Acquisition of a quantitative, stoichiometrically conserved ratiometric marker of maturation status in stem cell-derived cardiac myocytes.
Stem Cell Reports 2014;
3:594-605. [PMID:
25358788 PMCID:
PMC4223713 DOI:
10.1016/j.stemcr.2014.07.012]
[Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 07/22/2014] [Accepted: 07/24/2014] [Indexed: 12/11/2022] Open
Abstract
There is no consensus in the stem cell field as to what constitutes the mature cardiac myocyte. Thus, helping formalize a molecular signature for cardiac myocyte maturation would advance the field. In the mammalian heart, inactivation of the “fetal” TNNI gene, TNNI1 (ssTnI), together in temporal concert with its stoichiometric replacement by the adult TNNI gene product, TNNI3 (cTnI), represents a quantifiable ratiometric maturation signature. We examined the TNNI isoform transition in human induced pluripotent stem cell (iPSC) cardiac myocytes (hiPSC-CMs) and found the fetal TNNI signature, even during long-term culture. Rodent stem cell-derived and primary myocytes, however, transitioned to the adult TnI profile. Acute genetic engineering of hiPSC-CMs enabled a rapid conversion toward the mature TnI profile. While there is no single marker to denote the mature cardiac myocyte, we propose that tracking the cTnI:ssTnI protein isoform ratio provides a valuable maturation signature to quantify myocyte maturation status across laboratories.
The TNNI gene switch is a quantitative maturation signal for hiPSC-CMs
TnI isoform ratio is necessary, but not sufficient, to establish the mature state
TNNI protein isoform switching is stalled in hiPSC-CMs
Gene transfer enables acquisition of the mature TNNI signature in hiPSC-CMs
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