Growth factor requirements of organogenesis in serum-free metanephric organ culture

In order to define humoral growth factors which may regulate mammalian renal development, the growth requirements of fetal metanephric organogenesis were studied in serum-free murine organ culture. Metanephric growth, determined by cell proliferation and protein content, and metanephric differentiation, determined morphometrically as epithelial glomerular formation, were compared and contrasted following 144 hours of organ culture incubation in basal medium, basal medium supplemented with 10% fetal bovine serum, and basal medium supplemented with various combinations of growth factors. The basal medium was composed of equal volumes of Dulbecco's modified Eagle's medium and Ham's F-12 medium. Five humoral growth factors were studied in the following concentrations: selenium, 6.8 X 10(-9) M; insulin, 8.3 X 10(-7) M; triiodothyronine, 2 X 10(-9) M; transferrin, 6.2 X 10(-8) M; and prostaglandin E1, 7.1 X 10(-8) M. Results showed that transferrin and prostaglandin E1 were necessary for optimal growth in the system and that prostaglandin E1 was necessary for maximal metanephric differentiation. Such data provide guidelines for the creation of serum-free medium for future fetal renal cell and tissue culture systems, and provide insight into the factors which may regulate normal and abnormal renal embryogenesis and the reparative processes of renal hyperplasia and hypertrophy which follow renal injury.