The Regulatory Future of Stem Cell Therapies is yet to be Determined

By on March 25, 2011

The stem cell therapy market appears to have a bright future and recent stem cell therapies in clinical trials have shown much promise. Just a few days ago, the results of a study conducted by the University of Miami showed that stem cell therapy can shrink enlarged hearts by up to 25 percent. Researchers used the patients’ own bone marrow cells to replace heart scar tissue, which is caused by heart attacks and results in an enlarged heart. The bone marrow cells injected into the damaged heart transformed into heart muscle and also prompted the heart to produce new heart stem cells. After treatment, heart function improved dramatically. In comparison, current therapies for this condition have only been able to reduce size by about 5 percent. With the success of this safety focused trial, there are two more trials planned which will focus on efficacy.

Last year, the Food and Drug Administration (FDA) also approved two embryonic stem cell trials, one by Geron for treatment of spinal cord injury and one by Advanced Cell Technology for retinal cell treatment of Stargardt’s macular dystrophy. These approvals are a huge step forward for the stem cell therapy market, as studies with embryonic stem cells have never previously been approved in humans. With several promising therapies in clinical trials and many others on the way, one has to wonder about how the current regulatory framework will address these novel treatments.

It seems clear that the FDA is also considering this question. Last August, the FDA halted the work of Regenexx, a Denver based company, which collects patient’s bone marrow cells, expands them in the patient’s own blood, and injects them back into patient’s damaged joints. About 500 patients have received this treatment with positive results. One of the issues cited by the FDA in stopping treatment was that there was not enough effort made to prevent the spread of disease and that a patient’s own stem cells should be regulated as if they were being used on another human being. For the most part, the medical community has supported this approach. An October 2006 report, by the New England Journal of Medicine, stated that researchers should be able to prove that stem cells won’t transmit disease and will be pure, effective, and safe.

The issue is still unclear as to whether the FDA will consider these stem cell therapies drugs or some new class of therapy and specifically, what the regulatory requirements will be. One concern frequently raised is how the FDA will address concerns regarding possible viral or prion contamination. The same New England Journal of Medicine report states, with respect to animal components in cell culture, “When stem-cell–based products involve more than minimal manipulation (such as expansion or differentiation), the cells will probably be grown in culture. This process should involve the use of nonhuman serum, which is often obtained from fetal calves and is therefore a possible source of the prion that causes bovine spongiform encephalopathy. The FDA specifies that fetal-calf serum must come from a country certified to be free of this disease.” But is it enough to say that fetal calf serum is safe as long as it is from a country certified to be free of this disease? The United States certainly did not expect to have a case of mad cow disease in 2003 or cases in 2006. Can we be sure that this disease will not, or has not, appeared in countries considered safe?

Because stem cells are frequently grown in the presence of animal components including fetal calf serum, bovine serum albumin, and human plasma derived albumin, there is always a chance that adventitious infectious agents will contaminate the stem cells. While the use of these animal components have been discouraged and largely removed from biopharmaceutical manufacturing, no such mandate has been made with stem cells.

One thing seems clear, as these therapies continue to progress from clinical trials to FDA approved therapies, documenting the safety and confirming that the cells are free of viral and prion contaminants will become mandatory and will make removal of animal components from the production process a top priority.

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