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Human Skin Equivalent, Apligraf. — Cellular technology benefits wound repair
Indications for Use
Apligraf® represents the culmination of several recent advances in tissue culture techniques.2 It has been engineered using serially passaged human epidermal keratinocytes and human dermal fibroblasts, cells obtained from neonatal foreskin, with a matrix of acid dissociated type I bovine collagen. The overlying epidermis is developed on the surface of the dermal matrix and when a monolayer of epidermal cells is formed, the HSE is raised to the air-liquid interface to generate a protective cornified layer. Serum is not necessary for the development of the epidermis. HSE is strong and has handling characteristics similar to split-thickness skin allowing it to be meshed, stapled, and sutured.4
Clinical Studies in Venous Ulcers
Interim results from a prospective, controlled, parallel group, multicentre trial in 233 patients with venous ulcers are interesting.1 All patients entered into this trial had failed on previous venous ulcer treatments, the median duration of ulcers was approximately one year, and the median size of the treated ulcers was approximately 400 mm.4
Weekly visits for eight weeks with one mid-week visit the first week. Patients received up to five applications to their venous ulcers during the first three weeks of treatment. The Apligraf® was held firmly in place with a multilayered compression wrap and the active control group also received a multilayered compression bandage. After eight weeks, patients were placed in elastic stockings. If healing had not occurred, the bandaging technique was continued for up to six months. All patients were followed for one year with visits scheduled at three-month intervals.2,4 Practical details on how best to use this new product are important and will be detailed in Part II of this article in the next issue of the Letter.
Median time to 100% wound closure was 57 days with active treatment versus 181 days for standard care (P=0.0066). Of the 127 actively treated patients, 78 (64.1%) achieved complete wound closure, while only 47 of 109 (44.3%) of the control patients achieved 100% closure (P=0.012).1
Mechanism of Action
Unknown, but contact between the wound bed and human fibroblasts in the dermal layer of HSE seems to send out physiologic signals for wound repair.3 In many patients, HSE promotes new tissue growth at the wound edge. In others, it appears to take like any graft, rapidly integrating into surrounding tissue. Over time, HSE is replaced by the patient’s own skin cells.3
Clinical trials have found no sign of toxicity in over 352 HSE treated patients, and there have been no reports of allergic reactions or immunological responses with initial or repeated use.3 This product is said to have a safety profile similar to traditional wound-healing methods. Both the maternal donor blood and donor cells from neonatal foreskin are meticulously screened and certified free of CMV, hepatitis A, B and C, Epstein-Barr virus, and other infectious agents.3
Novartis have worldwide marketing rights. The cost of a 7.5 cm round disk will be approximately $950 Canadian. Usually only one treatment is needed.
HSE has a number of clinical advantages. Unlike much autografting, treatment with HSE does not necessitate hospitalization,3 and unlike other bioengineered skin alternatives, HSE has a well-defined stratum corneum. HSE contains both dermal fibroblasts and an epidermal sheet, with their commensurate cytokine and growth factor capabilities and natural biologic interaction. It also provides a collagenous matrix and a natural protective covering, the stratum corneum. It therefore has the potential to not only promote healing via different mechanisms (primary take, protective covering, growth factors2) but also serve as a source of new tissue.4
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Last modified: Friday, 11-Dec-2015 14:45:52 MST