Single-stranded, noncoding micro-ribonucleic acids (microRNAs), consisting of 18-23 nucleotides, play a key role in regulating gene expression. Levels of microRNAs circulating within blood can be correlated to different states of diseases such as cancer, neurodegenerative disorders and cardiovascular conditions. Many microRNAs within the blood are encapsulated within exosomes, nanoscale vesicles released by the cells.