Short-term myeloid growth factor mediated expansion of bone marrow haemopoiesis studied by localized magnetic resonance proton spectroscopy.

Previously we have shown that short-term myeloid growth factor priming of haemopoiesis prior to bone marrow harvest increased the yield of myeloid progenitors in the graft. The present study is intended to investigate the expansion of haemopoiesis by volume selective proton magnetic resonance spectroscopy (MRS). Six patients were treated with daily subcutaneous injections of recombinant human granulocyte colony-stimulating factor (rhG-CSF, n = 2) or granulocyte-macrophage colony-stimulating factor (rhGM-CSF, n = 4) for 5d before marrow harvest. MRS investigations were performed prior to treatment (day 0), day 5 and day 12. Spectroscopic examinations were performed with the stimulated echo acquisition mode (STEAM) method on a 1.5 T clinical whole-body imaging unit. A cubic volume of interest (VOI) was selected in the bone marrow of the left iliac bone. The patients responded with a rise in blood absolute neutrophil count from median 3.3 x 10(9)/l (range 1.3-7.3 x 10(9)/l) before to 15.6 x 10(9)/l (range 6.8-22.0 x 10(9)/l) after treatment. Concomitantly an increase in bone marrow cellularity and myeloid:erythroid ratios documented the stimulation of myelopoiesis. During priming, the light-density cell proliferation rate in marrow samples increased from median 21.9 (range 4.5-31) x 10(3) cpm to 54.7 (range 13.9-94) x 10(3) cpm and the total number of myeloid progenitors enumerated as day 7/14 GM-CFUs per volume aspirated marrow increased from median 11/8 x 10(3) (range 4.0-87.5/2.2-103.0) to 64/76 x 10(3) (range 28.4-1180.6/23.2-2850.0). MRS detected a significant increase in bone marrow 'relative water content' day 12, 1 week after myeloid growth factor treatment was stopped, from median 30.5% (range 16-45) to 79% (range 56-93). In parallel, haemopoiesis was detected in new areas of femur. In conclusion, the non-invasive MRS method may be a useful and reliable in vivo examination for expansion of haemopoiesis and a correspondent reduction of fat tissue in bone marrow after priming with recombinant human haemopoietic growth factors.