FIGURE 6.

Arrested HSCs are viable and retain their potential to sustain hematopoiesis. (A) Schema of secondary HCT experiment: BALB.K mice (H2^k; primary [first] recipient) received AKR/J HSC+CD4_conv grafts (H2^k; primary donor). On day 14 (d14) post-HCT, BM was harvested from first recipients for FACS isolation of KLS-CD34⁻Flt3⁻-HSC. A total of 3500–14,000 cells per mouse was obtained and infused into secondary (second) Rag2γc^−/− recipients (H2^b) (each first recipient served as a donor for one second recipient; n = 5 first and second recipients, respectively). (B) Blood chimerism for B220⁺, Mac1⁺, and Thy1⁺ populations at 1 mo after secondary HCT confirmed H2^k+ donor cell contribution. No T cells were derived from the first donor (Thy1.1⁺ AKR/J). (C) Compiled data on the level of lymphoid engraftment at 1 and 3 mo post-HCT in Rag2γc^−/− recipients of KLS-CD34⁻Flt3⁻-HSC grafts derived from first recipients (n = 5) as compared with WT donors (n = 2). The proportion of B and T cells achieved in second recipients at 1 and 3 mo post-HCT was significantly lower for HSCs that had been exposed to inflammation in the first recipient as compared with 7500 KLS-CD34⁻Flt3⁻HSCs derived from WT mice. *p ≤ 0.05, ***p ≤ 0.001.