Droplet digital polymerase chain reaction-based quantification of circulating microRNAs using small RNA concentration...

Area of Science:

• Biochemistry
• Molecular Biology
• Biomarker Discovery

Background:

• Plasma microRNAs (miRNAs) are promising non-invasive disease biomarkers.
• Technical variability challenges accurate miRNA quantification.
• Rodent plasma presents unique extraction and quantification hurdles.

Purpose of the Study:

• To develop an optimized protocol for miRNA quantification from rodent plasma.
• To compare fixed small RNA concentration input versus fixed RNA volume input for reverse transcription (RT).
• To reduce technical variability in plasma miRNA measurements.

Main Methods:

• Collected plasma from Sprague-Dawley rats.
• Measured plasma hemolysis using spectrophotometers.
• Extracted RNA from varying plasma volumes (50-μl, 100-μl, 200-μl).
• Quantified small RNA concentration using Qubit miRNA assay.
• Performed RT with either fixed RNA volume or fixed small RNA concentration.
• Validated miRNA levels using droplet digital PCR (ddPCR).

Main Results:

• Hemolysis measurements showed strong correlation between spectrophotometers.
• Small RNA concentration increased with larger starting plasma volumes.
• Concentration-normalized RT resulted in normalized miRNA levels across different plasma volumes.
• MiRNA levels from 100-µl and 200-µl plasma groups normalized to the 50-µl group level with concentration normalization.

Conclusions:

• Small RNA concentration normalization is crucial for accurate miRNA quantification in rodent plasma.
• This optimized protocol minimizes variations from RNA extraction.
• Standardizing RT input concentration enhances the reliability of plasma miRNA as biomarkers.