New Biotechnology

Cell therapies require a purification step that isolates the desired cell types from contaminating cells. Normally cell surface receptors are used as markers to distinguish cell types, but undesired cell types also show these receptors, compromising purification. Evidence suggests microRNA may be a better marker. New biotechnology, miRNA switches, purifies different cell types based on miRNA markers at levels suggesting applicability to patient care.

One of the reasons pluripotent stem cells are so popular in medical research is that they can be differentiated into any cell type. However, typical differentiation protocols lead to a heterogeneous population from which the desired type must be purified. Normally, antibodies that react to surface receptors unique to the desired cell are used for this purpose. However, in many cases the purification levels remain poor and the cells can be damaged. New RNA technology produced at CiRA may avoid these problems.

Professor Hirohide Saito at the Dept. of Reprogramming Science is a bioengineer who makes tools for iPSC researchers. His latest technology, the microRNA (miRNA) switch, is designed to detect and sort live cells not by surface receptors, but by miRNAs. miRNA is a better marker of cell types and can therefore improve purity levels. His miRNA switches consist of synthetic mRNA sequences that include a recognition sequence for miRNA and an open reading frame (ORF) that codes a desired gene, such as a regulatory protein that emits fluorescence or promotes cell death. If the miRNA recognition sequence binds to miRNA expressed in the desired cells, the expression of the regulatory protein is suppressed, thus distinguishing the cell type from others that do not contain the miRNA and express the protein.