Growth peptide release from biologic dressings: a comparison

Biologic dressings are believed to stimulate wound healing in a variety of wound types. Cryopreserved allograft skin (CAS) is used as a biologic dressing for excised wounds, partial-thickness wounds, and meshed split-thickness skin grafts, and the use of allogenic or autologous cultured epithelial sheets (CES) has been reported to enhance healing of skin ulcers and deep partial-thickness wounds. However, limitations of allograft skin include bacteriologic and viral safety, limited availability, cost, and ease of handling. Previously we have reported the successful use of human keratinocytes cultured to single-layer confluence on Hydroderm polyurethane membranes (HD/HK) for grafting of full-thickness wounds. In this study we evaluated the release of five different growth peptides (transforming growth factors alpha and beta (TGF-alpha, TGF-beta), interleukin-6, interleukin-8, and melanoma growth stimulatory activity from CAS, CES, and HD/HK grafts. Highest levels of TGF-alpha were found for HD/HK (728 +/- 115 pg/10 cm2 of membrane) followed by CES (491 +/- 137 pg/10 cm2; NS). No TGF-alpha was detectable for CAS, and 3.7-fold, and 25-fold higher levels of interleukin-6 were found for CES (257 +/- 12.7 U/10 cm2) compared with HD/HK and CAS, respectively. Interleukin-8 had similar levels for CES (0.65 +/- 0.7 ng/10 cm2) and HD/HK (0.88 +/- 0.12 ng/10 cm2), whereas melanoma growth stimulatory activity was elevated in CES (2314 +/- 97 pg/10 cm2) compared with HD/HK (1071 +/- 55 pg/10 cm2). TGF-beta was barely detectable for CES and HD/HK. Cryopreserved allograft showed high levels of TGF-beta (5.2 +/- 1.6 ng/10 cm2). Overall mitogenic activity of the supernatants on keratinocyte cultures was assessed. Highest proliferation was seen for CES supernatants followed by HD/HK (NS). Supernatants from CAS had an antiproliferative effect on keratinocytes. We conclude that a single layer of keratinocytes cultured on a polyurethane membrane facilitates keratinocyte proliferation similar to CES, whereas cryopreserved allograft has no mitogenic effect on keratinocytes.