Human Umbilical Cord Blood-Derived CD133⁺ Cells Enhance Function and Repair of the Infarcted Myocardium

¹ Neufeld Cardiac Research Institute; Sheba Medical Center, Tel-Aviv University, Tel-Hashomer, Israel
² Danek Gertner Institute of Human Genetics; Sheba Medical Center, Tel-Aviv University, Tel-Hashomer, Israel
³ Sheba Medical Center, Tel-Aviv University, Tel-Hashomer, Israel
⁴ Hematology Division and Cord Blood Bank, Sheba Medical Center, Tel-Aviv University, Tel-Hashomer, Israel

^* To whom correspondence should be addressed. E-mail: leorj{at}post.tau.ac.il.

	Abstract

The use of adult stem cells for myocardial tissue repair might be limited in elderly and sick people because their cells are depleted and exhausted. The present study was conducted to explore the potential of human umbilical cord blood (UCB) CD133+ progenitor cells for myocardial tissue repair in a model of extensive myocardial infarction (MI). CD133+ progenitor cells were isolated from newborn UCB. Cells (1.2-2x10e6) or saline (control) were infused intravenously at seven days after permanent coronary artery ligation in athymic nude rat. Left ventricular (LV) function was assessed before and one month after infusion by echocardiography. Tracking of human cells was performed by fluorescent in situ hybridization (FISH) for human X and Y chromosomes or immunostaining for HLA-DR or HLA-ABC. One month after delivery, LV fractional shortening improved by 42±17% in cell-treated hearts and decreased by 39±10% in controls (p=0.001). Anterior wall thickness decreased significantly in controls but not in treated hearts. Microscopic examination revealed that the UCB cells were able to migrate, colonize and survive in the infarcted myocardium. Human cells were identified near vessel walls, LV cavity and were occasionally incorporated into endothelial cells in six of nine cell-treated animals but not in controls. Scar tissue from cell-treated animals was significantly populated with autologous myofibroblasts as indicated by colocalization of HLA-DR and -smooth muscle actin staining. In conclusion, the present work suggests that after MI, intravenous delivery of human UCB-derived CD 133+ cells can produce functional recovery by preventing scar thinning and LV systolic dilatation.