Infarcted Therapy Renewed scar tissue

Researchers were able to convert scarred tissue into cardiac cells for the first time

04/27/2012

Can scarred heart muscle tissue be cured in the future after a heart attack? For the first time, a research team from Duke University Medical, based in the United States, successfully used a stem cell injection to successfully transform scar tissue into cardiomyocytes. The research results could be a first breakthrough in stem cell research, which has otherwise been unsuccessful for 15 years.

Regeneration of the heart with new, functioning cardiac cells remains an enormous challenge for cardiac medicine. A therapeutic approach could be the direct conversion of wounded heart regions into functional tissue. Apparently this has now been achieved by a research team.

Scarred tissue transformed into cardiomyocytes
After a heart attack, many sufferers have scarred tissue in their hearts. As a result, diseases such as heart failure and sometimes dangerous cardiac arrhythmias develop. US researchers were able to convert defective scar tissue directly into cardiomyocytes during an animal experiment with laboratory mice. This happened without detour via direct injection of stem cells into the affected tissue. The scientists believe that after a trial and probation period, a novel therapy can be developed that could also be used in heart attack patients.

Without use of stem cells
In the laboratory experiment, the scientists converted cardiac tissue into functional cardiomyocytes without the use of stem cells. In principle, the method "represents a new way to replace diseased or destroyed tissue in humans," as the researchers write to study leader Tilanthi Jayawardena Duke University Medical Center (Durham / US state of North Carolina) in their findings report. To convert the scar tissue they use so-called "microRNAs". These consist of microscopic molecules responsible for the regulation of numerous genes. To achieve an effect, the microRNAs were inserted into the fibroblasts. Fibroblasts are cells that form after myocardial infarction in the surrounding regions of the heart muscle. By forming the cells, the pumping and punching power of the heart is limited depending on the severity of the heart attack. Patients suffer from impaired cardiac performance, which is why cardiac insufficiency often develops in retrospect. Physical exertions such as gardening or climbing stairs are increasingly difficult for those affected. You suffer from shortness of breath, weak pulse, water in the legs and in the lungs.

Detour around ethical and technical reservations
In the first research round, the researchers examined the functionality of the microRNAs in some cell studies. The question was whether the molecules could actually resuscitate damaged tissue. In fact, cells that have a similar structure to conventional cardiomyocytes actually formed in the lab. Subsequently, mice were treated with the molecules in animal experiments. Also on the second pass the desired cell conversion was achieved. The therapeutic option "ethical and technical reservations that occur when using embryonic stem cells avoided," as the research team in the journal "Circulation Research" write.

Varied treatment options for injured tissue
The result opens up "a variety of therapeutic treatment options," as co-author Victor Dzau writes in a memo distributed by Duke University. "If the therapy succeeds in the heart, it can be used also in the brain, in the kidneys and other tissues". The researchers assume that they have explored a whole new way to regenerate tissue. "The results showed that microRNAs have the ability to directly convert fibroblasts into a cardiomyocyte-like phenotype," the researchers said in the abstract of the study.

Stem cell research has been controversial since the beginning. So far, participating research institutions have been focused on the processing of stem cells. Embryonic stem cells must be obtained from embryos, which are killed for this purpose. The cells can be laboratory transformed into any type of cell to replace damaged organ tissue. However, the methods involve numerous technical problems, and there is also a controversial debate as to whether embryos can be killed to obtain the stem cells. In many countries of the world therefore the criticized procedures are forbidden.

Instead of embryonic cells induced pluripotent stem cells
The US researchers now see a way out in the so-called induced pluripotent stem cells. Instead of embryonic stem cells, body cells in the laboratory are methodically returned to a state similar to that of embryonic cells. These can then practically turn into a novel cell type. The published by the US scientists method could form an alternative variant, without the described detours and without foreign cells to treat diseased tissue. In a next step, the researchers want to apply their discovery in larger live animals.

A possibly successful future of the novel method of first transforming cells in the subject's body is also attested by stem cell researcher Oliver Brüstle from Bonn. In another study, researchers have already succeeded in producing cells that produce insulin from progenitor cells in the pancreas directly in the tissue. "Then we come to completely new paradigms in regeneration - not to infiltrate cells, but to simply convert resident cells into the desired cell type," explained the expert. However, it may take several more years for therapies to be developed for humans. (Sb)

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