Cells have a remarkable ability to self-organize and rearrange in functional organoids, this process was greatly boosted by the recent advances in 3D culture technologies and materials. Presently, this approach can be applied to model human organ development and function "in a dish" and can be used to predict drug response in a patient specific fashion.Here we describe a protocol that allows for the derivation of functional cardiac mini organoids consisting of cocultured cardiomyocytes and cardiac fibroblast. Cells are suspended in a drop of medium and encapsulated with hydrophobic fumed silica powder nanoparticles. These nanoparticles are treated with hydrophobic chemicals, hexamethyldisilazane (nHMDS), and result in the formation of microbioreactors. These microenvironments are defined as "liquid marbles," stimulating cell coalescence and 3D aggregation. Then nHMDS shell ensures optimal gas exchange between the interior liquid and the surrounding environment. This microbioreactor makes working in smaller volumes possible and is therefore amenable for higher throughput applications. Moreover, the properties of liquid marble microbioreactors makes it an excellent culture technique for cocultures. Here we demonstrate how cocultures of cardiac fibroblast and cardiomyocytes in a cardiosphere can be a valuable tool to model cardiac diseases in vitro and to assess cell interactions to decipher disease mechanisms.
Keywords: Cardiac models; Cardiosphere; Coculture; Drug screening; Microbioreactor; Multicellular spheroids; Organoid; Three-dimensional culture; Tissue engineering; nHMDS.