Organic Semiconductor Photomodulation Enhances Maturation of PSC-Derived Cardiomyocytes

Cardiomyocytes differentiated from pluripotent stem cells (PSC-CMs) hold a great potential for the study and the cure of cardiovascular disease; indeed they have been extensively used as platform for disease modeling and drugs testing, and represent a promising source of cells for regenerative therapies. However, the immature phenotype of these cells, which differ from adult cardiomyocytes for molecular, metabolic and morpho-functional properties, is a major hurdle for their full application. Recently, a new technology based on optical excitation of light-sensitive organic semiconductors (OS) has been shown to be able to modulate cell behavior of many cell types by targeting different cellular pathways, as proliferation, angiogenesis, neuronal firing and contractility. Here, we adopted a multidisciplinary approach based on morpho-functional, metabolic and transcriptional analyses to investigate the effect of OS-photoexcitation on PSC-CMs. Analyses were performed on PSC-CMs seeded on either glass (control) or a red-light sensitive OS polymer, namely Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT), in form of a thin film. Our results revealed a significant modulation of markers of CM maturation in PSC-CMs exposed to PCPDTBT and photomodulation, showing an increased size, altered membrane capacitance, a shift of their maximal diastolic potential (MDP) toward more negative values, and augmented Ca²⁺ transient amplitude. Moreover, by Scanning Electro-Chemical Microscopy (SECM) we found a decrease in glucose uptake and lactate release upon PCPDTBT light stimulation, potentially indicating a switch toward a more adult-like metabolism in stimulated PSC-CMs. Recently obtained RNA sequencing data are in line with these results, and will provide us with hints on the underlying molecular mechanisms.<br/>In conclusion, our data are in support of a potential effect of polymer-mediated optical photoexcitation in boosting PSC-CMs toward a more mature phenotype. We believe that the proposed approach, with a relevant effect on PSC-CM maturation and functionality, will significantly promote their full applications toward personalized medicine applications.