Paracrine stimulation of preadipocyte-enriched cell cultures by mature adipocytes.

We developed a double-chamber system in which to examine the effects of mature adipocytes on the growth and differentiation of preadipocytes and other cells in the adipose tissue. In the present study we found that mature adipocytes from both lean and obese subjects release a factor that stimulates the growth of preadipocyte-enriched and dedifferentiated adipocyte-enriched cell cultures. This growth stimulation was dependent on both time of exposure to mature cells and the number of mature cells in the coculture. Proliferation of the preadipocyte-enriched (n = 4) and dedifferentiated adipocyte-enriched cultures (n = 5) in the presence of mature adipocytes from obese subjects [body mass index (BMI) > 35] was 4.1- and 2.9-fold more (P < 0.05) than that in the presence of adipocytes from lean subjects (BMI < or = 25). There was no difference in the growth of cultures enriched in preadipocytes or dedifferentiated adipocytes from lean or obese subjects in the absence of mature adipocytes. These observations demonstrate that mature adipocytes from obese patients stimulate the growth of preadipocyte-enriched cultures to a greater extent than those from lean individuals.