Tuesday, October 03, 2006

Is stemcell therapy for LV myocyte regeneration ready for primetime

Very often, patients who have suffered a large MI and who have survived (often with the help of angioplasty), have asked me about the stories that they hear about stemcells and re-growing of infarcted heart muscles. This is especially true of the more educated or informed patients. To add to the mix, non-medical periodicals such as the local daily like to carry anecdotal reports of isolated "successful" cases. This feeds a belief in survivors of heart attack that if my heart is damaged, I can grow back the damage muscles.

This is a genuine request. However, can medical science fulfill this need? Well, this week, the NEJM carried three articles on this subject, with their accompanying editorials. Two of the studies were out of Germany (the REPAIR-AMI and TOPCARE-CHD) and one study out of Norway (ASTAMI).

The REPAIR-AMI was a post MI study where bone marrow stem cells were infused intra-coronary, post PCI, and this study was positive, showing that IC infusion of BM derived stemcells improved LV function. This was also the largest of the three studies.

The other post-MI study, almost similar in design, was the ASTAMI, which showed no LV improvement. The TOPCARE-CHD was actually, in post MI patients with chronic CCF. This study was out of Germany, and again, is positive. Telling us that post-MI patients who had received percutaneous revascularisation, and followed longterm, who had developed CCF, when given IC bone marrow derived stem cells, showed LV function improvement.

A few points are worth noting. Could it be that the Germans have it right? They have two positive studies. It is important to note that the amount of stem cells that actually reach the target site was about 2-3% of the amunt delivered. We also should consider whether or not we need to home the bone marrow derived stemcells to the target with the use of growth factors or inflammatory markers, or even progenitor cells. Can we help the targetting process in order to achieve greater benefit? We also learn that the LV function improvement was in the 2-5% range, statistically important, but whether it will translate to better clinical outcome, is left to be seen. We assume that improvement in LV function, however small, will translate to improvement in clinical outcome (this is something we do not know yet). It is always good to ask if the LV function improvement is due to myocytes regeneration, primarily, or due to neo-vascularisation.

Lastly, one wonders what would be the outcome if embryionic stem cells had been used? Did President Bush do us a disfavour by banning embryonic stemcell research in USA. It has not escape attention that all these three studies were done out of Europe. Where are the Americans? Where are the Koreans? More importantly, where are the Chinese? We know that the Koreans and the Chinese, including the Hongkies, were doing quite alot of stemcell research. As you can see, there are still more questions then answers at the moment. There is still much work that needs be done.

However all is not lost. We do know that angioplasty with good revascularisation, certainly help to prolong life, and lessen re-hospitalisation. Drug therapy, especially with the use of ARBs like Valsartan, have also been shown to lessen re-hospitalisation and also be as effective as ACE-I is lessening mortality. Well BM derived stemcell therapy may not yet be ready for primetime, in patients with large LV infarcts. The supporting therapies of PCI revascularisation and drug therapy certainly are.

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