Sunday, August 8, 2010
REGENERATING HEART TISSUE !!!
A broken heart could soon be coaxed into mending itself, says an Indian-origin scientist who led an international team which claims to have discovered a way of converting ordinary tissue into beating muscle cells.
The revolutionary treatment could be possible after scientists discovered a technique for turning ordinary connective tissue into muscle cells inside the heart. What it means is that in as little as five years, researchers could be able to coax the heart into regenerating itself, repairing the damage caused by cardiac arrests and Old age.
Two studies published on Thursday show new ways to fix damaged hearts, one by turning structural heart cells into beating cells and another by restoring a primordial ability to regenerate lost tissue.
Deepak Srivastava of the Gladstone Institute at California University and his colleagues say their technique works in a similar way to stem cells but instead of the new cells being grown outside the body and then injected back in, their method simply makes the cells switch at the point where they are needed.
The main problem is that when beating muscles cells — known as cardiomyocytes — die during a heart attack there’s no way to reactivate them and the surrounding connective tissue — known as fibroblasts — cannot take over their role.
But, Srivastava has developed a way of reprogramming fibroblasts into cardiomyocytes. The system involves slowly administering three substances — using an artificial tube called a stent — into the blood that trigger the conversion. One day after the three factors were introduced into mouse hearts, fibroblasts turned into cardiomyocyte-like cells within the beating heart. Up to 20% made the switch.
For the second study, a team at California’s Stanford University looked to amphibians called newts. “Newts regenerate tissues very effectively,” said Helen Blau of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine.
Other studies suggest that mammals have had to give up regeneration because the same process can also lead to cancer. A so-called tumor suppressor gene called retinoblastoma, or Rb, helps control this process in mammals.
Working also with mice, they found a second gene called ARF is also involved. When they blocked both Rb and ARF in mouse heart muscle cells, they started to grow and divide.
The key will be to control this process, so the cells do not overproliferate and form tumors, the experts report in the journal Cell Stem Cell. They also want to see if this works for other organs.