加瀬 義高

Peri-implantitis, an inflammatory condition caused by bacterial infection around an implant, is currently the leading cause of implant failure. Porphyromonas gingivalis (P. gingivalis), an anaerobic bacterial pathogen associated with periodontitis, is known to play a key role in peri-implantitis. To address this issue, the present study examined the antibacterial properties of silver ion (Ag+)-coated titanium implants against P. gingivalis and their ability to prevent bone loss. Ag+-coated implants, i.e., Ti implants coated with Ag+ ions on a hydroxyapatite film chelated with inositol hexaphosphate, demonstrated significant antibacterial activity against P. gingivalis in the Ti wire configuration in inhibition zone assays (n = 4 per group). Furthermore, in a murine model of ligature-induced peri-implantitis, these implants significantly reduced alveolar bone resorption compared to uncoated titanium controls. This preclinical study suggests that applying an Ag+ coating to dental implants is an effective strategy for preventing P. gingivalis-induced peri-implantitis. In the control group, bone loss of 19-25% relative to baseline was observed at day 28, whereas the Ag+-coated group exhibited only 15-20% bone loss (n = 8 per group per time point). These findings suggest the potential of Ag+ coating as a preventive strategy against peri-implantitis-associated bone loss.

Driven by endogenous platelet-derived growth factor receptor α (PDGFRα)-positive cells, in-body tissue architecture (iBTA) enables the autonomous formation of vascularized tissues within subcutaneously implanted molds, overcoming the limitations of traditional cell therapies. The cellular mechanisms were investigated in PDGFRα reporter mice. Recruited PDGFRα-lineage cells were closely associated with Pecam-1-positive vessels and often adopted perivascular positions. Flow cytometry revealed that these cells expressed the mesenchymal stem/stromal cell (MSC) markers (CD73, CD90, and CD105). Additionally, the cultured isolates maintained MSC morphology and demonstrated osteogenic, chondrogenic, and adipogenic differentiation potential in vitro. The approach was successfully scaled to a porcine model, which exhibited organized tissue maturation, including vascular structures and collagen deposition, within 2 weeks. iBTA eliminates the need for cell isolation and immunosuppression by leveraging resident PDGFRα-positive MSCs for in situ tissue generation, providing a direct pathway for autologous vascular tissue engineering applications.