Jornal de Citologia e Histologia

Human Embryonic Non-haematopoietic SSEA-1+ Cells are Cardiac Progenitors Expressing Markers of Both the First and Second Heart Field

Abstract

Elzafir Elsheikh, Rami Genead, Agneta Mansson-Broberg, Ivana Bulatovic, Karin Ljung, Eva Wärdell, Ulrika Felldin, Cristián Ibarra, Evren Alici, Christer Sylvén and Karl-Henrik Grinnemo

Background: Damage to the myocardium following a myocardial infarction can be severe and possibly non
reversible leading to heart failure. However, recent evidence suggests that cardiomyocyte progenitor cells may be able to assist in healing the injured cells. The study purpose is to investigate the use of “Stage Specific Embryonic Antigen 1” (SSEA-1) surface marker to isolate cardiac progenitors from the human embryonic heart.

Materials and Methods: The surface marker SSEA-1 was used to isolate cardiac progenitor cells from human embryonic hearts obtained from abortion material. The fast and reliable Fluorescence Activated Cell Sorting (FACS) technique was used to sort out pure population of SSEA-1+ cells. Cells were then cultured and characterized for multipotent stem cells markers using qRT-PCR and flow cytometry. The cardiopoietic capacity of SSEA-1+ cells was evaluated using a 5-azacytidine differentiation protocol.

Results: Isolated SSEA-1+ cells expressed the pluripotent stem cell transcription factor (Oct4) as well as the
multipotent cardiac progenitor cell transcription factors (Nkx2.5, Isl-1 and Tbx5) at the mRNA level, but they did not express the mature cardiomyocyte marker-troponin T (TnT). Furthermore, these cells were found to co-express the mesenchymal stem cells markers (CD105, CD166, CD73, CD59 and CD44), but not the hematopoietic markers (CD45, CD133 and CD34). The cultured SSEA-1+ cells were cardiopoietic and responded to 5-azacytidine treatment by differentiating into cardiomyocytes with high expression of TnT and actin as well demonstrating contractile filaments on transmission electron microscopy.

Conclusions: These data demonstrate that isolated SSEA-1+ from human fetal hearts using the FACS method might be used as a template for the generation of cardiac progenitor cells from other stem cells sources. This knowledge assists in the expansion of our knowledge on the regeneration of damaged myocardium.