When it comes to health and longevity in most developed countries, heart attacks are public enemy number one.  In 2009 alone, more than half a million Americans will have their first heart attack. According to the American Heart Association, 18% percent of men and 35% of women who survive their first heart attack will have another heart attack within six years!  Are stem cells part of the solution to this terrible epidemic?

With its stem cell treatment Prochymal now entering phase II clinical trials, Osiris Therapheutics believes the answer is yes.

Normally after suffering heart attack (myocardial infarction in doctor speak!) the damaged heart develops scar tissue and continues to function in a degraded condition, sometimes operating at only 50% of its pre heart attack capacity.  This of course is bad news for the patient, leading to a lower health profile and partly explaining why those who have suffered one heart attack are so likely to suffer subsequent attacks.  So is there a way to avoid this unfortunate outcome?  It turns out their is a window of opportunity during the first week or two after a heart attack during which the damaged heart can be healed, avoiding the scarring and bringing the heart back to its original health.  The trick is coordinating the body to perform this healing process, and this is where Prochymal comes in.

Prochymal is a treatment of bone marrow stem cells that have been extracted from healthy human adults.  These stem cells have the natural ability to develop into other types of cells and generate new tissue, including heart muscle.  Animal studies have demonstrated Prochymal’s ability to return heart function to near normal levels in as few as 2 months!  Check out this stunning photo comparison from the Osiris Therapuetics website to see what we are talking about:

prochymal_treated

Above:  The circled region denotes the extent of the scar in each image. Left image: Dense scar formation and wall thinning is seen in control hearts. Right image: In contrast, the scar is limited and the ventricle wall remains thick in the hearts of MSC treated animals. These results demonstrate that MSC therapy limits heart wall thinning after myocardial infarction.

Clearly Prochymal has achieved stunning results in animal studies, but what about in humans?

To the delight of potential heart attack victims everywhere this exciting stem cell treatment has seen impressive success in human trials.  During the recently completed phase I trial of Prochymal, 53 patients were treated within 7 days of suffering a heart attack.  Not only were no major adverse side effects or safety issues uncovered, but there was a significant statistical improvement in heart pumping capacity, lung function, and overall condition of patients up to and including a period of 6 months after the procedure.  

Now, just days ago, the Heart Hospital of Austin has announced that one of its patients, a 58 year old man, was the first to begin a phase II trial of Prochymal.  The phase II double-blind, placebo-controlled trial will evaluate the safety and efficacy of Prochymal in a targeted enrollment of 220 patients.  The trial will be conducted at leading institutions and academic research centers in the United States and Canada. This trial focuses on patients who have suffered severe heart attacks, classified as having post heart attack left ventricular ejection fraction, or LVEF, at 30% and 45% of normal capacity.

Readers may question how it is possible that the patient’s immune system does not attack the foreign donor stem cells that are the key to the Prochymal treatment.  From the Osiris website we find the following:

Osiris’ technology is based on the pioneering work of Dr. Arnold Caplan and his colleagues at Case Western Reserve University. They showed that mesenchymal stem cells (MSCs) can engraft and selectively differentiate, based on the tissue environment, to such lineages as muscle, bone, cartilage, marrow stroma, tendon and fat. Due to their cellular origin and phenotype, these cells do not provoke an immune response, allowing for the development of products derived from unrelated human donors.

After reading the above excerpt one will correctly realize that these cells may be capable of healing much more than heart tissue.  Not only is Prochymal making headway as a treatment for heart repair, but it is also in trials to treat GvHD, Crohns’, and several other major afflictions.

Before we get too carried away with excitement, however, plenty of caution is in order. An alternative view of Prochymal, as well as the company Osiris Therapeutics, is on display at TheStreet.com by analyst Adam Feuerstein.  Feuerstein thinks the company is a big hype machine that will never produce a real product.

So who can we believe, and what is the future for this promising stem cell therapy?  Only time will tell, but in the meantime Prochymal is an exciting therapy to keep an eye on.

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