We develop at the moment a kit for isolation of miRNA from bodyfluids (samples ca. 1-5 ml) and look for beta tester : ask +49 3641 77 7444 or [email protected] for PME miRNA Kit from Innuscreen.

An important distinction should be made: are you using miRNeasy or are you using miRNeasy Serum/Plasma?

Hi Harris

In fact isolation of RNA from serum/plasma is a tricky bussiness. I am pretty familiar with Exiqon biofluids system and works smoothly in typical samples, unless they are hemolyzed. The aproximate yields vary from 10-50 ng/ul. IMPORTANT: You should use the pico-RNA chip in Bioanalyzer to see something, otherwise you will be in the detection limits of the system.

From CSF, and using the same kit, the yields use to be smaller (around 10 ng/ul). However under these levels, quantification is always very difficult and the results must be taken with caution.

Sometimes, you can have a decreased extraction yield due to insoluble material in your sample. I normally centrifugue the fluid (serum/plasma/CSF) at 10,000 x g during 10 minutes, before the extraction protocol.

Best of luck

Paco

Thank you for the suggestions. We have used the miRNeasy Serum/Plasma extraction kit for biofluids. The rationale for using the small RNA chip was to quantify microRNA concentration, as some papers used it instead of total RNA concentration for reverse transcription. We get in the range of 10-50 ng/ul of total RNA (from serum) when reading on the Nanodrop, less from CSF.

Send an email to one of the authors for more detailed protocols, i.e. perhaps they are loading the column multiple times to increase yield. Sometimes these methods sections are prepared from previous/other papers with lack of oversight for replication.

Slide 44 and onwards may be of interest to you.

https://www.slideshare.net/QIAGENscience/meeting-the-challenges-of-mirna-research-mirna-webinar-series-part-2