Concrete-Inspired Bionic Bone Glue Repairs Osteoporotic Bone Defects by Gluing and Remodeling Aging Macrophages

Modulating Osteoclast Activity and Immune Responses with Ultra-Low-Dose Silver Nanoparticle-Loaded TiO2 Nanotubes for Osteoporotic Bone Regeneration

INTRODUCTION

Osteoporosis results from the dysregulation of osteoclast activation mechanisms. The subsequent inflammation in osteoporotic environments further hampers bone healing and impedes osseointegration. Therefore, developing treatments that can modulate osteoclast activity and regulate immune responses is essential for effectively treating osteoporotic bone defects.

METHODS

In this study, silver nanoparticle-decorated TiO2 nanotubes (Ag@TiO2-NTs) were synthesized through an electrochemical anodization technique for surface modification. The morphology and elemental composition of the Ag@TiO2-NTs structures were characterized using scanning electron microscopy (SEM) and related methods. Subsequently, a series of in vitro and in vivo experiments were conducted to investigate the regenerative potential of Ag@TiO2-NTs in osteoporotic bone defects. In vitro assays focused on evaluating cell viability and osteoclast function, while in vivo assessments employed osteoporotic rat models to monitor bone healing via histological examination and micro-computed tomography (micro-CT) imaging.

RESULTS

Our results demonstrated that Ag@TiO2, through the controlled release of trace amounts of silver ions, significantly suppressed osteoclast activity and consequently alleviated bone resorption under osteoporotic conditions. In addition, Ag@TiO2-NTs facilitated the polarization of macrophages toward the M2 phenotype. These biological effects were associated with the stimulation of autophagy, a fundamental mechanism involved in cellular repair. Moreover, the activation of autophagy contributed to the suppression of RANKL-induced NF-κB signaling, a pathway essential for the regulation of bone metabolism Conclusion: These results suggest that this surface modification strategy has the potential to be an ideal implant biomaterial for treating osteoporotic bone defects and a promising strategy for future implant surgeries.

Innovative modification strategies and emerging applications of natural hydrogel scaffolds for osteoporotic bone defect regeneration

Osteoporosis, a prevalent systemic metabolic bone disease, is characterized by diminished bone mass, microarchitectural deterioration of bone tissue, and heightened bone fragility. In osteoporotic patients, chronic and progressive bone loss often leads to fractures and, in advanced cases, critical-sized bone defects. While traditional bone repair approaches are constrained by significant limitations, the advent of bioactive scaffolds has transformed the therapeutic paradigm for osteoporotic bone regeneration. Among these innovations, natural polymer-based hydrogel scaffolds have emerged as a particularly promising solution in bone tissue engineering, owing to their superior biocompatibility, tunable biodegradation properties, and exceptional ability to replicate the native extracellular matrix environment. This review systematically explores recent breakthroughs in modification techniques and therapeutic applications of natural hydrogel scaffolds for osteoporotic bone defect repair, while critically analyzing existing clinical challenges and proposing future research trajectories in this rapidly evolving field.

Injectable Functional Microspheres Capable of BMSC Recruitment and Osteogenic Induction for In Situ Bone Regeneration

Currently, bone defects remain a major challenge in clinical treatment. Recruiting target cells at the defect site and inducing them to differentiate into bone tissue are effective treatment methods. In previous studies, we used the CD271 antibody to construct bone marrow mesenchymal stem cell (BMSC) recruitment microspheres for the treatment of bone defects. However, the osteoconductivity of the microspheres themselves was poor, and the system lacked osteoinductivity, which affected the repair efficiency. In this study, we prepared submillimeter-sized porous chitosan (CS) microspheres through process optimization, and the BMSCs were able to directly adhere and proliferate on their surfaces. After the bioconjugation of the CD271 antibody, bone morphogenetic protein-2 (BMP-2) was further loaded onto the pore structure of microspheres to obtain the injectable microspheres with BMSC recruitment and osteogenic differentiation induction functions. Microspheres could efficiently recruit BMSCs through the combined action of the CD271 antibody and BMP-2 and further induce the recruited BMSCs, differentiating into osteoblasts through BMP-2, which ultimately exhibited promising bone regeneration ability in rats. We expect that the novel functional microspheres have great potential in biomedical applications for in situ treatment of bone defects.

The Potential of Siraitia grosvenorii to Promote Bone Regeneration via Modulating Macrophage Polarization: A Network Pharmacology and Experimental Study

Siraitia grosvenorii (SG), a traditional Chinese medicinal herb, possesses immunomodulatory and osteoinductive properties, yet its pharmacological mechanisms in bone defect repair remain largely unexplored. This study investigates the therapeutic potential of SG through a combination of network pharmacology and experimental approaches. Active compounds were identified using the Traditional Chinese Medicine Systems Pharmacology (TCMSP) Platform, and protein interaction targets were predicted. Molecular docking and dynamics simulations assessed interactions between SG compounds and critical targets. In vitro, RAW 264.7 macrophages treated with SG-conditioned medium exhibited enhanced M2 polarization and reduced inflammation, promoting osteogenic differentiation of co-cultured MC3T3-E1 cells as evidenced by increased alkaline phosphatase activity. In vivo, scaffolds loaded with low-dose or high-dose SG (LSG/HSG) significantly improved bone regeneration in rat calvarial defects, with HSG achieving near-complete repair and mature trabeculae at 8 weeks, alongside decreased CD86 and TNF-α levels and increased IL-10 expression. Network pharmacology identified 33 shared targets related to bone regeneration and macrophage polarization, with kaempferol and beta-sitosterol demonstrating strong binding affinities to targets such as TNF, PTGS2, and CASP3. These findings highlight the potential of SG in enhancing bone defect repair and its implications for regenerative medicine.

The targeting of YAP by kaempferol regulates bone homeostasis and improves osteoporosis in rats

This study investigated the potential therapeutic effect of kaempferol on osteoporosis by regulating bone homeostasis through the YAP. The ovariectomy model was constructed. The changes in bone and liver tissue were observed through HE staining. Bone metabolism and inflammatory markers were quantitatively analyzed using RT-qPCR and ELISA. Changes in the YAP/NF-κB signaling pathway were detected through Western blot and immunofluorescence. In vitro, the activity and secretion levels of MC3 T3-E1-differentiated osteoblasts were assessed using CCK- 8 and ELISA. The effects of osteoblast-secreted factors on osteoclast-induced differentiation were analyzed using alizarin red staining, phalloidin staining, ELISA, TRAP staining, and SEM. Finally, the regulatory effects of kaempferol on the expression of bone homeostasis in osteoclasts were examined by immunofluorescence and Western blot. Kaempferol treatment improved trabecular bone structure, increased bone density, and modulated bone metabolism by enhancing OPG expression and suppressing TRAP, NFATC1, and RANKL levels. Kaempferol inhibited the activation of the NF-κB pathway and increased YAP expression, reducing inflammatory factors. In vitro, kaempferol promoted osteoblast differentiation and inhibited osteoclast activity. These effects were most pronounced at higher kaempferol doses and were associated with improved bone remodeling and reduced bone resorption. Kaempferol exhibits significant potential for osteoporosis treatment by regulating bone homeostasis, mitigating inflammation through modulating the YAP.

Bone-Adhesive Peptide Hydrogel Loaded with Cisplatin for Postoperative Treatment of Osteosarcoma

The inhibition of residual tumor recurrence while repairing bone defects poses a challenging issue for postoperative osteosarcoma treatment. Here, we develop a self-assembling peptide hydrogel (GelA) for the targeted delivery of cisplatin (CDDP), aiming to integrate postoperative tumor inhibition with bone defect repair. GelA exhibits exceptional biocompatibility, high loading capacity for CDDP, and superior bone adhesion. After in situ injection to bone defects, CDDP-loaded hydrogel GelA-CDDP demonstrates a strong affinity for hydroxyapatite, thereby facilitating optimal bone adhesion and prolonging the retention time of CDDP in a postoperative wound. Furthermore, GelA-CDDP can regulate the distribution and release behavior of CDDP, minimizing off-target effects and optimizing the therapeutic outcomes of chemotherapy and osteogenesis. Finally, in the orthotopic osteosarcoma transplantation model in mice, postoperative treatment with GelA-CDDP significantly inhibits residual osteosarcoma recurrence as well as repair of bone defects through synergistic osteogenesis promotion and osteoclastic inhibition. We believe that this hydrogel-based therapy strategy holds great promise in achieving simultaneous tumor inhibition and bone defect repair for postoperative osteosarcoma treatment.