Epidermal growth factor enhances renal tubule cell regeneration and repair and accelerates the recovery of renal function in postischemic acute renal failure.

Abstract

To determine the timing and location of renal cell regeneration after ischemic injury to the kidney and to assess whether exogenous epidermal growth factor (EGF) enhances this regenerative repair process to accelerate recovery of renal function, experiments were undertaken in rats undergoing 30 min of bilateral renal artery clamp ischemia followed by reperfusion for varying time intervals. Renal cell regeneration, as reflected by incorporation of radiolabeled thymidine within the kidney, began between 24 to 48 h and reached a peak at 72 h after renal ischemia. As demonstrated by histoautoradiography, renal thymidine incorporation was essentially confined to tubule cells. After the rats were killed by decapitation and exsanguination, the kidneys were quickly removed and cut longitudinally. Portions (100 mg) of the kidney were placed in cryogenic tubes and snap-frozen in liquid nitrogen. Samples were stored at -20 to -70'C for a maximum of 6 d before processing. Tissue samples were homogenized in ice-cold distilled water using a tissumizer (Tekmar Co., Cincinnati, OH). DNA was purified from 1.0 ml of homogenate. To obtain a complete time course, some animals were allowed to recover for 7 d after renal ischemia and blood samples were then obtained daily for BUN or serum creatinine measurements. Radioactivity was measured on 0.5 ml of sample in 20 ml of Safety-Solve (Research Products International Corp., Mt. Prospect, IL) in a scintillation counter (model 9000; Beckman Instruments, Inc., Fullerton, CA). Counting efficiency was estimated by an internal standard. Serum samples were counted to assure consistent intraperitoneal absorption of the [3H]thymidine. Samples of the DNA extract were counted and corrected for sample DNA content.To localize and identify the cells incorporating the radiolabeled thymidine within the kidney, histoautoradiography of kidney samples was also accomplished using methods previously published from this laboratory (5). Kidneys were perfused in vivo with 2% glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.2). Tissue sections from kidneys were placed in 4% formaldehyde, 1% glutaraldehyde, 100 mM phosphate buffer (7.2). Specimens were dehydrated and embedded in methacrylate. Tissue sections (4 ,m) were dipped in NBT-2 nuclear emulsion (Eastman Kodak Co., Rochester, NY) and stored in the dark at 4°C for 21 d. The sections were developed and counterstained with Lee's methylene blue-basic fuchsin. For quantitative evaluation, a computerized operator-interactive system was used as described previously (5). Sections were examined at 176 magnification, and 10-15 fields were counted in the cortex and outer and inner stripes of the outer medulla in each section for an individual animal. The cell type of the labeled cells was identified as either tubular or interstitial.For the experiments that used EGF, rats were administered EGF (20 ,ug) subcutaneously 1-1.5 h after surgery. This dose of EGF is substantially lower than those employed in previously reported studies that administered EGF...

Increased epidermal growth factor in experimental diabetes related kidney growth in rats

“…For instance, the renal growth that follows unilateral nephrectomy is associated with increased renal EGF [11,10] and the associated tubular cell hyperplasia can be reduced by the administration of anti-EGF antibodies [28]. In acute tubular necrosis following ischaemic injury [29,30] or mercuric chloride toxicity exogenously administered EGF accelerates tubular regeneration and recovery. The factors responsible for increased EGF during early diabetes remain speculative.…”

The Membrane-bound Form of Heparin-binding Epidermal Growth Factor-like Growth Factor Promotes Survival of Cultured Renal Epithelial Cells

“…Accumulating evidence indicates that locally produced growth factors may serve as mediators of regeneration of renal epithelial cells following acute injuries (1,2,7). Specifically, previous studies have suggested that EGF, 1 or members of the EGF growth factor family, may play an important role in repair of renal injury (8,9). After either ischemic tubular injury or folic acid nephropathy, EGF receptor density increases (10 -12), and subcutaneous injection of EGF or TGF-␣ significantly accelerates [ 3 H]thymidine incorporation and recovery of epithelial cell function (8 -11, 13, 14).…”

Effects of Low Protein Intake on the Development of the Remaining Kidney in Subtotally Nephrectomized Immature Rats: Apoptosis and Epidermal Growth Factor

“…This finding indicates that EGF is involved in improving effects of protein restriction on renal failure. This notion is supported by reports that chronic renal failure caused by 5/6 nephrectomy is improved by extrinsic EGF [14] and that EGF accelerates regeneration of tubular cells and ameliorates renal failure [7].…”