The REPAIR-AMI clinical trial was a double-blind placebo-controlled trial in which 204 recent heart attach patients received either an infusion of bone marrow stem cells or a placebo. The results of this clinical trial have been published in three different papers (Schächinger, et al., N Engl J Med 2006 355: 1210-1221; Schächinger, et al., Eur Heart Journal 2006 27: 2775-2783; Schächinger, et al., Nat Clin Pract Cardvasc Med 2006 3(Suppl 1): 523-528).
This clinical trial showed that the bone marrow-treated group showed significant functional improvements over the placebo group. However, a long-term follow-up of these patients was required to demonstrate that the benefits conferred by the stem cell treatments were long-lasting and not merely transient.
Upon 5-year examination, the stem cell-treated group showed lower rates of a second heart attack, hospitalization, strokes, cancer, surgical interventions to open blocked vessels and death. Thus, the stem cell-treated group fared better in almost all the major categories.
There was, however, an additional experiment that gave a truly remarkable result. After each patient had their bone marrow extracted, the stem cells were subjected to individual tests, one of which were mobility tests. When this research group examined the stem cell motility data and correlated it to the five-year follow-up, they discovered a very tight association between the motility of the bone marrow stem cells and the absence of cardiac events. More active bone marrow cells provided greater recovery and fewer post-procedural events.
These data show that the quality of the bone marrow is a significant factor in the success of the stem cell treatment.
This also brings up another question: Can be beef up the quality of the bone marrow some how? Culturing stem cells can expand them, but it can also significantly change them. Therefore, this remains a fertile field for research and development, and the bone marrow quality may also explain why bone marrow transplants into the heart work so well or some patients and not at all for others.