Nucleic acids within urinary exosomes/microvesicles are potential biomarkers for renal disease

Abstract

Urinary exosomes or microvesicles are being studied intensively to identify potential new biomarkers for renal disease. We sought to identify whether these microvesicles contain nucleic acids. We isolated microvesicles from human urine in the same density range as that previously described for urinary exosomes and found them to have an RNA integrity profile similar to that of kidney tissue, including 18S and 28S rRNA. This profile was better preserved in urinary microvesicles compared with whole cells isolated from urine, suggesting that microvesicles may protect RNA during urine passage. We were able to detect mRNA in the human urinary microvesicles encoding proteins from all regions of the nephron and the collecting duct. Further, to provide a proof of principle, we found that microvesicles isolated from the urine of the V-ATPase B1 subunit knockout mice lacked mRNA of this subunit while containing a normal amount of the B2 subunit and aquaporin 2. The microvesicles were found to be contaminated with extraneous DNA potentially on their surface; therefore, we developed a rapid and reliable means to isolate nucleic acids from within urine microvesicles devoid of this extraneous contamination. Our study provides an experimental strategy for the routine isolation and use of urinary microvesicles as a novel and non-invasive source of nucleic acids to further renal disease biomarker discovery.

Evaluation of MicroRNAs miR-196a, miR-30a-5P, and miR-490 as Biomarkers of Disease Activity among Patients with FSGS

“…Previous studies suggested that urinary miRNAs, like circulating miRNAs in other body fluids, are derived from tissues and cells in the presence of ongoing disease (32,33). In general, cellular miRNAs can passively leak from damaged cells or can be actively secreted into the extracellular space or circulation via the microvesicle pathway (34,35) or within HDL protein complexes (36,37).…”

Extracellular Vesicles in Renal Diseases

“…10,22,23 After these vesicles fuse with the plasma membranes of the parent cell, they are released as exosomes into the extracellular environment ( Figure 1). Interestingly, the lipid-bilayered exosomes seem to be protected from RNAses, 24,25 sheltering the genetic cargo in exosomes. In addition, vesicles can transport biologic cargo to not only neighboring cells but also, relatively long distanced.…”

Renal Allograft Fibrosis: Biology and Therapeutic Targets

“…At the moment, proteomic analyses are not yet feasible for broad clinical application. Analyses of RNAs, in particular microRNAs, might be another potential diagnostic approach (336,415). This approach, either on biopsy tissue or in urine, is emerging as a promising approach for improving the diagnostic and predictive value of rejection, fibrosis development and graft loss in kidney transplantation (416)(417)(418)(419).…”