Bone Defects In Rats Research Articles

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

IntroductionDiabetes mellitus often leads to bone metabolism disorders, hindering bone regeneration and delaying the healing of bone defects. β-Ecdysone, a plant-derived hormone known for its wide range of physiological activities, possesses hypoglycemic effects and promotes osteogenic differentiation. This study developed a composite PLGA slow-release scaffold loaded with β-ecdysone to enhance its bioavailability through topical administration and to investigate its potential to heal diabetic bone defects.MethodsThe composite scaffolds were fabricated using solution casting/particle leaching and freeze-drying techniques. Then a series of characterizations were subjected to test the performance of composite scaffolds, and in vitro safety of the composite scaffolds was tested by CCK8 assay and live/dead cell staining. Further, micro-CT and histology to evaluate the effect of β-E/PLGA composite scaffolds on healing of skull defects in diabetic rats at 4 and 8 weeks after implantation. Simultaneously, the safety of the scaffolds in vivo was also evaluated.ResultsThe material characterization results indicated that, in comparison to the single-pore size scaffold, the composite scaffold exhibited superior porosity, swelling ratio, drug loading capacity, and mechanical properties. Additionally, the composite scaffolds showed appropriate degradation performance and sustained drug release profiles. The CCK8 cytotoxicity assay and live/dead cell staining demonstrated that BMSCs survived and proliferated on the composite scaffold under both low-glucose and high-glucose conditions. Micro-CT and histological investigation demonstrated that β-E/PLGA composite scaffolds promoted new bone growth in the skull defect region of diabetic rats.ConclusionOverall, these findings suggest that the β-E/PLGA composite scaffolds promote the healing of bone defects in diabetic rats. The combination of β-ecdysone and tissue-engineered scaffolds presents a promising approach for treating diabetes-related bone defects.

Bortezomib-releasing silica-collagen xerogels for local treatment of osteolytic bone- and minimal residual disease in multiple myeloma

BackgroundAccumulation of malignant plasma cells in the bone marrow causes lytic bone lesions in 80% of multiple myeloma patients. Frequently fracturing, they are challenging to treat surgically. Myeloma cells surviving treatment in the presumably protective environment of bone lesions impede their healing by continued impact on bone turnover and can explain regular progression of patients without detectable minimal residual disease (MRD). Locally applicable biomaterials could stabilize and foster healing of bone defects, simultaneously delivering anti-cancer compounds at systemically intolerable concentrations, overcoming drug resistance.MethodsWe developed silica-collagen xerogels (sicXer) and bortezomib-releasing silica-collagen xerogels (boXer) for local treatment of osteolytic bone disease and MRD. In vitro and in vivo (tissue sections) release of bortezomib was assessed by ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Material impact on bone formation was assessed in vitro regarding osteoclast/osteoblast numbers and activity. In vivo, drilling defects in a rat- and the 5T33-myeloma mouse model were treated by both materials and assessed by immunohistochemistry, UPLC-MS/MS, µCT, and ToF-SIMS. The material’s anti-myeloma activity was assessed using ten human myeloma cell lines (HMCLs) and eight primary myeloma cell samples including four patients refractory to systemic bortezomib treatment.ResultssicXer and boXer show primary stability comparable to trabecular bone. Granule size and preparation method tailor degradation as indicated by release of the xerogel components (silica and collagen) and bortezomib into culture medium. In vitro, both materials reduce osteoclast activity and do not negatively interfere with osteoblast differentiation and function. The presumed resulting net bone formation with maintained basic remodeling properties was validated in vivo in a rat bone defect model, showing significantly enhanced bone formation for boXer compared to non-treated defects. Both materials induce myeloma cell apoptosis in all HMCLs and primary myeloma cell samples. In the 5T33-myeloma mouse model, both materials stabilized drilling defects and locally controlled malignant plasma cell growth.ConclusionsThe combination of stabilization of fracture-prone lesions, stimulation of bone healing, and anti-tumor effect suggest clinical testing of sicXer and boXer as part of a combined systemic/local treatment strategy in multiple myeloma and non-malignant diseases.

Platelet-rich fibrin associated to bovine bone induces bone regeneration in model of critical-sized calvaria defect of rats submitted to Zoledronic Acid therapy: PRF induces bone healing

Reconstruction of bone defects prior to implant installation is a challenge, especially when the patient uses bisphosphonates. Given this difficulty, many studies investigate biomaterials that can improve the bone regeneration process. In this context, this study aimed to investigate the effect of platelet-rich fibrin (PRF) and Bio-Oss (BO) on bone regeneration of rats submitted to critical-sized calvaria defects and treated with ZA. Thirty Wistar rats received a single dose of ZA (120 μg/kg) and after 7 days, were submitted to an 8 mm calvaria defect. The animals were divided into 5 groups (n=6): ZA, BO, PRF or BO+PRF; animals from control group did not receive ZA. All animals were euthanized 12 weeks after surgical procedure and calvaria collected to histological, histomorphometric and micro-CT analyses. BO+PRF increased the number of osteoblasts (33%) and osteoclasts (58%), as well as blood vessels (70%) and Type I collagen (52%) (p<0.05) compared to ZA group. In summary, the association of BO+PRF improved bone healing of large bone defect in rats receiving ZA and this may be an interesting approach for the treatment to be tested in patients under anti-resorptive therapy.

YK11 promotes osteogenic differentiation of BMSCs and repair of bone defects.

The selective androgen receptor modulator (SARM), YK11, promotes the anabolism of muscle cells and osteoblastic precursor cells. Still, its effects on bone marrow-derived mesenchymal stem cells (BMSCs) and the repair of cranial bone defects are unknown. Here, the effects of different concentrations of YK11 on the osteogenic differentiation of BMSCs were determined. Subsequently, AR was inhibited to investigate whether the effect of YK11 on osteogenic differentiation of BMSCs was affected. A model of cranial defects was constructed to investigate the effects of YK11-equipped hydrogel on cranial defect repair as well as the effects of YK11 on cranial defect repair after inhibiting AR. Finally, the possible pathway of YK11 regulating osteogenic differentiation of BMSCs was explored. Our results show 2μM YK11 promoted the proliferation of BMSCs. 0.25-4μM YK11 could promote osteogenesis of BMSCs and the promoting effect was gradually enhanced with the concentration increase. In vivo, 0.5mg/ml YK11 and 1 mg/ml YK11 could promote the repair of cranial bone defects. After inhibiting AR, the effects of YK11 in promoting both osteogenic differentiation of BMSCs and repair of cranial defects were suppressed. YK11 may regulate the osteogenic differentiation of BMSCs through the BMP2/Smad signaling pathway. In conclusion, YK11 promoted the osteogenic differentiation of BMSCs by activation on AR. Meanwhile, YK11 promoted the repair of cranial bone defects in rats in vivo. The BMP2 (bone morphogenetic protein 2)/Smad signaling pathway may be involved in the regulation of osteogenic differentiation of BMSCs by YK11.

Rapid assessment of the osteogenic capacity of hydroxyapatite/aragonite using a murine tibial periosteal ossification model

Biomaterials are widely used as orthopaedic implants and bone graft substitutes. We aimed to develop a rapid osteogenic assessment method using a murine tibial periosteal ossification model to evaluate the bone formation/remodelling potential of a biomaterial within 2–4 weeks. A novel hydroxyapatite/aragonite (HAA) biomaterial was implanted into C57BL/6 mice juxtaskeletally between the tibia and tibialis anterior muscle. Rapid intramembranous bone formation was observed at 14 days, with 4- to 8-fold increases in bone thickness and callus volume in comparison with sham-operated animals (p < 0.0001), followed by bone remodelling and a new layer of cortical bone formation by 28 days after implantation. The addition of zoledronate, a clinically-utilised bisphosphonate, to HAA, promoted significantly more new bone formation than HAA alone over 28 days (p < 0.01). The osteogenic potential of HAA was further confirmed by implanting into a 3.5 mm diameter femoral cancellous bone defect in rats and a 5 mm diameter femoral cortical bone defect in minipigs. To understand the biodegradation and the cellular activity at the cell/biomaterial interfaces, non-decalcified specimens were resin embedded and sections subjected to combined scanning electron microscopy (SEM)/electron backscatter diffraction (EBSD)/energy dispersive X-ray spectrometry (EDS) analysis. We conclude that murine tibial periosteal ossification is a novel method for rapid assessment of the interaction of bioactive materials with osteogenic tissues. This study also highlights that combining calcium carbonate with hydroxyapatite enhances biodegradation and osteogenesis.

Dental Pulp Stem Cell Conditioned Medium Enhance Osteoblastic Differentiation and Bone Regeneration.

Cell-free approaches, utilizing mesenchymal stem cell secretome, have promising prospects in various fields of regenerative medicine. In this study, we examined in vitro and in vivo the potential of dental pulp stem cell-conditioned medium (DPSC-CM) for bone regeneration. The secretome of undifferentiated stem cells from dental pulp were collected, and the effects of this DPSC-CM were assessed for osteodifferentiation of osteoblast-like cells (MG-63) and osteoblasts deriving from DPSC. Cell proliferation, alkaline phosphatase (ALP) activity, gene expression of Runt-related transcription factor 2 (Runx2), Bone Sialoprotein (BSP), Osteocalcin (OCN), and extracellular matrix mineralization were evaluated. The rat caudal vertebrae critical size defect model was to investigate the effect of DPSC-CM in vivo. Results showed that DPSC-CM induced cell growth, and increased ALP activity and the expression of key marker genes at an early stage of osteoblastic differentiation compared to control. A rat bone defect model was used to illustrate the effect of DPSC-CM in vivo. The bone density within the defects were improved using conditioned medium, even though there was no significant difference between the control and DPSC-CM groups. The analysis of DPSC-CM by human growth factor antibody array revealed the presence of several factors involved in osteogenesis. Taken together, these findings indicate that DPSC-CM is a promising therapeutic candidate for bone regenerative therapy, accelerating the maturation of osteoblastic cells. And even though safety and efficiency of DPSC-CM have to be confirmed in preclinical studies, these results represent a first step toward clinical application.

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.

Serum biochemical evaluation of healing of critical-sized long bone defects in rats treated with biphasic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bioceramic scaffolds

Critical-sized long bone defects are those that would not heal spontaneously despite surgical stabilisation. The use of bioceramic scaffold has shown promising results in the repair of bone defects. The present study was undertaken to evaluate the serum biochemical parameters of Wistar rats treated for critical-sized segmental bone loss using biphasic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bioceramic scaffolds. The study was conducted in eighty male Wistar rats aged between 8-12 weeks, weighing 200-250 g body weight with critical-sized segmental defects in the femur. A 6 mm segmental mid-diaphyseal femoral defect was created under general anaesthesia. The bone defect was bridged with bioceramic scaffolds and retained in position with microplate and screws. Serum biochemical parameters serum calcium, phosphorous, acid phosphatase and alkaline phosphatase were evaluated four weeks before surgery, immediately after surgery and 4th, 8th, 12th, and 16th week after surgery. The evaluation of both serum calcium and phosphorous were found to be reliable indicators of new bone formation and mineralisation, whereas the evaluation of both serum acid phosphatase and alkaline phosphatase were found to be reliable indicators of bone healing during the treatment of critical-sized long bone defects in rats using biphasic hydroxyapatite and β-tricalcium phosphate bioceramic scaffolds Keywords: Beta-tricalcium phosphate, bioceramic scaffold, hydroxyapatite, serum acid phosphatase, serum alkaline phosphatase, serum calcium, serum phosphorous

Biomechanical evaluation of healing of critical-sized long bone defects in rats treated with biphasic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bioceramic scaffolds

Critical-sized bone defects are those that would not heal spontaneously despite surgical stabilisation. These defects are treated using autografts, allografts, xenografts and synthetic bone grafts. The present study was undertaken to evaluate the efficacy of biphasic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bioceramic scaffolds in treating critical-sized segmental bone loss in rats. The study was conducted in sixty male Wistar rats aged between 8-12 weeks, weighing 200-250 g body weight with critical-sized defects in the right femur. A six-mm segmental mid-diaphyseal femoral defect was created under general anaesthesia. The bone defect was bridged with biphasic hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bioceramic scaffolds and retained in position with microplate and screws. Fifteen rats were sacrificed as per the guidelines of CCSEA during the 4th, 8th, 12th and 16th week post-surgery. The treated bone and contralateral femur were harvested and subjected to a three-point bending test, torsion test and compression test to compare the regained strength of the repaired right femur with that of the intact contralateral left femur. From the present study, it was observed that the use of biphasic hydroxyapatite and β-tricalcium phosphate bioceramic scaffolds in the treatment of critical-sized long bone defects in rats resulted in biomechanical properties of the healed right femur greatly superior to the femur with untreated critical-sized diaphyseal defect by sixteenth week post-surgery and was only slightly inferior to the normal intact left femur. The results were suggestive of using biphasic hydroxyapatite and β-tricalcium phosphate bioceramics scaffolds as a safe and promising alternative for the treatment of critical-sized bone defects Keywords: Beta-tricalcium phosphate, bioceramic scaffold, compression test, hydroxyapatite, three-point bending test and torsion test

Osteogenic Potential and Long-Term Enzymatic Biodegradation of PHB-based Scaffolds with Composite Magnetic Nanofillers in a Magnetic Field.

Millions of people worldwide suffer from musculoskeletal damage, thus using the largest proportion of rehabilitation services. The limited self-regenerative capacity of bone and cartilage tissues necessitates the development of functional biomaterials. Magnetoactive materials are a promising solution due to clinical safety and deep tissue penetration of magnetic fields (MFs) without attenuation and tissue heating. Herein, electrospun microfibrous scaffolds were developed based on piezoelectric poly(3-hydroxybutyrate) (PHB) and composite magnetic nanofillers [magnetite with graphene oxide (GO) or reduced GO]. The scaffolds' morphology, structure, mechanical properties, surface potential, and piezoelectric response were systematically investigated. Furthermore, a complex mechanism of enzymatic biodegradation of these scaffolds is proposed that involves (i) a release of polymer crystallites, (ii) crystallization of the amorphous phase, and (iii) dissolution of the amorphous phase. Incorporation of Fe3O4, Fe3O4-GO, or Fe3O4-rGO accelerated the biodegradation of PHB scaffolds owing to pores on the surface of composite fibers and the enlarged content of polymer amorphous phase in the composite scaffolds. Six-month biodegradation caused a reduction in surface potential (1.5-fold) and in a vertical piezoresponse (3.5-fold) of the Fe3O4-GO scaffold because of a decrease in the PHB β-phase content. In vitro assays in the absence of an MF showed a significantly more pronounced mesenchymal stem cell proliferation on composite magnetic scaffolds compared to the neat scaffold, whereas in an MF (68 mT, 0.67 Hz), cell proliferation was not statistically significantly different when all the studied scaffolds were compared. The PHB/Fe3O4-GO scaffold was implanted into femur bone defects in rats, resulting in successful bone repair after nonperiodic magnetic stimulation (200 mT, 0.04 Hz) owing to a synergetic influence of increased surface roughness, the presence of hydrophilic groups near the surface, and magnetoelectric and magnetomechanical effects of the material.

Nanocarrier-Assisted Delivery of Berberine Promotes Diabetic Alveolar Bone Regeneration by Scavenging ROS and Improving Mitochondrial Dysfunction.

Oxidative stress and mitochondrial dysfunction are potential contributors to the compromised tissue regeneration capacity of alveolar bone in diabetic patients. Berberine, an active plant alkaloid, exhibits multiple pharmacological effects including antioxidation, blood glucose- and blood lipid-lowering properties. However, it remains uncertain whether berberine can improve impaired osteogenesis in type 2 diabetes mellitus (T2DM), and its poor solubility and oral bioavailability also constrain its applications in bone regeneration. Thus, our study aimed to probe the effects of berberine on bone marrow stem cells (BMSCs) in a diabetic microenvironment, with a greater emphasis on developing a suitable nano-delivery system for berberine and assessing its capability to repair diabetic alveolar bone defects. Firstly, BMSCs were exposed to berberine within a high glucose and palmitate (HG+PA) environment. Reactive oxygen species levels, mitochondrial membrane potential, ATP generation, cell apoptosis, and osteogenic potential were subsequently assessed. Next, we explored the regulatory mechanism of autophagy flux in the positive effects of berberine. Furthermore, a nanocarrier based on emulsion electrospinning for sustained local delivery of berberine (Ber@SF/PCL) was established. We assessed its capacity to enhance bone healing in the alveolar bone defect of T2DM rats through micro-computed tomography and histology analysis. Berberine treatment could inhibit reactive oxygen species overproduction, mitochondrial dysfunction, apoptosis, and improve osteogenesis differentiation by restoring autophagy flux under HG+PA conditions. Notably, Ber@SF/PCL electrospun nanofibrous membrane with excellent physicochemical properties and good biological safety had the potential to promote alveolar bone remodeling in T2DM rats. Our study shed new lights into the protective role of berberine on BMSCs under T2DM microenvironment. Furthermore, berberine-loaded composite electrospun membrane may serve as a promising approach for regenerating alveolar bone in diabetic patients.

Regeneration of Critical Calvarial Bone Defects Using Bovine Xenograft, Magnesium-Enriched Bovine Xenograft and Autologous Dentin in Rats: Micro-CT, Gene Expression and Immunohistochemical Analysis.

The aim of this study was to evaluate the efficacy of autologous dentin (AD), bovine xenograft (BX) and magnesium-enriched bovine xenograft (BX + Mg) in the healing of critical cranial bone defects (CCBDs) in rats. Eighty male Wistar rats were divided into four groups: BX, BX + Mg, AD and the control group (no intervention). Eight mm CCBDs were created and treated with the respective biomaterials. Healing was assessed 7, 15, 21 and 30 days after surgery by micro-computed tomography (micro-CT), real-time polymerase chain reaction (RT-PCR) and immunohistochemical analysis. Micro-CT analysis showed that AD had the highest bone volume and the least amount of residual biomaterial at day 30, indicating robust bone formation and efficient resorption. BX + Mg showed significant bone volume but had more residual biomaterial compared to AD. RT-PCR showed that the expression of osteocalcin (OC), the receptor activator of nuclear factor κB (RANK) and sclerostin (SOST), was highest in the AD group at day 21 and vascular endothelial growth factor (VEGF) at day 15, indicating increased osteogenesis and angiogenesis in the AD group. Immunohistochemical staining confirmed intense BMP-2/4 and SMAD-1/5/8 expression in the AD group, indicating osteoinductive properties. The favorable gene expression profile and biocompatibility of AD and BX + Mg make them promising candidates for clinical applications in bone tissue engineering. Further research is required to fully exploit their potential in regenerative surgery.

2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside–stimulated dental pulp stem cells-derived exosomes for wound healing and bone regeneration

Background/purpose-2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) is a bioactive component in the Chinese herb Polygonum multiflorum, recognized for its anti-inflammatory and lipid-lowering properties. Human dental pulp stem cells (hDPSCs) have excellent capabilities in tooth regeneration, wound healing, and neural repair. The exosomes (Exo) released by hDPSCs contain bioactive molecules that influence cell proliferation, differentiation, and immune responses. Therefore, we aimed to unveil the potential of THSG-Exo and evaluate its regenerative capabilities through the in vitro experiment and rat bone defect model. Materials and methodsThe effects of hDPSC-derived exosomes, with or without THSG treatment, on repair and bone regeneration were evaluated through in vitro and in vivo studies. Finally, we conducted a proteomic analysis to meticulously compare the compositional contents of the two types of exosomes. ResultsIn vitro data showed that 10 and 100 μM THSG-Exo enhanced cell proliferation and osteogenic differentiation, reducing wound size to 40 % of its original size. In our maxillary bone defect rat model, THSG-Exo significantly increased bone volume, trabecular thickness, and bone density in the bone defect area. In addition, proteomic analysis of THSG-Exo revealed diverse proteins linked to bone differentiation and tissue repair, including bone morphogenetic protein-1 (BMP-1) and tumor necrosis factor (TNF)-α-stimulated gene 6 (TNFAIP6). Our searches in functional databases revealed that THSG-Exo is involved in numerous biological pathways. ConclusionTHSG-Exo enhanced cell proliferation, wound healing, and osteogenesis in vitro, while also expediting tissue repair and bone regeneration in vivo. The protein diversity of THSG-Exo contributes significant value in both basic and regenerative medicine.

An Osteoimmunomodulatory Biopatch Potentiates Stem Cell Therapies for Bone Regeneration by Simultaneously Regulating IL-17/Ferroptosis Signaling Pathways.

Currently, there are still great challenges in promoting bone defect healing, a common health problem affecting millions of people. Herein an osteoimmunity-regulating biopatch capable of promoting stem cell-based therapies for bone regeneration is developed. A totally biodegradable conjugate is first synthesized, which can self-assemble into bioactive nano micelles (PPT NMs). This nanotherapy effectively improves the osteogenesis of periodontal ligament stem cells (PDLSCs) under pathological conditions, by simultaneously regulating IL-17 signaling and ferroptosis pathways. Incorporation of PPT NMs into biodegradable electrospun nanofibers affords a bioactive patch, which notably improves bone formation in two rat bone defect models. A Janus bio patch is then engineered by integrating the bioactive patch with a stem cell sheet of PDLSCs. The obtained biopatch shows additionally potentiated bone regeneration capacity, by synergistically regulating osteoimmune microenvironment and facilitating stem cell differentiation. Further surface functionalization of the biopatch with tannic acid considerably increases its adhesion to the bone defect, prolongs local retention, and sustains bioactivities, thereby offering much better repair effects in rats with mandibular or cranial bone defects. Moreover, the engineered bioactive patches display good safety. Besides bone defects, this osteoimmunity-regulating biopatch strategy can be applied to promote stem cell therapies for spinal cord injury, wound healing, and skin burns.

Carbon fiber felt scaffold from Brazilian textile PANfiber for regeneration of critical size bone defects in rats: A histomorphometric and microCT study.

The objective of the present study was to evaluate the carbon fiber obtained from textile PAN fiber, in its different forms, as a potential scaffolds synthetic bone. Thirty-four adult rats were used (Rattus norvegicus, albinus variation), two critical sized bone defects were made that were 5 mm in diameter. Twenty-four animals were randomly divided into four groups: control (C)-bone defect + blood clot, non-activated carbon fiber felt (NACFF)-bone defect + NACFF, activated carbon fiber felt (ACFF)-bone defect + ACFF, and silver activated carbon fiber felt (Ag-ACFF)-bone defect + Ag-ACFF, and was observed by 15 and 60 days for histomorphometric, three-dimensional computerized microtomography (microCT) and mineral apposition analysis. On histomorphometric and microCT analyses, NACFF were associated with higher proportion of neoformed bone and maintenance of bone structure. On fluorochrome bone label, there was no differences between the groups. NACFF has shown to be a promising synthetic material as a scaffold for bone regeneration.

Enhancement of Bone Repair in Diabetic Rats with Metformin-Modified Silicified Collagen Scaffolds.

Regenerating bone defects in diabetic rats presents a significant challenge due to the detrimental effects of reactive oxygen species and impaired autophagy on bone healing. To address these issues, a metformin-modified biomimetic silicified collagen scaffold is developed utilizing the principles of biomimetic silicification. In vitro and in vivo experiments demonstrated that the scaffold enhanced bone tissue regeneration within the diabetic microenvironment through the release of dual bio-factors. Further analysis reveals a potential therapeutic mechanism whereby these dual bio-factors synergistically promoted osteogenesis in areas of diabetic bone defects by improving mitochondrial autophagy and maintaining redox balance. The present study provides critical insights into the advancement of tissue engineering strategies aimed at bone regeneration in diabetic patients. The study also sheds light on the underlying biological mechanisms.

Zinc finger-inspired peptide-metal-phenolic nanointerface enhances bone-implant integration under bacterial infection microenvironment through immune modulation and osteogenesis promotion

Orthopedic and dental implantations under bacterial infection microenvironment face significant challenges in achieving high-quality bone-implant integration. Designing implant coatings that incorporate both immune defense and anti-inflammation is difficult in conventional single-functional coatings. We introduce a multifunctional nanointerface using a zinc finger-inspired peptide-metal-phenolic nanocoating, designed to enhance implant osseointegration under such conditions. Abaloparatide (ABL), a second-generation anabolic drug for treating osteoporosis, can be integrated into the design of a zinc-phenolic network constructed on the implant surface (ABL@ZnTA). Importantly, the phenolic-coordinated Zn2+ ions in ABL@ZnTA can act as zinc finger motif to co-stabilize the configuration of ABL through multiple molecular interactions, enabling high bioactivity, high loading capacity (1.36 times), and long-term release (>7 days) of ABL. Our results showed that ABL@ZnTA can modulate macrophage polarization from the pro-inflammatory M1 towards the anti-inflammatory M2 phenotype, promoting immune osteogenesis with increased OCN, ALP, and SOD 1 expression. Furthermore, the ABL@ZnTA significantly reduces inflammatory fibrous tissue encapsulation and enhances the long-term stability of the implants, indicated by enhanced binding strength (6 times) and functional connectivity (1.5−3 times) in the rat bone defect model infected by S. aureus. Overall, our research offers a nano-enabled synergistic strategy that balances infection defense and osteogenesis promotion in orthopedic and dental implantations.

Precision pore structure optimization of additive manufacturing porous tantalum scaffolds for bone regeneration: A proof-of-concept study

Currently, the treatment of bone defects in arthroplasty is a challenge in clinical practice. Nonetheless, commercially available orthopaedic scaffolds have shown limited therapeutic effects for large bone defects, especially for massiveand irregular defects. Additively manufactured porous tantalum, in particular, has emerged as a promising material for such scaffolds and is widely used in orthopaedics for its exceptional biocompatibility, osteoinduction, and mechanical properties. Porous tantalum has also exhibited unique advantages in personalised rapid manufacturing, which allows for the creation of customised scaffolds with complex geometric shapes for clinical applications at a low cost and high efficiency. However, studies on the effect of the pore structure of additively manufactured porous tantalum on bone regeneration have been rare. In this study, our group designed and fabricated a batch of precision porous tantalum scaffolds via laser powder bed fusion (LPBF) with pore sizes of 250 μm (Ta 250), 450 μm (Ta 450), 650 μm (Ta 650), and 850 μm (Ta 850). We then performed a series of in vitro experiments and observed that all four groups showed good biocompatibility. In particular, Ta 450 demonstrated the best osteogenic performance. Afterwards, our team used a rat bone defect model to determine the in vivo osteogenic effects. Based on micro-computed tomography and histology, we identified that Ta 450 exhibited the best bone ingrowth performance. Subsequently, sheep femur and hip defect models were used to further confirm the osteogenic effects of Ta 450 scaffolds. Finally, we verified the aforementioned in vitro and in vivo results via clinical application (seven patients waiting for revision total hip arthroplasty) of the Ta 450 scaffold. The clinical results confirmed that Ta 450 had satisfactory clinical outcomes up to the 12-month follow-up. In summary, our findings indicate that 450 μm is the suitable pore size for porous tantalum scaffolds. This study may provide a new therapeutic strategy for the treatment of massive, irreparable, and protracted bone defects in arthroplasty.

Fibrin-konjac glucomannan-black phosphorus hydrogel scaffolds loaded with nasal ectodermal mesenchymal stem cells accelerated alveolar bone regeneration

BackgroundEffective treatments for the alveolar bone defect remain a major concern in dental therapy. The objectives of this study were to develop a fibrin and konjac glucomannan (KGM) composite hydrogel as scaffolds for the osteogenesis of nasal mucosa-derived ectodermal mesenchymal stem cells (EMSCs) for the regeneration of alveolar bone defect, and to investigate the osteogenesis-accelerating effects of black phosphorus nanoparticles (BPNs) embedded in the hydrogels.MethodsPrimary EMSCs were isolated from rat nasal mucosa and used for the alveolar bone recovery. Fibrin and KGM were prepared in different ratios for osteomimetic hydrogel scaffolds, and the optimal ratio was determined by mechanical properties and biocompatibility analysis. Then, the optimal hydrogels were integrated with BPNs to obtain BPNs/fibrin-KGM hydrogels, and the effects on osteogenic EMSCs in vitro were evaluated. To explore the osteogenesis-enhancing effects of hydrogels in vivo, the BPNs/fibrin-KGM scaffolds combined with EMSCs were implanted to a rat model of alveolar bone defect. Micro-computed tomography (CT), histological examination, real-time quantitative polymerase chain reaction (RT-qPCR) and western blot were conducted to evaluate the bone morphology and expression of osteogenesis-related genes of the bone regeneration.ResultsThe addition of KGM improved the mechanical properties and biodegradation characteristics of the fibrin hydrogels. In vitro, the BPNs-containing compound hydrogel was proved to be biocompatible and capable of enhancing the osteogenesis of EMSCs by upregulating the mineralization and the activity of alkaline phosphatase. In vivo, the micro-CT analysis and histological evaluation demonstrated that rats implanted EMSCs-BPNs/fibrin-KGM hydrogels exhibited the best bone reconstruction. And compared to the model group, the expression of osteogenesis genes including osteopontin (Opn, p < 0.0001), osteocalcin (Ocn, p < 0.0001), type collagen (Col , p < 0.0001), bone morphogenetic protein-2 (Bmp2, p < 0.0001), Smad1 (p = 0.0006), and runt-related transcription factor 2 (Runx2, p < 0.0001) were all significantly upregulated.ConclusionsEMSCs/BPNs-containing fibrin-KGM hydrogels accelerated the recovery of the alveolar bone defect in rats by effectively up-regulating the expression of osteogenesis-related genes, promoting the formation and mineralisation of bone matrix.

Effects of Aging on New Bone Regeneration in a Mandibular Bone Defect in a Rat Model.

The effects of aging on the healing capacity of maxillofacial bone defects have not been studied. The aim of this study was to evaluate the effects of aging on the regeneration of round bony defects in the mandible. We created a round-shaped bony defect in the mandibular angle area in rats of different ages (2-[2 M], 10-[10 M], and 20-month-old [20 M]) and evaluated new bone regeneration in these groups. Changes in bone turnover markers such as alkaline phosphatase, procollagen type I N-terminal propeptide (PINP), cross-linked C-telopeptide of type I collagen, and tartrate-resistant acid phosphatase 5B (TRAP5b) were investigated. The bone volume/total volume and bone mineral density of the 20 M group were significantly higher than those of the 2 M group (p = 0.029, 0.019). A low level of the bone formation marker PINP was observed in the 20 M group, and a high level of the bone resorption marker TRAP5b was observed in the 10 M and 20 M groups. Micro-computed tomography (µ-CT) results showed that older rats had significantly higher bone formation than younger rats, with lower serum levels of PINP and higher levels of TRAP5b. The local environment of the old rat bone defects, surrounded by thickened bone, may have affected the results of our study. In conclusion, old rats showed greater new bone regeneration and healing capacity for round mandibular bone defects. This result was related to the fact that the bone defects in the 20 M rat group provided more favorable conditions for new bone regeneration.