Nephron endowment assessment in pre-transplantation kidneys using a digital histomorphometric approach

Introduction Kidney function largely depends on nephron number. However, the role of (donor’s) nephron endowment (NE) has been poorly investigated in kidney transplantation (KTx) probably because technically difficult and no reliable surrogate markers exists. The aim of this study was developing an easy and reliable algorithm for computation of NE in kidneys addressed to KTx. Materials and methods Fourty-one kidneys removed from 26 brain-dead donors (12 female, mean age of 62.6 years) were analyzed. Computed tomography was performed on kidneys to stereologically compute the cortical volume. Tissue sections from 6 standardized areas of each kidney were harvested and processed for histomorphometry. On each section stereological method was employed to evaluate glomerular density (GD), size and volume. NE was computed for each kidney by multiplying the cortical volume for GD and dividing by the average glomerular volume. Number of functional (FG) and atrophic (AG) glomeruli was also assessed. Results Mean volume of the cortical portion was 48.2cm3±17.7. Glomeruli represented 9.53%±2.19 of cortex. Mean glomerular volume was 5.75E-6±2.04E-06 cm3. Glomerular number was: 858,550±373,245 (NE), 650,606±310,400 (FG) and 207,944±99,837 (AG). GD was higher at the upper pole compared to medium and inferior areas but no significantly. Conclusions Nephron count is feasible with relatively limited resources by measuring GD in a single spot and applying the algorithm we have developed. The integration of traditional pathology with cutting-edge digital technologies and bioinformatics is a reproducible promising tool for diagnostics also in the area of KTx towards a better understanding of the mechanisms influencing the outcome