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

The aim of this study was to determine the optimal stage of development at which transplant hu-man ex vivo-produced oral mucosa equivalents (EVPOMEs) in vivo. EVPOMEs were generated in a serum-free culture system, without the use of an irradiated xenogeneic feeder layer, by seeding human oral keratinocytes onto a human cadaveric dermal equivalent, AlloDerm. EVPOMEs were cultured for 4 days submerged and then for 7 or 14 days at an air–liquid interface to initiate strat-ification before transplantation into SCID mice. AlloDerm, without epithelium, was used as a con-trol. Mice were killed on days 3, 10, and 21 posttransplantation. Epithelium of the transplanted EVPOMEs was evaluated with the differentiation marker keratin 10/13. Dermal microvessel in-growth was determined by immunohistochemistry with a mouse vascular marker, lectin binding from Triticum vulgaris. The presence and stratification of the epithelium were correlated with revas-cularization of the underlying dermis. The microvessel density of AlloDerm without epithelium was less than that of EVPOMEs with an epithelial layer. Microvessel density of the dermis varied di-rectly with the degree of epithelial stratification of the EVPOMEs. The EVPOMEs cultured at an air–liquid interface for 7 days had the optimal balance of neoangiogenesis and epithelial differenti-ation necessary for in vivo grafting. 16