Detection of incorporated iododeoxyuridine in colonies by immunoperoxidase staining: a novel method to measure the proportion of cycling colony-forming cells

In vitro suicide by tritiated thymidine (3H-TdR), hydroxyurea (HU), or cytosine arabinoside (Ara-C) is assumed to reflect the proportion of colony-forming cells in S-phase at the time of exposure. However, these techniques are not always accurate. Nonradioactive iododeoxyuridine (IdUrd) is incorporated into DNA during S-phase and can be detected by monoclonal antibodies. In the present study, a new IdUrd application was developed to investigate the kinetics of hematopoietic progenitor cells. After incubation with IdUrd, colony-forming cells were cultured in semisolid assay. An immunoperoxidase staining protocol was developed to detect IdUrd in cells of colonies in agar. Colony-forming cells in S-phase during the IdUrd exposure were postulated to give rise to IdUrd+ colonies, whereas non-S-phase cells would generate IdUrd- colonies. Toxicity, sensitivity, and IdUrd inactivation studies indicated that progenitor cells could safely be pulse-labeled for 2 hours with 40 microM IdUrd, whereas prolonged labeling with 1 microM IdUrd was at least feasible for 5 days. Molt-4 cells and normal bone marrow cells were used to compare IdUrd pulse-labeling with 3H-TdR suicide. Part of the Molt-4 cells were enriched for G1- and S-phase cells by counterflow centrifugation. The bone marrow cells were either unstimulated or stimulated with growth factors. As a result, the accuracy of both techniques could be tested in populations with different quantities of S-phase cells. Wide confidence intervals of the suicide technique contrasted with the small confidence intervals obtained with IdUrd pulse-labeling. For instance, the fraction of Molt-4 cells with 27.8% S-phase cells contained 17.7% (confidence interval -8.2 to 43.6%) clonogenic cells in S-phase when determined with 3H-TdR suicide. Of this fraction, the percentage of clonogenic cells in S-phase was 30.6% with a confidence interval of 25.5 to 36.2% when determined with IdUrd pulse-labeling. In our hands, the IdUrd pulse-labeling was more accurate than the 3H-TdR suicide technique. Thus far, kinetic studies of progenitors have been limited to the determination of the fraction of S-phase cells by suicide techniques. By prolonged IdUrd labeling, it is now possible to determine the proliferating fraction of progenitor cells.

In vitro response of blasts to IL-3, GM-CSF, and G-CSF is different for individual AML patients: factors that stimulate leukemic clonogenic cells also enhance Ara-C cytotoxicity

In vivo, growth factors are currently investigated for their capacity to trigger leukemic stem cells into cycle and thus overcome kinetic drug resistance. In this study, the susceptibility of leukemic clonogenic cells to individual growth factors was related to cytosine-arabinoside (Ara-C) sensitivity. The effects of interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (G-CSF), granulocyte colony-stimulating factor (G-CSF), and combinations of these recombinant hematopoietic factors were tested on blast cells of nine acute myeloid leukemia (AML) patients. Growth factor responses were assessed in semi-solid clonogenic assay and in a 10-day liquid culture followed by clonogenic assay. Heterogeneity in growth factor response was observed in both test systems, resulting in a variable pattern for individual leukemias. In the majority of cases (six of nine) the response patterns in the semi-solid and liquid cultures were divergent. To test the Ara-C sensitivity, leukemic blasts were exposed in liquid to various concentrations of Ara-C in the absence and presence of preselected growth factors. After 10 days, the number of surviving leukemic colony-forming cells (CFU-L) was assessed. Exposure to Ara-C in the presence of optimal stimulatory factor(s) resulted in a 3- to 1000-fold increase of the Ara-C toxicity in seven patients. The Ara-C concentrations resulting in 50% inhibition of clonogenicity (ID50) were 0.48-123 x 10(-8) M Ara-C in the absence of stimulatory growth factors, versus only 0.12-0.40 x 10(-8) M Ara-C in the presence of these factors. In two patients, addition of one or more factors neither increased the number of CFU-L in liquid nor enhanced the Ara-C toxicity. Even in the absence of growth factors the ID50 values in these cases were as low as 0.20 and 0.28 x 10(-8) M Ara-C and in the same range as the ID50 values observed with maximum growth factor stimulation in the other seven patients. These results indicate that Ara-C cytotoxicity can be enhanced by individually selected, clonogenic cell growth-promoting hematopoietic factors.

Cell cycle kinetics of hematopoiesis before and after in vivo administration of GM-CSF in refractory anemia: evidence for a shortening of the granulocyte release time

GM-CSF administration to patients with refractory anemia (RA) induces an increase in neutrophils and eosinophils. We studied cell kinetic mechanisms underlying this observation using clonogenic assays and in vivo iododeoxyuridine labeling of bone marrow cells. Cell cycle kinetics were studied in three patients before and during GM-CSF administration (two daily subcutaneous injections of 54 or 108 micrograms). No consistent effect on the relative number of bone marrow CFU-GM was noticed. The DNA synthesis time and potential doubling time of low-density bone marrow cells remained essentially the same. A slight decrease (1.5-3.7%) in labeling index was found, originating from the myelo(-mono)cytic lineage. In all three patients the release time of labeled granulocytes from the bone marrow into the peripheral blood was shortened (before GM-CSF treatment 5-7 days and during GM-CSF 3-4 days). Cell cycle kinetics of CD34+ cells were studied in order to obtain kinetic information on immature precursor and progenitor cells. The DNA synthesis time of the CD34+ cells was shortened during GM-CSF therapy, resulting in a shorter potential doubling time. GM-CSF administration to patients with RA results in a rise in granulocytes that might be due partly to an accelerated release of granulocytes from the bone marrow compartment into the circulating blood and partly to an increased proliferative activity of the immature precursor and progenitor cells.

Interphase cytogenetics on agar cultures: a novel approach to determine chromosomal aberrations in hematopoietic progenitor cells

We describe a novel approach to determine the presence of chromosomal aberrations in progenitor cells by in situ hybridization (ISH) on agar cultures. Bone marrow cells of 3 patients suffering from acute myeloid leukemia (AML) were selected to develop the method. In all 3 cases, numerical aberrations for chromosome 1 and/or 8 were detected by karyotyping and ISH using chromosome-specific centromeric-associated DNA probes. These aberrations were used as markers in this study. After in vitro culture of the bone marrow samples in agar, the cells were pretreated to perform ISH. This approach retains the cytological architecture of the agar assay, allowing discrimination between chromosomal aberrations detected in the clonogenic and non-clonogenic cells in culture. With this new technique, the presence of the cytogenetic aberration in clonogenic cells can be shown at the interphase level.

In vitro growth pattern and differentiation predict for progression of myelodysplastic syndromes to acute nonlymphocytic leukaemia

In 153 consecutive patients with myelodysplastic syndrome (MDS) the prognostic value of FAB-classification, cytogenetics, Bournemouth score, a history of previous radio- or chemotherapy and in vitro bone marrow growth were retrospectively analysed, for both acute nonlymphocytic leukaemia (ANLL) development and survival. Thirty-eight of the 153 patients (25%) showed progression to ANLL, 63 (41%) died during the myelodysplastic phase due to infection or bleeding and three (2%) received allogeneic bone marrow transplantation (BMT). Univariate analysis showed that the FAB-classification, in vitro growth pattern and differentiation, and cytogenetics had a predictive value for ANLL development and survival. The Bournemouth score was predictive only for survival. Most predictive for the development of ANLL were in vitro growth pattern and maturation. Patients with normal in vitro growth progressed to ANLL in 6% of the cases, in patients with hypoplastic or leukaemic growth 32.5% developed ANLL (P less than 0.0001). The ANLL incidence in patients with normally differentiated in vitro colonies was 14.5%, compared with a 52% incidence in cases showing no in vitro cell maturation (P = 0.001). The combination of growth pattern and differentiation revealed an ANLL incidence of 4.2% in cases of normal growth and differentiation, and 60.4% if the in vitro growth and/or differentiation was abnormal (P = 0.006). In vitro maturation was the only parameter predictive for ANLL development in multivariate analysis. From our data it is concluded that the predictive value of in vitro bone marrow culturing in patients with MDS can be increased by including in vitro maturation as a distinct parameter. The in vitro prognostic data can be important in selecting MDS patients for intensive chemotherapy or BMT.

Allogeneic bone marrow transplantation for leukemia with marrow grafts depleted of lymphocytes by counterflow centrifugation

Eighty consecutive patients were transplanted with human leukocyte antigen (HLA)-identical sibling marrow for acute myelogenous leukemia (AML, N = 29), acute lymphoid leukemia (ALL, N = 23), or chronic myelogenous leukemia (CML, N = 28). Donor marrow was depleted of lymphocytes using counterflow centrifugation. Median age of the recipients was 31 years. Pretransplant conditioning consisted of cyclophosphamide and fractionated total body irradiation (TBI) with a low (4.1 +/- 0.3 cGy/min) or high (13.1 +/- 1.6 cGy/min) midline average dose rate. In 43 patients, cytosine-arabinoside or anthracyclines were added to the conditioning regimen. Immunoprophylaxis posttransplant consisted of methotrexate (MTX) alone, cyclosporine A (CsA) in combination with MTX, or CsA alone; two patients received no immunoprophylaxis at all. Graft failure occurred in 4 of 77 evaluable patients (5%). The probability of acute graft-versus-host disease (GVHD) greater than or equal to grade 2 at day 100 after transplantation was 15%. The projected 3-year estimate of extensive chronic GVHD was 12%. Only three patients died of cytomegalovirus-interstitial pneumonitis. The projected 3-year probability of relapse was 30% (95% confidence interval [CI], range 8% to 53%) in transplants for AML in first complete remission (CR1), 35% (95% CI, 1% to 69%) after transplantation for ALL in CR1, and 38% (95% CI, 2% to 74%) after transplantation for CML in first chronic phase (CP1). The projected 3-year probability of leukemia-free survival (LFS) was 56% (95% CI, 35% to 77%) after transplantation for AML-CR1, 42% (95% CI, 16% to 69%) in patients transplanted for ALL-CR1, and 49% (95% CI, 18% to 80%) after transplantation for CML-CP1. After transplantation for AML-CR1, ALL-CR1, or CML-CP1, the median follow-up time for leukemia-free survivors was 31+, 30+, and 21+ months, respectively. Probabilities of relapse, survival, and LFS in AML-CR1 and ALL-CR1 transplants were comparable with those reported in recipients of untreated grafts. In patients transplanted for CML-CP1, probability of relapse was higher and probability of LFS was lower than in recipients of untreated grafts. In transplants for leukemia in CR1 and CP1, preparative regimen and immunoprophylaxis posttransplant were not associated significantly with the probability of acute GVHD greater than or equal to grade 2, extensive chronic GVHD, relapse, survival, or LFS. In bone marrow transplantation for leukemia, counterflow centrifugation is a useful technique for the prevention of GVHD.(ABSTRACT TRUNCATED AT 400 WORDS)

Prevention of leukemic relapse after transplantation with lymphocyte depleted marrow by intensification of the conditioning regimen with a 6-day continuous infusion of anthracyclines

In the present study we have evaluated the efficacy and toxicity of a 6-day continuous constant rate intravenous infusion of anthracyclines added to the standard conditioning regimen for allogeneic bone marrow transplantation (BMT). In 22 consecutive recipients of a lymphocyte depleted bone marrow graft, either demethoxydaunomycin (n = 11) or daunorubicin (n = 11) were added to high-dose cyclophosphamide and total body irradiation. Five patients had acute non-lymphoblastic leukemia in first complete remission, six patients acute lymphoblastic leukemia in first or second complete remission, nine patients chronic myelogenous leukemia in chronic phase and two patients refractory anemia with excess of blasts. After a median observation period of 18 months, only one leukemic relapse has been observed. Six patients died in the post-transplant period. In 17 of the 22 patients a severe, transient mucositis developed. No cardiac toxicity, as assessed with radioisotope studies, was observed. We conclude that anthracyclines may be effectively and safely incorporated in conditioning regimens before BMT, provided that they are administered as long-term continuous infusions in order to avoid toxicity due to excessive plasma levels.

Anthracyclines added to the conditioning regimen for allogeneic bone marrow transplantation are associated with a slower haematopoietic recovery

Factors which may influence haematopoietic recovery after allogeneic bone marrow transplantation were analysed. Forty-six evaluable patients transplanted with lymphocyte-depleted marrow for acute lymphoblastic leukaemia, acute non-lymphoblastic leukaemia, chronic myeloid leukaemia, myelodysplastic syndrome and severe aplastic anaemia were studied. The median time for platelet recovery to greater than or equal to 20 and to greater than or equal to 50 x 10(9)/l was 21 (9-72) and 26 (11-86) days respectively. The neutrophil recovery to greater than or equal to 0.5 x 10(9)/l and the leucocyte recovery to greater than or equal to 1.0 x 10(9)/l was 19 (8-47) and 18 (6-47) days respectively. No relation was found between the number of infused granulocyte-macrophage colony-forming cells, erythroid burst-forming cells, diagnosis, graft-versus-host disease, antibiotic administration and recovery. Addition of a continuous 6-day infusion of anthracyclines to the conditioning regimen delayed the median recovery of platelets, neutrophils and leucocytes by 7-9 days. Fever during aplasia also inhibited haematopoietic recovery. It is speculated that leakage of intracellular anthracyclines after bone marrow infusion or fever secondary to anthracyclines-induced oromucositis is responsible for the delayed bone marrow recovery.

GM-CSF enhances sensitivity of leukemic clonogenic cells to long-term low dose cytosine arabinoside with sparing of the normal clonogenic cells

Leukemic clonogenic cells (CFU-L) and normal myeloid progenitor cells (CFU-GM) were exposed to Ara-C in the presence of crude CSF obtained from placentas (HPCM) or recombinant human GM-CSF for varying periods. The cytotoxicity of Ara-C to CFU-L increased considerably when the exposure time to Ara-C in the presence of HPCM was extended from 20 hours to 10 days. The ID50 of the CFU-L was 1.5 +/- 2.2 x 10(-8) M Ara-C compared to 5.5 +/- 2.9 x 10(-8) M Ara-C for the CFU-GM after an exposure to Ara-C for 10 days (p less than 0.05). Replacement of crude CSF from placenta conditioned medium by rh GM-CSF resulted in identical observations. Interesting was the observation that secondary leukemic colony forming cells were more or at least equally sensitive to Ara-C in the presence of GM-CSF when compared to the primary leukemic clonogenic cells. This contrasted the secondary normal CFU-GM, which were less sensitive to Ara-C than the primary CFU-GM. This indicates that GM-CSF induces leukemic clonogenic cells with selfrenewal capacity into proliferation, and in doing so, it may enhance the cytotoxicity of a cell cycle specific drug like Ara-C with sparing of the normal clonogenic cells.