The hematopoietic system declines with age, resulting in decreased hematopoietic stem cell (HSC) self-renewal capacity, myeloid skewing, and immune cell depletion. Aging of the hematopoietic system is associated with an increased incidence of myeloid malignancies and a decline in adaptive immunity. Therefore, strategies to rejuvenate the hematopoietic system have important clinical implications. In this issue of the JCI, Poulos and colleagues demonstrate that infusions of bone marrow (BM) endothelial cells (ECs) from young mice promoted HSC self-renewal and restored immune cell content in aged mice. Additionally, delivery of young BM ECs along with HSCs following total body irradiation improved HSC engraftment and enhanced survival. These results suggest an important role for BM endothelial cells (ECs) in regulating hematopoietic aging and support further research to identify the rejuvenating factors elaborated by BM ECs that restore HSC function and the immune repertoire in aged mice.

造血系统会随着年龄的增长而下降，从而导致造血干细胞（HSC）的自我更新能力下降，骨髓偏斜和免疫细胞耗竭。造血系统的衰老与骨髓恶性肿瘤的发生率增加和适应性免疫力下降有关。因此，复兴造血系统的策略具有重要的临床意义。在本期JCI中，Poulos及其同事证明了从幼鼠中注入骨髓（BM）内皮细胞（EC）可以促进HSC自我更新并恢复衰老小鼠的免疫细胞含量。此外，在全身照射后，年轻的BM EC和HSC的分娩改善了HSC的植入并提高了生存率。