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 progenitors before (group A) or following cryopreservation from patients in complete remission (CR) of acute myeloid leukaemia before autologous transplantation (AML) (group B), to similarly treated normal cells (groups A and B). From each group, fibroblastic (F) colony-forming units (CFU) and SL were established and their growth quantitated. Upon confluence of SL, 1 x 10(4)selected CD34+ cells from patient or control samples (of group A and B) were seeded on pre-formed SL from AML or control group A and B layers and adhesive precursors were scored for the formation of blastic (-b1) CFU (>20 cells). Lastly, CD34+ cells from the 4 progenitor sources were cultured in the presence of growth factors and scored for the production of granulocyte-macrophage (GM) CFU, erythroid burst forming units (BFU-E) and mixed colonies (CFU-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 cryopreservation supported control CFU-bl adequately, contrary to the norm, this 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 cytokines. We conclude that cryopreservation of the bone marrow of patients in CR of AML results in an inhibition of the proliferation of the CD34+ precursors. It also modifies the stroma, leading to reductions in the support of normal clones.