Development and Characterization of a Tissue-engineered Human Oral Mucosa Equivalent Produced in a Serum-free Culture System

A problem maxillofacial surgeons face is a lack of sufficient autogenous oral mucosa for reconstruction of the oral cavity. Split-thickness or oral mucosa grafts require more than one surgical procedure and can result in donor site morbidity. Skin has disadvantages of adnexal structures and a different keratinization pattern than oral mucosa. In this study, we successfully assembled, ex vivo, a human oral mucosa equivalent, consisting of epidermal and dermal components, in a defined, essential-fatty-acid-deficient, serum-free culture medium without a feeder layer, that could be used for intra-oral grafting in humans. Autogenous oral keratinocytes were seeded onto a cadaveric dermis, AlloDerm. The oral mucosa equivalent was cultured at an air-liquid interface for 2 wks. The resulting equivalent had a well-stratified parakeratinized epithelial layer similar to native oral keratinized mucosa. Expression of differentiation markers, filaggrin and cytokeratin 10/13, suggested a premature keratinized state. The presence of proliferation markers, proliferating cell nuclear antigen (PCNA) and Ki-67, suggested a state of hyperproliferation. Fatty acid composition of the equivalent was similar to that of in vitro cultured oral keratinocytes but differed from the that of in vivo native tissue, showing a lower content of 18:2 and 20:4, and a higher content of 16:1 and 18:1 fatty acids, respectively. The keratinocytes of the equivalent appeared to be in a more active and proliferative state than native keratinized mucosa. The dynamic nature of the cell population on the oral mucosa equivalent may be beneficial for intra-oral grafting procedures and for transfection of the keratinocytes.