Transient reduction of systemic EPO levels in hosts using HBO increases BM homing of UCB CD34⁺cells. (A) Serum EPO levels in pg/mL in HBO-treated mice (n = 6) and in non-HBO mice (n = 6) 3 hours after UCB CD34⁺ cell infusion. (B) Percent of human CD34⁺ cells in BM and spleen of HBO mice (n = 8) and in non-HBO mice (n = 8) 3 hours after UCB CD34⁺ cell infusion. (C) EPO rescue effects on UCB CD34⁺EPOR⁺ cell homing and engraftment in HBO-treated mice (n = 8). (C, left) Representative flow cytometry data showing dual expression of human CD34⁺ and EPOR⁺ in EPO-treated (n = 4) and control mice (n = 4) BM-gated populations. (C, right) Bar graph showing the relative percentage of human CD34⁺ (hCD34⁺) and separately human CD34⁺EPOR⁺ (hCD34⁺EPOR⁺) cells in BM of HBO-treated mice with either EPO treatment (+EPO) or without EPO treatment (–EPO) normalized to 100%. The data are presented as mean ± SEM. Single (*) and triple (***) asterisks indicate statistical significance.