Isolation of pepsin-resistant laminin fragments from human placenta: effect on epithelial cells cultured from the kidneys of patients with autosomal dominant polycystic kidney disease (ADPKD).

Laminin isolated from human placenta was subjected to prolonged pepsin digestion. Seven peptide fragments (designated N1 to N7) were separated by ion-exchange chromatography and gel filtration and characterised by SDS-polyacrylamide gel electrophoresis and immunoblotting. The molecular size of the laminin fragments varied from approx. 900,000 (N1) to 28,000 (N7). Epithelial cells obtained from normal kidneys and patients with autosomal dominant polycystic kidney disease (ADPKD) were cultured. The incorporation of [3H]thymidine was measured over 96 h to determine the effect of the addition of the different fragments and whole laminin from EHS tumour to the cells. The rate of growth of both normal and polycystic cells was increased in the presence of the laminin fragments but this effect was more pronounced in the ADPKD cells.