Both exosome and microRNAs (miRNAs) in biological fluids can be good biomarkers for pathologic conditions. Thus, urinary exosome miRNAs would be reasonable non-invasive tools for biomarker development for diabetic kidney disease. To be eligible for exosome miRNA biomarker development, the performance of exosome isolation methods for miRNA profiling need to be tested. In the present study, using urine samples from patients with type 2 diabetes, we compared four different exosome isolation methods for their performance in urine exosome isolation and detectable urinary exosome miRNA profiles. Four methods compared in the present study were ultracentrifugation (UC), size exclusion chromatography using qEV column (qEV), ExoQuick-TC (ExoQuick), and Amicon tube 100K (Amicon). Isolated exosomes were subjected to next generation sequencing (NGS) to profile miRNAs. The counts, RNA concentrations, and protein marker expressions of isolated urine exosome were variable between the extraction methods, with the highest exosome count with the qEV method. The number of miRNAs detected (read count ≥1) in 100 mL urine each were 314, 174, 91, and 130 from UC, qEV, ExoQuicK, and Amiconmethods, respectivley. And, 57 miRNAs were detected with all 4 methods concordantly. There were correlations in the levels of exosomal miRNAs between samples from UC, qEV, and ExoQuick methods, whereas exosome miRNA profiles from Amicon sample showed only a weak correlation with those from other methods. Our results suggest that exosome isolation by using UC or qEV method may be a better option among different isolation methods to profile urinary exosome miRNAs in diabetic kidney disease. However, ultrafiltration method using Amicon tube produced a different profile of miRNAs with other methods. Further studies are needed to characterize both exosome and their genetic materials from different extraction sources.
K. Lee: None. D. Lee: None. I. Park: None.
