Bone Regeneration Induced by Functional Peptide SVVYGLR

Recently, a novel binding sequence Ser-Val-Val-Tyr-Gly-Leu-Arg (SVVYGLR) was found adjacent to the RGD sequence in osteopontin molecule, and in vivo angiogenesis due to the synthetic peptide SVVYGLR was demonstrated. Objectives: To investigate bioactive functions of SVVYGLR in osteoblasts and osteoclasts, and to examine its potential applications to bone regeneration. Methods: Effects of SVVYGLR (1-100 µg/ml) on adhesion and proliferation of human bone marrow-derived mesenchymal stem cells (hMSC) were assessed by an absorbance-based adhesion assay and WST-1 assay. Interaction of SVVYGLR with cell surface integrins was examined by the adhesion assay using monoclonal antibodies against several human integrins and integrin αvß3-overexpression CHO cells (ß3-CHO). Effects of SVVYGLR on RANKL-induced osteoclastogenesis of RAW264.7 were evaluated by counting the number of TRAP-positive multinucleated cells and RT-PCR analysis for the expression of osteoclastogenesis-related mRNAs (calcitonin receptor, cathepcin K, TRAP). In rat calvariae, standardized bone defects were filled with collagen sponge containing 10 µg SVVYGLR or PBS (control) and the new bone formed at the defects was histologically assessed. Results: SVVYGLR significantly induced adhesion and proliferation of hMSC in a dose-dependent manner. This adhesion was specifically blocked by an anti-integrin αvß3 antibody. The adherence level of ß3-CHO to culture plates treated with SVVYGLR was significantly higher than that of mock-CHO (P<0.01). SVVYGLR significantly reduced the number of TRAP-positive multinucleated RAW264.7 cells (P<0.01) and inhibited the expression of the osteoclastogenesis-related mRNAs. Three weeks after surgery, the number of TRAP-positive osteoclasts at the implanted sites in the peptide group was significantly lower than that in the control group (P<0.01). At the 5th week, SVVYGLR significantly induced resorption of the implanted collagen sponge and enhanced new bone formation within and surrounding the sponge. Conclusions: These data demonstrated that SVVYGLR is an effective bioactive peptide on bone tissue regeneration by promoting adhesion and proliferation of osteoblasts and suppressing osteoclastogenesis.