Histological evaluation of proximal tubule cell injury in isolated perfused pig kidneys exposed to cold ischemia

Abstract

Background: Ischemic injury of the renal allograft before transplantation is a major cause of impaired graft function. Proton nuclear spectroscopy provides a useful technique for evaluating proximal tubular activity. In addition to this technique, we proposed a histological grading system for quantifying proximal tubule alterations.

Methods: The aim of this study was to evaluate the histological lesions of tubule epithelial cells in the model of isolated perfused pig kidneys following 48 to 72 h of cold storage in Euro-Collins solution. Normothermic isolated perfused pig kidneys were randomized in three experimental groups : Group 1, control group; cold flush with cold heparinized solution followed by immediate reperfusion (n = 6); Group 2, 48 h of cold storage in Euro-Collins followed by reperfusion (n = 6); Group 3, 72 h of cold storage in Euro-Collins followed by reperfusion (n = 6). Proton nuclear spectroscopy of urine and biochemical studies were performed for whole renal functional evaluation during reperfusion. Optical and electron microscopy analyses of the reperfused kidneys were performed by four investigators and the degree of cell injury was assessed using 8 different criteria in a 5-scale numerical score.

Results: Numerical scores corroborate the results from NMR spectroscopy and differed significantly between the three groups studied. The degree of proximal tubule cell damage was increased with prolonged cold ischemia as shown particularly in Group 3.

Conclusion: The results from this study showed that analysis of cell injury based on an histological grading system in the model of isolated perfused kidney allows the quantification of the degree of proximal tubule injury. Thus, such morphological system analysis could be a useful method for quantifying tubule cell injuries observed under various physiopathological conditions.