Islamabad - New research suggests that youthful heart stem cells may be able to rejuvenate an aging heart and perhaps even reverse other signs of aging.

The treatment improved heart function, increased exercise capacity, and reversed several biomarkers of aging.

Such a demographic transformation brings new challenges to medicine. Nowadays, even in poorer nations, older people die from heart disease, diabetes, cancer, and other non-communicable illnesses as opposed to infectious and parasitic diseases.

The authors also discuss what happens in heart cells as the heart ages. One of the features they mention is the progressive shortening, as cells divide, of telomeres, which are the “caps” that protect the ends of chromosomes.

The researchers explain that “critical shortening” of telomeres is associated with a number of heart problems that arise with age, such as heart dysfunction.

Certain “rejuvenating strategies” - including transfusing young blood and reprogramming cells - have shown promise in tackling some of these problems, note the authors, but none have yet “addressed age-related heart dysfunction.”

Cardiosphere-derived cells are immature cells that can mature into any of the three major types of heart cell: cardiomyocytes, endothelial cells, and smooth muscle cells.

The team also treated another group of rats of the same age, which acted as controls, with saline injections instead of cardiosphere-derived cells. They then compared both groups with young rats aged around 4 months.

Before treatment, at baseline, the rats underwent tests of heart function, exercise capacity, and various blood markers. The tests were then repeated a month after treatment.

Comparisons of the before and after tests showed evidence of improvement not only in the heart itself, but also in other markers.

For example, compared with the control rats treated with saline, the rats that received the youthful cardiosphere-derived cells showed improved diastolic function.

Healthy diastolic function allows the heart to relax properly and fill with blood ready for pumping.

The older rats treated with the specialized stem cells also had longer telomeres in their heart cells, showing signs that their hearts had aged less rapidly than those of the control rats.

Finally, compared with the rats that did not receive the youthful cells, the treated rats also improved their exercise capacity by 20 percent and regrew hair faster.

On closer examination, the team discovered a possible explanation for the rejuvenating effect of the cardiosphere-derived cells.

“They secrete tiny vesicles that are chock-full of signalling molecules such as RNA and proteins,” explains senior author Eduardo Marbán, a professor of medicine and director of the Cedars-Sinai Heart Institute. “The vesicles from young cells appear to contain all the needed instructions to turn back the clock,” he adds.

The researchers point out that it will be up to future studies to find out whether or not treatment with the cardiosphere-derived cells increases lifespan.