Stability of selected microRNAs in human blood, semen and saliva samples exposed to different environmental conditions

Body fluid identification is an essential aspect of forensic investigations. MicroRNAs (miRNAs), a type of non-coding RNA has a lot of potential in forensic studies as biomarkers. Using a reference gene - GAPDH, this study ascertained the stability of hsa-mir-451a, hsa-miR-10b, and hsa-miR-205 in blood, semen and saliva respectively, exposed to different environmental conditions over different periods of time. Twenty adult males aged 20–35 donated blood, sperm, and saliva. These fluids were separated into four groups and exposed to Outdoor, Indoor, Fridge, and Freezer conditions for 37 days. Total RNA was isolated using Trizol-Isopropanol extraction protocol. FIREScript RT cDNA synthesis kit and Luna Universal qPCR Master Mix were used for cDNA synthesis and qPCR respectively. Under different environmental conditions, miR-451a and miR-10b was detected in all blood and semen samples but not in all saliva samples. Pearson's correlation test for Cq values showed multiple strong correlations (p < 0.05) within and outside the groups compared to GADPH. Regardless of the body fluid sample, the freezer group was more stable compared to other groups, although correlations are not homogeneous in all samples. Expression of the targeted genes in the body fluids showed that hsa-miR-451a, hsa-miR-10b, hsa-miR-205 could be utilized as biomarkers in forensics for body fluids identification.