Diabetic wound healing is accelerated by an oxygen-delivering hydrogel

Around one-fourth of diabetics develop severe foot ulcers that take a long time to cure due to a lack of oxygen in the wound caused by weakened blood vessels and increased inflammation. These wounds can become chronic, resulting in a decrease in quality of life and the possibility of amputation.

Jianjun Guan, a professor of mechanical engineering and materials science at Washington University in St. Louis' McKelvey School of Engineering, has invented a hydrogel that provides oxygen to a wound, reducing inflammation, helping to restructure tissue, and speeding up healing. The study's findings, which were conducted in a mouse model, were published in Science Advances on August 28. Co-first authors are Ya Guan, a doctorate student, and Hong Niu, a postdoctoral research associate in Guan's lab.

"Oxygen has two functions: one, it improves skin cell survival in the diabetic wound's low-oxygen environment; and two, it stimulates skin cells to create growth factors important for wound repair," Guan explained.

Tissues in the body require oxygen to survive, and when tissue is wounded, they demand even more. While there are numerous therapies for chronic wounds in diabetics, the most popular is dozens of sessions in a hyperbaric oxygen chamber, but its success is uneven and comes with the danger of oxygen toxicity.

Guan's hydrogel supplies oxygen to the wound using microspheres that slowly release oxygen to connect with the cells via an enzyme on their surface that converts the microsphere's contents into oxygen. Over the course of two weeks, oxygen is supplied to the site, and inflammation and swelling subside, allowing the lesion to heal.

Wounds treated with the hydrogel containing the oxygen-releasing microspheres closed faster in mice than wounds treated with only the gel or those that received no treatment. The lesions treated with the hydrogel were shrunk to 10.7% by day 16. Those who received only the gel were decreased to 30.4%, while those who had no therapy were lowered to 52%.

Furthermore, the wounds treated with the hydrogel containing the oxygen-releasing microspheres had the thickest epidermis on day 8 but the thinnest epidermis by day 16, showing that the wound was healing and inflammation had decreased.

Guan has been working on this form of gel for the past 14 years, and it now has approximately 70 different functionalities and chemical configurations.

He explained, "Because the gel is a liquid before we inject it into the skin tissue, it's easier to mix in the microspheres." "Once we inject the gel and microsphere mixture into the wound, it solidifies because it is temperature-sensitive — it is a liquid at lower temperatures and a solid at body temperature."

One danger of giving too much oxygen to wounds is that it produces reactive oxygen species (ROS), which can harm or kill cells at high quantities. Guan's hydrogel can scavenge for ROS and eliminate it, therefore removing any risk.

Guan's team plans to test the hydrogel in a big animal model next, may be with human clinical trials.

"This is a novel therapeutic strategy for expediting the healing of chronic diabetic lesions without the use of medicines," Guan explained. "It may also be used to treat other disorders characterized by a lack of oxygen, such as peripheral artery disease and coronary heart disease."