Connexin 40 promoter-based enrichment of embryonic stem cell-derived cardiovascular progenitor cells

The use of stem cells for the repair of cardiac tissue in ischemic heart disease

Ischemic heart diseases are the leading cause of death in the Western world. With increasing numbers of patients surviving their acute myocardial infarction owing to effective heart catheter techniques and intensive care treatment, congestive heart failure has become an increasing health concern. With therapeutic options for the prevention and treatment of ischemic heart disease being limited at present, huge efforts have been made in the field of stem cell research to try to establish new approaches for myocardial tissue regeneration. Owing to their pronounced differentiation potential, pluripotent stem cells seem to represent the most promising cell source for future engineering of myocardial replacement tissue. However, several crucial hurdles regarding cell yield and purity of the cultured cardiovascular progenitor cells have still not been overcome to facilitate a clinical application today. By contrast, plenty of adult stem and progenitor cells have already been well characterized and investigated in human disease. However, all of these heterogeneous cell lines primarily seem to work in a paracrine manner on ischemic myocardial tissue, rather than transdifferentiating into contractile cardiomyocytes. This article will focus on the production, application and present limitations of stem cells potentially applicable for myocardial repair.

Assessment of human MAPCs for stem cell transplantation and cardiac regeneration after myocardial infarction in SCID mice

OBJECTIVE

Clinical studies suggest that transplantation of total bone marrow (BM) after myocardial infarction (MI) is feasible and potentially effective. However, focusing on a defined BM-derived stem cell type may enable a more specific and optimized treatment. Multilineage differentiation potential makes BM-derived multipotent adult progenitor cells (MAPCs) a promising stem cell pool for regenerative purposes. We analyzed the cardioregenerative potential of human MAPCs in a murine model of myocardial infarction.

MATERIALS AND METHODS

Human MAPCs were selected by negative depletion of CD45(+)/glycophorin(+) BM cells and plated on fibronectin-coated dishes. In vitro, stem cells were analyzed by reverse transcription polymerase chain reaction. In vivo, we transplanted human MAPCs (5 × 10(5)) by intramyocardial injection after MI in severe combined immunodeficient (SCID) beige mice. Six and 30 days after the surgical procedure, pressure-volume relationships were investigated in vivo. Heart tissues were analyzed immunohistochemically.

RESULTS

Reverse transcription polymerase chain reaction experiments on early human MAPC passages evidenced an expression of Oct-4, a stem cell marker indicating pluripotency. In later passages, cardiac markers (Nkx2.5, GATA4, MLC-2v, MLC-2a, ANP, cTnT, cTnI,) and smooth muscle cell markers (SMA, SM22α) were expressed. Transplantation of human MAPCs into the ischemic border zone after MI resulted in an improved cardiac function at day 6 (ejection fraction, 26% vs 20%) and day 30 (ejection fraction, 30% vs 23%). Confirmation of human MAPC marker vimentin in immunohistochemistry demonstrated that human MAPC integrated in the peri-infarct region. The proliferation marker Ki67 was absent in immunohistochemistry and teratoma formation was not found, indicating no tumorous potential of transplanted human MAPCs in the tumor-sensitive SCID model.

CONCLUSIONS

Transplantation of human MAPCs after MI ameliorates myocardial function, which may be explained by trophic effects of human MAPCs. Lack of evidence of tumorous potential in the tumor-sensitive SCID model indicates that human MAPCs may deliver an effective and safe stem cell pool for potential treatment of ischemic heart disease.