Recombination of epithelial root sheath and dental papilla cells in vitro.

Hertwig's epithelial root sheath (HERS) cells were isolated and recombined with ectomesenchymal cells in vitro utilizing extracellular matrix components as substrate. After 14 days in culture, HERS cells were differentiated and exhibited a stratified organization. These features resembled those observed in vivo as epithelial rests of Malassez. A mineralization process was also present in HERS cells, in which calcium salts were deposited. This mineralization was correlated with the strong immunoexpression of osteopontin by HERS. The results obtained add support to the possible role of HERS in the secretion of hypocalcified material on the root during early cementogenesis.