Effect of quercetin on preosteoblasts and bone defects.

Quercetin is a flavonol, also a phytoestrogen, available commonly in onion and apple. Our laboratory investigated its effect on MC3T3-E1 cells' alkaline phosphatase activity in vitro and compared the amount of new bone produced by quercetin in collagen matrix to that produced by bone grafts and collagen matrix in vivo. Four bone defects, 5mm by 10mm were created in the parietal bone of 2 New Zealand White rabbits. In the experimental animal, 2 defects were grafted with quercetin solution mixed with collagen matrix. In the control animal, 2 defects were grafted with collagen matrix alone. Animals were killed on day 14 and the defects were dissected and prepared for histological qualitative assessment. Results showed that 10muM of quercetin increased alkaline phosphatase activity of MC3T3-E1 cells at 72 hours in vitro by 32%. In the experimental animal, there was new bone growing inside the bone defects. In conclusion, specific concentration of quercetin increased alkaline phosphatase activity of MC3T3-E1 cells in vitro and quercetin in collagen matrix has the effect of forming new bone across bone defects in vivo.