New tech aims to help soldiers battle limb injuries

The publicly funded Airlift Research Foundation is funding research to develop a flashlight that kills bacteria; metal implants that fight infection; and processes to regenerate bones via grafts and stem cells.

Ed Salau uses his prosthetic leg to his advantage in Iraq in 2009. Photo courtesy of Ed Salau

When Army National Guardsman Ed Salau's Bradley Fighting Vehicle filled with smoke on November 15, 2004--"sometime after George Bush declared victory on the aircraft carrier and sometime before we won the war in Iraq," he likes to say--Salau and his gunner managed to crawl out of the hatch.

The first thing that hit them was that they'd somehow managed to survive two rocket-propelled grenades that had been fired at their vehicle. But Salau's leg seemed to dangle and flop below him. With the battle still raging around him, he grabbed the radioman's belt and tied a tourniquet.

An hour later, he was undergoing surgery in a field hospital, where his leg was amputated at the knee. By the time he began rehabilitation at Walter Reed National Military Medical Center three weeks later, eight more inches were missing.

"Eight more inches--simply to beat the infection," he says. "We used all the ways possible to beat the infection that was technically designed to kill me." But it wasn't enough, and Salau was left wondering: why isn't the science better?

Thanks to research being funded by the charity Airlift Research Foundation, of which Salau is now a board member, those who follow in his path might not have to suffer the same fate. The public foundation has awarded four researchers $200,000 each as they work to ensure that those who sustain limb injuries on the battlefield have a chance to survive.

Specifically, the grantees are working to develop a flashlight that kills bacteria; metal implants that fight infection; and biochemical processes that regenerate bones via grafts and stem cells.

"The 9/11 anniversary just makes us more aware of the necessity and the urgency of what we're doing, and recommits us to that cause," says Airlift President Susan Lephart, who has a Ph.D. in sports medicine. "To realize that it's been 10 years is really, from my standpoint, somewhat remarkable, just the number of people who've been affected by it. Every single day, someone is injured. The time is really too urgent for us not to be making their care far better than it has been."

More than 80 percent of all war injuries from Iraq and Afghanistan involve extremities, according to the foundation. That's more than 27,000 limb injuries sustained by U.S. troops alone, with almost 2,000 (6 percent) of them resulting in actual amputation. And of course, the "injury" doesn't end at amputation; quality of life, addiction to painkillers, and depression are just a few after-effects that can plague the wounded.

Airlift, which grew out of the Aircast Foundation to support orthopedic research in 2008, aims to "promote excellence in clinical scientific research in orthopedics," which includes helping jump-start the careers of young investigators and clinicians working in the field of orthopedics.

Airlift has thus far awarded its two-year, $200,000 grants to: Tianhong Dai at Harvard, who is working on a portable flashlight that can kill drug-resistant bacteria; Christopher T. Born at Brown, who is building metal implants that fight infection; Yufeng Dong at the University of Rochester, who is hoping to devise a way to regenerate bones, cartilage, and connective tissue using stem cells; and Yunzhi Yang at the University of Texas at Houston, who is designing synthetic bone grafts that regenerate new bone.

The antibacterial flashlight
Tianhong Dai, an instructor of dermatology at Harvard Medical School, is investigating how to use ultraviolet light--already used to kill household germs--to treat drug-resistant bacteria common in wound infections in Iraq and Afghanistan. (These infections are the leading cause of death in injured service members, Airlift reports.)

Tianhong Dai at work in his lab. Sulbha K Sharma/Harvard

With a handheld device that resembles a flashlight, field medics and even regular troops could conceivably treat life-threatening wound infections right there on the battlefield.

Because UV can cause skin damage or even cancer, Dai is studying UV-C light, which characterizes the shortest wavelengths on the ultraviolet spectrum. Killing drug-resistant bacteria isn't necessarily the tricky part.

"Based on our research so far, doing animal studies using mice with very invasive infections, UV-C can save the lives of mice," Dai says. "And for chronic infections, UV-C can reduce the bacterial burden on the wound by 90 percent. So the biggest advantage in my mind of UV-C is that it could be used on the battlefield to delay the onset and progress of the infection until regular medical attention is available."

The complications arise in how exactly this "flashlight" will work; how much light should be shined into a wound? What are the maximum and minimum dependent doses required to kill a variety of bacteria strains that aren't going to be able to be tested and studied midbattle?

Dai anticipates being able to introduce in the next two or three years a portable, effective, and safe device that solves these issues.

Metal implants that fight infection
Christopher Born, professor of orthopedic surgery at the Warren Alpert Medical School of Brown University and the director of orthopedic trauma at the Rhode Island Hospital, is patenting a chemical process that treats the metal and pins implanted in multiple locations when bones are broken.

Metal implants can cause infections, which not only endangers the wounded area, but also lengthens recovery time and can result in considerable pain. Born is infusing these implants with drug-like characteristics designed to fight infections and prevent more from developing.

With fractures accounting for more than a quarter of the injuries sustained by soldiers in Iraq and Afghanistan, and often being the result of roadside bombs that tend to lead to several fractures, implants that treat and prevent infection could speed recovery for wounded soldiers in particular.

Stem cells that regenerate bones and cartilage
Yufeng Dong, an assistant professor at the Center for Musculoskeletal Research at the University of Rochester Medical Center, is working closely with Matthew Hilton, an assistant professor of orthopedics, to devise a method by which to grow bone, cartilage, and connective tissue from stem cells.

"Something on the order of 1 to 2, maximum 5 percent of the cells are actually stem or progenitor cells that can actually self-renew or self-populate," Hilton says. "So the goal of Yufeng's grant is to characterize these cells."

By studying progenitors (which are basically adult stem cells, not embryonic ones, but are more specific and do not replicate indefinitely), reserachers are able to be more specific as to what type of regeneration they hope to accomplish. (One of the tricks with stem cells is slowing down their maturation to focus how and where to use them.)

Dong hopes that, when they move from in vitro to studies with mice and ultimately clinical trials with humans, they'll be able to grow cells on a culture plate with a temperature-sensitive membrane at the bottom so that the entire sheet can be detached and wrapped like a sleeve around the damaged limb or region.

Hilton says many issues and questions remain, but he hopes their work will result in clinical trials in five years.

Synthetic bone grafts that regenerate new bone
Yunzhi Yang, an assistant professor at the University of Texas Health Science Center at Houston, is researching synthetic bone grafts and bone fillers that will not only support the weight of the original bone but also promote the regeneration of tissue while preventing infection.

To start, Yang has to develop the material. While surgeons can use bone tissue taken from the patient, this method isn't ideal, and cadaver bones only work half the time. To further complicate the issue, the material currently used in synthetic bones is both weak and prone to infection.

For the Airlift grant, Yang's research takes on the challenges that result from extensive fractures suffered in combat from high-energy explosives, where multiple fractures are often treated using bone grafts or fillers with the aforementioned weight-bearing problems. If he is able to devise material that can solve the weight and infection issues simultaneously, it will have a clear use for civilians as well.

 

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