Immunohistochemical distribution of keratin proteins in human gingival heterotransplants in nude mice.

Clinically healthy human gingivae from deciduous molar regions were transplanted to subcutaneous sites of nude mice (nu/nu NC). Transplants were harvested after posttransplantation periods of 5, 6, 7, 8.5, 10.5 and 12 weeks and examined histologically after staining with hematoxylin-eosin (H.E.), bisbenzimide, and a panel of mouse monoclonal anti-keratin antibodies in an indirect fluorescence technique. Central parts of transplants contained human connective tissue covered by human stratified squamous epithelium which were unkeratinized in 5- to 7-wk-old transplants and most frequently (75%) parakeratinized in 8.5-wk to 12-wk transplants. Comparison of keratin expression before and after transplantation revealed a progressive keratin reconstitution, i.e., keratin markers of basal/suprabasal cells preceded those of suprabasal/spinous cell layers and immunohistochemical markers of keratinization preceded routine histologically observed parakeratinization. Original keratin staining and essential features of histodifferentiation were reconstituted and maintained after 8.5 wk but graft recovery rate decreased drastically 12 wk after transplantation. This study shows that the human gingiva/nude mouse model is useful in experimental studies of the gingival keratin profile in the period 8.5 to 10.5 wk after transplantation.