Age-related changes in in vitro and in vivo survival of murine CFU-S and CFU-c

Present evidence suggests that the proliferative potential of most cell types declines with age. An apparent exception to this is the erythroid and myeloid colony-forming cell (CFU-S) of the marrow. In an effort to reveal a latent proliferative defect in old marrow, CFU-S from the marrow of young and old B6AF1 mice were serially transplanted every 12 days into lethally irradiated young syngeneic hosts. Contrary to expectation, it was found that the number of CFU-S declined more slowly if the marrow had been obtained from old donors. Similarly, it was found that CFU-S, but not CFU-c, from old marrow replicated or were recruited more vigorously in long-term culture than CFU-S from young donors. The results obtained with anti-Thy 1.2 serum and complement treatment of old marrow cells suggest that CFU-S from old marrow replicate more vigorously because old marrow has more theta + helper cells or the old CFU-S is more responsive to theta + helper stimuli.