Pluripotent (CFU-S) and granulocyte-committed (CFU-C) stem cells in intact and 89Sr marrow-ablated S1/S1d mice

Peripheral blood values, femur cell counts, spleen weights, pluripotent (CFU-S) and granulocyte progenitor cell (CFU-C) concentrations and total content of spleens and femurs have been evaluated in intact (non-marrow-ablated) and 89Sr marrow-ablated S1/S1d and +/+ mice. 89Sr-irradiated mice were studied 6 and 11 days after the administration of 89Sr. In intact S1/S1d mice the femur CFU-S concentration, total femur CFU-S, femur CFU-C concentration and total femur CFU-C were 84, 54, 105 and 68% that of +/+ mice femurs respectively; the respective values for the spleens of S1/S1d mice were 40, 46, 61 and 69%. These are the first simultaneous determinations of CFU-S and CFU-C concentrations, and content of spleens and marrows, of S1/S1d and +/+ mice. In 98Sr marrow-ablated mice, 11 days after injection of the radionuclide: (a) the total content of marrow CFU-C and CFU-S was about 1% of that found in the marrows of intact mice for both +/+ and S1/S1d groups; (b) the spleens of +/+ mice increased in weight to 162% of the control, but the spleens of S1/S1d mice did not increase in weight; and (c) the spleens of +/+ mice had a total content of CFU-C and CFU-S of 800% and 260% of the control, respectively, whereas the respective values for the S1/S1d mice were 120% and 76% of the control. Thus the S1/S1d spleen fails to compensate for marrow ablation by housing additional CFU-S and has an impaired ability to compensate by housing additional CFU-C.