The concentration of RNA isolated from plasma or serum can vary. For instance, in the study comparing different commercial kits, the concentration of RNA isolated using QIAGEN miRNeasy kits and the Macherey-Nagel NucleoSpin kit generally produced higher RNA yields compared to other kits. The average concentration achieved was around 40 pg/µL or higher, which correlated well with endogenous miRNA levels measured by qRT-PCR [1]. Another study that optimized extraction from larger plasma volumes (9 mL) using the Qiagen miRNeasy Serum/Plasma Kit reported obtaining around 35 ng of total RNA, sufficient for downstream applications like small RNA sequencing [2].

Recommended Protocol

Based on the literature, the following protocol is recommended for RNA isolation from frozen plasma or serum samples using a combination of TRIzol LS reagent and QIAvac24 Plus system for high-volume processing:

Using this protocol, you can expect to obtain RNA concentrations that are suitable for downstream applications such as qRT-PCR and RNA sequencing. This method efficiently isolates RNA even from fragmented and degraded samples, ensuring amplifiable RNA for further analysis [3][4].

Overall, RNA isolation from frozen plasma or serum samples can yield sufficient concentrations for various molecular biology applications, provided that optimized protocols and appropriate kits are used.

[1] Max, K., Bertram, K., Akat, K., Bogardus, K. A., Li, J., Morozov, P., Ben-Dov, I., Li, X., Weiss, Z. R., Azizian, A., Sopeyin, A., Diacovo, T., Adamidi, C., Williams, Z., & Tuschl, T. (2018). Human plasma and serum extracellular small RNA reference profiles and their clinical utility. Proceedings of the National Academy of Sciences of the United States of America, 115, E5334 - E5343.

[2] Danielson, K. M., Rubio, R., Abderazzaq, F., Das, S., & Wang, Y. E. (2017). High Throughput Sequencing of Extracellular RNA from Human Plasma. PLoS ONE, 12.

[3] Cerkovnik, P., Perhavec, A., Zgajnar, J., & Novaković, S. (2007). Optimization of an RNA isolation procedure from plasma samples.. International journal of molecular medicine, 20 3, 293-300 .

[4] Meerson, A., & Ploug, T. (2016). Assessment of six commercial plasma small RNA isolation kits using qRT-PCR and electrophoretic separation: higher recovery of microRNA following ultracentrifugation. Biology Methods & Protocols, 1.