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Nephrotoxicant inhibition of renal proximal tubule cell regeneration
R S Counts1, G Nowak, R D Wyatt
1Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602-7389, USA.
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)
Insights
Nephrotoxicants can impair kidney cell regeneration after injury. This study used an in vitro model to show how growth factors and toxins affect renal proximal tubule cell repair.
Area of Science:
- Nephrology
- Cell Biology
- Toxicology
Background:
- Nephrotoxicants cause direct cell death in renal proximal tubule cells (RPTC).
- The mechanisms governing RPTC regeneration remain unclear.
- Understanding RPTC regeneration is crucial for treating kidney injury.
Purpose of the Study:
- To investigate the effects of growth factors and nephrotoxicants on RPTC regeneration.
- To establish an in vitro model for studying renal regenerative processes.
- To elucidate the mechanisms underlying RPTC repair after injury.
Main Methods:
- Developed an in vitro model using mechanically injured primary rabbit RPTC cultures.
- Assessed regeneration by measuring swipe closure percentage and DNA content.
- Examined the effects of epidermal growth factor (EGF), transforming growth factor-beta 1 (TGF-beta 1), and various nephrotoxicants.
Main Results:
- Mechanical injury induced RPTC regeneration, with 77% swipe closure in 7 days.
- EGF (epidermal growth factor) accelerated regeneration (96% closure), while TGF-beta 1 (transforming growth factor-beta 1) inhibited it (22% closure).
- Nephrotoxicants like 5-fluorouracil, mercuric chloride, fumonisin B1, and dichlorovinyl-L-cysteine significantly inhibited regeneration.
Conclusions:
- EGF promotes RPTC regeneration, whereas TGF-beta 1 and several nephrotoxicants impede this process.
- The study highlights the differential impact of specific compounds on renal cell repair.
- This model provides a valuable tool for evaluating agents affecting kidney regeneration.