Stem-cell patch may fix damaged hearts

[lraynak]

Stem-cell patch may fix damaged hearts
By Ben Hirschler

LONDON (Reuters) - Scientists have made two significant advances in developing a stem-cell patch to repair the damage caused to the heart after an attack. Sian Harding of London's Imperial College said on Thursday her team had successfully matured beating heart cells in a laboratory dish for up to seven months and developed a biocompatible scaffold to form the basis of a patch.The idea is to stitch or glue a patch of new tissue derived from embryonic stem cells over the damaged area of the heart to make the muscle viable again.During a heart attack, or myocardial infarct, part of the heart muscle loses its blood supply and the oxygen-starved cells die, causing scarring. "We really would like to cover the area of the infarct scar as much as possible, so it might be quite a large patch," Harding said in an interview.
"We think the patch itself will stop the scar expanding, which is one of the big problems when you have a myocardial infarction because the scar becomes weak and can bulge out." The biomaterial developed for the patch is designed to have the same elasticity as heart muscle and can also be programmed to degrade safely in anything from two weeks upwards. Several groups around the world are working on different ways to use stem cells in heart repair but a key challenge is to get cells to function properly. By showing stem cell-derived heart cells can beat in a co-ordinated fashion for months on end, the Imperial team believes their patch should function smoothly alongside normal heart muscle, without causing abnormal heart rhythms. Harding, who will present her research at a UK Stem Cell Initiative conference, said initial human trials of the patch could be underway within five years -- after safety studies on animals and tests to see if the new cells are rejected. Stem cells are controversial but the field received a boost last month when researchers reported they had turned ordinary human skin cells into batches of cells that looked and acted like embryonic stem cells, without using human eggs or embryos. "That is a very promising development," Harding said. "They have made heart muscles from those cells and this technique has the potential both for getting round the ethical problems and for producing patient-specific cells." Making stem cells from a patient's own tissue would avoid the problems of transplant rejection.
(Editing by Julie Steenhuysen and Matthew Jones)

 

[barbara]

Thanks Larry

This is really some awesome news. Every week it seems more and more advancements are being made. What a change from even a year ago.

 

[cellmedicine]

HGF important in heart failure

There are numerous clinical trials been conducted that have demonstrated lack of adverse effects and some improvement in patients with cardiac conditions taking stem cells. However what is a more important question is not whether stem cells "work or not work", but HOW, they work. Recently, using a similar patch it was determined that the stem cell generated factor HGF is what accelerates healing and reducing infarct size, see article below. This finding should be useful for developing new ways of increasing the activity of stem cells so that even better results are attained than the current results.

Hepatocyte Growth Factor Helps After Heart Attack
Tuesday December 11th, 2007 @ 18:08:51 EST


From Category: Cardiac
Comments: No comments
Los Angeles, CA -

It is known that mesenchymal stem cells are useful for treating patients after a heart attack. What is however unknown is exactly how these cells mediate their effects. On the one hand mesenchymal stem cells are known to inhibit various inflammatory reactions by modulating the immune system. Therefore by suppressing inflammation administration of mesenchymal stem cells may be useful for the post heart attack period in order to suppress the cascade of ongoing tissue damage.

Recently, a publication came out (Anderson et al. The Role of Cytoprotective Cytokines in Cardiac Ischemia/Reperfusion Injury. J Surg Res. 2007 Aug 31) describing another mechanisms by which mesenchymal stem cells may be useful in the post-infarct period. The authors speculated that not the mesenchymal stem cells themselves, but different growth factors generated by the cells may contribute to repair of the injured myocardium after the heart attack. Specifically, two growth factors were assessed: hepatocyte growth factor (HGF) and stromal derived growth factor-1 (SDF-1), otherwise known as the CXCL12.

HGF is known to have various regenerative properties. For example, it is known that HGF stimulates production of new blood vessels which is a process that is important in healing the myocardium after injury. Additionally, CXCL12 is one of the "danger signals" that injured heart tissue makes after a heart attack in order to mobilize stem cells to the infarct area.

What the investigators of the current study did is they induced myocardial infarcts in rats and subsequently applied polymers that were soaked with either CXCL-12 or HGF to the injured myocardium.

Four weeks after the injury the left ventricular ejection fraction was increased in the mice that recieved HGF and the volume of the left ventricle was decreased. Twelve weeks after, contractility was increased in the mice that recieved the HGF. Additionally, HGF decreased the infarct size by 4 fold as compared to control.

No improvement was seen in the mice that recieved CXCL12.

These data suggest that in addition to beneficial effects in limb ischemia, HGF is useful for cardioprotection. It would have been nice however if the researchers included a group of rats recieving mesenchymal stem cells as a control. Even better if mesenchymal stem cells and HGF were administered together. No doubt that future experiments will do this, and we will discuss them here on StemCellPatents.com.


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