miRNA Profılıng of Cerebrospınal Fluıd: Isolatıon Method Matters
Introduction: micro RNA expression profiles of bodily fluids are exploited for the discovery of biomarkers implicating the
importance of microRNA extraction techniques. Cerebrospinal fluid (CSF) is a mirror of central nervous system and has
been interrogated for identification of biomarkers of neurodegenerative diseases, cancer and traumatic brain injury.
However, there is poor correlation between different reports indicating interlaboratory differences and the need to
standardize miRNA isolation method for CSF.
Methods:RNA isolation methods can be broadly classified as phenol-based and phenol-free techniques. Two commonly
used RNA isolation kits from both categories were compared for their efficiency to isolate miRNAs from CSF. CSF was
collected from healthy pregnant women between the age of 20 – 29 years old and 30 – 39 years old. miRNA profiles of
young and old pregnant women were analysed for miRNA differences using aforementioned RNA isolation methods.
Microfluidic gene expression system was used to identify differential miRNAs.
Results:Phenol-based technique was performant over the phenol-free technique. Out of seventy seven miRNAs, none was
found significant in the case of phenol-free method. However, two miRNAs were found significantly altered in phenol-based
Conclusion: The choice of RNA isolation method is critical in order to avoid masking effects due to the poor techniques
employed by the commercially available kits. In our hands, phenol-based technique allowed identification of age related
miRNA differences in the CSF of a healthy cohort of pregnant women. Therefore, for miRNA expression studies in bodily
fluids like CSF, phenol-based RNA isolation methods are recommended.
Keywords- Cerebrospinal fluid, RNA isolation, micro RNA, aging