Background and objective: An ex vivo -produced oral mucosa equivalent (EVPOME) is composed of a stratified layer of human oral keratinocytes seeded onto a human acellular dermis, AlloDerm ^® . Our preliminary clinical study showed the EVPOME grafts had enhanced maturation of the underlying submucosal layer associated with rapid epithelial coverage. Results of our animal study suggested that grafting of the EVPOME onto an oral wound promotes re-epithlialization of oral mucosa in the healing process. The objective of the present study was to investigate the change in the basement membrane of EVPOME during the healing process after intraoral grafting in athymic mice.

Materials and methods: Human oral keratinocytes were cultured and seeded on AlloDerm ^® for the fabrication of EVPOME. The buccal mucosa of 5-week-old athymic mice was resected and EVPOME was grafted on the defect. For a control, AlloDerm ^® alone was grafted instead of EVPOME. The grafted EVPOMEs were excised at 5, 7 14 and 21 days postgrafting and examined histologically and immunohistochemically for type IV collagen and laminin to identify the basement membrane of EVPOME or mouse mucosa and for cytokeratin 17 (CK17) to identify human cultured epithelial cells.

Results: The grafted EVPOME maintained both a CK17-immunopositive epithelium and type IV collagen-immunopositive, laminin-immunonegative basement membrane for up to 5 days postgrafting. By day 7 postgrafting, a portion of the EVPOME epithelial layer had peeled away from AlloDerm ^® with maintenance of the basement membrane. A thin CK17-immunonegative epithelial layer with type IV collagen immunopositivity underneath extended from the adjacent thick epithelial layer of the mouse. On day 21, the CK17-immunonegative continuous epithelium with laminin immunopositivity underneath that increased in stratification showed an appearance similar to that of the adjacent mouse mucosa.

Conclusions: The findings suggest degradation and rearrangement of the basement membrane during the healing process after intraoral grafting of EVPOME.

Key words: oral mucosa; tissue-engineering; wound healing