Cardiac-Derived ECM Microspheres for Enhanced hiPSC-CMs Maturation

The phenotypic immaturity of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) remains a critical barrier to their effective use in disease models, drug screening, and cardiac regeneration. Current culture platforms still find it hard to provide a physiologically relevant, stable, and scalable microenvironment to support cardiomyocyte maturation. We report a reproducible heart tissue-derived cardiac extracellular matrix (ECM) microsphere that integrates native biochemical cues with a porous three-dimensional (3D) architecture to support cardiac cell culture and maturation. These microspheres supported the attachment and proliferation of C2C12, HL-1, H9c2, and hiPSC-CMs culture, suggesting the broad applicability of multiple cell types. Compared with the conventional two-dimensional (2D) culture system, decellularized cardiac ECM microspheres provided a spherical 3D culture interface and significantly enhanced hiPSC-CM maturation, as indicated by upregulation of cardiac genes (ACTA2, TNNT2, GJA1), rapid calcium cycling, and synchronized calcium transients. Long-term culture (up to 8 months) on these ECM microspheres supported hiPSC-CM maturation, as evidenced by enhanced sarcomere alignment, robust α-actinin expression, contractile phenotype, elevated gap junction (connexin 43, CX-43) protein expression, and increased binucleation. This ECM microsphere system represents a scalable and bioactive platform for long-term cardiomyocyte culture and maturation and broader applications in cardiac tissue engineering.