Growth of ameloblast-lineage cells in a three-dimensional Matrigel environment

Enamel organ epithelial cells grow in culture as two distinct cell populations – either stellate‐shaped or polygonal‐shaped cells. The polygonal cells have an ameloblast cell phenotype and are difficult to grow in culture beyond two passages. This study was designed to determine the effects of a Matrigel three‐dimensional (3D) environment on polygonal cells, as compared with stellate cells, derived from porcine tooth enamel organ. Enamel organs were dissected free from the unerupted molars of 30‐kg pigs and then grown in LCH‐8e media, either with or without serum. Cells grown in serum‐free media were primarily polygonal shaped, whereas cells grown in media containing serum were stellate shaped. Both types of cells were grown in a 3D Matrigel matrix. In addition, polygonal‐shaped cells were mixed with hydroxyapatite powder and transplanted subcutaneously into nude mice. Polygonal‐shaped epithelial cells formed cell groups, similar to epithelial pearls, both in vitro and in vivo. The stellate‐shaped cells, in contrast, did not form similar structures, but remained suspended in the Matrigel and gradually disappeared from the culture. These results suggest that a Matrigel environment, rich in basement membrane and matrix proteins, selects for polygonal‐shaped ameloblast‐lineage cells and induces the formation of epithelial pearls.