Cardiogenic progenitor cells derived from skeletal muscle - A promising autologous cell source for cardiac cell therapy

Introduction: Cardiac cell transplantation is a promising approach for cardiac regeneration in heart failure patients. However, the ideal cell source has not been found yet. Here we present a method to proliferate a homogeneous cell population with cardiac characteristics from skeletal muscle without genomic manipulation.

Methods: Skeletal muscle cell preparations were produced from newborn C57/BL6 mice. Following primary expansion and purification based on established isolation protocols, the non-adherent cell fraction (NAC) was further cultured applying three different conditions: stationary (S), agitated (A) and hanging-drop (HD) incubation. Cell samples from each method were characterized by immunocytochemistry, quantitative PCR and single cell patch-clamping over the course of three weeks.

Results: HD-conditions achieved highest total cell number after three weeks (5.3fold±1.1 vs. S, p<0.05; 3.2fold±0.6 vs. A, p<0.05). Immunocytochemistry revealed downregulation of skeletal myoblast marker desmin and increased expression of cardiac markers (cardiac troponinT; alpha-myosin heavy-chain) for all three culturing conditions as compared to NAC. Expression analysis by quantitative-PCR confirmed strong upregulation of alpha-myosin heavy chain (HD vs. NAC: 550fold±130; p<0.01) and cardiac troponin T (HD vs. NAC: 830fold±220; p<0.01) after three weeks. Electrophysiological assessment under 8Hz stimulation resulted in action potentials with cardiomyocyte like shape.

Conclusions: Despite an ongoing controversial discussion about skeletal precursor cells as a cell source for cardiac cell therapy, we confirmed successful generation and enrichment of cells with a cardiac phenotype without genomic manipulation. This provides an alternative cell source for cardiac cell therapy with high potential for translation into clinical applications.