Genzyme's (NASDAQ:GENZ) announcement yesterday that it will join forces with Medtronic (NYSE:MDT) to develop new treatments for heart disease provides valuable insight into Genzyme's cardiac myoblast cell therapy program.

Genzyme began phase 2 trials for the therapy, which involve injecting damaged areas of patients' hearts with muscle cells, in Europe in late 2002. The hope is that the cells could stop or reverse damage done to heart muscle by a heart attack. In early phase trials in France, 10 patients realized a 35% improvement on average in their hearts' pumping efficiency, according to BusinessWeek.

Information on Genzyme's website, however, indicates that the company has not been as aggressive as it initially planned in its development of the therapy. In a brief and outdated blurb describing work on the treatment, the company anticipated its trials "expanding to North America in 2003." This expansion has yet to occur and does not appear to be in the works either.

One reason the firm has not followed through with North American trials could be that its resources have been deployed elsewhere. Genzyme announced plans to buyIlex Oncology (NASDAQ:ILXO) in March and, just six months before that, agreed to acquire Sangstat Medical.

Another factor in the delay, though, could relate to the therapy's delivery to damaged heart muscle. Some patients in the early myoblast trial suffered irregular heartbeats, which may have been related to the cell injection. Medtronic's TransAccess Delivery System, a catheter-based device that will be used in upcoming myoblast studies as part of the collaboration, could help deliver the cells more precisely, potentially mitigating side effects. In addition, the system promises to make delivery less invasive, increasing the treatment's market potential.

Investors should keep a close watch on the progress of these trials. The market is potentially large and lucrative, but only time will tell if Medtronic can inject new life into the treatment's progress.

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Fool contributor Brian Gorman is a freelance writer living in Chicago, Ill. He does not own shares of any companies mentioned here.