Implantation of tissue-engineered mucosal substitutes in the dog palate

Tissue shortage complicates the surgery of cleft palate (CP) anomalies. The healing of defects on the palate impairs growth of the dento-maxillary complex due to scar tissue formation. Implantation of grafts into the wound area might reduce this adverse effect of surgery. The aim of this study was to evaluate a cultured autologous mucosal substitute, which can be used as a graft material. Two different types of cultured mucosal substitutes composed of skin-derived substrates (unprocessed dermis and AlloDerm) and autologous oral keratinocytes were implanted in palatal wounds in six beagle dogs (1-1.5 years of age). The cultured substitutes were compared with a sham and a control group. The animals were sacrificed in pairs 1, 3, and 12 weeks after surgery. Epithelial regeneration, inflammatory response (leucocyte protein L1), ingrowth of (myo-) fibroblasts, collagen type III, and formation of a basal membrane (JM 403) were evaluated. The results demonstrated that all cultured substitutes possessed a multilayered epithelium, closely resembling normal palatal epithelium. After implantation, however, the epithelium was lost and an inflammatory response was observed in the first week. After 3 and 12 weeks, the implanted substitutes had completely disappeared and epithelial migration occurred from the wound margins. It is possible to culture an autologous epithelium on a skin-derived substrate and implant it as an oral mucosal substitute in palatal wounds. However, these substitutes do not improve the healing of palatal wounds. It is suggested that the revascularization of the wound area is too slow to allow survival and integration of the substitutes.