Morphological methods to evaluate protective agents against aminoglycoside-induced nephrotoxicity

*Corresponding author: Sandra Rodríguez Salgueiro, Electron Microscopy Laboratory, National Center for Scientific Research, Cubanacán, Havana, Cuba. E-mail: [email protected] Aminoglycosides are a family of antibiotics widely used in clinical practice. Their prescription is restricted by cytotoxicity and accumulation of antibiotic in renal tissues (1). Although renal damage induced by aminoglycosides is reversible, because the high regenerative capacity of tubular cells, it induces morbidity and sometimes is the cause of renal failure (2). Since aminoglycoside nephrotoxicity affects to 1025% of patients during treatment (3), preservation of renal function during critical life-saving treatments is a problem that needs to be solved (4). Moreover, acute renal damage induced by aminoglycosides may compromise the patient’s life and may progress to chronic renal disease in survivors (5). Aminoglycosides primarily affect epithelial cells of proximal tubules (6) and subsequently the interstitium (7) and glomeruli (8). Several studies have been performed to prevent aminoglycoside-induced renal damage in animal models (9-11). Histological evaluation of the kidneys is commonly made in these studies. Usually, qualitative descriptions of renal morphology using mainly hematoxylin and eosin (H&E) stained paraffin sections have been reported by scoring renal damage. Moreover, most of these morphological assessments are focused on tubular and interstitial effects of aminoglycosides (12-18). Some authors have also paid attention to glomerular effects (19,20). Up to now, only few groups have accomplished more accurate tools to evaluate renal morphology. Our group has developed a semi-quantitative method which validates tubular and glomerular conditions using periodic acid Schiff (PAS) stained kidney sections. Quantification of glomerular and tubular damage is carried out by means of a program developed for .Net platform, using the integrated development environment Visual Studio 2008 and c# language, whereby the normal condition of each variable is classified as 0 and the pathological condition is considered 1. For each variable the percentage of damaged tubules or glomeruli per histological field is calculated, by means of this program. Using this method, we have evaluated some cytoprotective treatments against kanamycin nephrotoxicity in rodents (21,22). On the other hand, Tavafi et al., have studied the volume density of proximal convoluted tubules per cortex and the glomerular volume per kidney, using stereological techniques in PAS stained kidney sections of rats treated with cytoprotective extracts and gentamicin (23,24). Interestingly, the group of Stojiljkovic et al., has Sandra Rodríguez Salgueiro1*, Lucía González Núñez2