Fig. 2.

Decreased reactive oxygen species (ROS) levels in the bone marrow (BM) of haematopoietic progenitors from young donors compared with those from older donors. Intercellular ROS levels in BM haematopoietic stem cells (HSCs) (a), CD34⁺ cells (b) and multi‐potent progenitors (MPPs) (c) among young, middle‐aged and old donors. ROS levels in BM lymphoid progenitors (d) and myeloid progenitors (e) in the three donor groups. Data are expressed as the mean ± standard error of the mean (s.e.m.). All P‐values < 0·05 were considered significant and are provided in the figure.