Cardiomyocytes can be generated in vitro with high throughput and quality at a clinically relevant scale using pluripotent stem cells. However, these cardiomyocytes are phenotypically similar to ones at early fetal stage and often lack the attributes of adult or mature cardiomyocytes which are desirable for drug screening, modelling of adult onset diseases or replacing cells lost to disease. The major difference between immature and mature cardiomyocytes lies in the electrophysiology of the cells, which is determined by the presence or absence of specific ion channels on the cell membrane.
Researchers at GW found that expression of Zim3-KRAB-dCas9 significantly upregulated the transcription of several key cardiac ion channels in human post differentiated pluripotent induced stem cell derived cardiomyocytes (iPSC-CMs). These channels include Kir2.1, HERG and Connexin 43- the main gap junction protein in ventricular cardiomyocytes. The combination of these effects produces desirable electrophysiological changes in line with more mature iPSC-CMs with anti-arrhythmic properties.
Figure: Summary of maturation/anti-arrhythmic effects of dCas9/Zim3 expressing human iPSC-CMs compared to unmodified control.