Introduction

The patients were at the end of the line – unable to climb a flight of steps, constantly short of breath, and prepared for a last, fatal heart attack. Using a long device vaguely resembling a fishing rod, a medical team led by Texas Heart Institute cardiologist Emerson Perin navigated through a small incision in the groin to reach the patients' hearts, where he made a series of injections.

The content of the injections was bone marrow mononuclear cells – a type of adult stem cell that gives rise to different blood types – freshly pulled from the back of each patient's hip. This would be one of the first attempts at cell therapy for heart disease. The theory, grounded in an important study performed at the NIH, was that some of the bone marrow would develop into cardiac cells and regenerate damaged heart tissue. Because the cells were derived from each patient, immune rejection was not anticipated to be a problem. Still, the procedure was a bold one: what if the cell mixture developed into bone? What if the cells caused abnormal rhythms in the heart? What if they clumped together and triggered an embolism?

Brazilian regulators took a favorable view of the protocol, and Perin, who was trained in Brazil and had working relationships wiThcardiologists there, took his study to Rio de Janeiro in 2001. The team, and their regulators, it turned out, guessed right: among the fourteen patients, none developed worrisome complications. Though the study was not rigorously controlled, volunteers receiving cells seemed to do better than patients who did not.