Hair follicle miRNAs: a novel biomarker for primary blast Induced-Mild traumatic brain injury

Context: Due to the wide use of improvised explosive devices during modern warfare, primary blast-derived mild traumatic brain injury (mTBI) has become a major medical condition in the military. With minimal visually identifiable symptoms, an effective molecular biomarker system is desirable. Objective: We assessed the potential of mammalian hair follicle miRNAs as an mTBI biomarker. Materials and methods: Due to their well-established roles in mTBI molecular pathology, the expression level of miR-183, miR-26a, miR-181c, miR-29a, miR-34a and miR-27b was determined using qRT-PCR in whisker hair follicles from rats subject to head-only exposure to a single-pulse shock wave. Based on established transcriptomics profiles, sub-network enrichment analysis (SNEA) was also conducted. Results: The results revealed that molecular networks involving miR-183, miR-26a and miR-181c were enriched in multiple treatments, whereas sub-networks of miR-29a, miR-34a and miR-27b were unique to individual exposure groups. Discussion: Our study showed that all six miRNAs were reflective of the mTBI signature involved in cellular responses. Noteworthy was that the decrease in the transcript levels of miR-181c was correlated with shockwave exposure severity. Conclusion: This study demonstrates for the first time that mammalian hair follicles are capable of housing miRNA biomarkers for TBI.