NEW YORK — Intracardiac injections of human fetal stem cells led to rapid improvements in heart function in a pilot study of 10 patients with nonischemic cardiomyopathy.
The promising results mean that the research should progress to larger, controlled studies, Valavanur A. Subramanian, M.D., said at the annual meeting of the International Society for Minimally Invasive Cardiothoracic Surgery.
The study, which was done at the Hospital Luis Vernaza in Guayaquil, Ecuador, used stem cells harvested from fetuses that had been either spontaneously or electively aborted at 5–12 weeks' gestation. Prior to 12 weeks, fetal cells contain no histocompatability antigens, so tissue matching wasn't necessary.
All 10 patients in the study had primary dilated cardiomyopathy that was not caused by ischemia or Chagas' disease. Five of the patients had New York Heart Association class III heart failure, and the other five had class IV disease. The average left ventricular ejection fraction of the entire group was 27.6%.
Each patient received 60–80 million stem cells that were suspended in 80 mL of saline solution and delivered in a series of 80 injections through the heart's surface. The injections were done using a 25-gauge butterfly needle and were placed 3 mm into the heart, said Federico Benetti, M.D., a cardiothoracic surgeon at the Benetti Foundation in Rosario, Argentina, who led the clinical team that did this work. Each injection delivered 1 mL, and the injections were spaced 1 cm apart. In nine cases, a sternotomy with general anesthesia was performed to expose the patient's heart. The 10th patient received the cell injections via a minithoracotomy.
The treatment did not result in any intraoperative or postoperative deaths by 90 days of follow-up, said Dr. Subramanian, chairman of the department of cardiothoracic surgery at Lenox Hill Hospital in New York. (Dr. Subramanian was not directly involved in the clinical work, but he helped analyze the results and he presented the findings at the meeting with Dr. Benetti.)
Two patients developed a temporary bradycardia following treatment, one patient had episodes of ventricular fibrillation, and one patient had an ischemic stroke 3 days after receiving the injections.
At 90 days after treatment, the eight patients who could be evaluated had New York Heart Association class II disease on average, compared with class III/IV at baseline. In these patients, the average left ventricular ejection fraction rose from 27.5% at baseline to 37.5% after 90 days. The average distance walked during a 6-minute walking test increased from 275 m at baseline to 553 m after 90 days.
Echocardiographic examination of treated patients showed a thickening of the myocardium, with increased muscle mass that began to be apparent by a week after treatment. This pattern of response differed from that described in previous reports of patients with ischemic cardiomyopathy treated with intracardiac injections of autologous stem cells, in whom angiogenesis seemed to be the main mechanism of action. In the current study, patients seemed to respond more quickly and by a different process than angiogenesis, Dr. Subramanian said.