Proliferation and differentiation in primary cultures of stromal-vascular cells and of pre-adipocytes from Large White and Piétrain pigs¹

SUMMARY: A comparison was made between the effects of 3.5% porcine serum and serum-free hormone-supplemented media (5 nM insulin-like growth factor 1 (IGF-1), 5 ng/ml insulin, 2 nM triiodothyronime (T₃), 5 ng/ml insulin + 2 nM T₃) on proliferation, differentiation, and lipolysis in a primary culture of stromal-vascular cells and of pre-adipocytes from subcutaneous adipose tissue of newborn Large White and Piétrain pigs. The effects on cell proliferation were measured by ³H-thymidine incorporation into stromal-vascular cells and pre-adipocytes and by soluble-protein content. Proliferation in serum-containing culture was much higher in both breeds. Large White pigs had a higher capacity for cell growth in medium supplemented with 3.5% porcine serum compared with Piétrain pigs. Parameters of cell differentiation were represented by the specific activities of α-glycerol-3-phosphate dehydrogenase, malic enzyme, and ATP-citrate lyase. Adipose conversion in serum-containing culture was lower in both breeds. Large White and Piétrain pigs had similar lipogenic capacities under serum-containing or serum-free conditions. Apart from the specific activity of α-glycerol-3-phosphate dehydrogenase, no significant effects of the tested growth factors could be found. In serum-containing culture, the specific activity of an α-glycerol-3-phosphate dehydrogenase was lower for control, IGF-1, and T₃ treatments in both breeds. Insulin and insulin + T₃ treatment in serum-supplemented medium led to the same enzyme activity as the values in serum-free medium. Another criterion for differentiation is lipolysis, which is measured by cellular-, basal-or hormonal-induced glycerol release into the medium. Piétrain pigs compared with Large White pigs showed a higher basal glycerol release in culture supplemented with 3.5% porcine serum, but the same basal glycerol release in serum-free culture. Adrenaline-induced glycerol release was higher under serum-free conditions for both breeds.