Organized Skin Structure Is Regenerated In Vivo from Collagen-GAG Matrices Seeded with Autologous Keratinocytes

Abstract

A well-characterized collagen-glycosaminoglycan matrix (CGM) that has been shown to function as a dermal analog was seeded with freshly disaggregated autologous keratinocytes and applied to full-thickness wounds in a porcine model. CGM were impregnated with 50,000 keratinocytes per cm2, a seeding density that produces a confluent epidermis within 19 d post-grafting and affords a 60-fold surface expansion of the donor epidermis. In this study, the temporal sequence of events in epidermal and neodermal formation was analyzed histopathologically and immunohistochemically from 4 to 35 d post-grafting. The epidermis was observed to form from clonal growth of individual keratinocytes into epithelial cords and islands that gradually enlarged, coalesced, differentiated to form large horn cysts, and finally reorganized at the graft surface to form a fully differentiated, normally oriented epidermis with rete ridges. Simultaneously, a neodermis formed from migration of endothelial cells, fibroblasts, and macrophages into the CGM from the underlying wound bed, resulting in formation of blood vessels, the production of abundant extracellular matrix, and the degradation of the CGM fibers, respectively. Gradually, the stromal cellularity of the CGM decreased and collagen deposition and remodeling increased to form a neodermal connective tissue matrix beneath the newly formed epidermis. Complete dissolution of the CGM occurred, partly as a result of degradation by an ongoing foreign-body giant cell reaction that peaked at 8-12 d post-grafting, but neither acute inflammation nor evidence of immune stimulation were observed. Within 1 mo, many structural components of normal skin were reconstituted.

Similarities and differences between induced organ regeneration in adults and early foetal regeneration

“…Detailed examples of induced skin regeneration have been described elsewhere (Yannas et al , 1982(Yannas et al , 1984Murphy et al 1990;Ferdman & Yannas 1993;Butler et al 1998Butler et al , 1999Compton et al 1998). The data describe the structural and functional similarities and differences among normal skin, scar and regenerated skin in the adult guinea pig and the swine following grafting of dermis-free defects with the keratinocyte-seeded dermis regeneration template (DRT), a scaffold characterized by unusual regenerative activity.…”

A novel collagen scaffold supports human osteogenesis—applications for bone tissue engineering

“…One potential substitute is type 1 collagen glycosaminoglycan (CG) based scaffolds which have been successfully used in a clinical setting as viable treatments for conjunctiva and epithelial regeneration (Yannas, 2001;Hsu et al, 2000;Compton et al, 1998). Much of this success is due to a number of useful properties including low antigenicity, biodegradability, high porosity and a high ligand density (O' Brien et al, 2005).…”

Evaluation of Transplanted Tissue-Engineered Oral Mucosa Equivalents in Severe Combined Immunodeficient Mice

“…5,6 To overcome these adverse events, artificial dermal substitutes have been used to assist in keratinocyte growth. [7][8][9][10][11][12] One dermal analog used for treatment of full-thickness wounds is an acellular human cadaver dermis, AlloDerm (LifeCell, Branchburg, NJ).…”