|Ph.D Thesis||Department of Medicine|
|Supervisor:||Prof. Gepstein Lior|
The adult heart has limited regenerative capacity and hence any significant loss of heart cells is mostly irreversible and may lead to progressive heart failure. Given these circumstances, it is of high importance that we develop new therapeutic strategies for the treatment of heart failure. A possible novel therapeutic strategy for heart failure may be to increase the number of working myocytes within the diseased area by implantation of functional cells. Since human fetal cardiomyocytes cannot be obtained in sufficient quantities for clinical use, a search for alternate cell sources has begun.
The recently described, human embryonic stem cells (ES) lines are continuously growing stem cells lines of embryonic origin first isolated from the inner cell mass of blastocysts. Here we describe the methodologies for derivation of human cardiomyocytes from the human ES cells. Using the embryoid body spontaneous differentiation system we coaxed these cells to differentiate to the cardiomyocyte lineage. We further show that the generated cardiomyocytes have the structural and functional phenotype of early human cardiomyocytes. Several lines of evidence confirmed the cardiomyocytic nature of these cells, including ultrastructural analysis, immunostaining, pharmacological, electrophysiological and calcium transient recordings. We then used spontaneously contracting cardiomyocyte aggregates derived from human embryonic stem cells as a novel in vitro model for conduction in human cardiac tissue. Finally, we have used a high resolution in vitro two-dimensional mapping system to assess the ability of the generated ES cell derived cardiomyocytes to structurally and functionally integrate with pre-existing cardiac cell cultures.