Allogeneic and autologous transplantation for haematological diseases, solid tumours and immune disorders: current practice in Europe 2009.

The European Group for Blood and Marrow Transplantation regularly publishes special reports on the current practice of haematopoietic SCT for haematological diseases, solid tumours and immune disorders in Europe. Major changes have occurred since the first report was published. HSCT today includes grafting with allogeneic and autologous stem cells derived from BM, peripheral blood and cord blood. With reduced-intensity conditioning regimens in allogeneic transplantation, the age limit has increased, permitting the inclusion of older patients. New indications have emerged, such as autoimmune disorders and AL amyloidosis for autologous HSCT and solid tumours, myeloproliferative syndromes and specific subgroups of lymphomas for allogeneic transplants. The introduction of alternative therapies, such as imatinib for CML, has challenged well-established indications. An updated report with revised tables and operating definitions is presented.

Characterization and quantitation of primitive hematopoietic progenitor cells present in peripheral blood autografts.

In this report, we assess the content of primitive hematopoietic progenitor cells (HPC) that circulate transiently in the peripheral blood (PB) of cancer patients (group A) who received a PB stem-cell-mobilizing regimen that included high-dose chemotherapy (HD-CTX) of 7 g/m2 cyclophosphamide followed by a combination of recombinant hematopoietic growth factors (C-HGF), including either interleukin-3 (IL-3) plus granulocyte-colony stimulating factor (G-CSF), IL-3 plus granulocyte-macrophage colony-stimulating factor (GM-CSF), or a recombinant GM-CSF/IL-3 fusion protein (PIXY-321). These data were compared to the HPC content of PB obtained from a similar group of cancer patients that had not received such a mobilization regimen (group B). Monoclonal antibody staining and fluorescence-activated cell sorting (FACS) were used to identify and isolate cell populations enriched for more differentiated HPC (CD34+HLA-DR+) and more primitive HPC (CD34+HLA-DR-). The content of CD34+HLA-DR+ and CD34+HLA-DR- cells in the PB of group A patients was significantly greater than that observed in the PB of group B patients. In addition, HD-CTX plus C-HGF mobilization resulted in the appearance of greater numbers of PB colony-forming units-granulocyte/macrophage, -granulocyte/erythroid/macrophage/megakaryocyte, and -megakaryocyte (CFU-GM, CFU-GEMM, and CFU-Mk), and burst-forming units-erythroid and -megakaryocyte (BFU-E and BFU-Mk) than those observed in the PB of group B patients (p < 0.01). CD34+HLA-DR- cells isolated from the PB of group A patients were capable of initiating long-term hematopoiesis in vitro, which persisted for 10 weeks, while CD34+HLA-DR- cells obtained from the PB of group B patients were capable of sustaining long-term hematopoiesis in vitro for only 4 weeks. As determined by a limiting dilution analysis of group A PB CD34+HLA-DR- cells, the frequency of cells capable of giving rise to hematopoietic progenitor cells (pre-CFC) after 2 weeks in liquid culture was 4.3% (range 1.0-8.3%). Pre-CFC constituted 0.01% (range 0.001-0.02%) of group A PB mononuclear cells, and 151 pre-CFC were calculated to be present in 1 mL mobilized PB (range 20-310/mL). These results suggest that peripheral blood mononuclear cells (PBMC) collected by leukapheresis following HD-CTX plus C-HGF mobilization contain not only differentiated HPC but also more primitive HPC.

Clinical implications of the heterogeneity of hematopoietic progenitors elicited in peripheral blood by anticancer therapy with cyclophosphamide and cytokine(s).

Clinical investigators have found that the hematopoietic system irreversibly damaged by cancer therapy with myeloablative high doses of chemoradiotherapy can be reconstituted by transplantation of autologous hematopoietic progenitors retrieved from peripheral blood. In comparison with patients transplanted with bone marrow, those who receive peripheral blood progenitors undergo shorter periods of neutropenia and thrombocytopenia, require less platelet and erythrocyte transfusions and, most importantly, experience overall reduced treatment-related morbidity. In this article, we speculate that an explantation for this clinical achievement may be that committed hematopoietic progenitors as well as ancestral uncommitted pluripotent stem cells are retrieved from circulation and transplanted after myeloablative cancer therapy. As indicated by studies in rodents, transplantation of hematopoietic progenitors is followed by two phases of engraftment associated with progenitors at different stages of maturation. An initial phase corresponding to early hematopoietic recovery is produced by committed progenitors, and a second sustained engraftment phase is produced by the pluripotent stem cell. Should this multiphase engraftment model be true of humans also, the exceptionally prompt and sustained blood cell count recovery achieved by transplanting blood progenitor cells may reflect transplantation of heterogeneous progenitors such as committed progenitors and pluripotent stem cells producing an early engraftment phase and then sustained hematopoiesis, respectively.

Hematopoietic stem cell transplantation in the treatment of lymphoma.

In 1990, high-dose chemotherapy, with or without radiotherapy, requiring the support of hematopoietic stem cell transplantation has been confirmed as an effective treatment modality for a fraction of recurring or refractory lymphomas. Most relevant clinical studies published in 1990 are summarized and commented on in this review. Upcoming developments expected to improve the therapeutic index of high-dose therapies comprise the identification of patients at high risk of relapse so they can be treated earlier in the course of the disease, and the utilization of hematopoietic growth factors for ameliorating myelosuppression, as well as for harvesting peripheral blood hematopoietic stem cells utilizable for transplantation.

Flow cytometry to estimate circulating hematopoietic progenitors for autologous transplantation: comparative analysis of different CD34 monoclonal antibodies.

We report that the 2 fluorescein (FITC) conjugated CD34 monoclonal antibodies available to date, namely FITC-8G12 and FITC-QBEND10, exhibit different capabilities of detecting circulating hematopoietic progenitors (CHP) as cells expressing the CD34 antigen (CD34+) by direct immunofluorescence flow cytometry. Mean fluorescence intensity conferred by FITC-QBEND10 to CD34+ CHP is 2.8-4.3 times lower than that conferred by FITC-8G12. By indirect immunofluorescence, native unconjugated QBEND10 and 8G12 antibodies detect CD34+ CHP in a comparable manner, thus indicating that the decrease in QBEND10 affinity is due to FITC-conjugation. Utilization of FITC-QBEND10 instead of FICT-8G12 to estimate infrequent (usually less than or equal to 5%) CD34+ CHP for clinical decision-making in autologous transplantation of CHP exposes clinicians to the risk of either overestimating (false positive) or underestimating (false negative) these cells in peripheral blood. Recently published guidelines for large-scale collection of CHP for autologous transplantation in cancer patients were based on data obtained with FITC-8G12. The same guidelines cannot be considered valid if FITC-QBEND10 is employed. We recommend FITC-8G12 as the optimal reagent to date for standardizing results of autologous CHP transplantation in cancer therapy.

GM-CSF-exposed peripheral blood progenitors as sole source of stem cells for autologous transplantation in two patients with multiple myeloma.

Two patients (aged 52 and 44) received high-dose sequential chemotherapy followed by myeloablative therapy and autotransplantation as first line treatment of a stage III multiple myeloma with high plasmacell labelling index. Autograft was performed with peripheral blood cells collected after high-dose etoposide followed by rhGM-CSF continuous infusion. During this period very high numbers of circulating hemopoietic progenitors were detected in both patients. Prompt, complete and durable hematological recovery was observed after autograft with peripheral blood stem cells. Thus, we conclude that massively released progenitors after high-dose chemotherapy and rhGM-CSF include stem cells capable of marrow reconstitution.

Granulocyte-macrophage colony-stimulating factor to harvest circulating haemopoietic stem cells for autotransplantation.

Granulocyte-macrophage colony-stimulating factor (GM-CSF), given to accelerate recovery from cytopenia induced by high-dose (7 g/m2) cyclophosphamide, reproducibly brought about a dramatic increase (up to 1000-fold) in the number of peripheral blood granulocyte-macrophage colony-forming units (CFU-GM). These circulating progenitors were harvested by leucapheresis and reinfused, together with autologous bone marrow cells, in seven patients with cancer after total body irradiation and melphalan. Complete haemopoietic recovery occurred in all seven transplanted patients in a very short time: mean (SD) 9.1 (0.9) days (range 8-11) to achieve more than 0.5 x 10(9)/l neutrophils, 9.9 (1.7) days (range 8-13) to over 1 x 10(9)/l neutrophils, 10.7 (2.6) days (range 9-16) to over 0.5 x 10(11)/l platelets, and 13.6 (4.2) days (range 13-21) to over 1.0 x 10(11)/l platelets. A reduction in the severity of mucositis was also observed. The rapid haematological recovery made possible by this approach promises to increase the therapeutic index of high-dose chemoradiotherapy regimens and to widen their role as treatment for chemoradiosensitive tumours.