Abstract
The aims of the current study were to determine whether side population (SP) cell selection is possible, to show an efficient approach for purifying rat dental pulp (DP) and dental germ (DG) stem cells, and to compare phenotypic differences with bone marrow SP cells. SP cells, isolated from murine adult incisor DP and DG based on exclusion of the DNA dye Hoechst 33342, exhibited potent stem cell activity compared to main population cells. Both bone and dentin are mineralized tissues and are structurally similar. However, in contrast to bone marrow stem cells, DP stem cells do not support establishment of hematopoietic marrow. To investigate whether the phenotype of DP or DG SP cells is distinct from bone marrow SP cells, we used FACS to isolate SP cells from biologically distinct tissues (bone marrow, DP and DG) and characterized expression of several surface marker genes. Direct comparison of surface marker expression on SP cells isolated from different tissues identified surface markers common to dental tissue SP cells as well as those specific to bone marrow SP cells. FACS analysis of specific differentiation markers confirmed the similarity of surface marker expression between bone marrow SP cells and DG SP cells. However, marker expression in DP SP cells was considerably different from that in bone marrow SP cells. Because these tissues consist of multiple types of cells, heterogeneity of these tissues might explain the differences in surface marker profiles. We concluded that isolating DP SP cells with a phenotype that is distinct from that of bone marrow SP cells is possible.
