A Liquid-Based Cytology System, without the Use of Cytocentrifugation, for Detection of Podocytes in Urine Samples of Patients with Diabetic Nephropathy

Abstract

Objective. Podocytes have highly differentiated functions and are extremely difficult to grow; thus, damage of podocytes is associated with glomerular dysfunction. Desquamated podocytes can be detected in urine of patients with severe renal impairment. Unlike the rapidly progressive glomerular damage in glomerulonephritis, only a few desquamated podocytes are usually detected in diabetic nephropathy (DN). It is not clear whether the low podocyte count in DN is due to limitation of the conventional method or true pathological feature. The aim of this study was to compare the conventional method with a newly modified method in detecting podocytes in morning urine samples of patients with DN. Materials and Methods. The study subjects were patients with type 2 diabetes. Urine samples from these patients were analyzed by the conventional method (Cytospin®) and the modified method (SurePath™). We determined the rate of detection of urinary podocytes and the number of detected cells. Results. The detection rate and podocyte count were significantly higher by the modified method than by the conventional method. The differences in the detection rates and numbers of podocytes were not significant between patients with normoalbuminuria and those with macroalbuminuria. However, they were significant in patients with microalbuminuria. The number of podocytes in the urine correlated significantly with the albumin-to-creatinine ratio, but not with the estimated glomerular filtration rate. Conclusions. The true number of urinary podocytes, as measured by the modified SurePath™-based method, in patients with DN is much higher than that estimated by the conventional method.

Urine-Derived Epithelial Cells as Models for Genetic Kidney Diseases

“…These methods are widely used in detecting urinary epithelial cells [43][44][45][46] and are considered the "gold standard" because of the highly specific interactions between the protein of interest and the targeted antibody, and also their ability to detect a very low amount of proteins. Although these colorimetric methods are widely used, they still come with some limitations, including unspecific binding as urine can contain several proteins, exosomes or extracellular vesicles and cell debris, thereby leading to examiner errors/bias [37]. Another major drawback of this technique is the production of antibodies which are usually cost and time consuming and the lack of commercially available antibodies for all isoforms of the protein, as in the case of podocin.…”

“…The general principle of quantifying urine-derived kidney epithelial cells is based on the identification of genes and proteins specific to these cells in fresh urine samples. These specific genes and proteins are mainly podocalyxin, nephrin, podocin and synaptopodin, which are markers of podocytes and aquaporin-1, megalin, cubilin and CD13, the markers of PTECs [6,25,[36][37][38][39].…”

“…There are several methods used for the quantification of urine-derived epithelial cells. These methods include: colorimetric quantitative methods [6,37], flow cytometry [36], Western Blot [25], mass spectrometry [40] and quantitative real-time polymerase chain reaction (qRT-PCR) [25,38].…”

Research progress in acute hypertensive renal injury by “in vivo cryotechnique”

“…In fact, podocyte injury and loss has been proved to be causally related to glomerulosclerosis in a variety of kidney diseases such as diabetic nephropathy, focal segmental glomerulosclerosis and minimal change disease. [9][10][11][12] The research on the pathogenesis of podocyte injury mainly focuses on the cytoskeletal abnormality of podocytes, oxidative stress, mitochondrial dysfunction, abnormal autophagy, and apoptosis. [13][14][15] The podocyte slit diaphragm (SD) complex is located in the adjacent foot processes, and it is an important structure for sensing extracellular stimulation and introducing extracellular biochemical signals into the cell.…”

Corrigendum to “A Liquid-Based Cytology System, without the Use of Cytocentrifugation, for Detection of Podocytes in Urine Samples of Patients with Diabetic Nephropathy”

“…In the article titled "A Liquid-Based Cytology System, without the Use of Cytocentrifugation, for Detection of Podocytes in Urine Samples of Patients with Diabetic Nephropathy" [1], the authors would like to clarify why the SurePath™ method was used in urine from diabetic nephropathy patients. The following text should be replaced with the addition of two missing references, 26 and 27 [2,3]:…”