An Assessment of Calcium Handling and Cardiovascular Drug-Profiling in Cytiva Embryonic Stem-Cell Derived Cardiomyocytes

Abstract

There is momentum towards using stem cell-derived cardiomyocytes (SCCM) to assess the safety and efficacy of cardiovascular (CV) drugs in early-phase development. However, issues of phenotypic heterogeneity and functional maturation impact on the utility of SCCM in CV drug development pathways. We used confocal imaging and our SALVO framework to profile spontaneous and field-stimulated Ca2+ handling and oscillatory behaviour in GE Healthcare's SCCM (CytivaTM). Cytiva were supplied as a heterogeneous cell population (47.5 ± 13.7% CMs, n=5 batches) and the proportion of cells that exhibited spontaneous Ca2+ oscillations correlated with cardiac troponin-T (cTNT) positive staining (CMs). In heterogeneous populations spontaneous Ca2+ oscillations in CMs exhibited significant batch-to-batch variability and were predominantly characterised by slow release and prolonged decay kinetics. Intercellular synchronization of Ca2+ release did not require physical cell-to-cell contact and was independent of the plating density and the local non-CM population. The amplitude and temporal patterning of spontaneous Ca2+ release in CMs became progressively disorganized beyond day 7 and we did not observe functional maturation of CMs in culture over 21 days. Ca2+ handling in those CMs exhibiting spontaneous oscillations could be positively modulated by field stimulation which improved amplitude and kinetic parameters of Ca2+ release and decay. Enrichment of CMs (>1.8-fold) using affinity methods directed at the cell-surface signal regulatory protein alpha (SIRPa) improved spontaneous Ca2+ handling possibly indicating a negative role of non-CMs in the heterogeneous population. Data will be presented on the concentration-response profiling of experimental and clinically-licensed cardioactive drugs using these SCCMs.