Rescue of th3 HSC impaired repopulating potential by transplantation into a normal BM niche. (A) Experimental scheme of primary and secondary competitive BMT. Transplantation of Lin⁻ BM cells from th3 CD45.2 and WT CD45.1 mice at a 1:1 HSC ratio into lethally irradiated WT and th3 CD45.1 animals. One year after primary BMT, total BM cells from WT mice were transplanted into both WT and th3 lethally irradiated secondary recipients. (B) Peripheral blood (PB) chimerism of th3 and WT cells in WT and th3 recipient mice at 12 months after primary BMT. WT, n = 13; th3, n = 8. Notation inside the bars refers to differences between WT and th3 competitor cells into the same recipient. (C) Cell cycle analysis on th3 and WT grafted HSCs from WT and th3 primary recipients. Frequencies of G0/G1 phase HSCs are reported. WT, n = 5; th3, n = 3. (D) PB chimerism of th3 and WT cells in WT (left) and th3 (right), observed for 6 months after secondary competitive BMT. WT, n = 6; th3, n = 3. (E) Analysis of cell cycles of th3 and WT HSCs transplanted in secondary WT recipients. WT, n = 3; th3, n = 3. *P < .05; **P < .01; NS, nonsignificant.