Recent trends in the application of widely used natural and synthetic polymer nanocomposites in bone tissue regeneration

Advancements in 3D printing technologies for personalized treatment of osteonecrosis of the femoral head

Three-dimensional (3D) printing technology has shown significant promise in the medical field, particularly in orthopedics, prosthetics, tissue engineering, and pharmaceutical preparations. This review focuses on the innovative application of 3D printing in addressing the challenges of osteonecrosis of the femoral head (ONFH). Unlike traditional hip replacement surgery, which is often suboptimal for younger patients, 3D printing offers precise localization of necrotic areas and the ability to create personalized implants. By integrating advanced biomaterials, this technology offers a promising strategy approach for early hip-preserving treatments. Additionally, 3D-printed bone tissue engineering scaffolds can mimic the natural bone environment, promoting bone regeneration and vascularization. In the future, the potential of 3D printing extends to combining with artificial intelligence for optimizing treatment plans, developing materials with enhanced bioactivity and compatibility, and translating these innovations from the laboratory to clinical practice. This review demonstrates how 3D printing technology uniquely addresses critical challenges in ONFH treatment, including insufficient vascularization, poor mechanical stability, and limited long-term success of conventional therapies. By introducing gradient porous scaffolds, bioactive material coatings, and AI-assisted design, this work outlines novel strategies to improve bone regeneration and personalized hip-preserving interventions. These advancements not only enhance treatment efficacy but also pave the way for translating laboratory findings into clinical applications.

Advanced progress of adipose-derived stem cells-related biomaterials in maxillofacial regeneration

The tissue injury in maxillofacial region affects patients' physical function and specific mental health. This decade, utilizing regenerative medicine to achieve tissue regeneration has been proved a hopeful direction. Seed cells play a vital role in regeneration strategy. Among various kinds of stem cells that effectively to regenerate the soft and hard tissue of maxillofacial region, adipose-derived stem cells (ADSCs) have gained increasing interests of researchers due to their abundant sources, easy availability and multi-differentiation potentials in recent decades. Thus, this review focuses on the advances of ADSCs-based biomaterial in maxillofacial regeneration from the progress and strategies perspective. It is structured as introducing the properties of ADSCs, biomaterials (polymers, ceramics and metals) within ADSCs and the latest applications of ADSCs in maxillofacial regeneration, including temporomandibular joint (TMJ), bone, periodontal tissue, tooth, nerve as well as cosmetic field. In order to further facilitate ADSCs-based therapies as an emerging platform for regenerative medicine, this review also emphasized current challenges in translating ADSC-based therapies into clinical application and dissussed the strategies to solve these obstacles.

Clinical challenges in bone tissue engineering - A narrative review

Bone tissue engineering (BTE) has emerged as a promising approach to address large bone defects caused by trauma, infections, congenital malformations, and tumors. This review focuses on scaffold design, cell sources, growth factors, and vascularization strategies, highlighting their roles in developing effective treatments. We explore the complexities of balancing mechanical properties, porosity, and biocompatibility in scaffold materials, alongside optimizing mesenchymal stem cell delivery methods. The critical role of growth factors in bone regeneration and the need for controlled release systems are discussed. Vascularization remains a significant hurdle, with strategies such as angiogenic factors, co-culture systems, and bioprinting under investigation. Mechanical challenges, tissue responses, and inflammation management are examined, alongside gene therapy's potential for enhancing osteogenesis and angiogenesis via both viral and non-viral delivery methods. The review emphasizes the impact of patient-specific factors on bone healing outcomes and the importance of personalized approaches. Future directions are described, emphasizing the necessity of interdisciplinary cooperation to advance the field of BTE and convert laboratory results into clinically feasible solutions.

Integrating microfluidic and bioprinting technologies: advanced strategies for tissue vascularization

Tissue engineering offers immense potential for addressing the unmet needs in repairing tissue damage and organ failure. Vascularization, the development of intricate blood vessel networks, is crucial for the survival and functions of engineered tissues. Nevertheless, the persistent challenge of ensuring an ample nutrient supply within implanted tissues remains, primarily due to the inadequate formation of blood vessels. This issue underscores the vital role of the human vascular system in sustaining cellular functions, facilitating nutrient exchange, and removing metabolic waste products. In response to this challenge, new approaches have been explored. Microfluidic devices, emulating natural blood vessels, serve as valuable tools for investigating angiogenesis and allowing the formation of microvascular networks. In parallel, bioprinting technologies enable precise placement of cells and biomaterials, culminating in vascular structures that closely resemble the native vessels. To this end, the synergy of microfluidics and bioprinting has further opened up exciting possibilities in vascularization, encompassing innovations such as microfluidic bioprinting. These advancements hold great promise in regenerative medicine, facilitating the creation of functional tissues for applications ranging from transplantation to disease modeling and drug testing. This review explores the potentially transformative impact of microfluidic and bioprinting technologies on vascularization strategies within the scope of tissue engineering.

Biodegradable cellulose scaffolds embedding kartogenin-loaded microspheres for cartilage regeneration

Due to the extreme difficulty of cartilage, we endeavored to fabricate a novel biodegradable scaffold using natural polysaccharide cellulose and poly(lactic-co-glycolic acid) (PLGA) microspheres incorporating controllably released the cartilage inducer kartogenin (KGN) for enhancing regenerative healing in cartilage tissue. Initially, to facilitate the loading of KGN, PLGA/KGN microspheres were fabricated using the solvent volatilization method. These microspheres exhibited high sphericity, with particle sizes diminishing from 12.11 to 3.27 μm as the emulsification rate increased. Demonstrating adequate encapsulation efficiency, the microspheres enabled controlled drug release, positively influencing cell migration and recruitment. Subsequently, a biodegradable cellulose composite scaffold loaded with PLGA/KGN microspheres was prepared using the freeze-drying method. Compared with pure MCC scaffolds, composite scaffolds had a lower degradation rate, and the incorporation of microspheres promoted cell proliferation and significantly elevated expression of cartilage-related specific genes. In a rat cartilage defect model, it was further demonstrated that the composite scaffold combined with stem cell implantation achieved an optimal repair effect, characterized by vigorous extracellular matrix secretion and increased maturity of the regenerated cartilage tissues, suggesting potential clinical application value as a novel articular cartilage repair product in the future.

Biodegradable Magnesium alloy Janus membrane with surface-selective osteoinduction and soft tissue healing properties in guided bone regeneration

Given that the guided bone regeneration (GBR) membrane acts at the interface between the bone and connective tissue, the membrane imposes high demands on the organization of the material. Magnesium (Mg) alloys have emerged as promising candidates for GBR due to their biodegradability and favorable biocompatibility. However, challenges remain in the risk of soft tissue dehiscence and limited osteogenesis for Mg membranes in the clinical application. A dicalcium phosphate dihydrate (CaHPO4·2H2O, denoted as DCPD)/MgF2 Janus membrane was fabricated via chemical conversion and deposition, showcasing suitable degradability, surface-selective osteogenic property and soft tissue healing in vitro and vivo. The DCPD coating was designed to support osteogenesis, while the MgF2 coating was specifically engineered to facilitate soft tissue healing. Furthermore, the Janus membrane utilized its two-sided properties to show selectivity in adhesion, proliferation, and migration of the MC3T3-E1 and HGFs. In vivo results exhibited its capability to promote bone formation and optimal space maintenance ability. Notably, further RNA-seq analysis demonstrated that different functional cells may respond specifically to two coatings and exert functions. Taken together, these results provide an alternative method for designing surface-selective biomaterials, underlining effective potential applications in bone tissue engineering. STATEMENT OF SIGNIFICANCE: Traditional clinical treatment of bone defects with GBR membranes is frequently constrained to a single superimposed osteogenesis without structural-functional integration. Such a DCPD/MgF2 coated Janus membrane was fabricated by incorporating chemical deposition and transformation to satisfy optimal osteogenesis and soft tissue healing. Of particular interest, the Janus membrane allowed for chemotactic movement with specific cellular responses to stimuli from different coatings. In vivo, the membrane demonstrated promising effects and showcased space maintenance ability. The design concept exhibits a new avenue to regulate tissue regeneration between different tissue interface, presenting new horizons for the development of GBR membranes.

Latest advancements and trends in biomedical polymers for disease prevention, diagnosis, treatment, and clinical application

Biomedical polymers are at the forefront of medical advancements, offering innovative solutions in disease prevention, diagnosis, treatment, and clinical use due to their exceptional physicochemical properties. This review delves into the characteristics, classification, and preparation methods of these polymers, highlighting their diverse applications in drug delivery, medical imaging, tissue engineering, and regenerative medicine. We present a thorough analysis of the recent advancements in biomedical polymer research and their clinical applications, acknowledging the challenges that remain, such as immune response management, controlled degradation rates, and mechanical property optimization. Addressing these issues, we explore future directions, including personalization and the integration of nanotechnology, which hold significant potential for further advancing the field. This comprehensive review aims to provide a deep understanding of biomedical polymers and serve as a valuable resource for the development of innovative polymer materials in both fundamental research and clinical practice.

Application and progress of 3D printed biomaterials in osteoporosis

Osteoporosis results from a disruption in skeletal homeostasis caused by an imbalance between bone resorption and bone formation. Conventional treatments, such as pharmaceutical drugs and hormone replacement therapy, often yield suboptimal results and are frequently associated with side effects. Recently, biomaterial-based approaches have gained attention as promising alternatives for managing osteoporosis. This review summarizes the current advancements in 3D-printed biomaterials designed for osteoporosis treatment. The benefits of biomaterial-based approaches compared to traditional systemic drug therapies are discussed. These 3D-printed materials can be broadly categorized based on their functionalities, including promoting osteogenesis, reducing inflammation, exhibiting antioxidant properties, and inhibiting osteoclast activity. 3D printing has the advantages of speed, precision, personalization, etc. It is able to satisfy the requirements of irregular geometry, differentiated composition, and multilayered structure of articular osteochondral scaffolds with boundary layer structure. The limitations of existing biomaterials are critically analyzed and future directions for biomaterial-based therapies are considered.

Bioprinted hydrogels in bone regeneration: a bibliometric analysis

Background

The application of bioprinted hydrogels in the field of bone regeneration is garnering increasing attention. The objective of this study is to provide a comprehensive overview of the current research status, hotspots and research directions in this field through bibliometric methods, and to predict the development trend of this field.

Methods

A search was conducted on 27 December 2024, for papers published on the Web of Science from 2010 to 2025. We used the bibliometrix package in the software program R to analyze the retrieved data and VOSviewer and CiteSpace to visualize hotspots and research trends in bioprinted hydrogels for bone regeneration.

Results

We identified and reviewed 684 articles published in this field between 2010 and 2025. A total of 811 institutions and 1,166 researchers from 41 countries/regions contributed to these publications. Among them, China led in terms of the number of articles published, single-country publications (SCP), and multi-country publications (MCP). Our bibliometric-based visualization analysis revealed that the mechanical properties and osteogenic differentiation capacity of biomaterials have been a focal research topic over the past decade, while emerging research has also concentrated on the in vitro fabrication of stem cells for bone regeneration and osteogenic differentiation, particularly the precise application of in situ stem cell-loaded bioprinted organoids.

Conclusion

This study provides an in-depth analysis of the research trajectory in the application of bioprinted hydrogels for bone regeneration. The number of research papers in this field is increasing annually, and the main research hotspots include bone regeneration, 3D printing, scaffolds, and hydrogels. Future research directions may focus on gelatin, additive manufacturing, and growth factors. Additionally, international collaboration is essential to enhance the effectiveness of bioprinted hydrogels in bone regeneration applications.

Engineered protein-based materials for tissue repair: A review

The human body may suffer multiple injuries and losses due to various external factors, such as tumors, diseases, traffic accidents, and war conflicts. Under such circumstances, engineered protein-based materials, as an innovative adjunctive material, can not only effectively promote the natural repair process of tissues, but also greatly circumvent the negative effects and complications that may be associated with conventional surgery. In this review, we first trace the definition and development of engineered protein-based materials and explain in detail their mechanism of action in promoting tissue repair. Subsequently, the advantages and disadvantages of various engineered protein-based materials in tissue repair are analyzed by comparison. In addition, the present review reveals in depth how material properties can be optimized by scientific means to meet different tissue repair needs. In addition, we present in detail specific application cases of engineered protein-based materials in the field of tissue repair. Finally, we summarize current challenges in engineered protein-based materials and provide an outlook for the future. This review not only provides theoretical support for the further exploration and development of engineered protein-based materials in the field of tissue repair, but also provides valuable references and inspiration for research in related fields.

Effect of graphene oxide in an injectable hydrogel on the osteogenic differentiation of mesenchymal stem cells

Graphene oxide (GO) is widely used in bone tissue engineering due to its good biocompatibility and proliferation, and is often used in combination with other hydrogels, which not only reduces the cytotoxicity of GO but also improves the mechanical properties of the hydrogels. We developed injectable carboxymethyl chitosan (CMC)/hydroxyethyl cellulose (HEC)/β-tricalcium phosphate (β-TCP)/GO hydrogel via hydrogen bonding cross-linked between (CMC) and (HEC), also, calcium cross-linked by β-TCP was also involved to further improvement of mechanical properties of the hydrogel, and incorporate different concentration of GO in these hydrogel systems. The characterization of the novel hydrogel was tested by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The swelling ratio and mechanical properties were investigated, the results showed that the addition of GO was able to reduce the swelling rate of hydrogels and improve their mechanical properties, with the best effect in the case of 1 mg/mL content. In vivo experimental studies showed that the hydrogel significantly promoted the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs), with the best effect at a concentration of 2 mg/mL. The results of the cellular experiments were similar. Therefore, the novel environment-friendly and non-toxic injectable CMC/HEC/β-TCP/GO hydrogel system may have potential applications in bone tissue engineering.

Comparative Analysis of Tunicate vs. Plant-Based Cellulose in Chitosan Hydrogels for Bone Regeneration

A novel hydrogel scaffold for bone regeneration based on chitosan, selected for its biocompatibility, biodegradability, and antimicrobial properties, was covalently functionalized with a bioactive peptide from bone morphogenetic protein-2 (BMP-2) to guide osteoblast growth and proliferation. This study evaluates the impact of incorporating different concentrations (8, 16, or 24% wt/wt) of plant-based micro-fibrillated cellulose or tunicate nanocellulose to improve the mechanical and biological properties of peptide-grafted chitosan hydrogel matrices. While the mechanical properties of the matrices increase with increasing cellulose content, regardless of its source, the behavior of human osteoblasts used in biological tests discriminates between the two types of cellulose and shows better results (proliferation at 2 and 7 days, and mineralization) for the enrichment with tunicate cellulose.

3D printed skin dressings manufactured with spongin-like collagen from marine sponges: physicochemical properties andin vitrobiological analysis

The search for innovative materials for manufacturing skin dressings is constant and high demand. In this context, the present study investigated the effects of a 3D printed skin dressing made of spongin-like collagen (SC) extract from marine sponge (Chondrilla caribensis), used in 3 concentrations of SC and alginate (C1, C2, C3). For this proposal, the physicochemical, morphological andin vitrobiological results were investigated. The results demonstrated that, after immersion, C2 presented a higher mass loss and C3 present a higher pH in experimental periods. Also, a higher porosity was observed for C1 and C2 skin dressings, with a higher swelling ratio for C2. For Fourier transform infrared, peaks of Amide A, -CH2, -COOH and C-O-C were seen. Moreover, the macroscopic image demonstrated a skin dressing with rough surface and grayish color that is naturally observed inChondrilla caribensis. For scanning electron microscopy analysis the presence of pores could be observed for all skin dressings, with fibers disposed in layers. Thein vitroanalyses demonstrated the viability of HFF-1 and L929 cell lines 70% of the values found for cell proliferation compared to Control Group. Furthermore, the cell adhesion analysis demonstrated that both cell lines adhered to the 3 different skin dressings and non-cytotoxicity was observed. Taking together, all the results suggest that the skin dressings are biocompatible and present non-cytotoxicity in thein vitrostudies, being considered a suitable material for tissue engineering proposals.

Systematic development and bioprinting of novel nanostructured multi-material bioinks for bone tissue engineering

A functional bioink with potential in bone tissue engineering must be subjected to critical investigation throughout its intended lifespan. The aim of this study was to develop alginate-gelatin-based (Alg-Gel) multicomponent bioinks systematically and to assess the short- and long-term exposure responses of human bone marrow stromal cells (hBMSCs) printed within these bioinks with and without crosslinking.The first generation of bioinkswas established by incorporating a range of cellulose nanofibrils (CNFs), to evaluate their effect on viscosity, printability and cell viability. Adding CNFs to Alg-Gel solution increased viscosity and printability without compromising cell viability. Inthe second generation of bioinks, the influence of nano-hydroxyapatite (nHA) on the performance of the optimized Alg-Gel-CNF formulation was investigated. The addition of nHA increased the viscosity and improved printability, and an adjustment in alginate concentration improved the stability of the structures in long-term culture. The third generation bioink incorporated RGD-functionalized alginate to support cell attachment and osteogenic differentiation. The optimized bioink composition exhibited improved printability, structural integrity in long-term culture and high hBMSC viability. In addition, the final bioink composition, RGD-Alg-Gel-CNF-nHA, showed osteogenic potential: production of the osteogenic marker proteins (Runx2, OCN), enzyme (ALP), and gene expression (Runx2,OCN). A further aim of the study was to evaluate the osteogenic functionality of cells released from the structures after bioprinting. Cells were printed in two bioinks with different viscosities and incubated at 37 °C in growth medium without additional CaCl2. This caused gelatin to dissolve, releasing the cells to attach to tissue culture plates. The results demonstrated differences in hBMSC osteogenic differentiation. Moreover, the osteogenic differentiation of the released cells was different from that of the embedded cells cultured in 3D. Thus, this systematic investigation into bioink development shows improved results through the generations and sheds light on the biological effects of the bioprinting process.

Comparison of Two Synthesis Methods for 3D PLA-Ibuprofen Nanofibrillar Scaffolds

OBJECTIVES

This study aimed to synthesize polylactic acid (PLA) nanofibrillar scaffolds loaded with ibuprofen (IBU) using electrospinning (ES) and air-jet spinning (AJS). The scaffolds were evaluated for their physicochemical properties, drug release profiles, and biocompatibility to assess their potential for local analgesic applications.

METHODS

Solutions of 10% (w/v) PLA combined with IBU at concentrations of 10%, 20%, and 30% were processed into nanofibrillar membranes using ES and AJS. The scaffolds were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transformed infrared (FT-IR) spectroscopy. The drug release profile was assessed by ultraviolet-visible spectrophotometry (UV-Vis), and cell adhesion and viability were evaluated using fibroblast culture assays. Statistical analyses included qualitative analyses, t-tests, and Likelihood ratio tests.

RESULTS

SEM revealed randomly arranged nanofibers forming reticulated meshes, with more uniform dimensions observed in the AJS group. TGA and DSC analyses confirmed the thermodynamic stability of the scaffolds and enthalpy changes consistent with IBU incorporation, which FT-IR and UV-Vis validated. Drug release was sustained over 384 h, showing no significant differences between ES and AJS scaffolds (p > 0.05). Cytotoxicity and cell viability assays confirmed scaffold biocompatibility, with cellular responses proportional to drug concentration but within safe limits.

CONCLUSIONS

PLA-IBU nanofibrillar scaffolds were successfully synthesized using ES and AJS. Both methods yielded biocompatible systems with stable properties and controlled drug release. Further, in vivo studies are necessary to confirm their clinical potential.

Photothermal Coating on Zinc Alloy for Controlled Biodegradation and Improved Osseointegration

Zinc (Zn) and its alloys are promising biomaterials for orthopedic applications due to their degradability and mechanical properties. Zn2+ plays a crucial role in bone formation, but excessive early release may cause cytotoxicity and inhibit osseointegration. To solve this, we developed a near-infrared (NIR) light-controlled polycaprolactone/copper-sulfur (PCL/CuS) coating that slows degradation and enhances osseointegration of Zn alloys. The zinc-lithium (Zn-Li) substrate is encapsulated with PCL, reducing Zn2+ release and maintaing biocompatibility. Controlled Zn2+ release and mild photothermal therapy via CuS nanoparticles promoted osteogenesis. In vitro studies demonstrated enhanced cell proliferation and osteogenic differentiation. In vivo Micro-Computed Tomography (Micro-CT), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), and immunohistochemical analyses confirmed improved osseointegration. Mechanistic studies using RNA sequencing and Western blotting revealed that the coating promotes osteogenesis by activating the Wnt/β-catenin and inhibiting NF-κB pathways. This NIR light-controlled PCL/CuS coating successfully regulates Zn alloy degradation, enhances osseointegration via controlled Zn2+ release and mild photothermal therapy effct, presenting a promising avenue for orthopedic biomaterials.

Integrating Micro- and Nanostructured Platforms and Biological Drugs to Enhance Biomaterial-Based Bone Regeneration Strategies

Bone defects resulting from congenital anomalies and trauma pose significant clinical challenges for orthopedics surgeries, where bone tissue engineering (BTE) aims to address these challenges by repairing defects that fail to heal spontaneously. Despite numerous advances, BTE still faces several challenges, i.e., difficulties in detecting and tracking implanted cells, high costs, and regulatory approval hurdles. Biomaterials promise to revolutionize bone grafting procedures, heralding a new era of regenerative medicine and advancing patient outcomes worldwide. Specifically, novel bioactive biomaterials have been developed that promote cell adhesion, proliferation, and differentiation and have osteoconductive and osteoinductive characteristics, stimulating tissue regeneration and repair, particularly in complex skeletal defects caused by trauma, degeneration, and neoplasia. A wide array of biological therapeutics for bone regeneration have emerged, drawing from the diverse spectrum of gene therapy, immune cell interactions, and RNA molecules. This review will provide insights into the current state and potential of future strategies for bone regeneration.

Construction of Nanohydroxyapatite/Poly(sodium lipoate)-Based Bioactive Hydrogels for Cranial Bone Regeneration

Persistent oxidative stress following bone defects significantly impedes the repair of bone tissue. Designing an antioxidative hydrogel with a suitable mechanical strength can help alter the local microenvironment and promote bone defect healing. In this work, α-lipoic acid (LA), a natural antioxidant small molecule, was chemically cross-linked with lipoic acid-functionalized poly(ethylene glycol) (PEGx, x = 6k or 10k) in sodium bicarbonate solution, to prepare LA-PEGx hydrogels (LPx, x = 6k or 10k). Furthermore, nanohydroxyapatite (nHA)-LA-PEGx (HLPx, x = 6k) hydrogels were constructed through incorporating nHA. The hydrogels exhibited moderate mechanical strength, facile injectability, self-healability, adhesion, biodegradability, biocompatibility, and promising antioxidation efficiency. We verify the advantage of the HLP6k-3 hydrogel in a rat cranial defect model. Through the regulation of reactive oxygen species (ROS), osteoconduction, and biomineralization capabilities, our system can promote new bone formation. Overall, bioactive hydrogels with multiple functions hold significant promise for repairing bone defects.

Histology Assessment of Chitosan-Polyvinyl Alcohol Scaffolds Incorporated with CaO Nanoparticles

Scaffolds for regenerative therapy can be made from natural or synthetic polymers, each offering distinct benefits. Natural biopolymers like chitosan (CS) are biocompatible and biodegradable, supporting cell interactions, but lack mechanical strength. Synthetic polymers like polyvinyl alcohol (PVA) provide superior mechanical strength and cost efficiency but are not biodegradable or supportive of cell adhesion. Combining these polymers optimizes their advantages while adding metal oxide nanoparticles like calcium oxide (CaO NPs) enhances antimicrobial properties by damaging bacterial membranes. In this study, we obtained the formation of CaO NPs by calcinating eggshells, which were mixed in a polymeric network of CS and PVA to obtain four different membrane formulations for subdermal tissue regeneration. The spherical nanoparticles measured 13.43 ± 0.46 nm in size. Their incorporation into the membranes broadened the hydroxyl bands in the Fourier transform infrared (FTIR) analysis at 3331 cm⁻1. X-ray diffraction (XRD) analysis showed changes in the crystalline structure, with new diffraction peaks at 2θ values of 7.2° for formulations F2, F3, and F4, likely due to the increased amorphous nature and concentration of CaO NPs. Additionally, higher CaO NPs concentrations led to a reduction in thermal properties and crystallinity. Scanning electron microscopy (SEM) revealed a heterogeneous morphology with needle-like structures on the surface, resulting from the uniform dispersion of CaO NPs among the polymer chains and the solvent evaporation process. A histological examination of the implanted membranes after 60 days indicated their biocompatibility and biodegradability, facilitated by incorporating CaO NPs. During the degradation process, the material fragmented and was absorbed by inflammatory cells, which promoted the proliferation of collagen fibers and blood vessels. These findings highlight the potential of incorporating CaO NPs in soft tissue regeneration scaffolds.

Preparation and osteogenesis of a multiple crosslinking silk fibroin/carboxymethyl chitosan/sodium alginate composite scaffold loading with mesoporous silica/poly (lactic acid-glycolic acid) microspheres

Large bone defect repair is a striking challenge in orthopedics. Currently, inorganic-organic composite scaffolds are considered as a promising approach to these bone regeneration. Silicon ions (Si4+) are bioactive and beneficial to bone regeneration and Si4+-containing inorganic mesoporous silica (MS) can effectively load drugs for bone repair. To better control the release of drug, we prepared biodegradable MS/PLGA (MP) microspheres. MP loaded organic silk fibroin/carboxymethyl chitosan/sodium alginate (MP/SF/CMCS/SA) composite scaffolds were further constructed by genipin and Ca2+ crosslinking. All MP/SF/CMCS/SA scaffolds had good swelling ability, degradation rate and high porosity. The incorporation of 1% MP significantly enhanced the compressive strength of composite scaffolds. Besides, MP loaded scaffold showed a sustained release of Si4+ and Ca2+. Moreover, the release rate of rhodamine (a model drug) of MP/SF/CMCS/SA scaffolds was obviously lower than that of MP. When culturing with rat bone marrow mesenchymal stem cells, scaffolds with 1% MP displayed good proliferation, adhesion and enhanced osteogenic differentiation ability. Based on the results above, the addition of 1% MP in SF/CMCS/SA scaffolds is a prospective way for drug release in bone regeneration and is promising for further in vivo bone repair applications.

Osteochondral Tissue Engineering: Scaffold Materials, Fabrication Techniques and Applications

Osteochondral damage, caused by trauma, tumors, or degenerative diseases, presents a major challenge due to the limited self-repair capacity of the tissue. Traditional treatments often result in significant trauma and unpredictable outcomes. Recent advances in bone/cartilage tissue engineering, particularly in scaffold materials and fabrication technologies, offer promising solutions for osteochondral regeneration. This review highlights the selection and design of scaffolds using natural and synthetic materials such as collagen, chitosan (Cs), and polylactic acid (PLA), alongside inorganic components like bioactive glass and nano-hydroxyapatite (nHAp). Key fabrication techniques-freeze-drying, electrospinning, and 3D printing-have improved scaffold porosity and mechanical properties. Special focus is placed on the design of multiphasic scaffolds that mimic natural tissue structures, promoting cell adhesion and differentiation and supporting the regeneration of cartilage and subchondral bone. In addition, the current obstacles and future directions for regenerating damaged osteochondral tissues will be discussed.

Osteogenic potential of esculetin-loaded chitosan nanoparticles in microporous alginate/polyvinyl alcohol scaffolds for bone tissue engineering

Bone tissue engineering (BTE) is an emerging strategy for the treatment of critical bone defects using biomaterials and cells. Esculetin (ES), a coumarin phytocompound, has demonstrated therapeutic potential, although its osteogenic effects remain insufficiently explored. Owing to its hydrophobic nature, which limits its bioavailability, this study developed a drug delivery system using chitosan nanoparticles (nCS) to achieve sustained release of ES. These ES-loaded nCS nanoparticles were incorporated into biocomposite scaffolds composed of alginate (Alg) and polyvinyl alcohol (PVA) using freeze-drying. The synthesized nCS-ES nanoparticles exhibited spherical morphology with a uniform size distribution, ranging from 105 to 117 nm, and demonstrated excellent entrapment efficiencies (94.07 to 97.61 %). The nanoparticles displayed high zeta potential values (+27.8 to +33.2 mV), ensuring stable dispersion. The biocomposite scaffolds exhibited a uniform distribution of pores, with pore diameters ranging from 106 ± 14 μm to 112 ± 14 μm. The biocomposite scaffolds exhibited excellent swelling, protein adsorption, biodegradation, and biomineralization properties. The ES-loaded scaffolds showed sustained ES release, promoting osteogenesis in vitro, with the activation of the Wnt/β-catenin signaling pathway. In vivo studies using a rat tibial bone defect model further confirmed that these scaffolds stimulated new bone formation, highlighting the ES's potential for BTE applications.

Immunomodulatory and osteogenic effects of chitosan-based injectable hydrogel with geniposide-loaded mesoporous bioactive glass

The immune response dominated by macrophages plays a pivotal role in the regeneration of bone tissue. In this work, an injectable temperature-responsive hydrogel composed of geniposide-loaded mesoporous bioactive glass, chitosan and β-glycerophosphate (G-M Gel) was prepared, showing robustly networks, uniform pore structure, excellent biocompatibility, immunomodulatory effect and osteogenic potential. In an inflammatory microenvironment elicited by lipopolysaccharide (LPS), the proportion of M1 and M2 macrophages measured by flow cytometry were 33.17 % and 2.07 %, respectively. After G-M Gel treatment, the proportion of M1 macrophages decreased to 14.4 %, while the proportion of M2 macrophages increased significantly to 16.2 %. LPS treated macrophage conditioned medium inhibited the expression of osteogenic related factors (OCN, OPN, Runx2), alkaline phosphatase (ALP) and alizarin red S (ARS) in MC3T3-E1 cells. In contrast, LPS + G-M Gel treated macrophage conditioned medium significantly increased the expression of osteogenic related factors, ALP and ARS. These results demonstrated that G-M Gel can augment bone formation by promoting the polarization of M2 macrophages, showing great potential clinical application of G-M Gel in bone regeneration field.

Biomaterial Cues for Regulation of Osteoclast Differentiation and Function in Bone Regeneration

Tissue regeneration involves dynamic dialogue between and among different cells and their surrounding matrices. Bone regeneration is specifically governed by reciprocity between osteoblasts and osteoclasts within the bone microenvironment. Osteoclast-directed resorption and osteoblast-directed formation of bone are essential to bone remodeling, and the crosstalk between these cells is vital to curating a sequence of events that culminate in the creation of bone tissue. Among bone biomaterial strategies, many have investigated the use of different material cues to direct the development and activity of osteoblasts. However, less attention has been given to exploring features that similarly target osteoclast formation and activity, with even fewer strategies demonstrating or integrating biomaterial-directed modulation of osteoblast-osteoclast coupling. This review aims to describe various biomaterial cues demonstrated to influence osteoclastogenesis and osteoclast function, emphasizing those that enhance a material construct's ability to achieve bone healing and regeneration. Additionally discussed are approaches that influence the communication between osteoclasts and osteoblasts, particularly in a manner that takes advantage of their coupling. Deepening our understanding of how biomaterial cues may dictate osteoclast differentiation, function, and influence on the microenvironment may enable the realization of bone-replacement interventions with enhanced integrative and regenerative capacities.

FRESH 3D printing of zoledronic acid-loaded chitosan/alginate/hydroxyapatite composite thermosensitive hydrogel for promoting bone regeneration

The aim of this study was to develop a composite thermosensitive hydrogel for bone regeneration applications. This hydrogel consisted of chitosan, alginate and hydroxyapatite, and was loaded with zoledronic acid as a model drug. The feasibility of three-dimensional (3D) printing of the thermosensitive hydrogel using the extrusion based technique was investigated. The 3D printing technique called Freeform Reversible Embedded Suspended Hydrogel (FRESH) printing was employed for this purpose. To characterize the composite hydrogels, several tests were conducted. The gelation time, rheological properties, and in vitro drug release were analyzed. Additionally, the cell viability test on human osteosarcoma MG-63 cells for the composite hydrogel was assessed using an MTT assay. The results of the study showed that the zoledronic acid-loaded composite thermosensitive hydrogel was successfully printed using the FRESH 3D printing technique which was not possible otherwise i.e., by using traditional 3D printing techniques. Further examination of the printed constructs using a Scanning Electron Microscope revealed the presence of porous and layered structures. The gelation times of the composite thermosensitive hydrogel was determined to be 10 and 20 min, respectively for scaffolds with and without HA, indicating the successful formation of the gel within a reasonable time to the FRESH technique. The flow behavior of the hydrogel was found to be pseudoplastic, following a non-Newtonian flow pattern with Farrow's constant (N) values of 1.708 and 1.853 for scaffolds with and without hydroxyapatite, respectively. In terms of drug release, scaffolds prepared with and without hydroxyapatite reached nearly 100% of zoledronic acid release in 360 h and 48 h, respectively. The cell viability test on human osteosarcoma MG-63 cells using MTT assay has shown increased cell viability % in the case of composite hydrogel, indicating biocompatibility of the scaffold. Overall, this study successfully developed a composite thermosensitive hydrogel loaded with zoledronic acid for bone regeneration applications and was 3D printed using the FRESH 3D printing technique. The results of this study provide valuable insights into the potential use of this composite hydrogel for future biomedical applications.

A new path in bone tissue engineering: polymer-based 3D-printed magnetic scaffolds (a comprehensive review of in vitro and in vivo studies)

Bone tissue engineering is a promising approach to address the increasing need for bone repair. Scaffolds play a crucial role in providing the structural framework for cell growth and differentiation. 3D printing offers precise control over scaffold design and fabrication. Polymers and inorganic compounds such as magnetic nanoparticles (MNPs) are used to create biocompatible and functional scaffolds. MNPs enhance mechanical properties, facilitate drug delivery, and enable the real-time monitoring of bone regeneration. This review highlights the potential of polymer-based 3D-printed magnetic scaffolds in advancing bone regenerative medicine.

Medical applications and prospects of polylactic acid materials

Polylactic acid (PLA) is a biodegradable and bio-based polymer that has gained significant attention as an environmentally friendly alternative to traditional petroleum-based plastics. In clinical treatment, biocompatible and non-toxic PLA materials enhance safety and reduce tissue reactions, while the biodegradability allows it to breakdown over time naturally, avoiding a second surgery. With the emergence of nanotechnology and three-dimensional (3D) printing, medical utilized-PLA has been produced with more structural and biological properties at both micro and macro scales for clinical therapy. This review summarizes current applications of the PLA-based biomaterials in drug delivery systems, orthopedic treatment, tissue regenerative engineering, and surgery and medical devices, providing viewpoints regarding the prospective medical utilization.

Advances in Injectable Polymeric Biomaterials and Their Contemporary Medical Practices

Injectable biomaterials have been engineered to operate within the human body, offering versatile solutions for minimally invasive therapies and meeting several stringent requirements such as biocompatibility, biodegradability, low viscosity for ease of injection, mechanical strength, rapid gelation postinjection, controlled release of therapeutic agents, hydrophobicity/hydrophilicity balance, stability under physiological conditions, and the ability to be sterilized. Their adaptability and performance in diverse clinical settings make them invaluable for modern medical treatments. This article reviews recent advancements in the design, synthesis, and characterization of injectable polymeric biomaterials, providing insights into their emerging applications. We discuss a broad spectrum of these materials, including natural, synthetic, hybrid, and composite types, that are being applied in targeted drug delivery, cell and protein transport, regenerative medicine, tissue adhesives, injectable implants, bioimaging, diagnostics, and 3D bioprinting. Ultimately, the review highlights the critical role of injectable polymeric biomaterials in shaping the future of medical treatments and improving patient outcomes across a wide range of therapeutic and diagnostic applications.

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.

Enhanced bacteriostasis and osseointegrative properties of SiRNA-modified polyetheretherketone surface for implant applications

Polyetheretherketone (PEEK), bearing an elastic modulus that effectively simulates the innate properties of natural bone, has come into the spotlight as a promising bone substitute material. Nonetheless, the biologically inert nature of PEEK, combined with its insubstantial osseointegration and sterilization capabilities, pose constraints on its clinical application in the realm of implants. RNA interference (RNAi), an effective technique used for gene expression regulation, has begun to be applied in implant surface modification. Herein, siCKIP-1 is securely affixed to the surface of PEEK implants, aided by an antibacterial polyphenol tannic acid (pTAN) coatings, enhancing physiologic osseointegration and inhibiting bacterial infection. This method breakthrough not merely facilitates the convenience, but also multifaceted PEEK implants' refinements. The modified PEEK implants have impressive biocompatibility coupled with a noteworthy degree of antibacterial properties. Meanwhile, modified PEEK implants improved osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs) and demonstrated excellent osteointegrative properties in rat femur implantation models. Therefore, identifying a new implant material with excellent biocompatibility and biomechanical properties is essential.

Application of loaded graphene oxide biomaterials in the repair and treatment of bone defects

Addressing bone defects is a complex medical challenge that involves dealing with various skeletal conditions, including fractures, osteoporosis (OP), bone tumours, and bone infection defects. Despite the availability of multiple conventional treatments for these skeletal conditions, numerous limitations and unresolved issues persist. As a solution, advancements in biomedical materials have recently resulted in novel therapeutic concepts. As an emerging biomaterial for bone defect treatment, graphene oxide (GO) in particular has gained substantial attention from researchers due to its potential applications and prospects. In other words, GO scaffolds have demonstrated remarkable potential for bone defect treatment. Furthermore, GO-loaded biomaterials can promote osteoblast adhesion, proliferation, and differentiation while stimulating bone matrix deposition and formation. Given their favourable biocompatibility and osteoinductive capabilities, these materials offer a novel therapeutic avenue for bone tissue regeneration and repair. This comprehensive review systematically outlines GO scaffolds' diverse roles and potential applications in bone defect treatment.

Nanoengineered Endocytic Biomaterials for Stem Cell Therapy

Stem cells, ideal for the tissue repair and regeneration, possess extraordinary capabilities of multidirectional differentiation and self‐renewal. However, the limited spontaneous differentiation potential makes it challenging to harness them for tissue repair without external intervention. Although conventional approaches using biomolecules, small organic molecules, and ions have shown specific and effective functions, they face challenges such as in vivo diffusion and degradation, poor internalization, and side effects on adjacent cells. Nanoengineered biomaterials offer a solution by solidifying and nanosizing these soluble regulating molecules and ions, facilitating their uptake by stem cells. Once inside lysosomes, these nanoparticles release their contents in a controlled “molecule or ion storm,” efficiently altering the intracellular biological and chemical microenvironment to tune the differentiation of stem cells. This newly emerged approach for regulating stem cell fate has attracted much attention in recent years. This method has shown promising results and is poised to enhance clinical stem cell therapy. This review provides an overview of the design principles for nanoengineered biomaterials, discusses the categories and characteristics of nanoparticles, summarizes the application of nanoparticles in tissue repair and regeneration, and discusses the direction of nanoparticle‐enhanced stem cell therapy and prospects for its clinical application in regenerative medicine.

Engineering of Bioresorbable Polymers for Tissue Engineering and Drug Delivery Applications

Herein, the recent advances in the development of resorbable polymeric-based biomaterials, their geometrical forms, resorption mechanisms, and their capabilities in various biomedical applications are critically reviewed. A comprehensive discussion of the engineering approaches for the fabrication of polymeric resorbable scaffolds for tissue engineering, drug delivery, surgical, cardiological, aesthetical, dental and cardiovascular applications, are also explained. Furthermore, to understand the internal structures of resorbable scaffolds, representative studies of their evaluation by medical imaging techniques, e.g., cardiac computer tomography, are succinctly highlighted. This approach provides crucial clinical insights which help to improve the materials' suitable and viable characteristics for them to meet the highly restrictive medical requirements. Finally, the aspects of the legal regulations and the associated challenges in translating research into desirable clinical and marketable materials of polymeric-based formulations, are presented.

Composite PCL Scaffold With 70% β-TCP as Suitable Structure for Bone Replacement

OBJECTIVES

The purpose of this work was to optimise printable polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP) biomaterials with high percentages of β-TCP endowed with balanced mechanical characteristics to resemble human cancellous bone, presumably improving osteogenesis.

METHODS

PCL/β-TCP scaffolds were obtained from customised filaments for fused deposition modelling (FDM) 3D printing with increasing amounts of β-TCP. Samples mechanical features, surface topography and wettability were evaluated as well as cytocompatibility assays, cell adhesion and differentiation.

RESULTS

The parameters of the newly fabricated materila were optimal for PCL/β-TCP scaffold fabrication. Composite surfaces showed higher hydrophilicity compared with the controls, and their surface roughness sharply was higher, possibly due to the presence of β-TCP. The Young's modulus of the composites was significantly higher than that of pristine PCL, indicating that the intrinsic strength of β-TCP is beneficial for enhancing the elastic modulus of the composite biomaterials. All novel composite biomaterials supported greater cellular growth and stronger osteoblastic differentiation compared with the PCL control.

CONCLUSIONS

This project highlights the possibility to fabricat, through an FDM solvent-free approach, PCL/β-TCP scaffolds of up to 70 % concentrations of β-TCP. overcoming the current lmit of 60 % stated in the literature. The combination of 3D printing and customised biomaterials allowed production of highly personalised scaffolds with optimal mechanical and biological features resembling the natural structure and the composition of bone. This underlines the promise of such structures for innovative approaches for bone and periodontal regeneration.

Research on silk fibroin composite materials for wet environment applications

Silk fibroin material has good mechanical properties and excellent biocompatibility as a natural biomaterial with broad application prospects. However, by applying regenerated silk fibroin in biomaterials with high mechanical strength requirements, such as bone materials, there are problems, such as insufficient mechanical properties and a significant decline in mechanical properties in the wet state. In this report, a silk fibroin composite that maintains high strength in the wet state was prepared by adding nano-SiO2 as a nano-strengthening filler to the silk protein material and employing an epoxy-based silane coupling agent KH560 as an interfacial reinforcing agent. The results showed that the dry compressive strength of the composite material was substantially increased compared with that of the pure silk protein material; the wet compressive strength was significantly increased compared with that of the pure silk fibroin material, and the decrease of the mechanical properties in the wet state was low. The cytotoxicity test results of the composites showed that the materials were not cytotoxic. Rat bone marrow mesenchymal stem cells were cultured on the surface of the composites, and the results indicated that the composites could support the proliferation of bone marrow mesenchymal stem cells. The silk fibroin nanocomposites developed in this work can be applied as bone repair materials.

Hydrogels for Nucleic Acid Drugs Delivery

Nucleic acid drugs are one of the hot spots in the field of biomedicine in recent years, and play a crucial role in the treatment of many diseases. However, its low stability and difficulty in target drug delivery are the bottlenecks restricting its application. Hydrogels are proven to be promising for improving the stability of nucleic acid drugs, reducing the adverse effects of rapid degradation, sudden release, and unnecessary diffusion of nucleic acid drugs. In this review, the strategies of loading nucleic acid drugs in hydrogels are summarized for various biomedical research, and classify the mechanism principles of these strategies, including electrostatic binding, hydrogen bond based binding, hydrophobic binding, covalent bond based binding and indirect binding using various carriers. In addition, this review also describes the release strategies of nucleic acid drugs, including photostimulation-based release, enzyme-responsive release, pH-responsive release, and temperature-responsive release. Finally, the applications and future research directions of hydrogels for delivering nucleic acid drugs in the field of medicine are discussed.

Recent Strategies and Advances in Hydrogel-Based Delivery Platforms for Bone Regeneration

Bioactive molecules have shown great promise for effectively regulating various bone formation processes, rendering them attractive therapeutics for bone regeneration. However, the widespread application of bioactive molecules is limited by their low accumulation and short half-lives in vivo. Hydrogels have emerged as ideal carriers to address these challenges, offering the potential to prolong retention times at lesion sites, extend half-lives in vivo and mitigate side effects, avoid burst release, and promote adsorption under physiological conditions. This review systematically summarizes the recent advances in the development of bioactive molecule-loaded hydrogels for bone regeneration, encompassing applications in cranial defect repair, femoral defect repair, periodontal bone regeneration, and bone regeneration with underlying diseases. Additionally, this review discusses the current strategies aimed at improving the release profiles of bioactive molecules through stimuli-responsive delivery, carrier-assisted delivery, and sequential delivery. Finally, this review elucidates the existing challenges and future directions of hydrogel encapsulated bioactive molecules in the field of bone regeneration.

Asymmetric Janus Nanofibrous Agar-Based Wound Dressing Infused with Enhanced Antioxidant and Antibacterial Properties

In the present study, we have developed an agar-based asymmetric Janus nanofibrous wound dressing comprising a support and an electrospun layer with antibacterial and antioxidant properties, respectively, to facilitate healing effectively. The support layer containing agar and silver nitrate was fabricated by using solvent casting for sustained release, combating the dose-dependent cytotoxicity of silver nanoparticles, where nanoparticles were synthesized using a one-pot reduction method. The electrospun layer, fabricated with a mixture of agar and polycaprolactone infused with gallic acid, was electrospun over the support layer to impart antioxidant properties. Characterizations using UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy validated the synthesis of nanoparticles in 10-20 nm diameter and the asymmetric Janus dressing. The developed Janus nanofibrous structure exhibited 98% porosity, excellent fluid-handling properties, a moisture permeability of 1200 g/m2/day, and a water absorption of ∼250%. Moreover, the time-kill assay confirmed potent bacteriostatic effect against Gram-positive and Gram-negative bacteria, and sustained release of silver nanoparticles followed the Korsmeyer-Peppas model. With over 90% free radical scavenging efficacy, 37% degradation in 7 days, and less than 2% hemolysis, the dressings demonstrated exceptional antioxidant, biodegradable, and hemocompatible properties. The biocompatibility assessment further confirmed its cytocompatible efficacy, with more than 79% wound closure in the wound scratch assay. Most importantly, in vivo studies demonstrated the efficacy of the developed Janus dressing, promoting over 97% healing within 12 days of injury with higher epithelial formation. Overall, the in vitro and in vivo assessment of the developed Janus dressing confirmed its potential to function as a versatile and effective material for wound care applications.

Scalable fabrication of porous membrane incorporating human extracellular matrix-like collagen for guided bone regeneration

Guided bone regeneration (GBR) is an extensively used technique for the treatment of maxillofacial bone defects and bone mass deficiency in clinical practice. However, to date, studies on membranes for GBR have not achieved the combination of suitable properties and cost-effective membrane production. Herein, we developed a polycaprolactone/human extracellular matrix-like collagen (PCL/hCol) membrane with an asymmetric porous structure via the nonsolvent-induced phase separation (NIPS) method, which is a highly efficient procedure with simple operation, scalable fabrication and low cost. This membrane possessed a porous rough surface, which is conducive to cell attachment and proliferation for guiding osteogenesis, together with a relatively smooth surface with micropores, which allows the passage of nutrients and is unfavorable for the adhesion of cells, thus preventing fibroblast invasion and overall meeting the demands for GBR. Besides, we evaluated the characteristics and biological properties of the membrane and compared them with those of commercially available membranes. Results showed that the PCL/hCol membrane exhibited excellent mechanical properties, degradation characteristics, barrier function, biocompatibility and osteoinductive potential. Furthermore, our in vivo study demonstrated the promotive effect of the PCL/hCol membrane on bone formation in rat calvarial defects. Taken together, our NIPS-prepared PCL/hCol membrane with promising properties and production advantages offers a new perspective for its development and potential use in GBR application.

A bilayer hydrogel mimicking the periosteum-bone structure for innervated bone regeneration

In bone tissue, nerves are primarily located in the periosteum and play an indispensable role in bone defect repair. However, most bone tissue engineering approaches ignored the reconstruction of the nerve network. Herein, we aimed to develop a bilayer hydrogel simulating periosteum-bone structure to induce innervated bone regeneration. The bottom "bone" layer consisted of gelatin methacryloyl (GelMA), poly(ethylene glycol) diacrylate (PEGDA), and nano-hydroxyapatite (nHA), whereas the upper "periosteum" layer consisted of GelMA, sodium alginate (SA) and MgCl2. The mechanical properties of the upper and bottom hydrogels were designed to be suitable for neurogenesis and osteogenesis, respectively. Besides, Mg2+ from the "periosteum" layer released at the early stage (within 7 d), which aligned with the optimal time window for nerve regeneration and osteogenic related neuropeptide release. Simultaneously, the prevention of long-term Mg2+ release (after 7 d) could avoid osteogenic inhibition caused by prolonged Mg2+ exposure. Additionally, the incorporation of nHA in the bottom "bone" layer supported the long-term osteogenesis due to its osteoconductivity and slow degradation. In vitro biological experiments revealed that the bilayer hydrogel (GS@Mg/GP@nHA) promoted neurite growth and calcitonin gene-related peptide (CGRP) expression in rat dorsal root ganglion (DRG) neurons, as well as the osteogenesis of rat bone-derived mesenchymal stem cells (BMSCs). Moreover, the in vivo experiments demonstrated that the GS@Mg/GP@nHA hydrogel efficiently promoted nerve network reconstruction and bone regeneration of rat calvarial bone defects. Altogether, the bilayer hydrogel GS@Mg/GP@nHA could promote innervated bone regeneration, providing new insights for biomaterial design for bone tissue engineering.

Exosomes derived from mucoperiosteum Krt14+Ctsk+ cells promote bone regeneration by coupling enhanced osteogenesis and angiogenesis

Repair of large bone defects is a sophisticated physiological process involving the meticulous orchestration of cell activation, proliferation, and differentiation. Cellular interactions between different cell types are paramount for successful bone regeneration, making it a challenging yet fascinating area of research and clinical practice. With increasing evidence underscoring the essential role of exosomes in facilitating intercellular and cell-microenvironment communication, they have emerged as an encouraging therapeutic strategy to promote bone repair due to their non-immunogenicity, diverse sources, and potent bioactivity. In this study, we characterized a distinctive population of Krt14+Ctsk+ cells from the orbital mucoperiosteum. In vitro experiments confirmed that exosomes from Krt14+Ctsk+ cells dramatically boosted the capacities of human umbilical vein endothelial cells (HUVECs) to proliferate, migrate, and induce angiogenesis. Additionally, the exosomes notably elevated the expression of osteogenic markers, thereby indicating their potential to augment osteogenic capabilities. Furthermore, in vivo experiments utilizing a rat calvarial defect model verified that exosome-loaded sodium alginate (SA) hydrogels accelerated local vascularized bone regeneration within the defective regions. Collectively, these findings suggest that exosomes secreted by Krt14+Ctsk+ cells offer an innovative method to accelerate bone repair via coupling enhanced osteogenesis and angiogenesis, highlighting the therapeutic potential in bone repair.

Sonification of Deproteinized Bovine Bone Functionalized with Genistein Enhances Bone Repair in Peri-Implant Bone Defects in Ovariectomized Rats

Estrogen deficiency is one of several contributing factors to catabolic changes in bone surrounding dental implants, impairing bone repair in defects requiring bone regeneration. Functionalizing bone substitutes is an alternative approach among various strategies to address this challenge. In this study, the aim was to evaluate the effect of functionalizing deproteinized bovine bone (Bio-Oss®, BO) with genistein via sonication on peri-implant bone defects in ovariectomized rats. The animals were randomly distributed according to the treatment into the following four groups (n = 10): BO sonicated with genistein (BOS + GEN), BO sonicated alone (BOS), untreated BO (BO), and blood clot only (CLOT). After twenty-eight days, implant removal torque was determined, and the peri-implant bone parameters were calculated based on computed microtomography. Additionally, the gene expression of bone turnover markers was evaluated. As a main result, the functionalization with genistein increased implant removal torque and the peri-implant bone volume in the BOS + GEN group compared to both BOS and BO groups (both p < 0.05). These findings suggest that the sonification of deproteinized bovine bone functionalized with genistein improves bone repair in peri-implant bone defects in ovariectomized rats.

Biomimetic mineralization of collagen from fish scale to construct a functionally gradient lamellar bone-like structure for guided bone regeneration

Wide used guided bone regeneration (GBR) membrane materials, such as collagen, Teflon, and other synthesized polymers, present a great challenge in term of integrating the mechanical property and degradation rate when addressing critical bone defects. Therefore, inspired by the distinctive architecture of fish scales, this study utilized epigallocatechin gallate to modify decellularized fish scales following biomimetic mineralization to fabricate a GBR membrane that mimics the structure of lamellar bone. The structure, physical and chemical properties, and biological functions of the novel GBR membrane were evaluated. Results indicate that the decellularized fish scale with 5 remineralization cycles (5R-E-DCFS) exhibited a composite and structure similar to natural bone and had a special functionally gradient mineral contents character, demonstrating excellent mechanical properties, hydrophilicity, and degradation properties. In vitro, the 5R-E-DCFS membrane exhibited excellent cytocompatibility promoting Sprague-Dawley (SD) rat bone marrow mesenchymal stem cell proliferation and differentiation up-regulating the expression of osteogenic-related genes and proteins. Furthermore, in vivo, the 5R-E-DCFS membrane promoted the critical skull bone defects of SD rats repairment and regeneration. Therefore, this innovative biomimetic membrane holds substantial clinical potential as an ideal GBR membrane with mechanical properties for space-making and suitable degradation rate for bone regeneration to manage bone defects.

Innovative Biocompatible Blend Scaffold of Poly(hydroxybutyrate-co-hydroxyvalerate) and Poly(ε-caprolactone) for Bone Tissue Engineering: In Vitro and In Vivo Evaluation

This study evaluated the biocompatibility of dense and porous forms of Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), Poly(ε-caprolactone) (PCL), and their 75/25 blend for bone tissue engineering applications. The biomaterials were characterized morphologically using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and the thickness and porosity of the scaffolds were determined. Functional assessments of mesenchymal stem cells (MSCs) included the MTT assay, alkaline phosphatase (ALP) production, and morphological and cytochemical analyses. Moreover, these polymers were implanted into rats to evaluate their in vivo performance. The morphology and FTIR spectra of the scaffolds were consistent with the expected results. Porous polymers were thicker than dense polymers, and porosity was higher than 92% in all samples. The cells exhibited good viability, activity, and growth on the scaffolds. A higher number of cells was observed on dense polymers, likely due to their smaller surface area. ALP production occurred in all samples, but enzyme activity was more intense in PCL samples. The scaffolds did not interfere with the osteogenic capacity of MSCs, and mineralized nodules were present in all samples. Histological analysis revealed new bone formation in all samples, although pure PHBV exhibited lower results compared to the other blends. In vivo results indicated that dense PCL and the dense 75/25 blend were the best materials tested, with PCL tending to improve the performance of PHBV in vivo.

Poly(lactide)-Based Materials Modified with Biomolecules: A Review

Poly(lactic acid) (PLA) is characterized by unique features, e.g., it is environmentally friendly, biocompatible, has good thermomechanical properties, and is readily available and biodegradable. Due to the increasing pollution of the environment, PLA is a promising alternative that can potentially replace petroleum-derived polymers. Different biodegradable polymers have numerous biomedical applications and are used as packaging materials. Because the pure form of PLA is delicate, brittle, and is characterized by a slow degradation rate and a low thermal resistance and crystallization rate, these disadvantages limit the range of applications of this polymer. However, the properties of PLA can be improved by chemical or physical modification, e.g., with biomolecules. The subject of this review is the modification of PLA properties with three classes of biomolecules: polysaccharides, proteins, and nucleic acids. A quite extensive description of the most promising strategies leading to improvement of the bioactivity of PLA, through modification with these biomolecules, is presented in this review. Thus, this article deals mainly with a presentation of the major developments and research results concerning PLA-based materials modified with different biomolecules (described in the world literature during the last decades), with a focus on such methods as blending, copolymerization, or composites fabrication. The biomedical and unique biological applications of PLA-based materials, especially modified with polysaccharides and proteins, are reviewed, taking into account the growing interest and great practical potential of these new biodegradable biomaterials.

Synchronized long-term delivery of growth hormone and insulin-like growth factor 1 through poly (lactic-co-glycolic acid) nanoparticles on polycaprolactone scaffolds for enhanced osteochondral regeneration

The regeneration of osteochondral defects is challenging due to the complex structure of the osteochondral unit. This study aimed to develop a biomimetic scaffold by loading growth hormone (GH) and insulin-like growth factor-1 (IGF-1) into poly (lactic-co-glycolic acid) (PLGA) nanoparticles and incorporating them into polycaprolactone (PCL) scaffolds to promote synchronized osteochondral regeneration. The nanoparticles were successfully immobilized onto PCL scaffolds pre-modified with polydopamine (PDA) to enhance cell adhesion and proliferation. The scaffolds exhibited a sustained release of GH and IGF-1 over 30 days. In vitro studies using rabbit adipose-derived stem cells (ADSCs) showed that the GH/IGF-1 nanoparticle-loaded scaffolds (PCL/PDA/M-PLGA) significantly promoted cell proliferation, chondrogenic differentiation, and osteogenic differentiation compared to control PCL/PDA scaffolds. In vivo experiments using a rabbit osteochondral defect model revealed that the PCL/PDA/M-PLGA scaffolds facilitated superior osteochondral regeneration, evidenced by increased subchondral bone formation and cartilage matrix deposition. Overall, this study demonstrates the potential of GH/IGF-1 nanoparticle-loaded PCL scaffolds for synchronized osteochondral regeneration and provides a promising strategy for treating osteochondral defects.

The recent progress of bone regeneration materials containing EGCG

Epigallocatechin-3-gallate (EGCG) is the most effective active ingredient in tea polyphenols and belongs to the category of catechins. EGCG has excellent antioxidant activity, anti-inflammatory, osteogenesis-promoting, and antibacterial properties, and has been widely studied in orthopedic diseases such as osteoporosis. To reach the lesion site, achieve sustained release, promote osteogenesis, regulate macrophage polarization, and improve the physical properties of materials, EGCG needs to be cross-linked or incorporated in bone regeneration materials. This article reviews the application of bone regeneration materials combined with EGCG, including natural polymer bone regeneration materials, synthetic polymer bone regeneration materials, bioceramic bone regeneration materials, metal bone regeneration materials, hydrogel bone regeneration materials and metal-EGCG networks. In addition, the fabrication methods for the regenerated scaffolds are also elaborated in the text. To sum up, it reveals the excellent development potential of materials containing EGCG and the shortcomings of current research, which will provide important reference for the future exploration of bone regeneration materials containing EGCG.

Effects of Photobiomodulation Using Low-Power Diode Laser Therapy and Nano-bone on Mandibular Bone Regeneration in Rats

Introduction: Recently, the positive effects of photobiomodulation (PBM) and nano-bone on bone regeneration have garnered significant attention. The purpose of the research was to assess the impact of PBM and nano-bone on the process of mandibular bone repair in mice. Methods: A 4-mm diameter bone defect was created in the left mandibular angle of 24 mice separated into 4 equal groups: group I: control; group II: PBM by irradiation at 100 mW of a 980 nm diode laser for one minute (three sessions per week; day on and day off); group III: nano-bone; group IV: PBM with nano-bone. Every group was sectioned into 3 equal subgroups corresponding to the evaluation method period: (A) one week, (B) two weeks, and (C) four weeks. Histological examination was done with hematoxylin, eosin, and Masson's Trichrome after one, two and four weeks for inflammation, bone defect coverage, vascularization within the newly formed bone, and new bone formation. Statistical analysis of the data was done and presented as percentage values using chi-square. The significance level was set at P value≤0.05 within all tests. Results: In general, by histological examination of the mandibular bone defect of the rats, the intensity of inflammation was the least in group IV when compared with groups II and III and the control group at all evaluation periods (P<0.001). Also, group IV showed a high significant rise in the percentage of new bone formation following four weeks when compared with the control (P≤ 0.001) and groups II and III (P<0.001). Conclusion: The present research results confirmed that the combination of PBM and nano-bone can aid in the repair of mandibular bone abnormalities. This animal study suggests that the use of PBM and nano-bone should be investigated further in clinical studies.

Quantum dots for bone tissue engineering

In confronting the global prevalence of bone-related disorders, bone tissue engineering (BTE) has developed into a critical discipline, seeking innovative materials to revolutionize treatment paradigms. Quantum dots (QDs), nanoscale semiconductor particles with tunable optical properties, are at the cutting edge of improving bone regeneration. This comprehensive review delves into the multifaceted roles that QDs play within the realm of BTE, emphasizing their potential to not only revolutionize imaging but also to osteogenesis, drug delivery, antimicrobial strategies and phototherapy. The customizable nature of QDs, attributed to their size-dependent optical and electronic properties, has been leveraged to develop precise imaging modalities, enabling the visualization of bone growth and scaffold integration at an unprecedented resolution. Their nanoscopic scale facilitates targeted drug delivery systems, ensuring the localized release of therapeutics. QDs also possess the potential to combat infections at bone defect sites, preventing and improving bacterial infections. Additionally, they can be used in phototherapy to stimulate important bone repair processes and work well with the immune system to improve the overall healing environment. In combination with current trendy artificial intelligence (AI) technology, the development of bone organoids can also be combined with QDs. While QDs demonstrate considerable promise in BTE, the transition from laboratory research to clinical application is fraught with challenges. Concerns regarding the biocompatibility, long-term stability of QDs within the biological environment, and the cost-effectiveness of their production pose significant hurdles to their clinical adoption. This review summarizes the potential of QDs in BTE and highlights the challenges that lie ahead. By overcoming these obstacles, more effective, efficient, and personalized bone regeneration strategies will emerge, offering new hope for patients suffering from debilitating bone diseases.