients in the PLGA group, only two presented with complications, so reoperation took place. The rest healed without complications or refractures. Two of those treated with metal screws (n = 52) had minor, and four had major complications with reoperation.

Discussion

In pediatric cases, PLGA implants may present excellent results for treating ankle fractures. They do not disturb the growth plate and do not require reoperation. For this reason, they reduce the burden on the patient and the healthcare provider while simultaneously decreasing the risk of complications, such as infections or problems due to general anesthesia.

Recent advances of chitosan-based composite hydrogel materials in application of bone tissue engineering

Bone defects, stemming from trauma, tumors, infections, and congenital conditions, pose significant challenges in orthopedics. Although the body possesses innate mechanisms for bone self-repairing, factors such as aging, disease, and injury can impair these processes, jeopardizing skeletal integrity. Addressing substantial bone defects remains a global orthopedic concern, with variables like gender, lifestyle and preexisting conditions influencing fracture risk and complication rates. Traditional repair methods, mainly bone transplantation including autografts, allografts and xenografts, have shown effectiveness but also present limitations. Autologous bone grafts, highly valued for their osteogenic properties, require additional surgeries with extended hospitalization, and carry risks associated with the donor site. The development of advanced biomaterials offers promising new avenues for bone repair. An ideal material should exhibit a combination of biocompatibility, biodegradability, bone conduction, porosity, strength, and the ability to stimulate bone formation. Chitosan (CS), derived from chitin, stands out due to its biocompatibility, biodegradability, low immunogenicity, non-toxicity, and a wide range of biological activities, including antioxidant, anti-tumor, anti-inflammatory, antimicrobial, and immunomodulatory properties. Notably, CS has shown the properties to promote bone regeneration, increase bone density, and accelerate fracture healing. This review provides a comprehensive examination of CS-based hydrogels for bone repair aiming to inspire researchers by presenting new ideas for innovative CS-based solutions, thereby advancing their potential applications in the field of bone repair.

Anti-aging Metabolite-Based Polymeric Microparticles for Intracellular Drug Delivery and Bone Regeneration

Alpha-ketoglutarate (AKG), a key component of the tricarboxylic acid (TCA) cycle, has attracted attention for its anti-aging properties. Our recent study indicates that locally delivered cell-permeable AKG significantly promotes osteogenic differentiation and mouse bone regeneration. However, the cytotoxicity and rapid hydrolysis of the metabolite limit its application. In this study, we synthesize novel AKG-based polymeric microparticles (PAKG MPs) for sustained release. In vitro data suggest that the chemical components, hydrophilicity, and size of the MPs can significantly affect their cytotoxicity and pro-osteogenic activity. Excitingly, these biodegradable PAKG MPs are highly phagocytosable for nonphagocytic pre-osteoblasts MC3T3-E1 and primary bone marrow mesenchymal stem cells (BMSCs), significantly promoting their osteoblastic differentiation. RNAseq data suggest that PAKG MPs strongly activate Wnt/β-catenin and PI3K-Akt pathways for osteogenic differentiation. Moreover, PAKG enables poly (L-lactic acid) and poly (lactic-co-glycolic acid) MPs (PLLA & PLGA MPs) for efficient phagocytosis. Our data indicate that PLGA-PAKG MPs-mediated intracellular drug delivery can significantly promote stronger osteoblastic differentiation compared to PLGA MPs-delivered phenamil. Notably, PAKG MPs significantly improve large bone regeneration in a mouse cranial bone defect model. Thus, the novel PAKG-based MPs show great promise to improve osteogenic differentiation, bone regeneration, and enable efficient intracellular drug delivery for broad regenerative medicine.

Osteogenic effect of poly(lactic-co-glycolic acid) microcapsules with different molecular weights encapsulating bone morphogenetic protein 2

OBJECTIVES

This study aimed to explore the effects of bone morphogenetic protein 2 (BMP-2) encapsula-ted in poly(lactic-co-glycolic acid) (PLGA) microcapsules with different molecular weights on the osteogenic ability of osteoblasts.

METHODS

PLGA microcapsules with different molecular weights (12 000, 30 000) encapsulating BMP-2, were prepared using a dual-channel microinjection pump. The morphology and structure of the microcapsules were characterized by optical microscopy and scanning electron microscopy. The sustained-release performance of the microcapsules was characterized by phosphate buffered saline immersion method. The cell compatibility of the microcapsules was detected by the Calcein-AM/PI staining and CCK-8 method. The chemotactic effect of BMP-2-encapsulated microcapsules on MC3T3-E1 cells after 48 h of treatment was detected by the Transwell assay. The alkaline phosphatase activity assay and Alizarin Red S staining were used to characterize the effect of microcapsules on the osteogenic ability of MC3T3-E1 cells.

RESULTS

Both types of microcapsules with different molecular weights exhibited smooth surfaces, as well as uniform and good cell compatibility. The chemotactic effect of the 12 000 microcapsules was outstanding. The 30 000 microcapsules had a longer sustained-release time, and the initial burst release was reduced by approximately 25% compared with the 12 000 microcapsules. In addition, 30 000 microcapsules performed better in long-term osteogenesis induction than 12 000 microcapsules.

CONCLUSIONS

In this study, the release of BMP-2 is regulated by adjusting the molecular weight of PLGA, and the results indicate that 30 000 microcapsules can better induce the long-term osteogenic ability of MC3T3-E1 cells.

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.

The efficiency of two different synthetic bone graft materials on alveolar ridge preservation after tooth extraction: a split-mouth study

BACKGROUND

Alveolar Bone loss occurs frequently during the first six months after tooth extraction. Various studies have proposed different methods to reduce as much as possible the atrophy of the alveolar ridge after tooth extraction. Filling the socket with biomaterials after extraction can reduce the resorption of the alveolar ridge. We compared the height of the alveolar process at the mesial and distal aspects of the extraction site and the resorption rate was calculated after the application of HA/β-TCP or synthetic co-polymer polyglycolic - polylactic acid PLGA mixed with blood to prevent socket resorption immediately and after tooth extraction.

METHODS

The study was conducted on 24 extraction sockets of impacted mandibular third molars bilaterally, vertically, and completely covered, with a thin bony layer. HA/β-TCP was inserted into 12 of the dental sockets immediately after extraction, and the synthetic polymer PLGA was inserted into 12 of the dental sockets. All sockets were covered completely with a full-thickness envelope flap. Follow-up was performed for one year after extraction, using radiographs and stents for the vertical alveolar ridge measurements.

RESULTS

The mean resorption rate in the HA/β-TCP and PLGA groups was ± 1.23 mm and ± 0.1 mm, respectively. A minimal alveolar bone height reduction of HA/β-TCP was observed after 9 months, the reduction showed a slight decrease to 0.93 mm, while this rate was 0.04 mm after 9 months in the PLGA group. Moreover, the bone height was maintained after three months, indicating a good HA/β-TCP graft performance in preserving alveolar bone (1.04 mm) while this rate was (0.04 mm) for PLGA.

CONCLUSION

The PLGA graft demonstrated adequate safety and efficacy in dental socket preservation following tooth extraction. However, HA/β-TCP causes greater resorption at augmented sites than PLGA, which clinicians should consider during treatment planning.

Preparation of composite calcium phosphate cement scaffold loaded with Hedysarum polysaccharides and its efficacy in repairing bone defects

It's imperative to create a more ideal biological scaffold for bone defect repair. Calcium phosphate bone cements (CPC) could be used as a scaffold. Some ingredients and osteogenic factors could be added to improve its poor mechanical properties and biological activity. As a macromolecule extracted from traditional Chinese medicine, Hedysarum polysaccharides (HPS) would significantly promote the osteogenic activity of bone biomaterials. Zirconium oxide and starch were added to the solid phase and citric acid was added to the liquid phase to optimize CPC. HPS was loaded onto the scaffold as an osteogenic factor, and the prepared CPS + HPS was characterized. Further, the cytocompatibility of CPS + HPS was assessed according to activity, differentiation, and calcification in neonatal rat calvarial osteoblasts, and the biosafety of CPS + HPS was evaluated according to acute toxicity, pyrogen, sensitization, and hemolysis. The success of CPS + HPS in repairing bone defects was evaluated by using a rabbit femur implantation experiment. After optimization, CPS-20-CA-5 containing 10% starch and 5% citric acid displayed the highest mechanical strength of 28.96 ± 0.03 MPa. HPS-50 was demonstrated to exert the best osteogenic effect. The combination of CPS + HPS achieved HPS-loaded CPC. Material characterization, cytocompatibility, biosafety, and femoral implantation experiments indicated that CPS + HPS possessed better pressure resistance and improved osteogenic ability in bone defect repair.CPS + HPS demonstrated effective pressure resistance and superior osteogenic ability, which may be of great significance for bone defects and bone tissue engineering to promote bone regeneration and repair.

Nanomedomics

Nanomaterials have attractive physicochemical properties. A variety of nanomaterials such as inorganic, lipid, polymers, and protein nanoparticles have been widely developed for nanomedicine via chemical conjugation or physical encapsulation of bioactive molecules. Superior to traditional drugs, nanomedicines offer high biocompatibility, good water solubility, long blood circulation times, and tumor-targeting properties. Capitalizing on this, several nanoformulations have already been clinically approved and many others are currently being studied in clinical trials. Despite their undoubtful success, the molecular mechanism of action of the vast majority of nanomedicines remains poorly understood. To tackle this limitation, herein, this review critically discusses the strategy of applying multiomics analysis to study the mechanism of action of nanomedicines, named nanomedomics, including advantages, applications, and future directions. A comprehensive understanding of the molecular mechanism could provide valuable insight and therefore foster the development and clinical translation of nanomedicines.

Black phosphorus, an advanced versatile nanoparticles of antitumor, antibacterial and bone regeneration for OS therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor. In the clinic, usual strategies for OS treatment include surgery, chemotherapy, and radiation. However, all of these therapies have complications that cannot be ignored. Therefore, the search for better OS treatments is urgent. Black phosphorus (BP), a rising star of 2D inorganic nanoparticles, has shown excellent results in OS therapy due to its outstanding photothermal, photodynamic, biodegradable and biocompatible properties. This review aims to present current advances in the use of BP nanoparticles in OS therapy, including the synthesis of BP nanoparticles, properties of BP nanoparticles, types of BP nanoparticles, and modification strategies for BP nanoparticles. In addition, we have discussed comprehensively the application of BP in OS therapy, including single, dual, and multimodal synergistic OS therapies, as well as studies about bone regeneration and antibacterial properties. Finally, we have summarized the conclusions, limitations and perspectives of BP nanoparticles for OS therapy.

Waste natural fibers for polymer toughening and biodegradability of epoxy-based polymer composite through toughness and thermal analysis

Polymeric materials are being increasingly used to replace many metallic components due to their beneficial properties such as higher strength-to-weight ratio and corrosion resistance. However, the widespread use of polymers poses a risk to the environment as they are not biodegradable. The addition of the waste jute fiber and sawdust fiber as reinforcement to the epoxy resin improved its toughness and induced the biodegradability of the polymer. To examine the effect of the jute fiber and sawdust fiber on biodegradability, the composites were then kept in the drainage system for one year, and the impact energy and fracture morphology of the as-cast and weathered samples were examined using a drop ball impact test and a Charpy impact test. During the weathering period, weight gain was initially observed due to the water absorption by the porous fibers, but after three months, the composites started to lose weight due to the degradation of the fiber by swelling and microbial attacks. Microorganisms in the drainage system used the fiber as their energy source, which resulted in the deterioration of the fiber and the production of CO2. The production of CO2 was identified by the FTIR analysis of the weathered composite samples. TGA analysis of the as-cast and weathered samples reveals the reduction of the onset thermal degradation temperature of the weathered composites due to the degradation of the composites. The fiber disintegrated through microbial attack and the fiber swelling caused by the absorption of water by jute fiber and sawdust fiber is identified through SEM imaging. The SEM image also reveals the formation of biofilms and the growth of microorganisms at the fibers. A higher growth rate of the microorganisms was observed in the jute fiber composite than in the sawdust fiber composite, as sawdust contains a high level of lignin that protects it from degradation. The results of this study suggest that both sawdust fiber and jute fiber composites induce biodegradability in the epoxy matrix, but jute fiber was more prominent in this regard. The discovery paves the way for using natural fibers in biodegradable polymer composites, reducing polymeric pollution in the environment.

Additive Manufacturing of Iron Carbide Incorporated Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug Delivery Applications

In this study, we have synthesized a bioactive glass with composition 45SiO2-20Na2O-23CaO-6P2O5-2.5B2O3-1ZnO-2MgO-0.5CaF2 (wt %). Further, it has been incorporated with 0.4 wt % iron carbide nanoparticles to prepare magnetic bioactive glass (MBG) with good heat generation capability for potential applications in magnetic field-assisted hyperthermia. The MBG scaffolds have been fabricated using extrusion-based additive manufacturing by mixing MBG powder with 25% Pluronic F-127 solution as the binder. The saturation magnetization of iron carbide nanoparticles in the bioactive glass matrix has been found to be 80 emu/g. The morphological analysis (pore size distribution, porosity, open pore network modeling, tortuosity, and pore interconnectivity) was done using an in-house developed methodology that revealed the suitability of the scaffolds for bone tissue engineering. The compressive strength (14.3 ± 1.6 MPa) of the MBG scaffold was within the range of trabecular bone. The in vitro test using simulated body fluid (SBF) showed the formation of apatite indicating the bioactive nature of scaffolds. Further, the drug delivery behaviors of uncoated and polycaprolactone (PCL) coated MBG scaffolds have been evaluated by loading an anticancer drug (Mitomycin C) onto the scaffolds. While the uncoated scaffold demonstrated the drug's burst release for the initial 80 h, the PCL-coated scaffold showed the gradual release of the drug. These results demonstrate the potential of the proposed MBG for bone tissue engineering and drug delivery applications.

Biological Activity of Poly(1,3-propanediol citrate) Films and Nonwovens: Mechanical, Thermal, Antimicrobial, and Cytotoxicity Studies

Polymers are of great interest for medical and cosmeceutical applications. The current trend is to combine materials of natural and synthetic origin in order to obtain products with appropriate mechanical strength and good biocompatibility, additionally biodegradable and bioresorbable. Citric acid, being an important metabolite, is an interesting substance for the synthesis of materials for biomedical applications. Due to the high functionality of the molecule, it is commonly used in biomaterials chemistry as a crosslinking agent. Among citric acid-based biopolyesters, poly(1,8-octanediol citrate) is the best known. It shows application potential in soft tissue engineering. This work focuses on a much less studied polyester, poly(1,3-propanediol citrate). Porous and non-porous materials based on the synthesized polyesters are prepared and characterized, including mechanical, thermal, and surface properties, morphology, and degradation. The main focus is on assessing the biocompatibility and antimicrobial properties of the materials.

Recent advancement in vascularized tissue-engineered bone based on materials design and modification

Bone is one of the most vascular network-rich tissues in the body and the vascular system is essential for the development, homeostasis, and regeneration of bone. When segmental irreversible damage occurs to the bone, restoring its vascular system by means other than autogenous bone grafts with vascular pedicles is a therapeutic challenge. By pre-generating the vascular network of the scaffold in vivo or in vitro, the pre-vascularization technique enables an abundant blood supply in the scaffold after implantation. However, pre-vascularization techniques are time-consuming, and in vivo pre-vascularization techniques can be damaging to the body. Critical bone deficiencies may be filled quickly with immediate implantation of a supporting bone tissue engineered scaffold. However, bone tissue engineered scaffolds generally lack vascularization, which requires modification of the scaffold to aid in enhancing internal vascularization. In this review, we summarize the relationship between the vascular system and osteogenesis and use it as a basis to further discuss surgical and cytotechnology-based pre-vascularization strategies and to describe the preparation of vascularized bone tissue engineered scaffolds that can be implanted immediately. We anticipate that this study will serve as inspiration for future vascularized bone tissue engineered scaffold construction and will aid in the achievement of clinical vascularized bone.

Amino-Functionalized Zirconium-Based Metal-Organic Frameworks as Bifunctional Nanomaterials to Treat Bone Tumors and Promote Osteogenesis

Bone tumor patients often encounter challenges associated with cancer cell residues and bone defects postoperation. To address this, there is an urgent need to develop a material that can enable tumor treatment and promote bone repair. Metal-organic frameworks (MOFs) have attracted the interest of many researchers due to their special porous structure, which has great potential in regenerative medicine and drug delivery. However, few studies explore MOFs with dual antitumor and bone regeneration properties. In this study, we investigated amino-functionalized zirconium-based MOF nanoparticles (UiO-66-NH2 NPs) as bifunctional nanomaterials for bone tumor treatment and osteogenesis promotion. UiO-66-NH2 NPs loading with doxorubicin (DOX) (DOX@UiO-66-NH2 NPs) showed good antitumor efficacy both in vitro and in vivo. Additionally, DOX@UiO-66-NH2 NPs significantly reduced lung injury compared to free DOX in vivo. Interestingly, the internalized UiO-66-NH2 NPs notably promoted the osteogenic differentiation of preosteoblasts. RNA-sequencing data revealed that PI3K-Akt signaling pathways or MAPK signaling pathways might be involved in this enhanced osteogenesis. Overall, UiO-66-NH2 NPs exhibit dual functionality in tumor treatment and bone repair, making them highly promising as a bifunctional material with broad application prospects.

Hydrogels as Scaffolds in Bone-Related Tissue Engineering and Regeneration

Several years have passed since the medical and scientific communities leaned toward tissue engineering as the most promising field to aid bone diseases and defects resulting from degenerative conditions or trauma. Owing to their histocompatibility and non-immunogenicity, bone grafts, precisely autografts, have long been the gold standard in bone tissue therapies. However, due to issues associated with grafting, especially the surgical risks and soaring prices of the procedures, alternatives are being extensively sought and researched. Fibrous and non-fibrous materials, synthetic substitutes, or cell-based products are just a few examples of research directions explored as potential solutions. A very promising subgroup of these replacements involves hydrogels. Biomaterials resembling the bone extracellular matrix and therefore acting as 3D scaffolds, providing the appropriate mechanical support and basis for cell growth and tissue regeneration. Additional possibility of using various stimuli in the form of growth factors, cells, etc., within the hydrogel structure, extends their use as bioactive agent delivery platforms and acts in favor of their further directed development. The aim of this review is to bring the reader closer to the fascinating subject of hydrogel scaffolds and present the potential of these materials, applied in bone and cartilage tissue engineering and regeneration.

Intelligent Vascularized 3D/4D/5D/6D-Printed Tissue Scaffolds

Blood vessels are essential for nutrient and oxygen delivery and waste removal. Scaffold-repairing materials with functional vascular networks are widely used in bone tissue engineering. Additive manufacturing is a manufacturing technology that creates three-dimensional solids by stacking substances layer by layer, mainly including but not limited to 3D printing, but also 4D printing, 5D printing and 6D printing. It can be effectively combined with vascularization to meet the needs of vascularized tissue scaffolds by precisely tuning the mechanical structure and biological properties of smart vascular scaffolds. Herein, the development of neovascularization to vascularization to bone tissue engineering is systematically discussed in terms of the importance of vascularization to the tissue. Additionally, the research progress and future prospects of vascularized 3D printed scaffold materials are highlighted and presented in four categories: functional vascularized 3D printed scaffolds, cell-based vascularized 3D printed scaffolds, vascularized 3D printed scaffolds loaded with specific carriers and bionic vascularized 3D printed scaffolds. Finally, a brief review of vascularized additive manufacturing-tissue scaffolds in related tissues such as the vascular tissue engineering, cardiovascular system, skeletal muscle, soft tissue and a discussion of the challenges and development efforts leading to significant advances in intelligent vascularized tissue regeneration is presented.

β-TCP from 3D-printed composite scaffolds acts as an effective phosphate source during osteogenic differentiation of human mesenchymal stromal cells

Introduction: Human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) are often combined with calcium phosphate (CaP)-based 3D-printed scaffolds with the goal of creating a bone substitute that can repair segmental bone defects. In vitro, the induction of osteogenic differentiation traditionally requires, among other supplements, the addition of β-glycerophosphate (BGP), which acts as a phosphate source. The aim of this study is to investigate whether phosphate contained within the 3D-printed scaffolds can effectively be used as a phosphate source during hBM-MSC in vitro osteogenesis. Methods: hBM-MSCs are cultured on 3D-printed discs composed of poly (lactic-co-glycolic acid) (PLGA) and β-tricalcium phosphate (β-TCP) for 28 days under osteogenic conditions, with and without the supplementation of BGP. The effects of BGP removal on various cellular parameters, including cell metabolic activity, alkaline phosphatase (ALP) presence and activity, proliferation, osteogenic gene expression, levels of free phosphate in the media and mineralisation, are assessed. Results: The removal of exogenous BGP increases cell metabolic activity, ALP activity, proliferation, and gene expression of matrix-related (COL1A1, IBSP, SPP1), transcriptional (SP7, RUNX2/SOX9, PPARγ) and phosphate-related (ALPL, ENPP1, ANKH, PHOSPHO1) markers in a donor dependent manner. BGP removal leads to decreased free phosphate concentration in the media and maintained of mineral deposition staining. Discussion: Our findings demonstrate the detrimental impact of exogenous BGP on hBM-MSCs cultured on a phosphate-based material and propose β-TCP embedded within 3D-printed scaffold as a sufficient phosphate source for hBM-MSCs during osteogenesis. The presented study provides novel insights into the interaction of hBM-MSCs with 3D-printed CaP based materials, an essential aspect for the advancement of bone tissue engineering strategies aimed at repairing segmental defects.

Berberine-Encapsulated Poly(lactic-co-glycolic acid)-Hydroxyapatite (PLGA/HA) Microspheres Synergistically Promote Bone Regeneration with DOPA-IGF-1 via the IGF-1R/PI3K/AKT/mTOR Pathway

Polymer microspheres have recently shown outstanding potential for bone tissue engineering due to their large specific surface area, good porosity, injectable property, good biocompatibility, and biodegradability. Their good load-release function and surface modifiability make them useful as a carrier of drugs or growth factors for the repair of bone defects in irregularly injured or complex microenvironments, such as skull defects. In this study, berberine (BBR)-encapsulated poly(lactic-co-glycolic acid) (PLGA)/hydroxyapatite (HA) microspheres were fabricated using electrified liquid jets and a phase-separation technique, followed by modification with the 3,4-hydroxyphenalyalanine-containing recombinant insulin-like growth-factor-1 (DOPA-IGF-1). Both the BBR and the IGF-1 exhibited sustained release from the IGF-1@PLGA/HA-BBR microspheres, and the composite microspheres exhibited good biocompatibility. The results of the alkaline phosphatase (ALP) activity assays showed that the BBR and IGF-1 in the composite microspheres synergistically promoted the osteogenic differentiation of MC3T3-E1 cells. Furthermore, it was confirmed that immobilized IGF-1 enhances the mRNA expression of an osteogenic-related extracellular matrix and that BBR accelerates the mRNA expression of IGF-1-mediated osteogenic differentiation and cell mineralization. Further cellular studies demonstrate that IGF-1 could further synergistically activate the IGF-1R/PI3K/AKT/mTOR pathway using BBR, thereby enhancing IGF-1-mediated osteogenesis. Rat calvarial defect repair experiments show that IGF-1@PLGA/HA-BBR microspheres can effectively promote the complete bony connection required to cover the defect site and enhance bone defect repair. These findings suggest that IGF-1@PLGA/HA-BBR composite microspheres show a great potential for bone regeneration.

Attributes of Nanomaterials and Nanotopographies for Improved Bone Tissue Engineering and Regeneration

Bone tissue engineering (BTE) is a multidisciplinary area that can solve the limitation of conventional grafting methods by developing viable and biocompatible bone replacements. The three essential components of BTE, i.e., Scaffold material and Cells and Growth factors altogether, facilitate support and guide for bone formation, differentiation of the bone tissues, and enhancement in the cellular activities and bone regeneration. However, there is a scarcity of the appropriate materials that can match the mechanical property as well as functional similarity to native tissue, considering the bone as hard tissue. In such scenarios, nanotechnology can be leveraged upon to achieve the desired aspects of BTE, and that is the key point of this review article. This review article examines the significant areas of nanotechnology research that have an impact on regeneration of bone: (a) scaffold with nanomaterials helps to enhance physicochemical interactions, biocompatibility, mechanical stability, and attachment; (b) nanoparticle-based approaches for delivering bioactive chemicals, growth factors, and genetic material. The article begins with the introduction of components and healing mechanisms of bone and the factors associated with them. The focus of this article is on the various nanotopographies that are now being used in scaffold formation, by describing how they are made, and how these nanotopographies affect the immune system and potential underlying mechanisms. The advantages of 4D bioprinting in BTE by using nanoink have also been mentioned. Additionally, we have investigated the importance of an in silico approach for finding the interaction between drugs and their related receptors, which can help to formulate suitable systems for delivery. This review emphasizes the role of nanoscale approach and how it helps to increase the efficacy of parameters of scaffold as well as drug delivery system for tissue engineering and bone regeneration.

A Bioglass-Poly(lactic-co-glycolic Acid) Scaffold@Fibrin Hydrogel Construct to Support Endochondral Bone Formation

Bone tissue engineering using stem cells to build bone directly on a scaffold matrix often fails due to lack of oxygen at the injury site. This may be avoided by following the endochondral ossification route; herein, a cartilage template is promoted first, which can survive hypoxic environments, followed by its hypertrophy and ossification. However, hypertrophy is so far only achieved using biological factors. This work introduces a Bioglass-Poly(lactic-co-glycolic acid@fibrin (Bg-PLGA@fibrin) construct where a fibrin hydrogel infiltrates and encapsulates a porous Bg-PLGA. The hypothesis is that mesenchymal stem cells (MSCs) loaded in the fibrin gel and induced into chondrogenesis degrade the gel and become hypertrophic upon reaching the stiffer, bioactive Bg-PLGA core, without external induction factors. Results show that Bg-PLGA@fibrin induces hypertrophy, as well as matrix mineralization and osteogenesis; it also promotes a change in morphology of the MSCs at the gel/scaffold interface, possibly a sign of osteoblast-like differentiation of hypertrophic chondrocytes. Thus, the Bg-PLGA@fibrin construct can sequentially support the different phases of endochondral ossification purely based on material cues. This may facilitate clinical translation by decreasing in-vitro cell culture time pre-implantation and the complexity associated with the use of external induction factors.

Seamlessly Adhesive Bionic Periosteum Patches Via Filling Microcracks for Defective Bone Healing

Current artificial designs of the periosteum focus on osteogenic or angiogenic properties, while ignoring the filling and integration with bone microcracks, which trigger a prolonged excessive inflammatory reaction and lead to failure of bone regeneration. In this study, seamless adhesive biomimetic periosteum patches (HABP/Sr-PLA) were prepared to fill microcracks in defective bone via interfacial self-assembly induced by Sr ions mediated metal-ligand interactions among pamidronate disodium-modified hyaluronic acid (HAPD), black phosphorus (BP), and hydrophilic polylactic acid (PLA). In vitro, HABP/Sr-PLA exhibited excellent self-healing properties, seamlessly filled bone microcracks, and significantly enhanced osteogenesis and angiogenesis. Furthermore, in a rat cranial defect model, HABP/Sr-PLA was demonstrated to significantly promote the formation of blood vessels and new bone under mild 808 nm photothermal stimulation (42.8 °C), and the highest protein expression of CD31 and OPN was five times higher than that of the control group and other groups. Therefore, the proposed seamless microcrack-filled bionic periosteum patch is a promising clinical strategy for promoting bone repair.

An anti-inflammatory chondroitin sulfate-poly(lactic-co-glycolic acid) composite electrospinning membrane for postoperative abdominal adhesion prevention

Postoperative abdominal adhesion is a very common and serious complication, resulting in pain, intestinal obstruction and heavy economic burden. Post-injury inflammation that could activate the coagulation cascade and deposition of fibrin is a major cause of adhesion. Many physical barrier membranes are used to prevent abdominal adhesion, but their efficiency is limited due to the lack of anti-inflammatory activity. Here, an electrospinning membrane composed of poly(lactic-co-glycolic acid) (PLGA) providing support and mechanical strength and chondroitin sulfate (CS) conferring anti-inflammation activity is fabricated for preventing abdominal adhesion after injury. The PLGA/CS membrane shows a highly dense fiber network structure with improved hydrophilicity and good cytocompatibility. Importantly, the PLGA/CS membrane with a mass ratio of CS at 20% provides superior anti-adhesion efficiency over a native PLGA membrane and commercial poly(D, L-lactide) (PDLLA) film in abdominal adhesion trauma rat models. The mechanism is that the PLGA/CS membrane could alleviate the local inflammatory response as indicated by the promoted percentage of anti-inflammatory M2-type macrophages and decreased expression of pro-inflammatory factors, such as IL-1β, TNF-α and IL-6, resulting in the suppression of the coagulation system and the activation of the fibrinolytic system. Furthermore, the deposition of fibrin at the abdominal wall was inhibited, and the damaged abdominal tissue was repaired with the treatment of the PLGA/CS membrane. Collectively, the PLGA/CS electrospinning membrane is a promising drug-/cytokine-free anti-inflammatory barrier for post-surgery abdominal adhesion prevention and a bioactive composite for tissue regeneration.

Aerogel-Based Materials in Bone and Cartilage Tissue Engineering-A Review with Future Implications

Aerogels are fascinating solid materials known for their highly porous nanostructure and exceptional physical, chemical, and mechanical properties. They show great promise in various technological and biomedical applications, including tissue engineering, and bone and cartilage substitution. To evaluate the bioactivity of bone substitutes, researchers typically conduct in vitro tests using simulated body fluids and specific cell lines, while in vivo testing involves the study of materials in different animal species. In this context, our primary focus is to investigate the applications of different types of aerogels, considering their specific materials, microstructure, and porosity in the field of bone and cartilage tissue engineering. From clinically approved materials to experimental aerogels, we present a comprehensive list and summary of various aerogel building blocks and their biological activities. Additionally, we explore how the complexity of aerogel scaffolds influences their in vivo performance, ranging from simple single-component or hybrid aerogels to more intricate and organized structures. We also discuss commonly used formulation and drying methods in aerogel chemistry, including molding, freeze casting, supercritical foaming, freeze drying, subcritical, and supercritical drying techniques. These techniques play a crucial role in shaping aerogels for specific applications. Alongside the progress made, we acknowledge the challenges ahead and assess the near and far future of aerogel-based hard tissue engineering materials, as well as their potential connection with emerging healing techniques.

Developed Bone Biomaterials Incorporated with MicroRNAs to Promote Bone Regeneration: A Systematic Review, Bioinformatics, and Meta-analysis Study

This systematic review and meta-analysis focused on the effectiveness of biomaterials integrated with specific microRNAs (miRNAs) for bone fracture repair treatment. We conducted a comprehensive search of the PubMed, Web of Science, and Scopus databases, identifying 42 relevant papers up to March 2022. Hydrogel-based scaffolds were the most commonly used, incorporating miRNAs like miR-26a, miR-21, and miR-222, with miR-26a being the most prevalent. The meta-analysis revealed significant benefits of incorporating miRNAs into scaffolds for bone repair, particularly in hydrogel scaffolds. However, some controversies were observed among studies, presenting challenges in selecting appropriate miRNAs for this purpose. The study concludes that incorporating specific miRNAs into bone biomaterials enhances bone regeneration, but further trials comparing different biomaterials and miRNAs are necessary to validate their potential applications for bone tissue regeneration.

3D-Printed lattice-inspired composites for bone reconstruction

Mechanical performance is crucial for biomedical applications of scaffolds. In this study, the stress distribution of six lattice-inspired structures was investigated using finite element simulations, and scaffolds with pre-designed structures were prepared using selective laser sintering (SLS) technology. The results showed that scaffolds with face-centered cubic (FCC) structures exhibited the highest compressive strength. Moreover, scaffolds composed of polylactic acid/anhydrous calcium hydrogen phosphate (PLA/DCPA) showed good mechanical properties and bioactivity. An in vitro study showed that these scaffolds promoted cell proliferation significantly and showed excellent osteogenic performance. Composite scaffolds with FCC structures are promising for bone tissue engineering.

Layered Double Hydroxides: A Novel Promising 2D Nanomaterial for Bone Diseases Treatment

Bone diseases including bone defects, bone infections, osteoarthritis, and bone tumors seriously affect life quality of the patient and bring serious economic burdens to social health management, for which the current clinical treatments bear dissatisfactory therapeutic effects. Biomaterial-based strategies have been widely applied in the treatment of orthopedic diseases but are still plagued by deficient bioreactivity. With the development of nanotechnology, layered double hydroxides (LDHs) with adjustable metal ion composition and alterable interlayer structure possessing charming physicochemical characteristics, versatile bioactive properties, and excellent drug loading and delivery capabilities arise widespread attention and have achieved considerable achievements for bone disease treatment in the last decade. However, to the authors' best knowledge, no review has comprehensively summarized the advances of LDHs in treating bone disease so far. Herein, the advantages of LDHs for orthopedic disorders treatment are outlined and the corresponding state-of-the-art achievements are summarized for the first time. The potential of LDHs-based nanocomposites for extended therapeutics for bone diseases is highlighted and perspectives for LDHs-based scaffold design are proposed for facilitated clinical translation.

Advances in the Study of Bionic Mineralized Collagen, PLGA, Magnesium Ionomer Materials, and Their Composite Scaffolds for Bone Defect Treatment

The healing of bone defects after a fracture remains a key issue to be addressed. Globally, more than 20 million patients experience bone defects annually. Among all artificial bone repair materials that can aid healing, implantable scaffolds made from a mineralized collagen (MC) base have the strongest bionic properties. The MC/PLGA scaffold, created by adding Poly (lactic-co-glycolic acid) copolymer (PLGA) and magnesium metal to the MC substrate, plays a powerful role in promoting fracture healing because, on the one hand, it has good biocompatibility similar to that of MC; on the other hand, the addition of PLGA provides the scaffold with an interconnected porous structure, and the addition of magnesium allows the scaffold to perform anti-inflammatory, osteogenic, and angiogenic activities. Using the latest 3D printing technology for scaffold fabrication, it is possible to model the scaffold in advance according to the requirement and produce a therapeutic scaffold suitable for various bone-defect shapes with less time and effort, which can promote bone tissue healing and regeneration to the maximum extent. This study reviews the material selection and technical preparation of MC/PLGA scaffolds, and the progress of their research on bone defect treatment.

Dispersant and Protective Roles of Amphiphilic Poly(ethylene phosphate) Block Copolymers in Polyester/Bone Mineral Composites

Composites of synthetic bone mineral substitutes (BMS) and biodegradable polyesters are of particular interest for bone surgery and orthopedics. Manufacturing of composite scaffolds commonly uses mixing of the BMS with polymer melts. Melt processing requires a high homogeneity of the mixing, and is complicated by BMS-promoted thermal degradation of polymers. In our work, poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) composites reinforced by commercial β-tricalcium phosphate (βTCP) or synthesized carbonated hydroxyapatite with hexagonal and plate-like crystallite shapes (hCAp and pCAp, respectively) were fabricated using injection molding. pCAp-based composites showed advanced mechanical and thermal characteristics, and the best set of mechanical characteristics was observed for the PLLA-based composite containing 25 wt% of pCAp. To achieve compatibility of polyesters and pCAp, reactive block copolymers of PLLA or PCL with poly(tert-butyl ethylene phosphate) (C1 and C2, respectively) were introduced to the composite. The formation of a polyester-b-poly(ethylene phosphoric acid) (PEPA) compatibilizer during composite preparation, followed by chemical binding of PEPA with pCAp, have been proved experimentally. The presence of 5 wt% of the compatibilizer provided deeper homogenization of the composite, resulting in a marked increase in strength and moduli as well as a more pronounced nucleation effect during isothermal crystallization. The use of C1 increased the thermal stability of the PLLA-based composite, containing 25 wt% of pCAp. In view of positive impacts of polyester-b-PEPA on composite homogeneity, mechanical characteristics, and thermal stability, polyester-b-PEPA will find application in the further development of composite materials for bone surgery and orthopedics.

PLGA-The Smart Biocompatible Polimer: Kinetic Degradation Studies and Active Principle Release

The aim of our research was the development of prolonged delivery systems for therapeutic agents with various properties (prevention and treatment of bone diseases, anti-neoplastic, anti-inflammatory, antioxidant) that would ensure sustained therapeutic levels of the active principle, above the minimum inhibitory concentration, without reaching toxic levels over a long period of time as alternatives to conventional routes of administration. PLGA (poly lactic-co-glycolic acid), a biodegradable and biocompatible synthetic polymer, FDA approved, with a 65:35 lactic acid (LA): glycolic acid (GA) copolymer ratio, was chosen as delivery system. Our studies have shown that in PBS it undergoes two simultaneous degradation processes, hydrolysis and autohydrolysis, degrading completely in about 40 days. The release of the active principle is determined by the diffusion from inside the polymer matrix to the outside, which occurs simultaneously with the erosion of the polymer, during 35 days.

Research Progress of Design Drugs and Composite Biomaterials in Bone Tissue Engineering

Bone, like most organs, has the ability to heal naturally and can be repaired slowly when it is slightly injured. However, in the case of bone defects caused by diseases or large shocks, surgical intervention and treatment of bone substitutes are needed, and drugs are actively matched to promote osteogenesis or prevent infection. Oral administration or injection for systemic therapy is a common way of administration in clinic, although it is not suitable for the long treatment cycle of bone tissue, and the drugs cannot exert the greatest effect or even produce toxic and side effects. In order to solve this problem, the structure or carrier simulating natural bone tissue is constructed to control the loading or release of the preparation with osteogenic potential, thus accelerating the repair of bone defect. Bioactive materials provide potential advantages for bone tissue regeneration, such as physical support, cell coverage and growth factors. In this review, we discuss the application of bone scaffolds with different structural characteristics made of polymers, ceramics and other composite materials in bone regeneration engineering and drug release, and look forward to its prospect.

Polyetheretherketone implants with hierarchical porous structure for boosted osseointegration

BACKGROUND

Good osseointegration is the key to the long-term stability of bone implants. Thermoplastic polyetheretherketone (PEEK) has been widely used in orthopedics; however, its inherent biological inertia causes fibrous tissue to wrap its surface, which leads to poor osseointegration and thus greatly limits its clinical applications.

METHODS

Herein, we developed a facile yet effective surface modification strategy. A commonly used sulfonation coupled with "cold pressing" treatment in the presence of porogenic agent formed a three-dimensional hierarchical porous structure on PEEK surface. Subsequently, the effects of porous surface on the in vitro adhesion, proliferation and differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) were evaluated. Finally, the osteoinduction and osseointegration of surface-porous PEEK implant were examined in the rat distal femoral defect model.

RESULTS

In vitro results showed that the surface modification did not significantly affect the mechanical performance and cytocompatibility of PEEK substance, and the porous structure on the modified PEEK substrate provided space for cellular ingrowth and enhanced osteogenic differentiation and mineralization of BMSCs. In vivo tests demonstrated that the surface-porous PEEK implant could effectively promote new bone formation and had higher bone-implant contact rate, thereby achieving good bone integration with the surrounding host bone. In addition, this modification technique was also successfully demonstrated on a medical PEEK interbody fusion cage.

CONCLUSION

The present study indicates that topological morphology plays a pivotal role in determining implant osseointegration and this facile and effective modification strategy developed by us is expected to achieve practical applications quickly.

Nanomaterials in tumor immunotherapy: new strategies and challenges

Tumor immunotherapy exerts its anti-tumor effects by stimulating and enhancing immune responses of the body. It has become another important modality of anti-tumor therapy with significant clinical efficacy and advantages compared to chemotherapy, radiotherapy and targeted therapy. Although various kinds of tumor immunotherapeutic drugs have emerged, the challenges faced in the delivery of these drugs, such as poor tumor permeability and low tumor cell uptake rate, had prevented their widespread application. Recently, nanomaterials had emerged as a means for treatment of different diseases due to their targeting properties, biocompatibility and functionalities. Moreover, nanomaterials possess various characteristics that overcome the defects of traditional tumor immunotherapy, such as large drug loading capacity, precise tumor targeting and easy modification, thus leading to their wide application in tumor immunotherapy. There are two main classes of novel nanoparticles mentioned in this review: organic (polymeric nanomaterials, liposomes and lipid nanoparticles) and inorganic (non-metallic nanomaterials and metallic nanomaterials). Besides, the fabrication method for nanoparticles, Nanoemulsions, was also introduced. In summary, this review article mainly discussed the research progress of tumor immunotherapy based on nanomaterials in the past few years and offers a theoretical basis for exploring novel tumor immunotherapy strategies in the future.

3D-Printed PLA Scaffold with Fibronectin Enhances In Vitro Osteogenesis

BACKGROUND

Tricalcium phosphate (TCP, Molecular formula: Ca₃(PO₄)₂) is a hydrophilic bone graft biomaterial extensively used for guided bone regeneration (GBR). However, few studies have investigated 3D-printed polylactic acid (PLA) combined with the osteo-inductive molecule fibronectin (FN) for enhanced osteoblast performance in vitro, and specialized bone defect treatments.

AIM

This study evaluated PLA properties and efficacy following glow discharge plasma (GDP) treatment and FN sputtering for fused deposition modeling (FDM) 3D printed PLA alloplastic bone grafts.

METHODS

3D trabecular bone scaffolds (8 × 1 mm) were printed by the 3D printer (XYZ printing, Inc. 3D printer da Vinci Jr. 1.0 3-in-1). After printing PLA scaffolds, additional groups for FN grafting were continually prepared with GDP treatment. Material characterization and biocompatibility evaluations were investigated at 1, 3 and 5 days.

RESULTS

SEM images showed the human bone mimicking patterns, and EDS illustrated the increased C and O after fibronectin grafting, XPS and FTIR results together confirmed the presence of FN within PLA material. Degradation increased after 150 days due to FN presence. 3D immunofluorescence at 24 h demonstrated better cell spreading, and MTT assay results showed the highest proliferation with PLA and FN (p < 0.001). Cells cultured on the materials exhibited similar alkaline phosphatase (ALP) production. Relative quantitative polymerase chain reaction (qPCR) at 1 and 5 days revealed a mixed osteoblast gene expression pattern.

CONCLUSION

In vitro observations over a period of five days, it was clear that PLA/FN 3D-printed alloplastic bone graft was more favorable for osteogenesis than PLA alone, thereby demonstrating great potential for applications in customized bone regeneration.

Functionalization of biomimetic mineralized collagen for bone tissue engineering

Mineralized collagen (MC) is the basic unit of bone structure and function and is the main component of the extracellular matrix (ECM) in bone tissue. In the biomimetic method, MC with different nanostructures of neo-bone have been constructed. Among these, extra-fibrous MC has been approved by regulatory agencies and applied in clinical practice to play an active role in bone defect repair. However, in the complex microenvironment of bone defects, such as in blood supply disorders and infections, MC is unable to effectively perform its pro-osteogenic activities and needs to be functionalized to include osteogenesis and the enhancement of angiogenesis, anti-infection, and immunomodulation. This article aimed to discuss the preparation and biological performance of MC with different nanostructures in detail, and summarize its functionalization strategy. Then we describe the recent advances in the osteo-inductive properties and multifunctional coordination of MC. Finally, the latest research progress of functionalized biomimetic MC, along with the development challenges and future trends, are discussed. This paper provides a theoretical basis and advanced design philosophy for bone tissue engineering in different bone microenvironments.

Metabolic regulation by biomaterials in osteoblast

The repair of bone defects resulting from high-energy trauma, infection, or pathological fracture remains a challenge in the field of medicine. The development of biomaterials involved in the metabolic regulation provides a promising solution to this problem and has emerged as a prominent research area in regenerative engineering. While recent research on cell metabolism has advanced our knowledge of metabolic regulation in bone regeneration, the extent to which materials affect intracellular metabolic remains unclear. This review provides a detailed discussion of the mechanisms of bone regeneration, an overview of metabolic regulation in bone regeneration in osteoblasts and biomaterials involved in the metabolic regulation for bone regeneration. Furthermore, it introduces how materials, such as promoting favorable physicochemical characteristics (e.g., bioactivity, appropriate porosity, and superior mechanical properties), incorporating external stimuli (e.g., photothermal, electrical, and magnetic stimulation), and delivering metabolic regulators (e.g., metal ions, bioactive molecules like drugs and peptides, and regulatory metabolites such as alpha ketoglutarate), can affect cell metabolism and lead to changes of cell state. Considering the growing interests in cell metabolic regulation, advanced materials have the potential to help a larger population in overcoming bone defects.