ABSTRACT: We designed microRNA-responsive, modified mRNA switches (miR-switches) that quantitatively control their own translation level by determining the miRNA activities. We found that the three miR-switches (i.e., miR-1-, miR-208-, and miR-499-switches) enable to purify cardiomyocytes differentiated from hPSCs with high efficiency, accuracy, and safety. The purified cardiomyocytes were engrafted in mouse heart and did not form tumor. Simultaneous purification of two different cell types, cardiomyocytes and endothelial cells, was also performed by transfecting the mRNA responding to the both miR-208 and miR-126, into heterogeneous cell population derived from hPSCs. In addition, selective induction of apoptosis in noncardiomyocytes triggered by miR-1/208-Bim switch enriched cardiomyocytes without cell sorting. The mRNA switch could purify desired cell types and control cell death pathways by monitoring the miRNA expression dynamics during cell fate conversion. MYH6-EIP4 iPSCs for mRNA, N=3 MYH6-EIP4 day18 cardiomyocytes (before transfection) for mRNA, N=3 MYH6-EIP4 day19 cardiomyocytes (miR-1-switch day1) for mRNA, N=3 MYH6-EIP4 day19 cardiomyocytes (without transfection) for mRNA, N=3 MYH6-EIP4 day25 cardiomyocytes (miR-1-switch day7) for mRNA, N=3 MYH6-EIP4 day25 cardiomyocytes (without transfection) for mRNA, N=3 201B7 d22 miR-208a-BFP sorted cells for mRNA, N=1 201B7 d22 miR-208a-BFP negative fraction sorted cells for mRNA, N=1 201B7 d22 SIRPA+LIN- sorted cells for mRNA, N=1 201B7 d22 SIRPA+LIN- negative fraction sorted cells for mRNA, N=1 201B7 d22 VCAM1+ sorted cells for mRNA, N=1 201B7 d22 VCAM1+negative fraction sorted cells for mRNA, N=1 MYH6-EIP4 day19 cardiomyocytes (miR-208a-Bim-switch day1) for mRNA, N=1 MYH6-EIP4 day19 cardiomyocytes (without transfection) for mRNA, N=1 MYH6-EIP4 day21 cardiomyocytes (miR-208a-Bim-switch day7) for mRNA, N=1 MYH6-EIP4 day21 cardiomyocytes (without transfection) for mRNA, N=1 MYH6-EIP4 day25 cardiomyocytes (miR-208a-Bim-switch day7) for mRNA, N=1 MYH6-EIP4 day25 cardiomyocytes (without transfection) for mRNA, N=1
