The long-term nonunion of bone defects remains a significant challenge in the field of orthopedics. Poly(L-lactic acid) (PLLA), widely used in bone tissue engineering, offers hope for addressing this issue. In our previous study, we aimed to enhance the poor toughness and slow degradation of PLLA by introducing flexible p-dioxanone (PDO) and highly reactive glycolide (GA) units into the molecular chain of PLLA to prepare PLLA-ran-PDO-ran-GA (PLPG) scaffolds, effectively mitigating the limitations of PLLA. However, the crystallization capacity of PLPG copolymers was weakened, resulting in insufficient mechanical properties. Therefore, in this study, poly(D-lactic acid) (PDLA) was introduced into PLPG via solution blending to enhance its crystallization properties through the in situ generation of stereocomplex poly(lactic acid) (SC-PLA). Subsequently, PLPG/PDLA scaffolds were prepared using 3D printing technology. The results demonstrated that PLPG/PDLA composites exhibited good machinability, while the scaffolds showed satisfactory mechanical and degradation properties. Additionally, cell experiments indicated that PLPG/PDLA scaffolds possess biocompatibility, allowing for cell growth and proliferation on their surfaces. We believe that PLPG/PDLA scaffolds have significant potential for application in bone tissue engineering, effectively addressing the issue of long-term non-healing bone defects.

Periodontal bone regeneration depends on the coordinated interplay between osteogenesis and angiogenesis; however, the molecular regulation underlying osteogenic–angiogenic coupling remains incompletely understood. Despite previous evidence that miR-508-5p downregulation enhances the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) in vitro, its role in regulating angiogenesis and bone formation in vivo remains unclear. In the present study, miR-508-5p was modulated using synthetic inhibitor and mimic oligonucleotides, and its effects on osteogenesis, angiogenesis, and osteogenic–angiogenic coupling were investigated by the use of alkaline phosphatase and alizarin red S staining, conditioned-medium assays, a chicken chorioallantoic membrane assay, and a nude mouse ectopic bone formation model. The responses to miR-508-5p inhibition differed by cell type: osteogenic differentiation increased in hPDLSCs, while human umbilical vein endothelial cells (HUVECs) showed greater proliferative, migratory, and tube-forming activity. Conditioned medium experiments further revealed that miR-508-5p inhibition enhanced the reciprocal paracrine effects between hPDLSCs and HUVECs, thereby promoting both osteogenic and angiogenic responses. In vivo, miR-508-5p inhibition enhanced bone-like tissue formation and collagen deposition, accompanied by the elevated expression of collagen type I alpha 1 chain, bone morphogenetic protein 2, and the angiogenic marker CD31. Taken together, the findings support a potential regulatory role for miR-508-5p in osteogenic–angiogenic coupling and indicate that this microRNA may warrant consideration as a candidate target in therapeutic strategies for periodontal bone regeneration.

Background/Objectives: Eupalinolide B (EB), a natural compound derived from Eupatorium lindleyanum DC, has demonstrated multiple pharmacological activities. However, its role in modulating oxidative stress remains incompletely understood. Methods: In this study, we investigated the antioxidant effect and underlying mechanism of EB in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. Results: EB significantly attenuated LPS-induced oxidative stress as evidenced by reduced levels of intracellular reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA) alongside enhanced superoxide dismutase (SOD) activity and an increased reduced/oxidized glutathione (GSH/GSSG) ratio. Using activity-based protein profiling, we identified peroxiredoxin 4 (PRDX4) as a key binding target of EB. Direct interaction was confirmed through labeling and competitive binding assays with purified PRDX4 protein. High-resolution mass spectrometry revealed that EB covalently binds to Cys54 and Cys248 residues of PRDX4. Furthermore, EB treatment upregulated PRDX4 protein expression in LPS-stimulated RAW264.7 cells. siRNA-mediated knockdown of PRDX4 significantly blunted the antioxidant effects of EB, confirming the functional relevance of this target. Conclusions: Our findings demonstrate that EB alleviates LPS-induced oxidative stress in macrophages by covalently binding to and stabilizing PRDX4, thereby enhancing cellular antioxidant capacity. This study unveils a novel mechanism whereby a natural product enhances cellular antioxidant capacity by covalently stabilizing a key peroxidase, highlighting the potential of EB as a therapeutic agent and PRDX4 as a promising target for oxidative stress-related diseases.

Modulating the immune microenvironment has become an emerging strategy for promoting functional bone regeneration, identifying key therapeutic targets remains challenging. Our previous work showed that Nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing protein 5 (NLRC5) is involved in bone destruction associated with periodontitis, but its potential and mechanism in regulating bone tissue repair and regeneration have not been fully elucidated. A monocortical bone defect model was established in the mouse femur to assess the impact of NLRC5 on in situ bone healing and regeneration. Mouse bone marrow-derived mesenchymal stem cells (BMSCs) were isolated to evaluate the effects of NLRC5 on osteogenic differentiation, proliferation, and migration. RNA sequencing was used to explore the direct regulatory mechanism of NLRC5 on osteogenic differentiation of mouse BMSCs. Mass cytometry was employed to examine the effect of NLRC5 on the bone marrow immune microenvironment, followed by in vitro validation experiments. Loss of NLRC5 impaired the healing and regeneration of femoral bone defects in mice, and led to a high inflammatory state in the early stage of healing. The absence of NLRC5 inhibited the osteogenic differentiation ability of BMSCs, and could be restored by NLRC5 overexpression, which was achieved through activation of the phosphatidylinositol 3-kinase/protein kinase B(PI3K/AKT) signaling pathway. Mass cytometry data revealed that NLRC5 may serve as an important factor in maintaining the differentiation and maturation of regulatory T cells (Tregs). By modulating the levels of inflammatory cytokines, NLRC5 further influences the osteogenic differentiation of BMSCs. NLRC5 serves as a key regulator and promising candidate for bone repair. NLRC5 contributes to bone regeneration through a dual mechanism: it promotes BMSCs osteogenic differentiation, at least in part via the PI3K/AKT/β-catenin signaling pathway, and indirectly modulates the local immune microenvironment to facilitate bone repair.