Immunohistochemical study during healing of free palatal mucosa grafts on plastic-embedded samples

This immunohistochemical study describes changes in the histology and in th e distribution of the basement membrane components laminin and collagen IV as well as of the cytokeratins (CK)1/2/10/11, CK5/6, CK13, CK14, CK17, CK19 during the take of free split mucosa (epithelial and connective tissue) tr ansplants in humans up to 36 months post-operative. Histology showed a flat tening of the epithelial layer within the first 2 weeks after grafting, fol lowed initially by an increase (25-30 layers, week 6) and later on by a dec rease of cell layers in the epithelium (15-20 layers, week 20). From that t ime onwards, clear stratification and reteridges as signs of differentiatio n were present. Up to day 14 of graft take, the linear staining patterns fo r laminin and collagen IV were interrupted, which was not observed at any l ater stage. During this early interval CK5/6, CK1/2/10/11, CK14 and CK17 we re expressed in all epithelial layers. The reactions for CK5/6 and CK1/2/10 /11 were less intensive. At 6 weeks, CK1/2/10/11 stained the intermediate a nd superficial layers, being consistent with findings after longer graft ta ke. CK5/6 reacted in the basal and intermediate cell layers, and CK13, CK14 and CK17 reacted in all layers. In the following period up to week 20, CK5 /6 were found in the parabasal cells of the intermediate cell layers and th e basal cells. CK14 staining was confined to these cell layers too, but als o showed some reaction in the superficial layers. CK13 and CK17 were still bound to all layers. At 7 months post-operative, CK5/6 and CK14 were seen i n their typical localisation in the basal cell layer and the parabasal cell s of the intermediate layers, CK17 was seen mainly in the intermediate laye r and CK13 was seen in focal areas of all layers. Anti-CK19 reacted only wi th single basal and parabasal cells up to week 20. These results suggest th at during healing of mucosal autografts there is a sequence of changes in t he expression of cell biological differentiation markers that may involve a n epithelio-connective tissue interaction before the typical patterns for t he donor side were observed again on the gingiva or mucosa of the hard pala te.