The effect of rhBMP-2 on delta12-PGJ2 induced osteoblastic differentiation and mineralization

Kim, Won Kyung; Kim, Kyoung Hwa; Kim, Jong Jin; Lee, Young Kyu; Ku, Young

Abstract

Prostaglandin plays a significant role in the local control of bone metabolism associated with periodontal disease. delta12-PGJ2 is a natural PGD2 metabolite that is formed in vivo in the presence of plasma. It is known for delta12-PGJ2 to stimulate calcification in osteoblastic cells. Bone morphogenetic protein(BMP) stimulated osteoblastic differentiation in various types of cells and greatly enhanced healing of bony defects. The purpose of this study was to evaluate the effect of rhBMP-2 on delta12-PGJ2 induced osteoblastic differentiation and mineralization in vitro. A human osteosarcoma cells line Saos-2 were cultured. In the test groups, 10-7M of delta12-PGJ2 or mixture of 10-8M of delta12-PGJ2 and 100ng/ml of rhBMP-2 or 100ng/ml of rhBMP-2 were added to culture media. After 1 day, 2 days and 4 days of culture period, the cell number was measured. Alkaline phosphatase activity was measure at 3 days. Reverse transcription polymerase chain reaction(RT-PCR) was performed to determine the expression of mRNA of bone matrix protein at 8 hours, 1 day and 7 days. The ability to produce mineralized nodules in rat osteoblasts(MC3T3-E1) was evaluated at 21 days. The results were as follows : 1. rhBMP-2 or mixture of rhBMP-2 and delta12-PGJ2 inhibited cell proliferation of human osteosarcoma cells. 2. rhBMP-2 or mixture of rhBMP-2 and delta12-PGJ2 stimulated alkaline phosphatase activity significantly higher than delta12-PGJ2 alone. 3. rhBMP-2 or mixture of rhBMP-2 and delta12-PGJ2 stimulated mineralization compared to delta12-PGJ2 alone. 4. mRNA of alkaline phosphatase, BMP-2, cbfa 1, Type I collagen were detected in the group treated with delta12-PGJ2/rhBMP-2, rhBMP-2 alone, delta12-PGJ2 alone. These results show that mixture of delta12-PGJ2 and rhBMP-2 causes more bone formation than delta12-PGJ2 alone while the bone formation effects of mixture of delta12-PGJ2 and rhBMP-2 are less than those of rhBMP-2 alone. Further researches would be necessary to clarify the interactions of these agents.