Intra-renal and urinary mRNA expression of podocyte-associated molecules for the estimation of glomerular podocyte loss

Background: Podocyte loss plays an important role in the pathogenesis of diabetic nephropathy, but counting the number of glomerular podocyte in renal biopsy specimen is a labor-intensive task. We study whether intra-renal and urinary messenger RNA expression of podocyte-associated molecules could be used to estimate glomerular podocyte number in patients with diabetic nephropathy. Method: We studied 21 consecutive patients with biopsy-proven diabetic nephropathy. The intra-renal and urinary mRNA expression of nephrin, podocin, and synaptopodin were measured by real-time quantitative polymerase chain reaction. Podocyte number was determined in micro-dissected glomerulus. The degree of histological scarring was quantified by morphometric analysis. Results: Glomerular podocyte number correlated with intra-renal expression of nephrin (r = 0.510, p = 0.044), podocin (r = 0.605, p = 0.013), and synaptopodin (r = 0.480, p = 0.060). Glomerular podocyte number also significantly correlated with urinary expression...