Cardiac stem cells can restore heart muscles, says study

They also help to reduce scar size

Infusion of cardiac stem cells into persons who suffered heart attack recently can help to regenerate their heart muscles, says a study published on February 14, in The Lancet.

Phase I of the study was conducted on 17 patients, who received stems cells, and eight, who received standard care (control group), at the Cedars-Sinai Heart Institute in Los Angeles and Johns Hopkins Hospital, Baltimore. All of them had had heart attacks about a month before the study began in May 2009. The stem cells were created from the patients' heart tissues.

Visible improvements were seen in those who received infusion of stem cells, compared with the control group at the end of six months and a year. While no change in the scar size was seen in the control group, there was more than 12 per cent reduction in the size at the end of six months in the treatment group.

As scar size is directly related to scar mass, a reduction of 8.4 gram (28 per cent) and almost 13 gram (42 per cent) in scar mass was seen in the treatment group at the end of six months and 12 months.

Surprisingly, scar mass reduction was accompanied by an increase in viable myocardial mass. In fact, on an average, the increase in viable myocardial mass was “about 60 per cent more than scar reduction.” This is significant as it had led to a “partial restoration of lost left ventricular mass in patients with CDCs [cardiosphere-derived cells],” the authors of the study noted.

The study thus “challenges the conventional wisdom that once established, cardiac scarring is permanent, and that, once lost, healthy heart muscle cannot be restored.”

However, a change in scar size was accompanied by only 2 per cent increase in ejection factor (the amount of blood pumped by the heart), which is not considered significant.

While “the reasons for the discrepancy are unclear,” the study noted that “ejection factor at baseline was only moderately impaired, leaving little room for improvement.”

Of the six patients in the treatment group who had serious adverse events, only one was found to be related to the study.

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Cardiac stem cells can restore heart muscles, says study