Autologous Cultured Skin Substitutes Conserve Donor Autograft in Elective Treatment of Congenital Giant Melanocytic Nevus

Abstract

Giant congenital melanocytic nevi, or bathing trunk nevi, have challenged reconstructive surgeons for many years. These large lesions can cover more than 50 percent of the total body surface area and have a lifetime risk of malignant degeneration of approximately 5 percent. 1-4 Histologically, nests of melanocytes may be found extending into the deep dermis and the subcutaneous layer. To completely eradicate these potentially malignant cells, surgeons must excise the lesions to the level of the muscle fascia. 5,6 Traditional modalities used to manage large nevi include serial excision and skin grafting. Serial excision, although an effective technique that minimizes scarring, is limited by finite skin elasticity and scar spread. Alternatively, skin grafts provide a readily available, autologous tissue for wound coverage. Donor sites from split-thickness skin graft harvesting, however, are prone to hypertrophic scarring in the pediatric population and are also very painful. Skin grafts can typically be expanded two to three times by meshing to reduce donor-site size, but the cosmetic result is poor. 2,5,7 Even if expanded grafts are used, extensive donor sites are required to treat some of the larger congenital nevi. In an attempt to avoid such large, unsightly, and painful donor areas, surgeons adopted tissue expansion technology. Tissue expanders are prosthetic devices that gradually stretch the surrounding normal skin to provide tissue for wound coverage. 8,9 The expanded skin is fullthickness, well-vascularized tissue that provides a good color and texture match. It is more aesthetically appealing than split grafts because scarring is limited to linear incisions as opposed to large areas of donor sites. The expanded flaps also contain subcutaneous adipose tissue and therefore provide a more natural contour and appearance. Tissue expansion does, however, have its limitations. Skin can be stretched up to approximately five times its area, and it cannot always reach distant sites. Skin expanders also require multiple procedures under general anesthesia and carry the significant risks of expander exposure or infection. Frequent office visits are needed during expansion for prosthesis inflation. Closure of the excised lesion may be performed effectively with tissue expanders for small lesions. The time required to inflate tissue expanders and the limited area of expansion reduce their effectiveness and increase risks of morbidity in large lesions. 6,8,9 Expanders also have unacceptably high complication rates when used on the extremities or in the perineum. Because of these limitations, traditional split-thickness skin grafting techniques remain an acceptable alternative despite the resultant donor-site morbidity. 8,9 Although attempts have been made in the past to use cultured keratinocytes in monolayer for wound coverage, the results were clinically unacceptable. These monolay-

Advances in Skin Regeneration Using Tissue Engineering

“…Tissue engineered skin provides both epidermal and dermal components required to achieve functional wound closure and have therefore been used to effectively close full-thickness burn wounds and treating burns that are greater than 50% of the total burn surface area (TBSA) [7,46,53,54]. The presence of a large number of cells, especially stem cells, in tissue engineered skin enables regeneration of native-like skin in burn patients.…”

Pediatric Thermal Injury: Acute Care and Reconstruction Update

“…Donor-site reharvest will be required in the absence of access to cultured skin substitutes. 16 Donor autograft must therefore be harvested more thinly to shorten time to donor reharvest. Unfortunately, wounds covered with either meshed autograft or reharvested donor skin may give less than optimal scarring results; however, this is a secondary consideration to achieving wound healing, reducing patient immobilization, and ensuring survival.…”

Differential Expression of Matrix Metalloproteinase-1 in Vitro Corresponds to Tissue Morphogenesis and Quality Assurance of Cultured Skin Substitutes1

“…Previous studies from this laboratory have reported the regulation of keratinocyte proliferation and barrier formation in skin substitutes by addition of vitamin C to the culture medium [14], generation of pigmentation by addition of selective cultures of epidermal melanocytes to CSS [15], formation of vascular analogs by addition of dermal microvascular endothelial cells to CSS [16], and successful grafting of autologous CSS for closure of full-thickness burns [17][18][19], reconstructive surgery [20], or chronic wounds [21]. In selected patients, it was observed that CSS in vitro demonstrated premature degradation of the collagen and chondroitinsulfate substrate during the maturation phase of the CSS incubation.…”