PARACRINE STIMULATION OF PREADIPOCYTE-ENRICHED CELL-CULTURES BY MATURE ADIPOCYTES

We developed a double-chamber system in which to examine the effects o f 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 fac tor that stimulates the growth of preadipocyte-enriched and dedifferen tiated adipocyte-enriched cell cultures. This growth stimulation was d ependent on both time of exposure to mature cells and the number of ma ture cells in the coculture. Proliferation of the preadipocyte-enriche d (n=4) and dedifferentiated adipocyte-enriched cultures (n=5) in the presence of mature adipocytes from obese subjects [body mass index (BM I)>35] was 4.1- and 2.9-fold more (P<0.05) than that in the presence o f adipocytes from lean subjects (BMI less than or equal to 25). There was no difference in the growth of cultures enriched in preadipocytes or dedifferentiated adipocytes from lean or obese subjects in the abse nce of mature adipocytes. These observations demonstrate that mature a dipocytes from obese patients stimulate the growth of preadipocyte-enr iched cultures to a greater extent than those from lean individuals.