Stimulation of proliferation and differentiation of dog dental pulp cells in serum-free culture medium by insulin-like growth factor

Insulin, insulin-like growth factors (IGF) I and II are considered to play an important part in the growth and differentiation of dental pulp cells. T he present study examined the effects of these factors on pulp cells in ser um-free culture conditions. The DNA content and alkaline phosphatase (ALPas e) activity of dog pulp cells increased when they were cultured in a serum- free medium supplemented with transferrin, yolk lipoprotein and basic fibro blast growth factor (TYF medium). The pulp cells produced type I collagen b ut not type III, suggesting that they might proliferate and differentiate i nto odontoblast-like cells in a serum-free culture. Both IGF-I and IGF-II e nhanced the ALPase activity of pulp cells cultured in TYF medium to an equi valent level, but a higher concentration of IGF-II was necessary to produce a similar effect on DNA synthesis to that of IGF-I. Insulin dose-dependent ly enhanced DNA synthesis and increased ALPase activity, but its effects we re weaker than those of the IGFs. These findings suggest that IGF-I might h ave a primary role in the growth and differentiation of pulp cells. (C) 199 9 Elsevier Science Ltd. All rights reserved.