EFFECT OF A DERIVATIZED DEXTRAN ON HUMAN OSTEOBLAST GROWTH AND PHENOTYPE EXPRESSION

Water soluble derivatized dextran named E9 with a molecular weight of 45 000 g l-1 containing 58% methyl carboxylic acid unit, 19% benzylami de unit, and 26% sulfonate with a specific anticoagulant activity of 0 .29 IU m g-1 was studied for its effects on human osteoblast growth an d phenotype expression for short-term treatment. At concentrations bet ween 1 ng ml-1 and 1 mug ml-1 E9 has no effect on DNA synthesis wherea s at higher concentrations DNA synthesis is inhibited in a dose relate d fashion (87% for 400 mg ml-1). For concentrations which do not modif y osteoblast growth, E9 promotes alkaline phosphatase activity, type I collagen and osteocalcin synthesis with a maximum effect for 0.1-1 mu g ml-1. It has a synergistic effect with hPTH increasing AMPc. Moreove r, osteonectin synthesis was enhanced in a dose-dependent manner betwe en 0.1 and 5 mug ml-1. These results seem to indicate that E9 is able to stimulate human osteoblast phenotype expression and could be useful in clinical applications.