Effective Bone Regeneration Research Articles

Gelatin methacrylate hydrogel scaffold carrying resveratrol-loaded solid lipid nanoparticles for enhancement of osteogenic differentiation of BMSCs and effective bone regeneration.

Critical-sized bone defects caused by traumatic fractures, tumour resection and congenital malformation are unlikely to heal spontaneously. Bone tissue engineering is a promising strategy aimed at developing in vitro replacements for bone transplantation and overcoming the limitations of natural bone grafts. In this study, we developed an innovative bone engineering scaffold based on gelatin methacrylate (GelMA) hydrogel, obtained via a two-step procedure: first, solid lipid nanoparticles (SLNs) were loaded with resveratrol (Res), a drug that can promote osteogenic differentiation and bone formation; these particles were then encapsulated at different concentrations (0.01%, 0.02%, 0.04% and 0.08%) in GelMA to obtain the final Res-SLNs/GelMA scaffolds. The effects of these scaffolds on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and bone regeneration in rat cranial defects were evaluated using various characterization assays. Our in vitro and in vivo investigations demonstrated that the different Res-SLNs/GelMA scaffolds improved the osteogenic differentiation of BMSCs, with the ideally slow and steady release of Res; the optimal scaffold was 0.02 Res-SLNs/GelMA. Therefore, the 0.02 Res-SLNs/GelMA hydrogel is an appropriate release system for Res with good biocompatibility, osteoconduction and osteoinduction, thereby showing potential for application in bone tissue engineering.

Effects of Pulsed Electromagnetic Field Intensity on Mesenchymal Stem Cells

Introduction: Bone fractures remain a common injury. Nonunion fractures are often a serious complication where delays in tissue regeneration occur. The use of pulsed electromagnetic fields (PEMFs) for treatment has been studied for years, having reportedly been able to enhance bone regeneration. However, as various PEMF parameters can affect cellular properties differently, it is necessary to adjust each PEMF parameter to achieve the optimal regeneration. Methods: Primary rabbit mesenchymal stem cells (rMSCs) were cultured in vitro in two types of media, namely nondifferentiation and osteogenic differentiation media. The effect of various intensities of PEMF was assessed by evaluating properties such as cellular metabolism, proliferation, and osteogenic differentiation at different time points. Results: The findings suggest that PEMFs had no adverse effect on cellular morphology and mineralization. In contrast, increased metabolic activity was observed at higher PEMF intensity, whereas moderate PEMF intensities had the strongest effect on cell proliferation in both types of culture media. A comparison study was also done between the primary rMSCs against the MC3T3-E1 cells from a previously published article. It was shown that PEMFs improved cell metabolism of MSCs, while maintaining the metabolic activity of MC3T3. Conclusions: PEMFs generally improved cell proliferation for both cell types, whereas leaving cell mineralization unaffected. Taken together, it can be understood that the optimal application of PEMF stimulus, along with the right cell types, is indeed crucial in achieving effective bone regeneration in vitro.

The Therapeutic Potential of Hematopoietic Stem Cells in Bone Regeneration.

The repair process of bone fractures is a complex biological mechanism requiring the recruitment and in situ functionality of stem/stromal cells from the bone marrow (BM). BM mesenchymal stem/stromal cells have been widely explored in multiple bone tissue engineering applications, whereas the use of hematopoietic stem cells (HSCs) has been poorly investigated in this context. A reasonable explanation is the fact that the role of HSCs and their combined effect with other elements of the hematopoietic niches in the bone-healing process is still elusive. Therefore, in this review we intend to highlight the influence of HSCs in the bone repair process, mainly through the promotion of osteogenesis and angiogenesis at the bone injury site. For that, we briefly describe the main biological characteristics of HSCs, as well as their hematopoietic niches, while reviewing the biomimetic engineered BM niche models. Moreover, we also highlighted the role of HSCs in translational in vivo transplantation or implantation as promoters of bone tissue repair. Impact statement The ability of bone to natural self-heal depends on the size and stabilization level of the tissue fracture, and it is impaired in several pathophysiological conditions. Considering that the available treatment options have demonstrated limited regenerative performance, the hematopoietic stem cells (HSCs) co-cultured in different tissue engineering strategies have emerged as a powerful tool to promote effective bone regeneration and healing. Here, we reviewed the most important biomimetic bone-marrow hematopoietic niches and showed the regenerative potential of these cells, both in vitro and in translational in vivo transplantation/implantation approaches. This knowledge encourages the development of new HSC-related bone regenerative therapies.

Discovery of synergistic material-topography combinations to achieve immunomodulatory osteoinductive biomaterials using a novel in vitro screening method: The ChemoTopoChip

Human mesenchymal stem cells (hMSCs) are widely represented in regenerative medicine clinical strategies due to their compatibility with autologous implantation. Effective bone regeneration involves crosstalk between macrophages and hMSCs, with macrophages playing a key role in the recruitment and differentiation of hMSCs. However, engineered biomaterials able to simultaneously direct hMSC fate and modulate macrophage phenotype have not yet been identified. A novel combinatorial chemistry-topography screening platform, the ChemoTopoChip, is used here to identify materials suitable for bone regeneration by screening 1008 combinations in each experiment for human immortalized mesenchymal stem cell (hiMSCs) and human macrophage response. The osteoinduction achieved in hiMSCs cultured on the “hit” materials in basal media is comparable to that seen when cells are cultured in osteogenic media, illustrating that these materials offer a materials-induced alternative to osteo-inductive supplements in bone-regeneration. Some of these same chemistry-microtopography combinations also exhibit immunomodulatory stimuli, polarizing macrophages towards a pro-healing phenotype. Maximum control of cell response is achieved when both chemistry and topography are recruited to instruct the required cell phenotype, combining synergistically. The large combinatorial library allows us for the first time to probe the relative cell-instructive roles of microtopography and material chemistry which we find to provide similar ranges of cell modulation for both cues. Machine learning is used to generate structure-activity relationships that identify key chemical and topographical features enhancing the response of both cell types, providing a basis for a better understanding of cell response to micro topographically patterned polymers.

Rational Design and Fabrication of Biomimetic Hierarchical Scaffolds With Bone-Matchable Strength for Bone Regeneration

The development of scaffolds with bone-mimicking compositions, hierarchical structure, and bone-matchable mechanical properties may offer a novel route for the achievement of effective bone regeneration. Although bioactive glasses have been widely utilized for bone regeneration at the clinical level, their brittleness and uncontrolled pore structure limit further applications. Herein, this study aims to develop a kind of bioactive scaffold with a macroporous/microporous/mesoporous structure via impregnating a sponge template with mesoporous bioactive glass (MBG) sol, followed by sponge template removal. In order to improve the mechanical properties and stability of the MBG scaffolds, desaminotyrosyl ethyl tyrosine polycarbonates (PDTEC), a biodegradable polymer which does not induce acid side-effects caused by conventional polylactide, was selected to decorate the resulting hierarchical scaffolds through a surface coating approach. The PDTEC functionalization endowed the scaffolds with improved mechanical strength matching the bearable range of trabecular bone (2–12 MPa). Meanwhile, the relative neutral pH value was maintained during their degradation process. In vitro studies demonstrated that the PDTEC accelerated the biomineralization of the scaffolds, and promoted the attachment and proliferation, holding high promise for bone regeneration.

Low Dose BMP2-Doped Calcium Phosphate Graft Promotes Bone Defect Healing in a Large Animal Model.

Background: Bone grafts are in high demand due to the increase in the cases of bone defects mainly caused by trauma, old age, and disease-related bone damages. Tissue-engineered calcium phosphate (CaP) biomaterials match the major inorganic contents of bone, thereby could be the potential bone graft substitute. However, CaP-bone grafts lack the osteoinductivity that is vital for effective bone regeneration. In this study, we aimed to test the bone defect healing potential of biomimetically fabricated low dose BMP2-doped CaP (BMP2.BioCaP) grafts in a large animal model.Methods: Low dose BMP2 was doped internally (BMP2-int.BioCaP) or on the surface of CaP (BMP2-sur.BioCaP) grafts during the fabrication process. Our previous study showed the robust bone regenerative potential of BMP2-int.BioCaP and BMP2-sur.BioCaP grafts in the rat ectopic model. In this study, we investigated the bone defect healing potential of BMP2.BioCaP grafts in sheep humerus/femoral defects, as well as compared with that of autologous bone graft and clinically used deproteinized bovine bone (DBB) xenograft.Results: Different ways of BMP2 doping did not affect the surface morphology and degradation properties of the graft materials. Micro-CT and histology results showed robustly higher bone defect-healing potential of the BMP2.BioCaP grafts compared to clinically used DBB grafts. The bone defect healing potential of BMP2.BioCaP grafts was as effective as that of the autologous bone graft. Although, BMP2-int.BioCaP doped half the amount of BMP2 compared to BMP2-sur.BioCaP, its' bone defect healing potential was even robust. The BMP2.BioCaP grafts showed less immunogenicity compared to BioCaP or DBB grafts. The volume density of blood vessel-like and bone marrow-like structures in both BMP2.BioCaP graft groups were in a similar extent to the autologous group. Meticulous observation of higher magnification histological images showed active bone regeneration and remodeling during bone defect healing in BMP2.BioCaP graft groups.Conclusion: The robust bone regenerative potential of BMP2.BioCaP grafts in the ectopic model and in-situ bone defects in small and large animals warrant the pre-clinical studies on large animal critical-sized segmental bone defects.

Treatment of Chronic Hematogenous Osteomyelitis in Children With Antibiotic Impregnated Calcium Sulphate.

The purpose of this study was to evaluate the clinical and radiologic outcome of chronic hematogenous osteomyelitis (CHOM) in children, treated with single-stage debridement and dead space management using antibiotic impregnated calcium sulphate pellets. The authors retrospectively evaluated a consecutive series of 34 patients who presented with CHOM from 2011 to 2017. In each case, CHOM was classified according to the Beit CURE classification. Following thorough surgical debridement, the resulting dead space in the bone was filled with the antibiotic impregnated beads before primary closure. Of the 31 patients available for follow up, effective regeneration of bone was confirmed in all cases, with radiographic bone healing typically observed at around 12 weeks. None of the children required reoperation for infection and none had recurrence of infection at the time of final review. The beads were completely absorbed within 3 months. No systemic adverse reactions to the local delivery of antibiotics were observed in this study. The authors found that single-stage debridement in conjunction with antibiotic impregnated calcium sulphate was an effective means of treating CHOM in children, with effective eradication of infection in every case. Level IV-Retrospective case series. See instructions for authors for a complete description of levels of evidence.

Remote Tuning of Built‐In Magnetoelectric Microenvironment to Promote Bone Regeneration by Modulating Cellular Exposure to Arginylglycylaspartic Acid Peptide

AbstractMimicking the endogenous physical microenvironment is a promising strategy for biomaterial‐mediated tissue regeneration. However, precise control of physical cues such as electric/magnetic fields within extracellular environments to facilitate tissue regeneration remains a formidable challenge. Here, remote tuning of the magnetoelectric microenvironment is achieved by a built‐in CoFe2O4/poly(vinylidene fluoridetrifluoroethylene) [P(VDF‐TrFE)] magnetoelectric membrane for effective bone regeneration. The magnetoelectric microenvironment from the nanocomposite membranes promotes osteogenic differentiation of bone marrow mesenchymal stem cells (BM‐MSCs) and enhances bone defect regeneration by increasing cellular exposure and integrin binding to arginylglycylaspartic acid peptide, as predicted by molecular dynamics simulations. Moreover, BM‐MSCs are directed to the osteogenic lineage by osteoimmuomodulation which involves accelerating transition from an initial inflammatory immune response to a pro‐healing regenerative immune response. This work offers a strategy to mimic the magnetoelectric microenvironment for achieving precise and effective tissue regenerative therapies, as well as provides fundamental insights into the biological effects driven by the built‐in magnetoelectric membrane, which can be remotely tuned to precisely modulate osteogenesis in situ.

A Novel Approach to Enhance Bone Regeneration by Controlling the Polarity of GaN/AlGaN Heterostructures

AbstractRapid and effective bone regeneration is still a major challenge in the clinical treatment of various bone diseases. Although recently developed electroactive materials have demonstrated high bone regeneration potential, the instability of the electrical stimulation and the unclear effects of the charge polarity on osteogenic differentiation hinder their clinical applications. In this work, GaN/AlGaN materials with well‐controlled polarity are used for the first time to induce endogenous electric stimulation and facilitate bone regeneration. By controlling the direction and magnitude of the piezoelectric and spontaneous polarization in the functional layer (GaN), charged GaN/AlGaN surfaces of opposite polarity, whose zeta potentials are within the range of the physiological potential, are obtained. Compared with N‐polarity GaN/AlGaN (with a positively charged surface), Ga‐polarity GaN/AlGaN (with a negatively charged surface) nanofilms show rapid and superior bone repair in vivo. In addition, the Ga‐polarity GaN/AlGaN hetero‐structures significantly promote the attachment, spreading, recruitment, and osteogenic differentiation of bone mesenchymal stem cells in vitro. Moreover, the bone morphogenetic protein‐6 (BMP6) expression profile in the early stages of osteogenic differentiation reveals that BMP6 may be an electrically sensitive osteogenic protein. This work sheds light on the application of III‐nitride materials in bone regeneration.

PCL/HA Hybrid Microspheres for Effective Osteogenic Differentiation and Bone Regeneration.

The purpose of this study is to develop a bioactive bone graft based on polycaprolactone (PCL, synthetic polymer; used in clinical practices as a grafting material for craniofacial bone defects) and hyaluronic acid (HA, bioactive natural polymer; known as a promoting substance for bone regeneration) that would be fabricated by clinically available procedures (mild condition without toxic chemicals) and provide bioactivity for sufficient period, and thus effectively induce bone reconstruction. For this, PCL/HA hybrid microspheres were produced by a spray-precipitation technique using clinically adapted solvents. The HA was stably and evenly entrapped in the PCL/HA hybrid microspheres. It was demonstrated that the PCL/HA hybrid microspheres provide an appropriate environment for proliferation and osteogenic differentiation of human periosteum-derived cells (hPDCs) (in vitro) and allow significantly enhanced bone regeneration (in vivo) compared with PCL microspheres without HA. The PCL/HA hybrid microspheres can be a simple but clinically applicable bioactive bone graft for large-sized bone defects.

Collagen, polycaprolactone and attapulgite composite scaffolds for in vivo bone repair in rabbit models

Although numerous materials have been explored as bone scaffolds, many of them are limited by their low osteoconductivity and high biodegradability. Therefore, new materials are desired to induce bone cell proliferation and facilitate bone formation. Attapulgite (ATP) is a hydrated silicate that exists in nature as a fibrillar clay mineral and is well known for its large specific surface area, high viscosity, and high absorption capacity, and therefore has the potential to be a new type of bone repair material due to its unique physicochemical properties. In this study, composite scaffolds composed of collagen/polycaprolactone/attapulgite (CPA) or collagen/polycaprolactone (CP) were fabricated through a salt-leaching method. The morphology, composition, microstructure, physical, and mechanical characteristics of the CPA and CP scaffolds were assessed. Cells from the mouse multipotent mesenchymal precursor cell line (D1 cells) were cocultured with the scaffolds, and cell adhesion, proliferation, and gene expression on the CPA and CP scaffolds were analyzed. Adult rabbits with radius defects were used to evaluate the performance of these scaffolds in repairing bone defects over 4–12 weeks. The experimental results showed that the cells demonstrated excellent attachment ability on the CPA scaffolds, as well as remarkable upregulation of the levels of osteoblastic markers such as Runx2, Osterix, collagen 1, osteopontin, and osteocalcin. Furthermore, results from radiography, micro-computed tomography, histological and immunohistochemical analysis demonstrated that abundant new bones were formed on the CPA scaffolds. Ultimately, these results demonstrated that CPA composite scaffolds show excellent potential in bone tissue engineering applications, with the capacity to be used as effective bone regeneration and repair scaffolds in clinical applications.

3D Printed Gene-activated Octacalcium Phosphate Implants for Large Bone Defects Engineering.

The aim of the study was the development of three-dimensional (3D) printed gene-activated implants based on octacalcium phosphate (OCP) and plasmid DNA encoding VEGFA. The first objective of the present work involved design and fabrication of gene-activated bone substitutes based on the OCP and plasmid DNA with VEGFA gene using 3D printing approach of ceramic constructs, providing the control of its architectonics compliance to the initial digital models. X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and compressive strength analyses were applied to investigate the chemical composition, microstructure, and mechanical properties of the experimental samples. The biodegradation rate and the efficacy of plasmid DNA delivery in vivo were assessed during standard tests with subcutaneous implantation to rodents in the next stage. The final part of the study involved substitution of segmental tibia and mandibular defects in adult pigs with 3D printed gene-activated implants. Biodegradation, osteointegration, and effectiveness of a reparative osteogenesis were evaluated with computerized tomography, SEM, and a histological examination. The combination of gene therapy and 3D printed implants manifested the significant clinical potential for effective bone regeneration in large/critical size defect cases.

Electrospun Icariin-Loaded Core-Shell Collagen, Polycaprolactone, Hydroxyapatite Composite Scaffolds for the Repair of Rabbit Tibia Bone Defects.

BackgroundElectrospinning is a widely used technology that can produce scaffolds with high porosity and surface area for bone regeneration. However, the small pore sizes in electrospun scaffolds constrain cell growth and tissue-ingrowth. In this study, novel drug-loading core-shell scaffolds were fabricated via electrospinning and freeze drying to facilitate the repair of tibia bone defects in rabbit models.Materials and MethodsThe collagen core scaffolds were freeze-dried containing icariin (ICA)-loaded chitosan microspheres. The shell scaffolds were electrospun using collagen, polycaprolactone and hydroxyapatite materials to form CPH composite scaffolds with the ones containing ICA microspheres named CPHI. The core-shell scaffolds were then cross-linked by genipin. The morphology, microstructure, physical and mechanical properties of the scaffolds were assessed. Rat marrow mesenchymal stem cells from the wistar rat were cultured with the scaffolds. The cell adhesion and proliferation were analysed. Adult rabbit models with tibial plateau defects were used to evaluate the performance of these scaffolds in repairing the bone defects over 4 to 12 weeks.ResultsThe results reveal that the novel drug-loading core-shell scaffolds were successfully fabricated, which showed good physical and chemical properties and appropriate mechanical properties. Furthermore, excellent cells attachment was observed on the CPHI scaffolds. The results from radiography, micro-computed tomography, histological and immunohistochemical analysis demonstrated that abundant new bones were formed on the CPHI scaffolds.ConclusionThese new core-shell composite scaffolds have great potential for bone tissue engineering applications and may lead to effective bone regeneration and repair.

Plasmid DNA-loaded asymmetrically porous membrane for guided bone regeneration

Although bone defects can be restored spontaneously, bone reconstruction with sufficient strength and volume continues to be a challenge in clinical practices. In recent years, the use of a variety of biomaterials with bioactivity has been attempted to compensate for this limitation. Herein, we fabricated a pDNA (encoding for BMP-2)-loaded asymmetrically porous polycaprolactone (PCL)/Pluronic F127 membrane as a bioactive guided bone regeneration (GBR) membrane, using a modified immersion-precipitation method. It was observed that the GBR membrane allows continuous release of pDNA for more than 20 weeks. The pDNA was sufficiently transfected into human bone marrow stem cells (hBMSCs) without significant cytotoxicity and the gene-transfected cells showed prolonged synthesis of BMP-2. From in vitro osteogenic differentiation and in vivo animal studies, the effective induction of osteogenic differentiation of hBMSCs and enhanced bone regeneration by the pDNA-loaded asymmetrically porous PCL/Pluronic F127 membrane was observed, suggesting that the pDNA-loaded membrane as a bioactive GBR membrane can be an alternative therapeutic technique for effective bone regeneration.

3D-Printed Titanium Cage with PVA-Vancomycin Coating Prevents Surgical Site Infections (SSIs).

Many coating materials have been studied to prevent surgical site infections (SSIs). However, antibacterial coating on surfaces show weak adhesion using the traditional titanium (Ti) cage, resulting in low efficacy for preventing SSIs after spinal surgery. Herein, a 3D-printed Ti cage combined with a drug-releasing system is developed for in situ drug release and bacteria killing, leading to prevention of SSIs in vitro and in vivo. First, a 3D-printed Ti cage is designed and prepared by the Electron Beam Melting (EBM) method. Second, polyvinyl alcohol (PVA) containing hydrophilic vancomycin hydrochloride (VH) is scattered across the surface of 3D-printed porous Ti (Ti-VH@PVA) cages. Ti-VH@PVA cages show an efficient drug-releasing profile and excellent bactericidal effect for three common bacteria after more than seven days in vitro. In addition, Ti-VH@PVA cages exhibit reliable inhibition of inflammation associated with Staphylococcus aureus and effective bone regeneration capacity in a rabbit model of SSIs. The results indicate that Ti-VH@PVA cages have potential advantages for preventing SSIs after spinal surgery.

Calcium Phosphate Nanoparticles-Based Systems for RNAi Delivery: Applications in Bone Tissue Regeneration.

Bone-related injury and disease constitute a significant global burden both socially and economically. Current treatments have many limitations and thus the development of new approaches for bone-related conditions is imperative. Gene therapy is an emerging approach for effective bone repair and regeneration, with notable interest in the use of RNA interference (RNAi) systems to regulate gene expression in the bone microenvironment. Calcium phosphate nanoparticles represent promising materials for use as non-viral vectors for gene therapy in bone tissue engineering applications due to their many favorable properties, including biocompatibility, osteoinductivity, osteoconductivity, and strong affinity for binding to nucleic acids. However, low transfection rates present a significant barrier to their clinical use. This article reviews the benefits of calcium phosphate nanoparticles for RNAi delivery and highlights the role of surface functionalization in increasing calcium phosphate nanoparticles stability, improving cellular uptake and increasing transfection efficiency. Currently, the underlying mechanistic principles relating to these systems and their interplay during in vivo bone formation is not wholly understood. Furthermore, the optimal microRNA targets for particular bone tissue regeneration applications are still unclear. Therefore, further research is required in order to achieve the optimal calcium phosphate nanoparticles-based systems for RNAi delivery for bone tissue regeneration.

The Development of Extracellular Vesicle-Integrated Biomaterials for Bone Regeneration.

The clinical need for effective bone regeneration remains in huge demands. Although autologous and allogeneic bone grafts are generally considered "gold standard" treatments for bone defects, these approaches may result in various complications. Furthermore, safety considerations of gene- and cell-based therapies require further clarification and approval from regulatory authorities. Therefore, developing new therapeutic biomaterials that can empower endogenous regenerative properties to accelerate bone repair and regeneration is of great significance. Extracellular vesicles (EVs) comprise a heterogeneous population of naturally derived nanoparticles that play a critical role in mediating cell-cell communication. The vast amount of biological processes that EVs are involved in, such as immune modulation, senescence, and angiogenesis, and the versatility of manner in which they can influence the behavior of recipient cells make EVs an interesting source for both diagnostic and therapeutic applications. Advancement of knowledge in the fields of immunology and cell biology has sparked the exploration of the potential of EVs in the field of regenerative medicine. EVs travel between cells and deliver functional cargoes, such as proteins and RNAs, thereby regulating the recruitment, proliferation, and differentiation of recipient cells. Numerous studies have demonstrated the pivotal role of EVs in tissue regeneration both in vitro and in vivo. In this chapter, we will outline current knowledge surrounding EVs, summarize their functional roles in bone regenerative medicine, and elaborate on potential application and challenges of EV-integrated biomaterials in bone tissue engineering.

A sericin/ graphene oxide composite scaffold as a biomimetic extracellular matrix for structural and functional repair of calvarial bone.

Bone defects affect millions of people worldwide each year, leading to severe disabilities. Biomimetic scaffolds mediated tissue regeneration represents a promising alternative for bone repair. However, the major problem associated with most currently clinical available artificial bone substitutes (scaffolds) is that they mainly possess filling function but lack of osteo-induction abilities. Therefore, development of biomaterials with osteo-induction property for effective bone regeneration is highly desired.Methods: We report the design and fabrication of a photo-crosslinked sericin methacryloyl (SerMA)/ graphene oxide (GO) hydrogel (SMH/GO) as a biomimetic scaffold for the functional repair of the bone. The mechanical strength, degradation and biocompatibility behavior of SMH/GO hydrogel were measured in vitro. The effect of SMH/GO hydrogel on BMSCs proliferation, migration, osteogenesis differentiation was assessed. After that, SMH/GO-2 was used as an artificial bone substitute for bone regeneration after calvarial defects and effect on bone repair was evaluated by histological, X-Ray and microCT analysis. Furthermore, the potential mechanism of SMH/GO hydrogel regulating BMSCs migration and differentiation was investigated by RNA sequencing.Results: This scaffold has good biocompatibility, cell adhesive property, proliferation- and migration-promoting effects, and osteogenic induction property. After being implanted in a rat calvarial defect model, this SMH/GO scaffold effectively promotes new bone regeneration and achieves structural and functional repair within 12 weeks by inducing autologous bone marrow-derived mesenchymal stem cells (BMSCs) differentiation. By utilizing cell-biological assays and RNA sequencing, we reveal its possible regeneration mechanisms: the SMH/GO hydrogel regulates BMSCs migration and osteo-differentiation via activating MAPK, TNF, and chemokine signaling for bone regeneration.Conclusion: Aiming to meet clinical demands and overcome current limitations of existing artificial bones, we have developed a new type of sericin/ graphene oxide composite scaffold and provided histological, functional, and molecular evidence demonstrating that it is capable of effectively repairing defective bones by inducing autologous BMSCs directional migration and osteogenic differentiation.

Biofabrication and application of decellularized bone extracellular matrix for effective bone regeneration

In order to promote effective healing of a bone defect, various bone grafts have been widely implanted into defect sites. However, several drawbacks, such as immunologic rejection, insufficient tissue healing, or secondary damage to the donor site, are still concerns. These limitations of the current bone grafts can be overcome by use of a natural ECM that can influence basic cellular behaviors, such as proliferation, migration, and differentiation. Herein, we introduce a novel bone decellularized ECM (bdECM) material extracted from bovine bones via demineralization and decellularization. This sequential process enabled us to prepare raw material possessing higher contents of native BMP-2 and BMP-7, and a fibrous microarchitecture resembling the collagen bundle in the ECM was maintained. Furthermore, residual calcium and phosphate originated from the bovine bone were considerably removed, and contamination by residual DNA was significantly reduced during the fabrication process. These features enabled the scaffold successfully promote mineralization of the cultured primary osteoblasts in vitro, which was significantly better than those from the bone powder or demineralized bone matrix. In a mouse calvarial defect, new bone formation was improved in the bdECM group and the density of those was also higher than other groups.

Synthetic presentation of noncanonical Wnt5a motif promotes mechanosensing-dependent differentiation of stem cells and regeneration.

Noncanonical Wnt signaling in stem cells is essential to numerous developmental events. However, no prior studies have capitalized on the osteoinductive potential of noncanonical Wnt ligands to functionalize biomaterials in enhancing the osteogenesis and associated skeleton formation. Here, we investigated the efficacy of the functionalization of biomaterials with a synthetic Wnt5a mimetic ligand (Foxy5 peptide) to promote the mechanosensing and osteogenesis of human mesenchymal stem cells by activating noncanonical Wnt signaling. Our findings showed that the immobilized Wnt5a mimetic ligand activated noncanonical Wnt signaling via the up-regulation of Disheveled 2 and downstream RhoA-ROCK signaling, leading to enhanced intracellular calcium level, F-actin stability, actomyosin contractility, and cell adhesion structure development. This enhanced mechanotransduction in stem cells promoted the in vitro osteogenic lineage commitment and the in vivo healing of rat calvarial defects. Our work provides valuable guidance for the developmentally inspired design of biomaterials for a wide array of therapeutic applications.