Question: 

In this study the effects of bone marrow mesenchymal stem cells (BM-MSCs) on cardiac remodeling in a rat model of ischemia/reperfusion (I/R) were investigated.

Methods: 

BM-MSCs were delivered by i.v. (each 1 Mill. cells on day 1, 2 and 3 after MI) or direct intramyocardial injections (each 1Mill. cells on day 1 and 3 [early] or day 7 [late] after MI). After 6 weeks, heart function was measured by LV catheterization. The mRNA expression of IL-1b, IL-6, and TGF-b1-3 isoforms was analyzed by real-time PCR and histological sections were stained with picrosirius red for analysis of collagen content.

Results: 

In all I/R groups, the content of collagen I and collagen III was significantly higher in the infarct area compared to the non-infarcted septum and the free LV wall of sham-operated animals. All MSC-treated groups showed significantly higher collagen type III content in the infarct scar compared with untreated I/R, but not the respective medium treated control. Of note, both BM-MSC and medium early IM treated groups showed significantly higher collagen type I content in the infarct scar than control and late IM, but there were no further statistical significant differences compared with untreated I/R or medium treated controls. Also of note, both early IM groups had significantly higher IL1-b expression in the infarct area than I/R control and the worst cardiac function of all I/R groups.

Conclusion: 

Despite increased collagen III, there was, however, no functional improvement in the BM-MCS treated groups.