Objectives Diabetes mellitus (DM) induces oxidative tissue impairment and suppresses bone formation. Some studies have shown that phytic acid has antioxidant and anti-diabetic properties. This study aimed to investigate the potential of calcium phytate (Ca-phytate) to reverse inhibited osteogenesis of human bone marrow mesenchymal stem cells (hBMSCs) in a high glucose (HG) environment and to determine the underlying mechanism. Materials and Methods hBMSCs were exposed to HG and palmitic acid to simulate DM in vitro. Osteogenic differentiation was measured using alkaline phosphatase staining and activity assay, alizarin red S staining, qRT-PCR, Western blot and immunofluorescence staining. A critical-size cranial defect model of type 2 diabetes mellitus (T2DM) rats was established to evaluate bone regeneration. A specific pathway inhibitor was used to explore whether the MAPK/JNK pathway was involved. Results Treatment with 34 μM Ca-phytate had the highest effect on osteogenic differentiation in HG. Ca-phytate improved cranial bone defect healing in T2DM rats. The long-term HG environment inhibited the activation of the MAPK/JNK signalling pathway, which was restored by Ca-phytate. Blocking the JNK pathway reduced the Ca-phytate-mediated osteogenic differentiation of hBMSCs. Conclusion Ca-phytate induced bone regeneration in vivo and reversed HG-inhibited osteogenesis of hBMSCs in vitro via the MAPK/JNK signalling pathway.
Infectious bone defects pose significant clinical challenges due to persistent infection and impaired bone healing. Icam1+ macrophages were identified as crucial and previously unrecognized regulators in the repair of bone defects, where impaired oxidative phosphorylation within this macrophage subset represents a significant barrier to effective bone regeneration. To address this challenge, dual-responsive iron-doped barium titanate (BFTO) nanoparticles were synthesized with magnetic and ultrasonic properties. These nanoparticles were further loaded with the anti-inflammatory agent curcumin and coated with engineered mesenchymal stem cell membranes (EMM) modified with γ3 peptide, creating BFTO-Cur@EMM nanoparticles specifically designed to target Icam1+ macrophages. These nanoparticles were shown to disrupt bacterial biofilms under alternating magnetic fields (AMF) and to activate oxidative phosphorylation and osteogenic immune responses in Icam1+ macrophages via low-intensity pulsed ultrasound (LIPUS). Transcriptomic sequencing and validation experiments demonstrated that this approach activates oxidative phosphorylation (OXPHOS) by stimulating the JAK2-STAT3 pathway and inhibiting the MAPK-JNK pathway, thereby promoting the polarization of Icam1+ macrophages toward a pro-reparative phenotype and enhancing the secretion of pro-angiogenic and osteogenic cytokines. These nanoparticles were subsequently integrated into quaternized chitosan (QCS) and tricalcium phosphate (TCP) to create a bioink for three-dimensional (3D) printing anti-infection QT/BFTO-Cur@EMM bone repair scaffolds. In vivo studies indicated that these scaffolds significantly improved the healing of infectious bone defects without causing thermal damage to surrounding tissues. This work highlights the potential of this material and the targeting of Icam1+ macrophages as an effective strategy for simultaneously controlling infection and promoting bone regeneration.
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