In Vitro Generation of Heart Field Specific Cardiomyocytes.

Myocardial infarction (MI) can lead to irreversible loss of cardiomyocytes (CMs), primarily localized to the left ventricle (LV) of the heart. The CMs of the LV are predominantly derived from first heart field (FHF) progenitors, whereas the majority of CMs within the right ventricle originate from the second heart field (SHF) during early cardiogenesis. Human embryonic stem cells (hESCs) serve as a valuable source of CMs for understanding early cardiac development and lineage commitment of CMs within these two heart fields that ultimately enable the development of more effective candidates for cell therapy. An ideal candidate may be FHF CMs that share the same ontogeny with the LV CMs that die after MI. We previously generated a double reporter hESC line that utilizes two important cardiac transcription factors, TBX5 and NKX2-5. TBX5 marks FHF progenitors and CMs, while NKX2-5 is expressed in nearly all myocytes of the developing heart. Here, we describe a step-by-step approach to efficiently generate FHF and SHF CMs using this double reporter hESC line. In addition, this approach can be applied to any non-genetically modified hESC lines to enrich FHF and SHF CMs. Obtaining enriched populations of these two CM subtypes provides a platform for downstream comparative analyses and in vitro studies to facilitate a deeper understanding of cardiovascular lineage commitment and the development of more effective candidates for cell therapy to treat diseases or defects that affect specific regions of the heart.