Primary culture and characterization of enamel organ epithelial cells.

The cells of the enamel organ are programmed by signals such as growth factors and extracellular matrix components to differentiate and form dental enamel. To study how the enamel organ epithelial cells control enamel development, we have begun to characterize a primary porcine enamel organ epithelial cell culture system. The unerupted molars of 3 month old pigs were isolated, the cells were digested into a single cell suspension and grown in media either with or without serum. Expression of amelogenin and ameloblastin mRNA was monitored by RT PCR, and protein secretion was identified by immunohistochemistry. Cells grown in MEM formed a mixed cell population of epithelial- and fibroblast-like cells which grew past confluence, formed nodules, mineralized, and expressed low levels of amelogenin and ameloblastin protein. In LHC-9 media, which is selective for epithelial cells, the cells did not grow past confluence but secreted amelogenin and ameloblastin proteins more strongly. Cell viability was maintained in both serum-free and serum-containing media. However, in the serum-free media, cell proliferation proceeded slowly. Although cells grown in MEM mineralized, the mixed cell population may make studies of specific ameloblast-like cells more difficult. However, cells grown in a culture media selective for epithelial cells will require modifications such as cell immortalization to allow long term studies of cell regulation and interaction. In summary, we have established an enamel organ epithelial cell culture system which will enable us to study the role of ameloblasts in enamel matrix formation, ameloblast regulation, as well as cell-matrix interactions. Selection of specific culture conditions will depend on the questions being addressed in individual studies.