The use of stem cells for ischemic heart disease is a no-brainer. Ischemic myocardium secretes various stem cell chemoattractants and this is believed to actually cause new blood vessels to be formed. By "redistributing" stem cells through taking out bone marrow and placing it systemically, the stem cells have an opportunity to home to ischemic tissue at an increased frequency than without mobilization, and there is improvement in the ischemia. The more interesting thing is that stem cells hypothetically can also help non-ischemic heart disease through immune modulation. This is an interesting video of a pateint with heart failure that was successfully treated with stem cells by the clinic Cellmedicine.
http://www.youtube.com/watch?v=PcFQeRNuPDo