Characteristics of long-term human epithelial cell cultures derived from normal human fetal kidney.

Epithelial cell cultures were prepared from normal human fetal kidney and established in long-term culture. The growth characteristics and production of keratin, and alkaline phosphatase (AP) and gamma-glutamyl transpeptidase (GGT) activities were compared in a modified minimal essential medium (mMEM), D-valine-containing modified alpha-MEM (mALPHA) and L-valine mALPHA. The mean number of cumulative population doublings (CPDL) was significantly (P less than 0.001) enhanced with the L-valine mALPHA (40.8 CPDL) over that achievable in mMEM (14.2 CPDL) or D-valine mALPHA (18.3 CPDL) media. In all three media, greater than 95% of the cells in culture produced keratin throughout the life span of these cultures. Surface-associated fibronectin was absent in these cell cultures. AP and GGT activities increased as a function of subpassage and time in culture, with the greatest activity in the L-valine mALPHA. The expression of these renal cell-associated functions suggests that these cells in culture are proximal tubule epithelial cells. The conditions and procedures described in this paper can provide a human kidney epithelial cell culture system for studying human renal function, metabolism, cytotoxicity, genotoxicity, and transformation.