Determination and Comparison of the Characteristics of Mesenchymal Stem Cells from Pulp of the Milk Teeth of Children of Different Sex

Abstract

Two new nonimmortalized fibroblast-like cell lineages (MSC-DP-1 and MSC-DP-2) isolated from the pulp of milk teeth of two 6-year-old children of different sex were obtained and characterized. The status of mesenchymal stem cells was confirmed by comparative analysis of a number of characteristics of these cells at early and late passages. The long-term cultivation revealed significant interstrain differences in growth characteristics and replicative senescence (RS). The MSC-DP-1 cells were characterized by a later entry into the MS active stage and more active proliferation compared to MSC-DP-2 cells. Karyotypic analysis showed that both lineages at early passages have a normal human diploid karyotype. Late (18th passage) in the stage of active RS, MSC-DP-2 cells retain the normal karyotype. MSC-DP-1 cells, which enter the active RS much later (at the 42nd passage), had an abnormal karyotype with a large the number of clonal and nonclonal chromosomal rearrangements. Both lineages showed a high proportion of cells carrying surface antigens characteristic of human MSCs—CD44, CD73, CD90, CD105, and HLA-ABC—and a low frequency of cells with CD34, CD45, and HLA-DR antigens. Cells of both lineages at an early passage demonstrated the ability to differentiate in the adipogenic, osteogenic, and chondrogenic directions. However, MSC-DP-2 cells showed a weaker differentiation capacity in the adipogenic direction than MSC-DP-1 cells. During RS, adipogenic differentiation in MSC-DP-1 cells is significantly weakened, while in MSC-DP-2 cells it disappeared. The activity of other differentiations did not change during RS. In general, the results obtained confirmed the MSC status of obtained lineages and revealed interlineage differences in the RS. However, the comparison with the previously obtained MSC-DP lineages did not indicate a gendered nature of the observed differences between these cells. Apparently, they are associated with the genetic characteristics of different donors.