Capturing Neonatal Cardiomyocyte - Endothelial interactions on-a-Chip

The neonatal heart has been the focus of numerous investigations due to its inherent regenerative potential. However, the interactions between neonatal cardiomyocytes (CMs) and endothelial cells (ECs) have been difficult to model and study due to the lack of an appropriate device. Here, we developed a method to culture primary neonatal CMs and ECs in a microchip and characterise their behavioural properties over a 14-day period. By implementing cell migration analyses coupled with immunostaining and confocal microscopy, we were able to identify and quantify sub-populations of migratory and non-migratory ECs. In CM-EC co-cultures, migrating ECs were found to move in higher numbers and longer distances compared to migrating CMs. In the presence of CMs, non-migrating ECs established connexin gap junctions and formed CM-EC cell aggregates, which were likely a priming event for endothelial organoid formation. This microfluidic device also enabled us to visualise the temporal sequence organoid formation and phenomena such as collective cell migration, CM-EC trans-differentiation and synchronisation of CM beating. This microchip based culture system has potential applications for tissue engineering and drug discovery.