In this study the effect of mononuclear cord blood cells (MN- CBCs) and unrestricted somatic stem cells (USSCs) after ischemia(60 min)/reperfusion (I/R) or chronic MI was analyzed. I/R or MI was induced in 12 weeks old rats by ligation of left coronary artery and 3x10e6 MN-CBCs, 5x10e5 USSCs or medium was injected either via a tail vein (MI) or directly into the myocardium (I/R and MI). Cell or medium injected sham- operated rats served as further controls. Heart function was monitored by echocardiography and measured with tip catheters after 8 (MI) or 12 weeks (I/R and MI). Additional hearts were examined 6 or 24 h or 1 week after cell or medium injection. Labeled cells were detected in the border zone adjacent to the infarct area at 6 and 24 h as well as 1 week after cell injection. Cumulative survival, however, was comparable in cell and medium treated rats and MI size not significantly different. Moreover, the parameters of impaired heart function were comparable and histological analyses did not provide evidence for cardiac regeneration by cell therapy. However, mRNA expression of main components and regulators of extracellular matrix was attenuated in the MI-area of the cell treated MI, but not I/R rats, while IL-6 expression was significantly pronounced in the I/R+USSC group.

Conclusion:

The benefit and mechanisms of stem and progenitor cell therapy for MI remain controversial.