New York, NY - Direct intramyocardial injections of fetal-derived stem cells in eight patients with NYHA class 3 or 4 heart failure (HF) were followed by pronounced improvements in LVEF, functional class, and exercise tolerance over three months, reported investigators here last week at the International Society for Minimally Invasive Cardiothoracic Surgery (ISMICS) 8th annual scientific meeting. Although fetal stem cells have been used to treat immune deficiencies, spinal-cord injuries, stroke damage, and other conditions, last week's report is the first of their use in HF patients, investigators say.

One advantage fetal stem cells may have over other progenitor cells that have been explored for myocardial regeneration, predominantly myoblasts and marrow-derived stem cells, is a faster therapeutic effect. "The difference we observed initially is that fetal stem cells [appear] more powerful," Dr Frederico Benetti (Benetti Foundation, Rosario, Argentina) told heartwire. "Ejection fractions in patients improved within seven days initially. That didn't happen with our stem cells from bone marrow." Symptoms and other clinical features also improved more rapidly than they did in HF patients he had previously treated with marrow-derived stem cells, which have less potential for differentiation, according to Benetti, one of the surgeons who did the procedures at Luis Vernaza Hospital in Guayaquil, Ecuador.

Ejection fractions in patients improved within seven days initially. That didn't happen with our stem cells from bone marrow.

Initially, 10 patients with nonischemic cardiomyopathy and an LVEF <35% who were in NYHA class 3 or 4 despite optimal medications were injected with a total of 60 million to 80 million fetal-derived stem cells. Access to the heart was achieved by midline sternotomy in seven cases and by minithoracotomy in one. No patients died during the follow-up, but one patient who suffered an ischemic stroke three days after surgery and another who developed "clinically insignificant" pericardial effusion were excluded from further analysis.

The remaining eight patients showed a mean relative LVEF increase of 41% within the first 30 days, an effect sustained at 90 days, reported lead investigator Dr Valavanur A Subramanian (Lenox Hill Hospital, New York, NY) at the ISMICS meeting. Both six-minute-walk distance and exercise tolerance had more than doubled by the 90-day evaluation.

In the patient who received the injections through a minithoracotomy, a technique Benetti says will probably be the standard if this form of cell therapy pans out in larger studies, LVEF improved from 22% to 35% at 90 days; the patient also showed gains in the other functional parameters.