부산대학교 도서관

Adult stem cells are critical for maintaining cellular homeostasis throughout life, yet the effects of age on their regenerative capacity are poorly understood. All lymphoid and myeloid blood cell lineages are continuously generated from hematopoietic stem cells present in human bone marrow. With age, significant changes in the function and composition of mature blood cells are observed. In this study, we report that age-related changes also occur in the human hematopoietic stem cell compartment. We find that the proportion of multipotent CD34CD38 cells increases in the bone marrow of elderly (>70 years) individuals. CD34CD38CD90CD45RACD10 and CD34CD33 myeloid progenitors persist at the same level in the bone marrow, while the frequency of early CD34CD38CD90CD45RACD10 and committed CD34CD19 B-lymphoid progenitors decreases with age. In contrast to mice models of aging, transplantation experiments with immunodeficient NOD/SCID/IL-2Rγ null (NSG) mice showed that the frequency of NSG repopulating cells does not change significantly with age, and there is a decrease in myeloid lineage reconstitution. An age-related decrease in the capacity of CD34 cells to generate myeloid cells was also seen in colony-forming assays in vitro. Thus, with increasing age, human hematopoietic stem/progenitor cells undergo quantitative changes as well as functional modifications. [ABSTRACT FROM AUTHOR]