Fig 2. Hematopoietic stem and progenitors were equally radiation sensitive in R4^KO vs Wt mice, but stromal and endothelial cells were more significantly impacted in R4^KO mice.

A. Representative flow cytometry plots for the BM HSC, MPP and Myeloid Progenitor (MyPro) populations with and without radiation preconditioning. B. Representative flow cytometry plots for the collagenase-released fraction of the BM for total live, stroma, and VEC (CD45^-/Ter119^-/CD31⁺/Sca1⁺) populations with and without radiation preconditioning. C. Radiation preconditioning significantly impacted the levels of Wt and R4^KO HSC, MPP, and MyPro in the bone marrow. However, the levels were not significantly different between Wt or R4^KO radiation preconditioned cohorts. Data represent n = 2 independent experiments with n = 6 Wt at 0 rads, n = 8 Wt at 450 rads, n = 6 R4^KO at 0 rads, and n = 8 R4^KO 450 rads. Statistics: Unpaired two tailed student’s t-test. * p≤ 0.05, ** p≤ 0.01, and **** p≤0.0001. One-way Anova: HSC p < 0.0001, MPP p < 0.0001, and MyPro p < 0.0001. D. R4^KO total live cells, stromal cells, and VECs were significantly more radiation sensitive than the Wt equivalent cell types. Data represent n = 2 independent experiments with n = 6 Wt at 0 rads, n = 8 Wt at 450 rads, n = 6 R4^KO at 0 rads, and n = 8 R4^KO at 450 rads. Statistics: Unpaired two tailed student’s t-test. * p≤ 0.05, ** p≤ 0.01, and **** p≤0.0001. One-way Anova: Live p = 0.0049, stroma p = 0.0028, and VEC p = 0.1315.