THE EFFECT OF HYALURONAN ON MOUSE INTRAMEMBRANOUS OSTEOGENESIS IN-VITRO

Hyaluronan (HA) is an almost ubiquitous component of extracellular mat rices. Early in embryogenesis mesenchymal cells migrate, proliferate a nd differentiate, in part, because of the influence of HA. Because man y of the features of embryogenesis are revisited during wound repair, including bone fracture repair, this study was initiated to evaluate w hether HA has an effect on calcification and bone formation in an in v itro system of osteogenesis. Enzyme-digested calvarial mesenchymal cel ls from 13-day-old mouse embryos were cultured in BGJb medium with roo ster comb hyaluronan in seven different molecular weights (30, 40, 90, 160, 550, 660, and 1300 kDa). The dosages for each molecular weight w ere 0.5, 1.0 and 2.0 mg/ml. HA was added once to the medium at the pla ting of cells. After 10 days in culture, with low molecular weight hya luronan (30 and 40 kDa) bone colonies were identifiable on a base of c onfluent fibroblasts. The number of colonies was larger than controls, particularly in the 1.0 and 2.0 mg/ml dosages of both 30 and 40 kDa o f HA. Hyaluronan of high molecular weight, no matter what the dose, sh owed no significant bone colony formation, with apparent cell growth i nhibition. Higher molecular weights were thereafter not included in th is study. No statistically significant difference in the size of colon ies was found when compared to controls in the 30 and 40 kDa bone colo nies no matter what the dose.