Decline in bone marrow proliferative capacity as a function of age

Bone marrow from old (greater than 2 yr of age) and young (8-10 wk of age) male C3H/HeJ mice was grown in long-term bone marrow cultures and assayed for weekly hematopoietic stem cell (CFUs) production and interval self-renewal capacity (R5). Greater numbers of CFUs were noted in old marrow as compared to young marrow cultures over the first 4 wk duration, but subsequently, greater numbers of CFUs were seen weekly in the young marrow cultures. Over 1 3 wk in culture, the total CFUs determination was greater in young marrow cultures. Similarly. self-renewal capacity (R1) was greater in old as compared to young marrow-adherent CFUs over the first