The ability of transplanted progenitor cells to improve function within the failing heart has been shown in experimental animal models and in some human clinical trials.
In a study that is currently underway (February 2012), however, more positive results were being reported: In the SCIPIO trial, patients treated with autologous cardiac stem cells post MI have been reported to be showing statistically significant increases in LVEF and reduction in infarct size over the control group at four months after implant.
With the goal of recreating human tissue, the use of embryonic stem cells (ESC) was the initial logical choice.
Adult stem cells exhibit a minimal[clarification needed] commitment to engraft into the damaged myocardium, they have low survival rates and they have limited proliferation.
[16] The positive effects observed in clinical trials today are a result of the work of donated stem cells that persist in the damaged myocardium for just days to weeks after delivery.