Bone marrow¹ stem cell therapy offers "moderate improvement" to heart attack patients, according to a large UK review of clinical trials.

英国一项临床实验显示，骨髓干细胞疗法对心脏病患者有“适度的治疗效果”。

The analysis by the Cochrane Collaboration² looked at 33 trials involving more than 1,700 patients.

It said longer-term studies were needed to see if the experimental therapy affected³ life expectancy⁴.

The review comes a day after doctors reported the first case of using heart cells to heal heart attack damage.

If a patient survives a heart attack, dead heart muscle is replaced with scar tissue - leaving the patient weaker and possibly on a lifetime of medicine.

Researchers are beginning to show that taking cells from a heart, growing millions of new heart cells in the laboratory and pumping those back into the heart may reduce scar tissue and lead to new heart muscle.

However, the trials are at a very early stage and in only a handful of patients. Using a similar technique with cells taken from the bone marrow, which is a prime source of stem cells, has a much longer pedigree（血统） .

The report by Cochrane pooled the data from all 33 bone marrow trials which had taken place up to 2011.

It concluded that bone marrow therapy "may lead to a moderate long-term improvement" in heart function which "might be clinically very important".