25 August 2016

Hydrogel will help with a heart attack

In myocardial infarction, blood clots or narrowing of the arteries block blood flow, which leads to damage or death of myocardial cells. However, at the end of the acute period, cell death does not stop, instead, the heart wall becomes thinner, the organ increases in size and scar tissue forms. In the absence of appropriate measures, the patient inevitably develops heart failure.

Every year in the USA alone, 750,000 people develop myocardial infarction, and more than 5 million US residents suffer from heart failure, the symptoms of which progress from chronic fatigue to severe shortness of breath and, eventually, the death of the patient.

To date, the therapy of myocardial infarction includes lifestyle changes, the use of pharmacological drugs, the introduction of implants or heart transplantation. However, in many cases, these interventions do not have the proper effects or, as with heart transplantation, are associated with serious difficulties. Therefore, researchers are working on new therapeutic approaches. One of such approaches developed in animal experiments is the introduction of stem cells into the damaged area of the myocardium. To prevent the cells from leaving the myocardium, they are encapsulated inside biodegradable hydrogels – water-saturated polymer structures with a gel-like structure. However, when conducting such studies, scientists noticed an unexpected effect – in animals of control groups that were injected with a cell-free hydrogel, in some cases there was also an improvement in the state of the heart compared to animals that did not receive any treatment.

Inspired by these results, researchers in a number of laboratories are currently experimenting with various hydrogels, including two materials already undergoing clinical trials. Some of the experimental approaches to the treatment of myocardial infarction require open-heart surgery, however, the two hydrogels mentioned above are delivered to the damaged tissue using a long catheter inserted through the skin, which eliminates the need for opening the chest.

Researchers from the University of Pennsylvania, working under the guidance of Dr. Jason A. Burdick, also use this minimally invasive technology in their work. However, they improved it by identifying properties that can increase the effectiveness of therapy and creating new hydrogels with these properties. For example, they have developed a hydrogel that forms additional bonds between polymer chains after being injected into the tissue. The resulting material is denser and more durable than existing hydrogels, which provides mechanical support sufficient to stabilize the damaged tissue.

In experiments on sheep, the new gel limited the formation of scar tissue, thinning of the heart wall and enlargement of the heart. By preserving the size of the organ, it also reduced the leakage of blood through the mitral valve. In combination, these positive effects ensured the preservation of the alluvial function of the heart and prevented the development of heart failure.

The main component of the materials developed by the authors is hyaluronic acid, a carbohydrate polymer that is part of the body. The researchers modified the hyaluronic acid molecules by adding thiol and methacrylate groups, which provided the possibility of cross-linking of polymer molecules occurring after the introduction. After finalizing the composition of the hydrogel and the method of its introduction, they hope to enter into cooperation with a catheter manufacturing company and present their product on the market. In addition, the authors, as well as other research groups, are developing hydrogels containing drugs or cells that help repair damage to heart tissue.

The results of the work were presented at the 252nd Congress of the American Chemical Society, held on August 21-25 in Philadelphia, Pennsylvania.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the American Chemical Society: After the heart attack: Injectable gels could prevent future heart failure (video).


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