INTRODUCTION. Subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) are associated with different clinical outcome and possibly different miRNA profile in cerebrospinal fluid (CSF) and plasma (PL). MicroRNAs (miRNAs) are key post-transcriptional regulators of gene expression. Recent investigations evaluating the role of miRNAs in the pathophysiology of cerebral injury have suggested that miRNAs profile change in relation to cerebrovascular diseases such as ischemic and hemorrhagic stroke. Some miRNAs appear differentially expressed in the CSF as compared to blood in ICH patients. The relationship between circulating miRNA in  spontaneous ICH and SAH is not well understood. We aim to determine the difference in miRNA expression profile in CSF and blood (plasma) of patients with acute spontaneous ICH and SAH.  
METHODS. After informed consent, whole blood and CSF were collected from ICH and SAH patients (n=3 each) with 48 hrs.  Non-ICH/SAH plasma and CSF controls (Cont, n=3 each) were also processed. Total RNA containing small RNA were isolated from a 200 ul sample and used for small library construction and sequencing and analyzed for differentially expression (p<0.05) using the Ballgown Rpackage. Gene set enrichment analysis of KEGG pathways and Gene Ontology (GO) were done in miRWalk (p<0.01).
RESULTS. In CSF, 21 known and 4 novel miRNA highly expressed in the controls but reduced in SAH and ICH were identified (Table 1; Figure 1).  In plasma, 11 miRNA were downregulated in SAH and ICH compared to control.  In CSF of SAH vs ICH, 5 miRNA were found at higher levels in SAH than ICH. In plasma, only 1 significant miRNA was identified.  Pathway enrichment analysis found axon guidance for upregulated miRNA and cell adhesion for downregulated miRNA in SAH and ICH CSF. In plasma, enrichment for Ras signaling, axon guidance platelet activation, and hemophilic cell adhesion were found. 
CONCLUSION. Expression of these miRNA or lack thereof may serve as potential biomarkers for ICH and SAH pathogenesis and may be helpful for future therapeutic applications

Plasma and Cerebrospinal Fluid miRNA Biomarkers and Regulated Pathways in Intracerebral and Subarachnoid Hemorrhage