Injectable biodegradable microcarriers for iPSC expansion and cardiomyocyte differentiation

Cell therapy is a potential novel treatment for cardiac regeneration and numerous studies have attempted to transplant cells to regenerate the myocardium lost during myocardial infarction. To date, only minimal improvements to cardiac function have been reported. This is likely to be the result of low cell retention and survival following transplantation. This study aimed to improve the delivery and engraftment of viable cells by using an injectable microcarrier that provides an implantable, biodegradable substrate for attachment and growth of cardiomyocytes derived from induced pluripotent stem cells (iPSC). We describe the fabrication and characterisation of Thermally Induced Phase Separation (TIPS) microcarriers and their surface modification to enable iPSC‐derived cardiomyocyte attachment in xeno‐free conditions is described. The selected formulation resulted in iPSC attachment, expansion, and retention of pluripotent phenotype. Differentiation of iPSC into cardiomyocytes on the microcarriers is investigated in comparison with culture on 2D tissue culture plastic surfaces. Microcarrier culture is shown to support culture of a mature cardiomyocyte phenotype, be compatible with injectable delivery, and reduce anoikis. The findings from this study demonstrate that TIPS microcarriers provide a supporting matrix for culturing iPSC and iPSC‐derived cardiomyocytes in vitro and are suitable as an injectable cell‐substrate for cardiac regeneration. A novel type of implantable biodegradable polymer microcarrier fabricated using thermally induced phase separation is designed to facilitate the attachment and differentiation of iPSC‐derived cardiomyocytes. The injectable microcarriers address existing challenges associated with use of iPSC‐derived cardiomyocyte cell‐based therapy, including the impact of cell anoikis during bioprocessing, clinical compatibility, and the production of physiologically relevant cardiomyocytes.