Label-free method to monitor metabolism during long-term culture of human pluripotent stem cell derived cardiomyocytes.

Significance: Human pluripotent stem-cell-derived cardiomyocytes (hPSC-CMs) are a powerful tool for drug discovery, and metabolic changes are associated with their long-term culture and maturation. However, the lack of technologies to monitor hPSC-derived cardiomyocyte metabolism during long-term culture presents a major technical bottleneck.

Aim: Efforts to monitor in vitro metabolic maturation of hPSC-CMs are limited by traditional assessment methods, which are generally time-consuming, destructive to samples, and lack single-cell resolution. We report a rapid, noninvasive imaging-based method to monitor hPSC-CM metabolism throughout extended culture (90+ days).

Approach: Label-free optical metabolic imaging (OMI) of autofluorescent metabolic coenzymes was performed at multiple time points during the extended culture maturation process. In addition, OMI monitored hPSC-CMs grown on substrates with varying stiffness and on cardiomyocytes derived from induced pluripotent stem cells associated with cardiac arrhythmia. OMI was paired with immunofluorescence to validate structural maturation.

Results: Single-cell OMI can identify metabolic changes during cardiomyocyte maturation through extended in vitro culturing. It can also detect metabolic differences induced by substrates of varying stiffnesses, can distinguish diseased from normal cell lines, and is sensitive to patient-level metabolic heterogeneity.

Conclusions: Our results demonstrate that label-free OMI can be used to monitor metabolic changes in hPSC-CMs under varying culture conditions in a rapid, non-destructive manner with single-cell resolution, providing insight into metabolic transitions arising from time in culture, culture conditions, or disease states.