Department of Physiology, Yonsei University College of Medicine, Seoul-t'ukpyolsi, Republic of Korea
Abstract: Direct reprogramming, which converts one cell type directly into another without passing through a pluripotent state, provides a unique and promising source for therapeutic applications. Reprogramming fibroblasts into chemically induced cardiomyocyte-like cells (CiCMs) using small molecules has emerged as a valuable approach for cardiac regeneration and therapeutic development. However, the presence of contaminating non-cardiomyocytes, primarily untransformed fibroblasts, undermines the functionality of CiCMs in various applications. Although several strategies exist for enriching cardiomyocytes such as transgenic selection methods via drug-selectable elements or fluorescence-activated cell sorting (FACS), these approaches often involve significant technical challenges. To address these limitations, our group investigated a metabolic selection approach that leverages the ability of cardiomyocytes to utilize lactate as an energy source in addition to glucose. Primary mouse embryonic fibroblasts (pMEFs) were reprogrammed into CiCMs and treated with a glucose-depleted medium supplemented with lactate. Under lactate-enriched conditions, the proportion of non-cardiomyocytes was significantly reduced while CiCMs (CiCM-LAC) remained largely unaffected. The CiCM-LAC group exhibited higher expression levels of cardiac-related genes and showed more pronounced and intense expression of cardiac troponin T (cTnT) compared to the untreated group (CiCM-NT). Moreover, metabolically purified CiCMs exhibited enhanced contractile force, higher contraction frequency, and elevated drug responsiveness compared to non-purified CiCMs. Taken together, our study suggests that lactate-based metabolic selection not only provides a highly purified cardiomyocyte population but also preserves their functional integrity, offering a promising platform for potential clinical applications.
Funding Source: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2021R1C1C2009131) and the Brain Korea 21 Project for Medical Science, Yonsei University.
