We have previously shown that rat skeletal muscle derived stem cells differentiate into an immature cardiomyocyte (CM) phenotype within a 3-dimensional collagen gel engineered cardiac tissue (ECT). Here, we investigated whether human skeletal muscle derived progenitor cells (skMDCs) can differentiate into a CM phenotype within ECT similar to rat skeletal muscle stem cells and compared the human skMDC-ECT properties with ECT from human induced pluripotent stem cell (iPSc) derived CMs. SkMDCs differentiated into a cardiac muscle phenotype within ECT and exhibited spontaneous beating activity as early as culture day 4 and maintained their activity for more than 2 weeks. SkMDC-ECTs stained positive for cardiac specific troponin-T and troponin-I, and were co-localized with fast skeletal muscle myosin heavy chain (sk-fMHC) with a striated muscle pattern similar to fetal myocardium. The iPS-CM-ECTs maintained spontaneous beating activity for more than 2 weeks from ECT construction. iPS-CM stained positive for both cardiac troponin-T and troponin-I, and were also co-localized with sk-fMHC while the striated expression pattern of sk-fMHC was lost similar to post-natal immature myocardium. Connexin-43 protein was expressed in both engineered tissue types, and the expression pattern was similar to immature myocardium. The skMDC-ECT significantly upregulated expression of cardiac-specific genes compared to conventional 2D culture. SkMDC-ECT displayed cardiac muscle like intracellular calcium ion transients. The contractile force measurements demonstrated functional properties of fetal type myocardium in both ECTs. Our results suggest that engineered human cardiac tissue from skeletal muscle progenitor cells mimics developing fetal myocardium while the engineered cardiac tissue from inducible pluripotent stem cell-derived cardiomyocytes mimics post-natal immature myocardium.
A Chemically Defined Common Medium for Culture of C2C12 Skeletal Muscle and Human Induced Pluripotent Stem Cell Derived Spinal Spheroids
