JOHNS HOPKINS (US) — A new jelly-like material appears to promote the repair of severe burns, regenerating healthy, scar-free tissue in early experiments with animals.
The new material has not yet been tested on human patients, but researchers say the substance, used as part of a new wound treatment method, appears to promote the formation of new blood vessels and skin in mouse tissue.
It could lead to greatly improved healing for injured soldiers, fire victims, and other people with third-degree burns, the researchers say. The results are published in the journal Proceedings of the National Academy of Sciences.
The treatment, developed at Johns Hopkins University, involves a simple wound dressing that includes a specially designed hydrogel, a water-based, three-dimensional framework of polymers.
Third-degree burns typically destroy the top layers of skin down to the muscle. They require complex medical care, and with current treatment methods, leave behind ugly scarring.
“This (new) treatment promoted the development of new blood vessels and the regeneration of complex layers of skin, including hair follicles and the glands that produce skin oil,” says Sharon Gerecht, an assistant professor of chemical and biomolecular engineering who was principal investigator on the study.
Gerecht says the hydrogel could form the basis of an inexpensive burn wound treatment that works better than currently available clinical therapies, adding that it would be easy to manufacture on a large scale.
Because the hydrogel contains no drugs or biological components to make it work, the Food and Drug Administration would most likely classify it as a device, Gerecht says.
Further animal testing is planned before trials on human patients begin, but, Gerecht says, “It could be approved for clinical use after just a few years of testing.”
Co-author John Harmon, professor of surgery, describes the mouse study results as “absolutely remarkable. We got complete skin regeneration, which never happens in typical burn wound treatment.”
About 100,000 third-degree burns are treated every year in U. S. burn centers. A burn wound dressing using the new hydrogel could have enormous potential for use in applications beyond burns, including treatment of diabetic patients with foot ulcers.
Guoming Sun, a postdoctoral fellow in Gerecht’s lab and lead author on the paper, has been working with hydrogels for three years, developing ways to improve the growth of blood vessels, a process called angiogenesis.
“Our goal was to induce the growth of functional new blood vessels within the hydrogel to treat wounds and ischemic disease, which reduces blood flow to organs like the heart,” Sun says. “These tests on burn injuries just proved its potential.”
The hydrogel is constructed in such a way that it allows tissue regeneration and blood vessel formation to occur very quickly.
“Inflammatory cells are able to easily penetrate and degrade the hydrogel, enabling blood vessels to fill in and support wound healing and the growth of new tissue,” she says. For burns, the faster this process occurs, Gerecht adds, the less there is a chance for scarring.
Originally, her team intended to load the gel with stem cells and infuse it with growth factors to trigger and direct the tissue development. Instead, they tested the gel alone.
“We were surprised to see such complete regeneration in the absence of any added biological signals,” Gerecht says.
Sun adds, “Complete skin regeneration is desired for various wound injuries. With further fine-tuning of these kinds of biomaterial frameworks, we may restore normal skin structures for other injuries such as skin ulcers.”
The researchers don’t yet fully understand how the hydrogel dressing is working. After it is applied, the tissue progresses through the various stages of wound repair, Gerecht says. After 21 days, the gel is absorbed and the tissue continues to return to the appearance of normal skin.
The hydrogel is mainly made of water with dissolved dextran, a polysaccharide (sugar molecule chains). Harmon speculates that the hydrogel may recruit circulating bone marrow stem cells in the bloodstream. Stem cells are special cells that can grow into practically any sort of tissue if provided with the right chemical cue.
“It’s possible the gel is somehow signaling the stem cells to become new skin and blood vessels,” Harmon says.
“It also could be that the physical structure of the hydrogel guides the repair,” Gerecht says.
The work was funded in part by a Maryland Stem Cell Research Fund Exploratory Grant and Postdoctoral Fellowship and by the National Institutes of Health.
The Johns Hopkins Technology Transfer staff has filed a provisional patent application to protect the intellectual property involved in this project.
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