Wednesday, May 23, 2012

Heart damage can be repaired with patient's own skin

While our body has several repair mechanisms, restoring lost organ function is usually not very easy. Organs such as the brain or the heart often do not recover after damage induced by a stroke or heart attack. When it comes to the heart, parts that do not receive any more oxygen and nutrients due to obstruction of coronary arteries die, leaving the patient with a partly dysfunctional heart. This reduces the pump function of the heart, which can, in severe cases, result in death. Because the body just removes the dead cells and fills holes with scar tissue, scientists are trying to regenerate the heart themselves. Stem cell therapy has been tried, but so far that remains problematic. Now, a study from Israeli researchers has shown how to repair damage by using a patient's own skin cells. It builds upon studies that have used a patient's own stem cells, which were found to be effective to restore heart damage. Isolating skin cells is much easier, meaning the Israeli therapy is of greater interest for clinical use.

Over the last decade, scientists have improved their ability to reprogram cells. When programming stem cells, for example, it is possible to let them specialize in cells belonging to a certain organ. That way, it is possible to create heart tissue, even though the body itself would not produce it. By elaborating on programming techniques, scientists found a way to use another source to build heart tissue: skin cells. By reprogramming skin into stem cells, so called iPS cells, they regain the ability to differentiate into specialized tissue. Basically, skin is transformed into something more primitive, rendering it capable to specialize again, even though this time the scientists choose in which direction. Creating these iPS cells has recently been made a lot faster, making them even more interesting for new treatment options.
From adult cell to stem cell,  and back to adult cell: skin can be reprogrammed by activating three special genes: klf4, oct4 and sox2. It makes them multifunctional iPS cells that can turn into any of the three cellular pathways that form all of the body's tissue: the external layer (ectoderm), middle layer (mesoderm), or internal layer (endoderm). (source)
The Israeli scientists based their heart therapy on the same principle as stem cell programming: they took skin from a patient with heart failure and transformed it into heart tissue, grown in a lab tube. After culturing the cells for a while, they showed signs of synchronized beating, indicating they are able to function as heart tissue, in which synchronized beating is of paramount importance. While the ability to reprogram cells is remarkable by itself, the scientists also proved they are able to modify cells obtained from diseased people. Existing experimental therapies make use of a patient's own stem cells, but those with heart damage often have dysfunctional heart stem cells as well. That goes for a lot of diseases: the most interesting cells to use are often those found to be diseased and therefore unusable for regeneration therapies.

One benefit of using a patient's own cells is that they are compatible: using cells from another source can activate the immune system, which recognizes the foreign cells and starts attacking them. Even though the tissue was tailor-made for the patient, the scientists opted for implantation in rats: before human transplants are possible, much more data about safety and efficacy is required. In rats, the reprogrammed skin tissue showed integration with existing heart tissue, helping it to pump blood into the body.

Basically, the Israeli scientists did not discover any new techniques to artificially create heart tissue suitable for transplantation. They did however show proof of success, and that has not yet been achieved by many scientists working with either reprogrammed body cells or full-blown stem cells taken from an embryo. Even though human clinical data is still lacking, their treatment looks promising. While many more studies are required, we are getting closer to an actual clinical treatment that only requires a few simple skin cells to restore complex organ function.

1 comment:

  1. Stem cells will repair heart muscle cells damaged by the heart attack, by preventing late scar formation and hence impaired heart contraction. Cardiac stem cell therapy aims to repair the damaged heart as it has the potential to replace the damaged tissue. Thanks a lot.