FIGURE 1. The establishment of reversibly immortalized umbilical cord-derived mesenchymal stem cell (UC-MSC) lines through piggyBac transposon-mediated expression of SV40 T antigen.
(A) Representative images of primary UM-MSCs derived from donors #79 (UC79) and #86 (UC86). Representative images of passage #3 cells are shown. (B) Schematic representation of the piggyBac transposon-based immortalization vector MPH86 as described in Refs. #11, 18. (C) Establishment of the immortalized UC-MSC lines iUC79 and iUC86. Primary UC-MSCs from the two donors were co-transfected with MPH86 and pCMV-PBase and selected in the presence of hygromycin. Clonal growth was visible after one week (a & b). The resultant stable pools, namely iUC79 and iUC86, can be passaged for long-term maintenance in culture. Representative images of passage #5 are shown (c & d). (D) Detection of SV40 T antigen expression in the immortalized lines. Subconfluent iUC79 and iUC86 cells and the respective primary cells were lysed in Laemmli sample buffer and subjected to Western blotting analysis with SV40 T antigen or β-actin (loading control) antibody. Representative results are shown.