Characterization of cardiomyocytes from heart tissue and from human stem cells

 

Focus of research

 

Maturation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) and investigation of involved signaling pathways

 

We aim to investigate approaches to promote the maturation of human embryonic and human induced pluripotent stem cell-derived cardiomyocytes (hES- and hiPSC-CMs, resp.) towards an adult ventricle-like phenotype as well as involved signaling pathways in cooperation with the group of Dr. Robert Zweigerdt, LEBAO, MHH. Remarkably, hPSC-CMs demonstrate a pronounced heterogeneity, e.g. with regard to the expression of  isoforms of the motor protein myosin (MyHC), a and β. MyHCb is predominantly expressed in ventricles of the human heart and therefore is together with other factors a marker for the maturation of hPSC-CMs towards an adult-like phenotype. A mature state of hPSC-CMs is important for modeling cardiac diseases like hypertrophic cardiomyopathy (HCM) in cell culture and for clinical applications like cell therapies in regenerative medicine or for drug screening.

 

Approaches to promote maturation of hPSC-CMs include on the one hand mechanical stimuli like the stiffness of the extracellular matrix and stretching and on the other the modification of involved signaling pathways. The focus of investigation of markers of maturation is on isoforms of sarcomeric proteins and proteins of calcium handling as well as on ion channel proteins related to the resting membrane and action potential. Mechanosensing and mechanotransduction signaling like integrin- and calcium-dependent signaling pathways are also investigated in the context of maturation of hPSC-CMs. Global analysis of protein abundance and phosphorylation is performed by gel electrophoresis and Western Blot. With regard to the heterogeneity of the hPSC-CMs, expression is also determined on the single cell level by immunofluorescence. In addition, gene expression is analysed by RNA sequencing, DNA oligonucleotide microarrays and qPCR with focus on distinct groups of cardiac genes and on mechanosensing/-transduction. Furthermore, data from expression analysis can be assigned to functional parameters of calciums transients and contractions in cooperation with other groups in the department by using a recently developed single cell remapping method.