Abstract 11711: Chondro-osteogenic Mass Formation Postinfarction is a Natural Part of the Necrotic Process and is Independent of Stem Cell Implantation
Background: Chondro-osteogenic masses within the infarcted myocardium have been observed in several experimental stem cell therapy studies, and there has been a concern that they may be an adverse effect of stem cell therapy. Whether the formation of such masses is induced by the transplanted stem cells remain unclear. In this study, we assessed postinfarction chondro-osteogenic mass formation in athymic nude rats with myocardial infarction (MI) treated with stem cells.
Methods: MI was induced by left coronary ligation in 61 nude rats. One week later, human fetal heart-derived stem cells (OK99, 2 millions, n=20), and human fetal brain-derived stem cells (OK90, 2 millions, n=21), or saline (n=18) was directly injected into the infarcted myocardium. In addition, 2 rats received combination of OK99 and OK90 cells. At 6 weeks after treatment, the hearts were harvested and processed for histology. Cardiac function was assessed by echocardiogram.
Results: The infarct size, thickness of infarct wall, expansion index, postmortem LV volume, and LV fractional shortening were comparable among the 3 groups. Chondro-osteogenic mass formation was observed in rats that received OK99 (4 out of 20), OK90 (6 out of 21) and saline (8 out of 18; p=NS). Because the cell therapy did not affect postinfarction LV remodeling and cardiac function, we divided the 61 rats into those with chondro-osteogenic mass formation (+COM) and those without chondro-osteogenic mass formation (-COM) based on the histological findings. Chondro-osteogenic mass formation was observed in 20 out of 61 hearts. Infarct size, expressed as % of LV circumference, was significantly larger in +COM (49.4±1.7%) compared to -COM (41.3±1.5%; p=0.00088). Echocardiogram showed that LV fractional shortening was significantly lower in +COM (20.4±1.8%) than in -COM (25.2±1.6%; p=0.046) at the time immediately prior to treatment. However, LV fractional shortening were comparable between the 2 groups at 6 weeks after treatment.
Conclusion: Chondro-osteogenic mass formation postinfarction is independent of cell transplantation. These masses appear to be a natural part of the necrotic process and a histologic marker of larger infarcts with depressed function.
- © 2012 by American Heart Association, Inc.