World first as scientists use synthetic stem cells to repair a damaged heart

Hearts are having a busy time in the limelight recently, whether it's because people are 3D printing heart tissue at the edge of space, or putting them on a chip. Now scientists have announced the successful trial of a new pioneering stem cell technique - and in the field of stem cell research, which itself is still regarded as a pioneering area, that's a big statement indeed. What made the technique so notable was the fact that it was the first ever use of synthetic cardiac stem cells, and the team managed to use them to successfully repair a persons heart tissue after it had been damaged by a heart attack.

Traditionally stem cell therapies work by promoting what's known as "Endogenous repair," that is to say they help damaged tissue repair itself by secreting cocktails of proteins and genetic materials, but in the past scientists inability to control the make up of these cocktails has meant that many stem cell therapies have resulted in a higher risk of cancer for patients because the cells replicate uncontrollably. In addition to that most of the stem cells that are used in therapies are fragile and require specialised storage, processing and typing - matching the proteins of donor and recipient - before they can be used on patients.

The new synthetic stem cell technique, which was developed by a team at North Carolina State University, was led by Professor Ke Cheng who made the new cells using a Cell Mimicking Microparticle (CMMP) made from Poly Lactic-co-Glycolic Acid (PLGA), a biodegradable and biocompatible polymer. The researchers then harvested growth factor proteins from cultured human cardiac stem cells and added them to the PLGA. Finally, they coated the particle with cardiac stem cell membrane.

“We took the cargo and the shell of the stem cell and packaged it into a biodegradable particle,” Cheng says.

When tested in vitro, both the CMMP and cardiac stem cell membrane promoted the growth of new cardiac muscle cells in the patient, repairing the injured heart muscle perfectly. They also tested the CMMP in a mouse model with Myocardial Infarction (MI), and found that its ability to bind to cardiac tissue and promote growth after a heart attack was comparable to that of naturally occurring cardiac stem cells, but because of its structure - CMMP cannot replicate - it eliminated the risk of tumour formation.

“The synthetic cells operate much the same way a deactivated vaccine works,” Cheng says, “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 the risks.”

The synthetic stem cells are much more durable than human stem cells too, and can tolerate harsh freezing and thawing. Also, as an additional benefit, they also don’t have to be derived from the patient’s own cells and the manufacturing process can be used with any type of stem cell which gives the new treatment significantly broader appeal because it will allow doctors and scientists to store banks of "generic" synthetic stem cells and use them on tap to help cure other patients without the need to first harvest those patients own stem cells - a process which in itself can be complicated and prone to risk.

“We are hoping that this may be a first step toward a truly off-the-shelf stem cell product that would enable people to receive beneficial stem cell therapies when they’re needed, without costly delays,” Cheng says.

The research appears in Nature Communications.