Scientists at Johns Hopkins in the US announced this week that stem cell therapy can be used effectively to treat heart damage caused by heart attacks (known as myocardial infacts) in pigs, paving the way for using the same technique in humans. The scientists injected each pig with about 200 million mesenchymal stem cells collected from the bone marrow of other adult pigs. The injections, which covered an area of the heart wall about the size of a small coin, were placed directly into a region of heart muscle recently damaged by an infarct, by threading a small catheter into the heart via an artery. A second 'control' group of pigs received placebo injections lacking any stem cells. The pigs were then followed up for 2 months. The pigs that received placebo injections became much worse and they developed congestive heart failure. But those that had received the stem cell injections showed full recovery of heart function and their hearts contained virtually no signs of 'scarring', a cardinal signature of previous heart attacks. In such scars muscle tissue is replaced by stiff fibrous tissue which cannot contract properly, reducing the heart's pumping ability, and the scar itself can also affect the electrical properties of the heart, sometimes triggering rhythm disturbances and cardiac arrest. Pigs provide a useful comparison with humans because their organs and physiology are very similar to our own. These encouraging findings suggest that this technique may work effectively in humans.


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