Background: The repair of osteoporotic bone defects remains challenging due to excessive reactive oxygen species (ROS), persistent inflammation, and an imbalance between osteogenesis and osteoclastogenesis. Methods: Here, an injectable H2-releasing hydrogel (magnesium@polyethylene glycol-poly(lactic-co-glycolic acid), Mg@PEG-PLGA) was developed to remodel the challenging bone environment and accelerate the repair of osteoporotic bone defects. Results: This Mg@PEG-PLGA gel shows excellent injectability, shape adaptability, and phase-transition ability, can fill irregular bone defect areas via minimally invasive injection, and can transform into a porous scaffold in situ to provide mechanical support. With the appropriate release of H2 and magnesium ions, the 2Mg@PEG-PLGA gel (loaded with 2 mg of Mg) displayed significant immunomodulatory effects through reducing intracellular ROS, guiding macrophage polarization toward the M2 phenotype, and inhibiting the IκB/NF-κB signaling pathway. Moreover, in vitro experiments showed that the 2Mg@PEG-PLGA gel inhibited osteoclastogenesis while promoting osteogenesis. Most notably, in animal experiments, the 2Mg@PEG-PLGA gel significantly promoted the repair of osteoporotic bone defects in vivo by scavenging ROS and inhibiting inflammation and osteoclastogenesis. Conclusions: Overall, our study provides critical insight into the design and development of H2-releasing magnesium-based hydrogels as potential implants for repairing osteoporotic bone defects.

Hydroxyapatite (HAp) coatings currently have limited therapeutic applications because they lack anti-infection, osteoinductivity, and poor mechanical characteristics. On the titanium substrate, electrochemical deposition (ECD) was used to construct the strontium (Sr)-featuring hydroxyapatite (HAp)/graphene oxides (GO)/linezolid (LZ) nanomaterial coated with antibacterial and drug delivery properties. The newly fabricated nanomaterials were confirmed by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis and morphological features were examined by scanning electron microscope (SEM) analysis. The results reveal multiple nucleation sites for SrHAp/GO/LZ composite coatings due to oxygen-comprising moieties on the 2D surface of GO. It was shown to be favorable for osteoblast proliferation and differentiation. The elastic modulus and hardness of LZ nanocomposite with SrHAp/GO/LZ coatings were increased by 67 % and 121 %, respectively. An initial 5 h burst of LZ release from the SrHAp/GO/LZ coating was followed by 14 h of gradual release, owing to LZ\'s physical and chemical adsorption. The SrHAp/GO/LZ coating effectively inhibited both S. epidermidis and S. aureus, and the inhibition lasted for three days, as demonstrated by the inhibition zone and colony count assays. When MG-63 cells are coated with SrHAp/GO/LZ composite coating, their adhesion, proliferation, and differentiation greatly improve when coated with pure titanium. A novel surface engineering nanomaterial for treating and preventing osteoporotic bone defects, SrHAp/GO/LZ, was shown to have high mechanical characteristics, superior antibacterial abilities, and osteoinductivity.

The local application of drug-loaded bioactive scaffold materials is one of the important directions to solve the clinical problem of osteoporotic (OP) bone defects. This study retains the advantages of drug loading and mechanical properties of natural 3D bioactive scaffolds. The scaffolds are functionally modified through chemical and self-assembly approaches with application of polydopamine (PDA) nanoparticles and parathyroid hormone-related peptide-1 (PTHrP-1) for efficient local drug loading. This study investigates the effects of the novel bioactive scaffolds on ossification, osteoclastogenesis, and macrophage polarization. This work elucidates the effects of the scaffolds in regulating osteoclastic activity and new bone formation in vitro. Further studies on the establishment and repair of OP bone defects in small animals are conducted, and the potential of natural bioactive porous scaffold materials to promote the repair of OP bone defects is initially verified. The preparation of safe and economical anti-OP bone repair material provides a theoretical basis for clinical translational applications.

Bone disease and disorder treatment might be difficult because of its complicated nature. Millions of patients each year need bone substitutes that may help them recover quickly from a variety of illnesses. Synthetic bone replacements that mirror the structural, chemical, and biological features of bone matrix structure will be very helpful and in high demand. In this research, the inorganic bioactive glass nanoparticles matrixed with organic collagen and silk fibroin structure (COL/SF/CaO-SiO2) were used to create multifunctional bone-like fibers in this study, which we describe here. The fiber structure is organized in a layered fashion comparable to the sequence in which apatite and neo tissue are formed. The amino groups in COL and SF combined with CaO-SiO2 to stabilize the resulting composite nanofiber. Morphological and functional studies confirmed that crystalline CaO-SiO2 nanoparticles with average sizes of 20 ± 5 nm are anchored on a 115 ± 10 nm COL/SF nanofiber matrix. X-ray photoelectron spectroscopic (XPS) results confirmed the presence of C, N, O, Ca, and Si in the composite fiber with an atomic percentage of 59.46, 3.30, 20.25, 3.38 and 13.61%. respectively. The biocompatibility examination with osteoblast cells (Saos-2) revealed that the CAL/SF/CaO-SiO2 composite nanofiber had enhanced osteogenic activity. Finally, when the CAL/SF/CaO-SiO2 composite nanofiber scaffolds were used to treat an osteoporotic bone defect in a rat model, the composite nanofiber scaffolds significantly promoted bone regeneration and vascularization. This novel fibrous scaffold class represents a potential breakthrough in the design of advanced materials for complicated bone regeneration.

Local application of lithium or aspirin with biological scaffold has been identified as a potent means to improve bone formation. In this study, lithium and aspirin modified calcium phosphate cement (Asp-Li/CPC) was prepared, and the feasibility of this biological scaffold in the treatment of osteoporotic bone defect was observed in vivo and in vitro. In vitro experiments confirmed that Asp-Li/CPC had better ability to promote MC3T3-E1 cells differentiation into osteoblasts, osteoblast mineralization and viability, and promote cell expression of ALP, OP, RUNX-2, OC and COL-1 protein than simple CPC or lithium modified CPC by MTT, Alizarin red staining and Western blot evaluation. In vivo experiments confirmed that Asp-Li/CPC presented the strongest effect on bone regeneration and bone mineralization through the comparison with CPC group and Li/CPC group with X-ray images, Micro-CT and Histological evaluation. RT-qPCR analysis showed that Asp-Li/CPC, Li/CPC group and CPC group demonstrated increased BMP2, Smad1, OPG than the OVX group (P<0.05), while Asp-Li/CPC exhibited decreased TNF-α, IFN-γ and RANKL than the OVX group (P<0.05). Experiments in vivo and in vitro show that Asp-Li/CPC is a scheme for rapid repair of femoral condylar defects, and these effects may be achieved by inhibiting local inflammation and through BMP-2/Smad1 and OPG/RANKL signaling pathway.

BACKGROUND: The use of antiepileptic drugs and estrogen deficiency put forward higher requirements for bone defect regeneration. The present study investigated the effects of alendronate (ALN) on femoral bone defect in ovariectomized (OVX) rats under the influence of carbamazepine (CBZ).
METHODS: One hundred female SD rats at 3 months of age were either sham-operated or OVX and divided into four groups: sham control (CON); OVX control (OVX); ovariectomized rats treated with CBZ via gavage (75 mg/kg/day; CBZ); ovariectomized rats treated with CBZ plus ALN (2 mg/kg/day; CBZ-ALN). A critical-sized femoral metaphyseal bone defect was established in all female SD rats. Animals from the CBZ and CBZ-ALN groups received drugs by gavage the day after bone defect surgery was performed. After the rats were sacrificed, the defected area located in the distal femur was harvested for evaluation by microcomputed tomography (micro-CT), hematoxylin and eosin (HE) staining, and Masson\'s trichrome staining. The samples were also analyzed by biomechanics and immunohistochemical evaluation (IHC). Besides, biochemical analysis evaluates all serum samples.
RESULTS: The present study showed that ovariectomy changed the microstructural parameters of bone. The use of CBZ further decreased femur bone mass while treatment with ALN prevented bone loss. Compared to OVX and CBZ groups, CBZ-ALN group promoted bone neoformation and enhanced the ultimate load of the femur bone. However, the group of CBZ-ALN did not return to normal levels compared with the CON group. Besides, we noticed that CBZ-ALN group reduced tartrate-resistant acid phosphatase-5b (Tracp-5b) expression and had no significant effect on the expression of osteocalcin (OCN) and type I collagen (Col-I) in IHC compared with CBZ group. Biochemical analysis results presented that systemic delivery of CBZ showed pernicious effects on bone formation and resorption in ovariectomized rats, with the worse effects on C-terminal crosslinked telopeptide of type I collagen (CTX-1). Besides, a significant decrease in CTX-1 levels was observed in CBZ-ALN group as compared to the group of CBZ.
CONCLUSIONS: These results demonstrated that ALN can effectively reverse the effects of CBZ on the microarchitectural properties of bone, and thus can have a positive effect on local bone neoformation in rats with osteoporosis.
CONCLUSIONS: The dose of 2 mg/kg ALN improves the negative effect of prescription of CBZ at 75 mg/kg and promotes bone neoformation of femoral bony deficits.

The purpose was to observe whether local administration Strontium (Sr) and Aspirin (Asp) can enhance the efficacy of β-Tricalcium phosphate(β-TCP) in the treatment of osteoporotic bone defect. The MC3T3-E1 cells were co-cultured with β-TCP, Sr/β-TCP, Asp-Sr/β-TCP scaffold and induced to osteogenesis, and the cell viability, mineralization ability were observed by MTT, Alizarin Red staining(ARS) and Western blotting(WB). Then this scaffolds were implanted into the femoral epiphysis bone defect model of ovariectomized(OVX) rats for 8 weeks. X-ray, Micro-CT, histology and Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis were used to observe the therapeutic effect and explore the possible mechanism. MTT, ARS results show that the cell mineralization and viability of Asp-Sr/β-TCP group is significantly higher than Control group, β-TCP group and Sr/β-TCP group. Protein expression show that the osteogenic protein expression such as ALP、OP、RUNX-2、OC and COL-1 of Asp-Sr/β-TCP group is significantly higher than Control group, β-TCP group and Sr/β-TCP group. X-ray images, Micro-CT and Histological analysis evaluation show that, group Asp-Sr/β-TCP presented the strongest effect on bone regeneration and bone mineralization, when compared with β-TCP group and Sr/β-TCP group. RT-qPCR analysis show that Asp-Sr/β-TCP, β-TCP group and Sr/β-TCP group showed increased BMP2, Smad1, OPG than the OVX group(p < 0.05), while Asp-Sr/β-TCP exhibited decreased TNF-α、IFN-γ and RANKL than the OVX group(p < 0.05). Our current study demonstrated that Asp-Sr/ β-TCP is a scheme for rapid repair of femoral condylar defects, and these effects may be achieved by inhibiting local inflammation and through BMP-2/Smad1 and OPG/RANKL signaling pathway.

Graphene Oxide (GO)-related hydrogels have been extensively studied in hard tissue repair, because GO can not only enhance the mechanical properties of polymers but also promote osteogenic differentiation of mesenchymal stem cells. However, simple GO-related hydrogels are not ideal for the repair of osteoporotic bone defects as the overactive osteoclasts in osteoporosis. Alendronate (Aln) is known to inhibit osteoclasts and may bind to GO through covalent connection. Therefore, delivering Aln in GO-related hydrogels may be effective to repair osteoporotic bone defects. Here, we developed a control-released system which is constructed by collagen (Col)-GO sponges loaded with Aln (Col-GO-Aln) for osteoporotic bone defect repair. In vitro, Col-GO-Aln sponges prolonged the release period of Aln, and the sponge containing 0.05% (w/v) GO released Aln faster than sponge with 0.2% GO. Furthermore, tartrate-resistant acid phosphatase (TRAP) and F-actin staining demonstrated that Col-GO-Aln sponges effectively inhibited osteoclastogenesis of monocyte-macrophages. In vivo, micro-CT scan showed that the volume of newborn bone in defect site by 0.05% GO sponge was nearly three times larger than that of other groups. Moreover, the CT and histological examinations of rat femur proved that Col-GO-Aln sponges decreased the number of osteoclasts and suppressed the systemic bone loss in osteoporotic rats. These findings reveal that the application of GO as carriers of anti-osteoporosis drugs is a viable treatment for osteoporosis. The results also underscore the potential of GO-related hydrogels with Aln-releasing capacity for bone regeneration in osteoporosis.

Researches of biomaterials for osteoporotic bone defects focus on the improvement of its anti-osteoporosis ability, due to osteoporosis is a kind of systemic and long-range bone metabolism disorder. Nevertheless, how to steadily deliver anti-osteoporosis drugs in osteoporotic bone defects is rarely studied. Reported evidences have shown that alendronate (Aln) is known to not only restrain osteoclasts from mediating bone resorption but also stimulate osteoblasts to regenerate bone tissue. Here, we developed an engineered implantable scaffold that could sustainably release Aln for osteoporotic bone defects. Briefly, Aln was added into 2% collagen (Col) solution to form a 5 mg/ml mixture. Then the mixture was filled into pre-designed round models (diameter: 5 mm, height: 2 mm) and crosslinked to obtain engineered Col-Aln scaffolds. The release kinetics showed that Aln was released at an average rate of 2.99 μg/d in the initial 8 days and could sustainably release for 1 month. To detect the repair effects of the Col-Aln scaffolds for osteoporotic defects, the Col and Col-Aln scaffolds were implanted into 5 mm cranial defects in ovariectomized rats. After 3 months, the cranial defects implanted with Col-Aln scaffolds achieved more bone regeneration in defect area (11.74 ± 3.82%) than Col scaffold (5.12 ± 1.15%) (p < .05). Moreover, ovariectomized rats in Col-Aln scaffold group possessed more trabecular bone in femur metaphysis than Col scaffold group as analyzed by Micro-CT. This study demonstrated the engineered Col-Aln scaffold has the potential to repair osteoporotic bone defects and resist bone loss in osteoporosis.

Composite materials β-tricalcium phosphate (β-TCP) and poly-lactic-co-glycolic acid (PLGA) have achieved stable bone regeneration without cell transplantation in previous studies. Recent research shows that aspirin (ASP) has great potential in promoting bone regeneration. The objective of the present study was to incorporate PLGA into β-TCP combined with a lower single-dose local administration of ASP to enhance its in vivo biodegradation and bone tissue growth. After the creation of a rodent critical-sized femoral metaphyseal bone defect, PLGA -modified β-TCP (TP) was prepared by mixing sieved granules of β-TCP and PLGA (50:50, v/v) for medical use, then TP with dripped 50 µg/0.1 ml and 100 µg/0.1 ml aspirin solution was implanted into the defect of OVX rats until death at 8 weeks. The defected area in distal femurs of rats was harvested for evaluation by histology, micro-CT, biomechanics and real time RT-PCR. The results of our study show that a single-dose local administration of ASP combined with the local usage of TP can increase the healing of defects in OVX rats. Single-dose local administration of aspirin can improve the transcription of genes involved in the regulation of bone formation and vascularization in the defect area, and inhibits osteoclast activity. Furthermore, treatments with a higher single-dose local administration of ASP and TP showed a stronger effect on accelerating the local bone formation than while using a lower dose of ASP. The results from our study demonstrate that the combination of a single-dose local administration of ASP and β-TCP/PLGA had an additive effect on local bone formation in osteoporosis rats, and bone regeneration by PLGA/β-TCP/ASP occured in a dose-dependent manner.