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Updated: Mar 25, 2026
High Throughput MicroRNA Profiling: Optimized Multiplex qRT-PCR at Nanoliter Scale on the Fluidigm Dynamic ArrayTM IFCs
Published on: August 3, 2011
Protocol for miRNA isolation from biofluids
Evgeny A Lekchnov1, Ivan A Zaporozhchenko2, Evgeny S Morozkin2
1Institute of Chemical Biology and Fundamental Medicine of SB RAS, Novosibirsk 630090, Russia.
Abstract:
MicroRNAs (miRNAs) have been identified as promising biomarkers in cancer and other diseases. Packaging of miRNAs into vesicles and complexes with proteins ensures their stability in biological fluids but also complicates their isolation. Conventional protocols used to isolate cell-free RNA are generally successful in overcoming these difficulties; however, they are costly, labor-intensive, or heavily reliant on the use of hazardous chemicals. Here we describe a protocol that is suitable for isolating miRNAs from biofluids, including blood plasma and urine. The protocol is based on precipitation of proteins, denaturation of miRNA-containing complexes with octanoic acid and guanidine isothiocyanate, and subsequent purification of miRNA on spin columns. The efficacy of miRNA extraction by phenol-chloroform extraction, miRCURY RNA isolation kit--biofluids (Exiqon), and the proposed protocol was compared by quantitative reverse-transcription PCR of miR-16 and miR-126. The proposed protocol was slightly more effective for isolating miRNA from plasma and significantly superior to the other two methods for miRNA isolation from urine. Spectrophotometry and SDS-PAGE data suggest that the disparity in performance between miRCURY Biofluids and the proposed protocol can be attributed to differences in precipitation mechanisms, as confirmed by the retention of different proteins in the supernatant.
Insights
This study presents a novel, cost-effective protocol for isolating microRNAs (miRNAs) from biofluids like blood plasma and urine. The new method is more effective than existing techniques, especially for urine samples, offering a simpler alternative for biomarker research.
Area of Science:
- Biochemistry
- Molecular Biology
- Biomarker Discovery
Background:
- MicroRNAs (miRNAs) are crucial biomarkers for diseases, but their isolation from biofluids is challenging due to protective packaging.
- Existing cell-free RNA isolation methods are often expensive, labor-intensive, or use hazardous chemicals.
Purpose of the Study:
- To develop and validate a new, efficient protocol for isolating miRNAs from biofluids such as blood plasma and urine.
- To compare the efficacy of the proposed protocol against conventional methods.
Main Methods:
- The protocol involves protein precipitation, denaturation of miRNA complexes using octanoic acid and guanidine isothiocyanate, and purification using spin columns.
- Quantitative reverse-transcription PCR (qRT-PCR) was used to assess miRNA extraction efficiency for miR-16 and miR-126.
- Spectrophotometry and SDS-PAGE were employed to analyze protein content and compare precipitation mechanisms.
Main Results:
- The proposed protocol demonstrated slightly higher miRNA isolation efficiency from plasma compared to phenol-chloroform extraction and the miRCURY RNA isolation kit.
- The new protocol was significantly more effective for miRNA isolation from urine than the other two tested methods.
- Differences in protein precipitation mechanisms likely explain the performance variations observed between the methods.
Conclusions:
- The developed protocol offers an effective and potentially more accessible method for miRNA isolation from biofluids, particularly urine.
- This improved isolation technique can facilitate advancements in miRNA-based diagnostics and research.
- The findings highlight the importance of considering protein precipitation mechanisms in miRNA isolation strategies.
