bFGF induces an earlier expression of nephrogenic proteins after ischemic acute renal failure

Abstract

Recovery from acute renal failure (ARF) requires the replacement of injured cells with new cells that restore tubule epithelial integrity. We described recently the expression of a wide range of nephrogenic proteins in tubular cells after ARF induced by ischemia-reperfusion (I/R) (Villanueva S, Cespedes C, and Vio CP. Am J Physiol Regul Integr Comp Physiol 290: R861-R870, 2006). These markers, namely, Vimentin, neural cell adhesion molecules (Ncam), basic fibroblast growth factor (bFGF), paired homeobox-2 (Pax-2), bone morphogene protein-7 (BMP-7), Noggin, Lim-1, Engrailed, Smad, phospho-Smad, hypoxia-induced factor-1alpha (HIF-1alpha), VEGF, and Tie-2, are expressed in a time frame similar to that observed in normal kidney development. bFGF participates in early kidney development as a morphogen involved in mesenchyme/epithelial transition, and it is reexpressed in the recovery phase of ARF. To test the hypothesis that bFGF can accelerate the regeneration after renal damage, we used recombinant bFGF and studied the expression pattern of the above described morphogens in ARF. Male Sprague-Dawley rats were subjected to 30 min of renal ischemic injury and were injected with bFGF 30 microg/kg followed by reperfusion. Rats were killed and the expression of nephrogenic proteins were analyzed by immunohistochemistry and Western blot analysis. In the animals subjected to I/R treated with bFGF, we observed a 12- to 24-h earlier and more abundant reexpression of the proteins Ncam, bFGF, Pax-2, BMP-7, Noggin, Lim-1, Engrailed, VEGF, and Tie-2 than the I/R untreated rats. In addition, we observed a reduction in renal damage markers ED-1 and alpha-smooth muscle actin. These results indicate that bFGF can participate in the regeneration process and suggest that the treatment with bFGF can induce an earlier regeneration process after ischemic acute renal failure.

Enhancement of in vitro human tubulogenesis by endothelial cell-derived factors: implications for in vivo tubular regeneration after injury

“…PDGF-B plays an important role in the regeneration of tubular cells from acute ischemic injury (24). bFGF, which is produced by capillary endothelial cells (22,29), participates in the recovery process after renal ischemia (32,33). However, these factors could not reproduce the stimulatory effect of coculture with HUVEC (Fig.…”

Cyclooxygenase-2 and hypoxia-regulated proteins are modulated by basic fibroblast growth factor in acute renal failure

“…Immunolocalization studies were performed using an indirect immunoperoxidase technique (Villanueva et al, 2006a). Briefl y, tissue sections were dewaxed, rehydrated, rinsed in 0.05 M tris-phosphate-saline (TPS) buffer (pH 7.6) and incubated with the primary antibody overnight at 22°C.…”

“…The protein concentration was determined by the method of Bradford (Bio-Rad, Richmond, CA). Western blotting was performed as previously described (Villanueva et al, 2006a). Briefl y, sixty micrograms of protein were mixed with an equal volume of SDS-PAGE sample buffer (100 mM tris-HCl, pH 6.8, 200 mM dithiothreitol, 4% SDS, 0.2% bromophenol blue, 20% glycerol).…”

“…The immunoreactive area in each fi eld (whole kidney sections) was determined by image analysis using Simple PCI software (Compix). Total immunostained (brown) cells were averaged and expressed as the mean absolute values or the mean percentage of stained cell area per fi eld, as previously described (Villanueva et al, 2006a) with minor modifi cations.…”

“…Furthermore, basic-FGF (FGF-2) has been postulated to be involved in epithelialmesenchymal transition and early tubulogenesis (Perantoni et al, 1995). Using a recombinant protein (r-FGF), we have observed a correlation between the increase of FGF-2 and the increase of some proteins during ATN recovery, which are known to be implicated in kidney development (Villanueva et al, 2006a;Villanueva et al, 2006b, Villanueva et al, 2008. Nevertheless, the complete regenerative responses induced by FGF-2 in experimental I/R cannot be understood based solely on the induction of these proteins.…”