SHORT-TERM MYELOID GROWTH-FACTOR MEDIATED EXPANSION OF BONE-MARROW HEMATOPOIESIS 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 m yeloid progenitors in the graft. The present study is intended to inve stigate the expansion of haemopoiesis by volume selective proton magne tic resonance spectroscopy (MRS). Six patients were treated with daily subcutaneous injections of recombinant human granulocyte colony-stimu lating factor (rhG-CSF, n = 2) or granulocyte-macrophage colony-stimul ating factor (rhGM-CSF, n = 4) for 5 d before marrow harvest. MRS inve stigations were performed prior to treatment (day 0), day 5 and day 12 . Spectroscopic examinations were performed with the stimulated echo a cquisition 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 a bsolute 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 treat ment. Concomitantly an increase in bone marrow cellularity and myeloid : erythroid ratios documented the stimulation of myelopoiesis. During printing, 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 1 3.9-94) x 10(3) cpm and the total number of myeloid progenitors enumer ated as day 7/14 GM-CFUs per volume aspirated marrow increased from me dian 11/8 x 10(3) (range 4.0-87.5/2.2-103.0) to 64/76 x 10(3) (range 2 8.4-1180.6/23.2-2850.0). MRS detected a significant increase in bone m arrow 'relative water content' day 12, 1 week after myeloid growth fac tor treatment was stopped, from median 30.5% (range 16-45) to 79% (ran ge 56-93). In parallel, haemopoiesis was detected in new areas of femu r. In conclusion, the non-invasive MRS method may be a useful and reli able in vivo examination for expansion of haemopoiesis and a correspon dent reduction of fat tissue in bone marrow after priming with recombi nant human haemopoietic growth factors.