Characterization of the Palatal Mucosa of Cleft Palate Patients

Objectives: To characterize the different types of epithelium in the region of the palatal cleft. The surgical closure of a palatal cleft is complicated by a shortage of mucosal tissue. This problem may be solved by the development of tissue engineered substitutes with autologous cells. We started this approach by characterizing the palatal mucosa of cleft palate patients. Methods: Patients with a non-syndromic palatal cleft (1-2 yr old) were selected. During surgery, samples from the hard palatal mucosa were obtained with a 3-mm biopsy punch and from the cleft region by excision. Sections were stained with H&E for a general tissue survey. Immunostaining was performed for the following antigens: cytokeratins (CK) 7, 8, 10, 16 and 18, and the basal membrane markers heparan sulphate (HS) and collagen type IV (COL IV). Results: The epithelium of the mucoperiosteum of the hard palate is orthokeratinized, multilayered and stratified (CK10+, 16+). The soft palatal mucosa at the margin of the cleft resembles both oral and nasal mucosa. At the oral side a non-keratinized epithelium is found (CK4+, CK13+). At the nasal side fewer cell layers are present and the keratinocytes are more ovoid (CK7+, CK8+, CK18+). Also, higher numbers of inflammatory cells are present and a lower expression of HS and COL IV is found in the basal membrane. Conclusions: The margin of the cleft presents a unique type of epithelium showing a clear transition from an oral type to a more nasal type. The specific properties of the marginal epithelium may underlie the impaired fusion of the palate. This study was supported by the Royal Academy of Sciences (KNAW)of the Netherlands.