American and Chinese researchers have developed synthetic cardiac stem cells that could have the same therapeutic impact as human stem cells, with the added benefit of reducing the risk of graft rejection in cellular therapy.

Cellular therapy consists of the injection of stem cells to restore damaged tissue and organs. Scientists today can extract stem cells, clone them in vitro, program their differentiation, limit their potential to cause tumors, and inject them by the million into damaged tissue.

In cardiology, numerous research teams have used stem cells to regenerate necrotic heart tissue that has been damaged, for example, by a heart attack.

The cells they inject are obtained from 'pluripotent' cells, which can give rise to every other cell type, or 'multi-potent' cells that can only give rise to limited number of cell types, both of which are sourced either from donors or patients themselves.

However, when therapeutic stem cells are sourced from a person other than the patient, they can often be rejected and attacked by the patient's immune system.

Now researchers at the University of North Carolina in the US and China's First Affiliated Hospital of Zhengzhou University have succeeded in developing synthetic stem cells that have the potential to restore human cardiac muscle tissue.

Synthetic cells limit the risk of immune rejection and tumor growth

In concrete terms, the medical team fabricated cell-mimicking micro-particles from PLGA (poly-lactic-co-glycolic acid), a biodegradable and biocompatible polymer, and then loaded them with human growth factor proteins before coating them with a human cardiac stem cell membrane. The resulting cells promoted the growth of cardiac muscle in vitro.

“The synthetic cells operate much the same way a deactivated vaccine works,” explained Dr Ke Cheng, of North Carolina University. “Their membranes allow them to bypass the immune response, bind to cardiac tissue, release the growth factors and generate repair, but they cannot amplify by themselves. So you get the benefits of stem cell therapy without risks.”

Stem cells that can survive freezing and defrosting

The researchers point out that synthetic stem cells are much less delicate than human stem cells and can survive freezing and defrosting.

In 2013, researchers launched a major European clinical trial named "BAMI", which aimed to recruit 3,000 patients who have recently suffered a serious heart attack, and to inject them with bone marrow stem cells. Data from initial cohorts of 100 to 200 subjects have already shown modest but positive results.

The research was published in the journal Nature Communications. More information is available at https://news.ncsu.edu/2016/12/synthetic-stem-cells