Exploring The Potential Of Bioengineered Alternative Tissues

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This intraoperative photo shows a chronic wound after debridement. The surgeon has applied Integra. Paul Kim, DPM, says Integra works well in deeper wounds and decreases the overall wound depth. (Photo courtesy of Paul Kim, DPM, and John Steinberg, DPM)
Here one can see the aforementioned wound six weeks after the application of Integra. (Photo courtesy of Paul Kim, DPM, and John Steinberg, DPM)
Exploring The Potential Of Bioengineered Alternative Tissues
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Author(s): 
Clinical Editor: Lawrence Karlock, DPM

Q: Do you ever utilize split-thickness or full-thickness skin grafts on the plantar foot?
A:
To cover defects on weightbearing areas, one can use a well-designed rotational or transpositional flap, according to Dr. Kim. He recommends designing the flap in such a fashion so it is derived from a non-weightbearing area. Dr. Kim says one can use a STSG to graft the area vacated by the flap. By using such a technique, Dr. Kim says he has not had to use a full-thickness graft.
Dr. Steinberg uses both types of grafts. He says clinicians may now use bioengineered alternative tissues and VAC therapy (KCI) to regenerate the plantar soft tissue layers first and then apply a glabrous STSG. “We perform drastically fewer free flaps using this approach,” notes Dr. Steinberg.
On the other hand, Dr. Miller says with the availability of “so many excellent skin substitutes out there,” he is reluctant to create a donor wound to heal a patient’s primary wound.

Q: How would you compare Graft Jacket to Apligraf and Oasis?
A:
Oasis, a porcine intestinal submucosa, offers an acellular matrix scaffold that provides a foundation for wound healing, according to Dr. Miller. He notes the tissues replace the porcine cells with human cells. Oasis, which Dr. Kim calls “readily available and accessible,” has worked better for him for superficial venous ulcers. Dr. Steinberg mostly uses the biologic dressing for superficial wounds or as a follow-up to Apligraf or a STSG.
As Dr. Miller describes it, Apligraf is a living bilayer skin substitute that provides a dermal and epidermal layer with 48 growth factors. The product is layered on a bovine collagen scaffold and, as he says, “provides all the tissues needed to heal a wound and the growth factors to jumpstart the wound.” Dr. Kim says Apligraf is “more versatile” and one can use it in both deep and superficial diabetic and venous wounds. However, he notes Apligraf is more expensive than Oasis and needs more preparation. Apligraf has been “of great benefit” in Dr. Steinberg’s practice and he notes it is the only living bioengineered tissue for diabetic foot ulcerations.
Dr. Steinberg describes Graft Jacket as a processed allograft that serves as a biologic dressing with a number of wound benefits.
“They are each very unique products and can offer significant benefit when applied to the right wound at the right time,” notes Dr. Steinberg.

Q: When do you utilize these advanced skin substitutes, earlier or later, in the treatment of a wound?
A:
Early utilization of these advanced wound products is important, according to Dr. Steinberg. “The mentality of waiting for a wound to become chronic and fail a lengthy care regimen is outdated,” he continues. “The sooner you intervene with advanced healing modalities, the better the wound bed will be prepared to receive them.” He says it is not very difficult to identify patients who will have problems with wound healing. Measuring wounds weekly “will tell you volumes,” emphasizes Dr. Steinberg.

Dr. Kim reiterates that BAT products are not “skin substitutes” as they are not meant to replace skin. He adds that BATs convert chronic wounds to acute wounds or provide a scaffold for tissue to penetrate. Dr. Kim says one can use BATs early in wound care but he normally waits until seeing evidence that the wound has become chronic.
To measure this, he uses Sheehan’s yardstick, saying one should expect wounds to heal at a rate of about 10 to 15 percent per week or decrease by 50 percent in one month.1 If the healing rate is below the aforementioned benchmark, Dr. Kim uses BAT products to “kick-start” the wound. If Dr. Kim is unhappy with the wound’s healing progression, he will change the BAT product to another. Dr. Kim lets smaller wounds heal by secondary intention. When it comes to a wound with a large surface area and a nice granular bed, Dr. Kim says he will apply a STSG.
Initially, Dr. Miller tends to use less expensive products. He says offloading is key and also cites the basic tenets of wound care (i.e. frequent debridement, keeping the wound moist, etc.) and good glycemic control. If a patient does not respond or plateaus, Dr. Miller reassesses the patient and tends “to go to a more advanced product.”

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