Cryopreservation of the bone marrow from patients with acute myeloid leukaemia leads to functional abnormalities

We compared the performance of the stroma (SL) and haematopoietic progenito rs before (group A) or following cryopreservation from patients in complete remission (CR) of acute myeloid leukaemia before autologous transplantatio n (AML) (group B), to similarly treated normal cells (groups A and B). From each group, fibroblastic (F) colony-forming units (CFU) and SL were establ ished and their growth quantitated. Upon confluence of SL, 1x10(4) selected CD34(+) cells from patient or control samples (of group A and B) were seed ed on pre-formed SL from AML or control group A and B layers and adhesive p recursors were scored for the formation of blastic (-bl) CFU (>20 cells). L astly, CD34(+) cells from the 4 progenitor sources were cultured in the pre sence of growth factors and scored for the production of granulocyte-macrop hage (GM) CFU, erythroid burst forming units (BFU-E) and mixed colonies (CF U-MIX). In the patients, CFU-F numbers were decreased and by 5 wk SL failed to reach confluence. Group A AML CD34(+) progenitors gave a mean of 119.2 (SD 80.4) CFU-bl/10(4) CD34(+) cells, but following cryopreservation these numbers declined (83.2, SD 72.71; p = 0.009). Although AML SL prior to cryo preservation supported control CFU-bl adequately, contrary to the norm, thi s property decreased in group B stroma (mean 50.9/10(4)CD34(+) cells, SD 49 .33; p=0.02). Group B AML samples gave significantly fewer CFU-MIX and BFU- E than pre-freezing cultures and than control samples at the first 2-growth factor combination but numbers improved following further addition of cyto kines. We conclude that cryopreservation of the bone marrow of patients in CR of AML results in an inhibition of the proliferation of the CD34(+) prec ursors. It also modifies the stroma, leading to reductions in the support o f normal clones.