A new chemically treated wound dressing could address the mushrooming problem of diabetes-related amputations by introducing the first moist gauze bandage with the ability to ventilate ulcerations that often fester in diabetics, partly because these sores don’t get enough oxygen to heal properly. Surita Bhatia and Susan Roberts of the Chemical Engineering Department at the University of Massachusetts Amherst have developed the only moist dressing ever conceived that showers wounds with oxygen to promote healing and foster the formation of healthy new tissue.
As Dr. Bhatia explains, “Our wound dressing consists of an alginate gel containing oxygen-storing droplets, all interspersed throughout the layers of a standard gauze dressing.”
Alginate, the main chemical component in many moist dressings, is a naturally occurring polymer found in brown algae. The technical innovation in this new dressing is the concept of peppering the alginate gel with millions of these droplets, which store and channel oxygen to sores that, in diabetics, are often hard to heal due to low oxygen concentration at the wound site.
The researchers are currently preparing to apply for a patent on the dressing by setting up animal testing and further laboratory measurements through a $25,000 grant from the UMass office of Commercial Ventures and Intellectual Property (CVIP).
“The main activity we want to do with this CVIP funding is to perform in vivo experiments of the wound dressing with rats,” says Bhatia. “Our prototype dressing has been formulated in the laboratory. The dressing will protect wounds from outside pathogens and create a moist environment for healthy healing, as other alginate dressings do. But ours is the only dressing that will also promote improved transport of oxygen to the wound, as predicted by our computer modeling of the dressing. Before applying for a patent, we also want to do some additional laboratory measurements of oxygen diffusion throughout our dressing.”
Some 7.8 percent of the U.S. population has been diagnosed with diabetes, with 1.6 million new cases occurring annually. That diabetic population is vulnerable to foot and leg ulcers, which, if left untreated, can lead to serious infections, as demonstrated by the 71,000 diabetes-related amputations performed in the U.S. annually. Restricted flow of oxygen to extremities is characteristic of type 2 diabetics, who often suffer from foot ulcers that develop from low blood flow and nerve damage, a condition which increases the severity of the wounds. Lack of oxygen also leads to diminished tissue formation during wound healing.
The initial focus of this new dressing is on diabetes-related wounds, but it can also be applied to any moist or chronic wound, such as burns and battlefield injuries. The market research shows that there was a $300-million market for moist dressings in 2009 and that alginates are the fastest growing segment of this market.
The concept of oxygen-transporting dressings really sprang from research that Bhatia and Roberts have been working on for almost a decade, in which they embed various kinds of human organ cells in polymer capsules that serve as magic bullets to deliver them into the human body. This special-delivery service is designed to replace risky organ transplants for people desperately in need of new livers, thyroids, pancreases, and other lifesaving tissues.
Dr. Roberts says that “The inclusion of oxygen carriers in polymer capsules can both increase oxygen supply to encapsulated cells and modulate oxygen at appropriate cell-specific levels. These devices have been successfully designed in our lab for a number of cell types including liver, chondrocyte, and islet cells, and we are very excited about the potential of this technology in wound healing applications. Preliminary experiments indicate a several fold enhancement of oxygen transport to the wound site, which can significantly speed up healing.”
The wound dressing was inspired about three years ago by chemical engineering graduate students and Institute for Cellular Engineering IGERT fellows Joseph White and Whitney Stoppel, who suggested to Bhatia and Roberts that they adapt their polymer capsule work to deliver oxygen to wounds through their dressings.
“The idea came from previous works from the Bhatia and Roberts groups regarding alginate hydrogels as wound dressing materials and enhancing oxygen transport within engineered scaffolds to improve viability of transplanted cells in the body,” recalls White. “The combination of ideas allowed for a design for a dressing that offers a greater concentration of oxygen delivered to a healing wound than do commercial wound dressings.”
White was also the person who came up with the process for casting these alginate materials as gel-like films.
“He takes a layer of gauze and puts a layer of gel on the gauze,” says Bhatia, “and then dries it all under controlled humidity to make sure we don’t get a brittle or non-robust film.”
The design of the dressings would allow diabetic patients to use these special gauze bandages in much the same fashion as those already on the market, applying them on their ulcers or wounds and securing them in place. But, in this case, the new dressing will not only guard against harmful germs, but bathe the ulcerations in healing oxygen. (March 2011)