|
In what can be a major breakthrough, scientists have managed to implant human embryonic stem cell grafts into damaged hearts of laboratory mice and heal them. This finding, if confirmed in humans, means stem cells can repair the damaged heart muscle and also halt heart failure in its tracks.
Previous studies had also managed to implant stem cells in diseased hearts. However these stem cells could not sustain themselves and were unable to get converted into heart muscle cells. Stem cell research is the most promising avenue in medical science simply because these stem cells are the foundation blocks that can be converted into any type of cell, be it muscle, nerve or bone.
According to the US National Institutes of Health, studying stem cells will help us to understand how they transform into the dazzling array of specialized cells that make us what we are. Some of the most serious medical conditions, such as cancer and birth defects, are due to problems that occur somewhere in this process.
Scientists say that understanding the normal process will allow them to identify the area or the exact point at which these processes fail and lead to diseases like heart disease or cancer.
In the present study researchers at the University of Washington School of Medicine in Seattle and at Geron Corp successfully managed to convert embryonic stem cells into heart cells. Furthermore they also devised a method by which these cells were sustained long enough to repair the diseased hearts in lab rats.
Earlier efforts managed to get stem cells to convert into cardiac or heart cells, but most of them were unable to sustain themselves. In fact, researchers said that just about 1 percent of the differentiated cells were heart muscle cells. This percentage is too minimal to cause any positive effect in repairing the damaged heart muscle.
In order to ensure that a majority of stem cells were converted into heart cells or cardiomyocytes, researchers treated the stem cells with growth factors or proteins that encouraged growth of the heart cells. In this way they ensured that over 90 percent of the stem cells were sustainable cardiomyocytes.
The next issue facing the researchers was the problem of premature stem cell death.
"When we try to regenerate with liquid tissues, like blood or bone marrow, we're pretty good at it, but we haven't been very successful with solid tissues like skeletal muscle, brain tissue, or heart muscle. This is one of the most successful attempts so far using cells to repair solid tissues -- every one of the treated hearts had a well-developed tissue graft," explained Dr. Chuck Murry, director of the Center for Cardiovascular Biology in the UW Institute for Stem Cell and Regenerative Medicine, and corresponding author on the study.
To simply the process researchers suspended the cells in a growth "matrix." this meant the growing cells had a surface to attach themselves and grow unhindered.
Reporting in the August 27 online issue of Nature Biotechnology, the researchers said they divided the lab rats into four groups. One group received successful heart muscle grafts with the pro-growth cocktail and the results in this group were compared to three other groups.
One group of rats received only injections of water, while another was given the pro-growth cocktail without cells. The last group was given non-cardiac cells. Rats that did not receive human heart cells went on to develop heart failure, while those that received human heart cells had a complete reversal of the progression of heart failure.
When the pro-growth "cocktail" was used, researchers said heart muscle grafts were successful in 100 percent of the cases. When this cocktail was not used, only 18 percent of the heart muscle grafts were successful.
Researchers also found the stem-cell treatment to be successful because the grafts helped thicken the heart muscle walls and improve the functioning in the lab rats.
The next step according to researchers is to test out in larger animals like pigs and sheep. This is because as Dr Murray put it "a rat is not a person." Additionally the rat's heart beats at 450 beats per minute, while a human heart beats 70 times a minute.
"In patients who had suffered a heart attack, if we were able to re-muscularize their heart with stem cell-derived heart muscle cells, this should prevent them from developing heart failure," Murry pointed out.
Experts though feel there are many considerations yet to be fulfilled before this experiment can go to full-fledged clinical trials. While the finding is promising clinical applications may still be some years away.
The NIH says that thus far adult stem cells such as blood-forming stem cells in bone marrow are the only ones used to treat diseases. Although the clinical potential has been demonstrated in many studies the practical implications are yet to be clarified.
 Add as favourites (51)
Powered by AkoComment Tweaked Special Edition v.1.4.4 |
Health 
