Multilineage Cells from Apical Pulp of Human Tooth with Immature Apex

The human tooth with immature apex is a developing organ available for investigation. In this tooth, especially in the apical pulp, the proliferation and differentiation of various cells are activated to make a complete tooth. We investigated the notion that unique cells are included in the apical pulp of human tooth with immature apex. Human impacted third molars with immature apex freshly extracted for orthodontic reasons or treatment were obtained. Histological analyses revealed that BrdU-incorporating cells and cells positive for the mesenchymal stem cell markers SH2 and SH3 were located in the same region. The cells from the apical pulp of a human tooth with immature apex, designated here as apical pulp-derived cells (APDCs), can be cultured easily in vitro under ordinary serum-supplemented culture condition. The expression of surface markers of expanded APDCs is similar to that of bone marrow mesenchymal stem cells, except for CD49d (α4-integrin). APDCs differentiated into mineralized cells, adipocytes, chondroblasts and neural cells in vitro. APDCs have a high capacity for proliferation and multilineage potential in vitro. Our results indicate that human tooth with immature apex is a precious tissue source for the research of human adult stem cells and for the advancement of dental and regenerative medicine.