Stem cells boost the recovery of damaged hearts, German researchers have found. A report, published in the journal The Lancet, reveals that stem cells taken from the bone marrow increase the efficiency of hearts that have been damaged by heart attacks. The way in which this works still remains unclear, with scientists proposing various explanations and suggesting further studies.
The research team, from Hanover Medical School in Germany, conducted the first randomised trial using stem cells as a heart treatment. The study involved sixty heart attack patients, half of whom were treated with stem cells and half of whom received normal medical treatment. The researchers extracted the stem cells from the bone marrow of the patients and injected them into the artery leading to the damaged area of the heart. As the patients received their own cells as treatment, there were no problems of rejection.
The research team determined improvement to the heart's function by measuring the ejection fraction of the left ventricle, the percentage of blood pumped out of the heart with each contraction. In six months after the trial, the ejection fraction of stem cell treated percentage rose an average of 6.7 per cent from 50 per cent, whilst the ejection fraction of the control group increased by a mere 0.7 per cent. The ejection fraction is normally around 66 per cent, so patients treated with stem cells made a significant step to recovery.
Previous experiments have shown that the beneficial effects observed do not arise from the bone marrow stem cells turning into heart tissue, which is the aim of most stem cell based therapy. Instead, the team suggest that the stem cells may trigger some kind of hormone that stimulates the development of new blood vessels. There have also been results that question the safety of injecting stem cells into the heart: one experiment using stem cells extracted blood was found to cause re-narrowing of the arteries. Another, experimenting on dogs, found that other types of bone marrow cells, which may collected along with bone marrow stem cells, cause restricted blood flow. However, no such side effects were found in the German study.