Stem-cell-derived ECM sheet-implant complexes for enhancing osseointegration

Numerous treatment methods have been developed to modify the surface of dental implants to improve cell migration and proliferation, removal torque, and osseointegration. Recent studies have constructed cell sheet-implant complexes with enhanced osteogenic capabilities. However, these complexes have some limitations, such as requirements for complex preparation processes, cell vitality maintenance, strict preservation conditions, and the induction of immunogenicity. Extracellular matrix (ECM) sheets without cells may be a more desirable material. To date, the effect of ECM sheets on implant osseointegration has not been reported. In this study, we fabricated ECM sheet-implant complexes through the combination of rat bone marrow mesenchymal stem cell (BMSC)-derived ECM sheets with sandblasted, large-grit, acid-etched (SLA) implants. These complexes were characterized by light microscopy, scanning electron microscopy (SEM), and immunofluorescence (IF) assays. The adhesion, proliferation, and osteogenic differentiation of BMSCs cultured on ECM sheets were detected in vitro. Then, the ECM sheet-implant complexes were transplanted into the metaphysis of the tibias of rats to evaluate the implant osseointegration in vivo. The results showed that ECM sheets were successfully constructed and showed significantly improved adhesion and proliferation. BMSCs cultured on ECM sheets upregulated the expression levels of the osteogenic-related genes alkaline phosphatase (ALP), bone morphogenetic protein 2 (BMP2), and runt-related transcription factor 2 (Runx2) compared to controls. In vivo, ECM sheet-implant complexes demonstrated superior new bone formation. Our findings proved that the BMSC-derived ECM sheets promoted osseointegration in vitro and in vivo. The current study indicated that the ECM sheet could be an ideal tissue engineering material, and ECM sheet-implant complexes could provide a strategy with low immunogenicity and easy storage and transportation. This research provides a novel strategy for the development of implant surface modification approaches.