The mesenchymal substrate influences the epithelial phenotype in a three-dimensional cell culture

Cell-matrix interactions are thought to influence epithelial structure, growth, and differentiation. Three-dimensional cell cultures were used to study the effects of the composition of the dermal equivalent on the morphology of epithelium grown from HaCaT skin keratinocytes. Three commercial preparations, a basement membrane preparation from a tumor (matrix 1), two preparations consisting of collagen type I and III (matrix 3 and 4) and a noncommercial preparation containing collagen type I (matrix 2) were investigated. The effects of fibroblasts of different origin (vaginal mucosa, oral buccal mucosa, and skin) were investigated in connection with matrix 4. The histomorphology and expression of the proteins PCNA, Ki-67, p53, p21, pankeratin, involucrin, cytokeratin 10 (Ck10), Ck17, Ck19 and collagen type IV were evaluated. Three-dimensional cultures of HaCaT cells gave rise to an epithelium with an immature and hyperproliferative character, showing active proliferation with intense PCNA staining. Both matrix 1 and matrix 2 resulted in an epithelium with budding into the matrix and some degree of layering. These epithelia showed only scattered Ck17 and Ck19 expression but a low terminal differentiation potential as indicated by scattered Ck10 and involucrin staining. The epithelia of cocultures with matrices 3 and 4 were positive for Ck17 and Ck19. However, the epithelium on matrix 3 showed strong expression of the terminal differentiation marker Ck10 and involucrin. This methodological study provides evidence of the importance of standardization of the composition of the matrix to avoid confounding effects on epithelial morphology and protein expression in studies using a three-dimensional epithelial culture model.