UC Riverside

MicroRNA (miRNA) are short 20 to 25 nucleotide, non-coding RNA strands that bind to messenger RNAs (mRNAs) to inhibit translation through post-transcriptional modifications and induced mRNA degradation. The dysregulation of the expression of various miRNA could be the result of abnormal states, such as cancers, coronary artery disease, diabetes, Alzheimer’s disease, etc. MiRNAs have been found to be more closely related to disease stages and more tissue specific than the widely used mRNA disease markers. As a result, being able to quantitate miRNA levels is essential to early-stage disease detection and prognosis. MiRNAs can be released into the circulatory system and present at stable levels detectable by sensitive techniques. However, the perceived ranges of healthy miRNA levels can span several orders of magnitude and the overall serum content may differ very little in diseased states, making early stage detection difficult. Quantifying the levels of miRNA bound to a particular carrier can make it possible to identify miRNA biomarkers, and allow for earlier and more accurate diagnosis of disease.

Asymmetrical flow field-flow fractionation (AF4) is an open channel separation method which offers an alternative to conventional packed column techniques. AF4 is a size-based separation technique capable of separating the variety of serum components while maintaining native interactions. Correlation of miRNA content associated to different fractions of miRNA carriers reveals highly specific association and larger differences between diseased and healthy states than total serum content.

Microfluidic technology allows for increased rate of sample processing and analysis, and reduced sample consumption. A simple microfluidic technique was developed for the rapid and selective isolation of miRNA bound to three fractions of miRNA carriers; proteins, lipoprotein complexes, and exosomes. Application to the analysis of case and control sera shows differentiation between disease state and cancer stages.

The development of highly sensitive isothermal miRNA detection platforms offers an alternative to conventional RT-qPCR analysis techniques. These novel detection techniques are more clinically relevant and offer simpler detection which is competitive with the sensitivity of qPCR. Finally, solid-phase extraction techniques for isolation and enrichment of miRNA have been pursued and optimized to yield high recovery from complex media.