Cell death mechanisms in human endogenous cardiac progenitor cells due to receptor tyrosine kinase inhibitor toxicity

The development of receptor tyrosine kinase inhibitors as anti-cancer drugs has improved patient prognosis, however they have also been linked to cardiotoxic side-effects. The impact of receptor tyrosine kinase inhibitors on human endogenous cardiac progenitor cells could have long-term impacts on myocardial ability to repair itself after damage. To study these toxic effects on cardiac progenitor cells, we isolated these cells from human right atrial appendage samples by immunomagnetic cell sorting, to obtain c-Kit-positive, CD45-negative cells. Cells were characterised and maintained in vitro, then imatinib, sunitinib or sorafenib was applied at concentrations equivalent to peak or trough plasma levels. Impact on cardiac progenitor cells viability and activation of cell death pathway mechanisms were investigated by: viability assay (fluorescein diacetate) and live cell staining to identify apoptotic or alternative cell death pathway activation. Further reverse transcription qPCR analyses of apoptosis, Western blotting, immunocytochemistry and calcium imaging provided a broad screen of underlying mechanisms and possible therapeutic targets.