Abstract
The purpose of this investigation was to reveal the physiological bone remodeling mechanism by means of cellular interaction phenomenon between osteoblasts (OB) and bone marrow cells (BM) in vitro. When OB (1×105 cells) originated from newborn mouse calvaria and BM (1×106 cells) obtained from 4 weeks old mouse long bones were co-cultivated by using millicell as a separator in a CO2 incubator for 14 days, the number of BM was increased and the markedly high incorporation of 3H-thymidine into the cellular DNA of BM was recognized after 3 days incubation. However, the number of BM and uptake of 3H-thymidine into BM did not increase in only the BM cultivation. The increased BM were identified to have surface antigens of Mac-1 and LFA-1 by FACS analysis. However, ALPase activity of OB co-cultivated with BM was remarkably suppressed after 3 days incubation and reduced to one half of that of the control after 5 days incubation. These results clearly indicate that both OB and BM produced some differential factors of the clonal growth of Mac-1 and LFA-1 positive cells from BM cells and the suppression of ALPase of OB in co-cultivation with OB and BM. It is suggested that the factors produced from the interaction between OB and BM might regulate the mechanism of physiological bone remodeling.
