Nephrotoxicant inhibition of renal proximal tubule cell regeneration

Abstract

Although nephrotoxicants have been shown to have direct lethal effects on renal proximal tubule cells (RPTC), little is known concerning their effects on the renal regenerative process. Additionally, the mechanisms of RPT regeneration are still not clear. To examine these issues, an in vitro model of mechanically induced injury to primary cultures of rabbit RPTC was developed, and the effects of epidermal growth factor (EGF), transforming growth factor-beta 1 (TGF-beta 1), and nephrotoxicants on the regenerative process were examined. Experiments demonstrated that confluent monolayers swiped with a 4-mm Teflon policeman regenerated with 77% closure of the swipe in 7 days. DNA content in swiped monolayers increased, reached a maximum on day 3 (1.4-fold), and remained constant through day 7. EGF accelerated regeneration and resulted in 96% swipe closure on day 7 and increased DNA content 2.3-fold. TGF-beta 1 inhibited regeneration and resulted in 22% swipe closure on day 7 but did not inhibit the increase in DNA content. 5-Fluorouracil inhibited regeneration and resulted in 27% swipe closure on day 3, compared with 46% in the controls, and inhibited the increase in DNA content. Mercuric chloride, fumonisin B1, and dichlorovinyl-L-cysteine, at concentrations < or = 50% of their lethal concentration, inhibited regeneration and resulted in swiped areas 3.7, 4.2, and 2.1 times larger, respectively, than controls on day 7. At concentrations < or = 50% of its lethal concentration, tert-butylhydroperoxide had no effect on swipe closure.(ABSTRACT TRUNCATED AT 250 WORDS)