Effect of Allogenic Bone Marrow Mesenchymal Stem Cell Transplantation on T Cells of Old Mice

To evaluate age-related changes in T cells and stem cell-related genes in mice and the changes in T cells and stem cell-related genes after allogenic bone marrow mesenchymal stem cell (BMSC) transplantation, BALB/c mice were divided into young (2 months, n=5) and old (20 months, n=5) groups and 1x10(7) BMSCs from 3-week-old C57BL/6J mice were injected into the old mice (n=5). T lymphocytes including CD3(+), CD8(+), CD8(+)CD28(+), and CD8(+)CD44(low)CD62L(high)Sca-1(+) stem cell-like memory T cells from spleens were analyzed by flow cytometry. mRNA transcriptions of the tumor suppressor p16(INK4A) and the senescence inhibiting AUF 1 and stem cell-related ADAM12, GIL3, c-MYC, NANOG, Wnt, HOX11, Sox2, Oct3/4, and KLF4 genes were analyzed by quantitative reverse transcription-polymerase chain reaction for comparison between young and old mice and old mice after BMSC application. Stem cell-related genes were reduced transcribed in old mice, an action that could be partly or completely reversed for some genes by BMSC injections. The proportion of CD8(+)CD28(+) T cells in the spleens of old mice was significantly reduced (p<0.01), indicating advanced proliferative T cell senescence. The CD8(+)CD44(low)CD62L(high) cell fraction was significantly reduced and that of CD8(+)CD44(low)CD62L(high)Sca-1(+) increased in splenic CD8(+) cells of old mice, both actions of which were reversed by BMSC injections. p16(INK4A) transcription was enhanced and AUF1 transcription was reduced in old mice, the latter effect partly reversed by BMSC injections. BMSC injections led to recovery of stem cell-related gene activation or BMSC stem cell-related gene expression tolerance in spleens of old mice.