Isolation and Comparative Characteristics of Mesenchymal Stem-Cell Lines Derived from Foreskin of Two Donors of Similar Age

Two new nonimmortalized human cell lines FRSN-1 and FRSN-2 were established from foreskin of two similarly aged donors (2.5 years). Growth characteristics and differentiation potential of these cell lines studied on the sixth passage confirmed their status as mesenchymal stem cells (MSCs). A number of characteristics have been analyzed during long-term cultivation up to the 26th passage. The dynamics of the process of replicative senescence defined by the activity of β-galactosidase differed between these lines. However, at the 26th passage, the process of replicative senescence was equally enhanced in both lines. The plating efficiency markedly differed between the lines on the sixth passage. In FRSN-1, it was higher than in FRSN-2. The plating efficiency substantially dropped to the 26th passage in FRSN-1 and was lost in FRSN-2 line. Growth curves showed active proliferation of these lines at the 6th passage. The average doubling time did not differ between the lines and was 36.9 and 39.0 h, respectively. Analysis of growth curves on the 26th passage revealed a decline in proliferative activity and increase in average doubling time of cell populations in both lines, more in FRSN-2 than in FRSN-1 lines. The patterns of growth curves differed in these lines. Morphological analysis revealed increased cell size and spreading typical for the phase of the replicative senescence. Numerical and structural karyotypic analysis at the sixth passage showed that both lines have normal karyotype 46, XY. We did not discover interline differences in the frequency of chromosomal aberrations. To determine the status of these cell lines, comparative analysis of the surface markers was performed using flow cytometry. It was revealed that cells of both lines expressed surface antigens characteristic of human MSCs: CD44, CD73, CD90, CD105, and HLA-ABC and did not express CD34, CD45 and HLADR. Cells of both lines displayed SSEA-4 and SOX2, markers of human embryonic stem cells (ESCs). Expression of SSEA-4 was also detected at the 26th passage in both lines. FRSN-1 and FRSN-2 cells expressed the markers of early ESC differentiation into three germ layers. The ability of these cell lines to differentiate into osteogenic, chondrogenic, and adipogenic lineages was shown on the sixth passage. Both lines exhibited substantially reduced adipogenic potential on the 20th passage. These data indicate that in contrast to growth characteristics the adipogenic differentiation potential changes even with an average degree of replicative senescence. It appears that the cell replicative senescence contributed to the change in MSC differentiation potential. Overall, the results demonstrate that cell lines derived from different donors are distinguished in growth characteristics and pattern of replicative senescence. The disparity is due to a direct genetic influence and indirectly by different microenvironment in their donor organisms before cell isolation.