Altered expression levels of miRNAs in serum as sensitive biomarkers for early diagnosis of traumatic injury.

MicroRNAs (miRNAs) are small non-coding RNAs of approximately 22 nucleotides in length which regulate gene expression negatively and play important roles in many pathological processes. It has been demonstrated that circulating miRNAs hold promise to serve as practicable molecular markers for diverse physiological and pathological conditions. In this investigation, we chose partial hepatectomy (PH) as traumatic injury model. There were significantly differential expression of miRNAs in rat serum post-traumatic injury (21 miRNAs were more than twofold up-regulated). Especially, the expression of miR-9 showed the highest up-regulated (>70-fold), and it possessed the characteristics of biomarker that was more sensitive than aspartate aminotransferase and alanine aminotransferase and C-reactive protein for traumatic liver injury. There was also a prominent increase in the expression levels of miR-9 in different brain areas after traumatic injury. Our data suggest that serum miR-9 may serve as promising biomarker for traumatic injury with high sensitivity. Furthermore, these findings may help to elucidate the complex network which mediates stress response to traumatic injury.