Characterization of iCell cardiomyocytes using single-cell RNA-sequencing methods

Area of Science:

• Cardiovascular Biology
• Stem Cell Biology
• Pharmacology

Background:

• Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes are crucial for drug testing, especially for electrophysiological effects.
• Limited knowledge exists on the cellular composition and transcriptomic profile of commercial iCell cardiomyocyte cultures.

Purpose of the Study:

• To characterize the cellular composition and transcriptomic phenotype of iCell cardiomyocytes.
• To investigate cellular heterogeneity within these cultures using advanced sequencing techniques.

Main Methods:

• Bulk RNA-sequencing to identify expressed genes.
• Single-cell RNA-sequencing on two platforms to analyze cellular heterogeneity.
• Bromodeoxyuridine incorporation to confirm cell cycle activity.

Main Results:

• Bulk RNA-sequencing revealed cardiac, fibroblast, and ion channel genes.
• Single-cell RNA-sequencing identified two cell clusters, not matching known cardiac subtypes.
• One cluster (10.8%) showed co-expression of cardiac and cell cycle genes (e.g., TOP2A), confirmed by bromodeoxyuridine incorporation.

Conclusions:

• iCell cardiomyocytes exhibit co-expression of cardiac genes with cell cycle or fibroblast markers, suggesting immaturity.
• These findings exclude a non-cardiomyocyte subpopulation and indicate that cardiomyocytes can re-enter the cell cycle.