Interactions of melatonin with mammalian mitochondria. Reducer of energy capacity and amplifier of permeability transition.

Melatonin, a metabolic product of the amino acid tryptophan, induces a dose-dependent energy drop correlated with a decrease in the oxidative phosphorylation process in isolated rat liver mitochondria. This effect involves a gradual decrease in the respiratory control index and significant alterations in the state 4/state 3 transition of membrane potential (ΔΨ). Melatonin, alone, does not affect the insulating properties of the inner membrane but, in the presence of supraphysiological Ca2+, induces a ΔΨ drop and colloid-osmotic mitochondrial swelling. These events are sensitive to cyclosporin A and the inhibitors of Ca2+ transport, indicative of the induction or amplification of the mitochondrial permeability transition. This phenomenon is triggered by oxidative stress induced by melatonin and Ca2+, with the generation of hydrogen peroxide and the consequent oxidation of sulfydryl groups, glutathione and pyridine nucleotides. In addition, melatonin, again in the presence of Ca2+, can also induce substantial release of cytochrome C and AIF (apoptosis-inducing factor), thus revealing its potential as a pro-apoptotic agent.

HOXB7 expression by myeloma cells regulates their pro-angiogenic properties in multiple myeloma patients.

The deregulation of the homeobox genes as homeoboxB (HOXB)-7 has been previously associated to tumor progression and angiogenesis; here we investigated the potential role of HOXB7 in the pro-angiogenic properties of multiple myeloma (MM) cells. We found that HOXB7 was expressed in 10 out of 22 MM patients analyzed at the diagnosis related to high bone marrow angiogenesis and overexpressed in about 40% of myeloma cell lines compared with normal plasma cells. Enforced HOXB7 expression in MM cells by a lentiviral vector significantly modified their transcriptional and angiogenic profile, checked by combined microarray and angiogenesis PCR analyses, upregulating VEGFA, FGF2, MMP2, WNT5a and PDGFA and downregulating thrombospoindin-2. The pro- and anti-angiogenic HOXB7-related gene signature was also validated in a large independent dataset of MM patients. Accordingly, MM-induced vessel formation was significantly increased by HOXB7 overexpression both in vitro angiogenic and chorioallantoic membrane assays, as well as the HOXB7 silencing by small interfering RNA inhibited the production of angiogenic factors, and the pro-angiogenic properties of MM cells. Finally, in SCID-NOD mice we confirmed that HOXB7 overexpression by MM cells stimulated tumor growth, increased MM-associated angiogenesis and the expression of pro-angiogenic genes by microarray analysis supporting the critical role of HOXB7 in the angiogenic switch in MM.

Arsenic trioxide in hematological malignancies: the new discovery of an ancient drug.

Currently, Arsenic Trioxide (ATO) is considered the treatment of choice for patients with relapsed acute promyelocytic leukemia (APL). Recently, a durable remission with minimal toxicity by single agent ATO or ATO + ATRA in newly diagnosed APL was reported by different groups. These regimens have minimal toxicity and can be administered on an outpatient basis after remission induction, thus they could become a real, less toxic and more economic option to ATRA + anthracyclines in particular in low risk APL, or in patients that cannot undergo chemotherapy because of age or comorbid conditions and in patients that refuse chemotherapy. Significantly, these therapies are a successful attempt to cure a tumoral disease without chemotherapy. The results of clinical trials of ATO administration as single agent in multiple myeloma (MM) and myelodisplastic syndromes (MDS) were encouraging and showed clinical effects but they were not close to APL success. On the contrary, results of clinical trials to treat non-APL acute myeloid leukemia (AML) were disappointing. We suggest that a combination therapy with drugs targeting specific pro-survival molecules or capable to enhance pro-apoptotic pathways may lead to an improvement of ATO efficacy against hematological malignancies, in particular AML. Our pre-clinical studies showed that ATO is capable to induce cell death in acute leukemia cells but the apoptotic function is limited since it can induce also a mechanism of cell defense by activating pro-survival molecules such as MEK-ERK, Bcl-xL, Bcl-2. By combining ATO with specific MEK inhibitors, we demonstrated that the block of MEK-ERK phosphorylation, the induction of Bad de-phosphorylation, and activation of p53AIP1 apoptotic pathway interrupt the pro-survival mechanisms of ATO and kill the leukemic cells by apoptotic synergism. Our results provide an experimental basis for combined or sequential treatment with MEK inhibitors and ATO in AML. The renaissance of ATO as a drug in moderne medicine may be considered, together with ATRA success, a victory of empirical analysis, that had (and has) great impact on Chinese culture.

Non-infusional vs intravenous consolidation chemotherapy in elderly patients with acute myeloid leukemia: final results of the EORTC-GIMEMA AML-13 randomized phase III trial.

In this trial, acute myeloid leukemia patients (pts) aged 61-80 years received MICE (mitoxantrone, etoposide and cytarabine) induction chemotherapy in combination with different schedules of granulocyte colony-stimulating factor administration. Pts in complete remission were subsequently randomized for two cycles of consolidation therapy: mini-ICE regimen (idarubicin, etoposide and cytarabine) given according to either an intravenous (i.v.) or a 'non-infusional' schedule. Among the 346 pts randomized for the second step, 331 pts received consolidation-1 and 182 consolidation-2. A total of 290 events (255 relapses, 35 deaths in first CR) have been reported. The median follow-up was 4.4 years. No significant differences were detected in terms of disease-free survival (median 9 vs 10.4 months, P=0.15, hazard ratio (HR) =1.18, 95% confidence interval (CI) 0.94-1.49) - primary end point - and survival (median 15.7 vs 17.8 months, P=0.19, HR=1.17, 95% CI 0.92-1.50). In the 'non-infusional' arm grade 3-4 vomiting (10 vs 2%; P=0.001) and diarrhea (10 vs 4%; P=0.03) were higher than in the 'i.v.' arm, whereas time to platelet recovery >20 x 10(9)/l (median: 19 vs 23 days; P=0.02) and duration of hospitalization (mean: 15 vs 27 days; P<0.0001) was shorter. The 'non-infusional' consolidation regimen resulted in an antileukemic effect similar to the intravenous regimen, which was less myelosuppressive and associated with less hospitalization days.

Human myeloma cells express the bone regulating gene Runx2/Cbfa1 and produce osteopontin that is involved in angiogenesis in multiple myeloma patients.

Osteopontin (OPN) is a multifunctional bone matrix glycoprotein that is involved in angiogenesis, cell survival and tumor progression. In this study we show that human myeloma cells directly produce OPN and express its major regulating gene Runx2/Cbfa1. The activity of Runx2/Cbfa1 protein in human myeloma cells has also been demonstrated. Moreover, using small interfering RNA (siRNA) to silent Runx2 in myeloma cells, we suppressed OPN mRNA and protein expression. OPN production in myeloma cells was stimulated by growth factors as IL-6 and IFG-1 and in turn OPN stimulated myeloma cell proliferation. In an 'in vitro' angiogenesis system we showed that OPN production by myeloma cells is critical for the proangiogenic effect of myeloma cells. The expression of OPN by purified bone marrow (BM) CD138(+) cells has also been investigated in 60 newly diagnosed multiple myeloma (MM) patients, finding that 40% of MM patients tested expressed OPN. Higher OPN levels have been detected in the BM plasma of MM patients positive for OPN as compared to controls. Moreover, significantly higher BM angiogenesis has been observed in MM patients positive for OPN as compared to those negative. Our data highlight that human myeloma cells with active Runx2/Cbfa1 protein directly produce OPN that is involved in the pathophysiology of MM-induced angiogenesis.

Downmodulation of ERK protein kinase activity inhibits VEGF secretion by human myeloma cells and myeloma-induced angiogenesis.

The mitogen-activated protein (MAP) cascade leading to the activation of extracellular signal-regulated kinases 1/2 (ERK1/2) is critical for regulating myeloma cell growth; however, the relationship of ERK1/2 activity with vascular endothelial growth factor (VEGF) production and the effects of its downmodulation in myeloma cells are not elucidated. We found that the treatment with MAP/ERK kinase 1 (MEK1) inhibitors PD98059 or PD184352 produced a reduction of phosphorylated ERK1/2 (p-ERK1/2) levels in myeloma cells of more than 80% and prevented the increase of p-ERK1/2 induced by interleukin-6 (IL-6). MEK1 inhibitors also induced a significant inhibition of myeloma cell proliferation and blunted the stimulatory effect induced by IL-6. A significant inhibition of basal VEGF secretion by myeloma cells as well as a suppression of the stimulatory effect of IL-6 on VEGF was observed by either PD98059 or PD184352. Moreover, we also found that the PI3K kinase inhibitors, but not p38 MAPK inhibitors, reduced VEGF secretion by myeloma cells and increase the inhibitory effect of MEK1 inhibitors. In an 'in vitro' model of angiogenesis, we found that MEK1 inhibitors impair vessel formation induced by myeloma cells and restored by VEGF treatment, suggesting that the downmodulation of ERK1/2 activity reduces myeloma-induced angiogenesis by inhibiting VEGF secretion.

Cemp, a mitoxantrone containing combination, in the treatment of intermediate and high grade non-hodgkin's lymphoma: an effective and non toxic therapeutic alternative for adult and elderly patients.

Here we report the results of a randomised multicenter phase III clinical trial which assesses the therapeutic efficacy and tolerability of a chemotherapy protocol CEMP (cyclophosphamide, etoposide, mitoxantrone and prednisone) in adult and elderly patients with advanced intermediate and high-grade NHL. Between October 1991 and October 1995, 139 patients, aged 55 to 79 years, with diffuse intermediate and high-grade lymphoma, were enrolled. A considerable percentage of patients had clinically aggressive disease: 32.4% had systemic symptoms, 79% had stage III or IV disease, 33.8% had bone marrow involvement, 46% had splenic involvement and 42.5% had increased values of serum lactate dehydrogenate. Complete remission was achieved in 70 of the 139 patients (51.9%) and PR in 12 (16.6%) with an overall response of 68.5%. The overall response survival rate at 6 years was 39%, whereas DFS rate was 48.7% and PFS rate was 28.5%. At four years 49% of the patients were still in CR. Dividing the patients in two groups, under and over 65 years of age, we obtained the same results as far as overall response is concerned. No toxic deaths occurred, neither cardiac, renal nor liver complications happened. CEMP regimen is an effective and safe protocol with good results in elderly people, well comparable to those achieved in younger ones.

Limited engraftment capacity of bone marrow-derived mesenchymal cells following T-cell-depleted hematopoietic stem cell transplantation.

The engraftment capacity of bone marrow-derived mesenchymal cells was investigated in 41 patients who had received a sex-mismatched, T-cell-depleted allograft from human leukocyte antigen (HLA)-matched or -mismatched family donors. Polymerase chain reaction (PCR) analysis of the human androgen receptor (HUMARA) or the amelogenin genes was used to detect donor-derived mesenchymal cells. Only 14 marrow samples (34%) from 41 consenting patients generated a marrow stromal layer adequate for PCR analysis. Monocyte-macrophage contamination of marrow stromal layers was reduced below the levels of sensitivity of HUMARA and amelogenin assays (5% and 3%, respectively) by repeated trypsinizations and treatment with the leucyl-leucine (leu-leu) methyl ester. Patients who received allografts from 12 female donors were analyzed by means of the HUMARA assay, and in 5 of 12 cases a partial female origin of stromal cells was demonstrated. Two patients who received allografts from male donors were analyzed by amplifying the amelogenin gene, and in both cases a partial male origin of stromal cells was shown. Fluorescent in situ hybridization analysis using a Y probe confirmed the results of PCR analysis and demonstrated in 2 cases the existence of a mixed chimerism at the stromal cell level. There was no statistical difference detected between the dose of fibroblast progenitors (colony-forming unit-F [CFU-F]) infused to patients with donor- or host-derived stromal cells (1.18 +/- 0.13 x 10(4)/kg vs 1. 19 +/- 0.19 x 10(4)/kg; P >/=.97). In conclusion, marrow stromal progenitors reinfused in patients receiving a T-cell-depleted allograft have a limited capacity of reconstituting marrow mesenchymal cells.

Amifostine (WR-2721) selective protection against melphalan genotoxicity.

Amifostine (WR-2721) is an aminothiol compound dephosphorylated at the tissue site by alkaline phosphatase to the active metabolite, which is able to inactivate electrophilic substances and scavenge free radicals. Amifostine effects against melphalan-induced DNA strand breaks were studied in normal human white blood cells (WBC) and K562 leukemic cells using the single cell gel electrophoresis (SCGE) or Comet assay, a reported method for measuring DNA damage in individual cells. Prior to treatment (1 h, 37 degrees C) with increasing doses of melphalan, with or without S9, the cells were treated (15 min, 37 degrees C) with a control medium or amifostine (3 mg/ml). Treatment of normal and leukemic cells with melphalan induced a dose-dependent 'comet formation'. Melphalan-induced DNA damage follows a normal distribution in WBC. On the other hand, in K562, a significant proportion of undamaged cells remains even with doses at which mean DNA damage is serious. Pretreatment with WR-2721 protects WBC, but not K562, against the genotoxic effect of melphalan. Amifostine might even strengthen the action of the antiblastic drug against K562 cells. S9 addition appears to enhance melphalan effectiveness. SCGE appears as a suitable primary screening method for in vitro and in vivo studies on drug-DNA interactions and their modulations by endogenous/exogenous factors.

Peripheral blood progenitor cell mobilization in healthy donors receiving recombinant human granulocyte colony-stimulating factor.

OBJECTIVE: We analyzed the incidence of primitive (LTC-IC) and committed (CFU-mix, BFU-E, CFU-GM) hematopoietic progenitors detected under steady-state conditions and upon progenitor cell mobilization in a cohort of healthy donors receiving recombinant human granulocyte colony-stimulating factor (rhG-CSF). MATERIALS AND METHODS: Healthy donors (n = 30) of HLA-mismatched or -matched stem cell transplants were mobilized with rhG-CSF (8 microg/Kg body weight subcutaneously twice daily until completion of leukapheresis). PBPC collections were started after 4 days of rhG-CSF therapy. RESULTS: Steady-state incidence of bone marrow LTC-IC, but not committed progenitors, significantly correlated with the numbers of mobilized CD34+ cells (r = 0.6, p = 0.004), CFU-GM (r = 0.79, p = 0.0005) and CFC (r = 0.76, p = 0.001) detected after 4 days of rhG-CSF therapy. Statistically significant correlations were also found between steady-state blood CFU-GM and peak numbers of CD341 cells (r = 0.68, p = 0.001), numbers of day 4 CD341 cells (r = 0.52, p = 0.005), CFU-GM (r = 0.63, p = 0.002), and CFC (r = 0.61, p = 0.003). CONCLUSION: Our data show that in normal volunteers baseline marrow LTC-IC and blood CFU-GM correlate with rhG-CSF-mobilized PBPC. The potential clinical relevance of these findings in the identification of poor mobilizers will be tested in a prospective study.

VACOP-B, high-dose cyclophosphamide and high-dose therapy with peripheral blood progenitor cell rescue for aggressive non-Hodgkin's lymphoma with bone marrow involvement: a study by the non-Hodgkin's Lymphoma Co-operative Study Group.

BACKGROUND AND OBJECTIVE: Sequential treatment with the addition of high-dose therapy (HDT) and peripheral blood progenitor cell (PBPC) rescue has been reported to be active as front-line therapy in aggressive non-Hodgkin's lymphoma (NHL) with bone marrow (BM) involvement. We designed an intensive sequential therapy as front-line therapy in this subset of patients and conducted a phase II study. DESIGN AND METHODS: Patients with aggressive non-Hodgkin's lymphoma and BM involvement at diagnosis received 8 weeks of VACOP-B chemotherapy as induction therapy. The second phase included high-dose cyclophosphamide (HDCY) (7 g/m(2)) with granulocyte colony-stimulating factor (G-CSF) followed by leukaphereses. The third phase included HDT according to the BEAM protocol or melphalan (140 mg/m(2)) plus total body irradiation (8 Gy in a single dose). RESULTS: Forty patients were included in the study. According to the intention-to-treat, after VACOP-B, 11 (27.5%) and 22 (55%) patients achieved complete remission (CR) and partial remission (PR), respectively. Thirty-four received HDCY. After HDCY, 18 patients (45%) were in CR and 13 (32.5%) in PR. Twenty-nine underwent HDT plus peripheral blood cell rescue (PBPC) rescue. At the completion of treatment 29 patients (72.5%) were in CR, and 3 patients (7.5%) in PR. The actuarial 3-year overall survival, disease free survival and failure free survival are 48%, 55% and 40%, respectively. Overall severe toxicity was 7.5%. INTERPRETATION AND CONCLUSIONS: This phase II study suggests that the intensified treatment described is feasible and active in aggressive NHL with BM involvement. A randomized trial is now underway to test this approach.

DNA damage by tobacco smoke and some antiblastic drugs evaluated using the Comet assay.

The Comet assay was used in human leukocytes to detect, in vivo, DNA strand-breaks induced by smoking habit to evaluate the test sensitivity to an environmental factor, and by several antiblastic drugs to note their effectiveness at single cell level. Differences related to smoking habit, gender and age are evident. Melphalan shows the widest DNA damage. The damage induced by etoposide can be ascribed to the balancing between the production of strand-breaks and cross-links which limit the migration of DNA fragments. Interferon, fludarabine, prednisone, and oncocarbide appear to induce unexpected strand-breaks. Single cell gel electrophoresis (SCGE) is highly effective in revealing the association between DNA damage and environmental, genetic, and acquired factors, providing further data on the possible applicability of this assay in genotoxic human surveillance in addition to established tests. Moreover, the ability to point out cell subpopulations varying in mean damage levels could allow detection of potentially emerging drug-resistant populations.

Induction of apoptosis by arachidonic acid in chronic myeloid leukemia cells.

The hallmark of chronic myeloid leukemia (CML) is the presence of the bcr-abl oncogene, which is associated with transforming ability and an intrinsic resistance to induction of apoptosis by genotoxic agents. Arachidonic acid (AA), a biologically active fatty acid, plays a crucial role as a mediator of signaling pathways involved in cell proliferation and survival. In this study, we investigated the potential role of AA as a proapoptotic agent in CML. Pretreatment of human CML isolated progenitor cells with AA (100 microM for 18 h) induced 71-75% inhibition of in vitro colony formation of granulocyte-macrophage colony-forming units, multilineage colony-forming units, and erythroid burst-forming units. This inhibition was significantly greater than the effect on normal progenitor cells (19-39% growth inhibition of erythroid burst-forming units, multilineage colony-forming units, and granulocyte-macrophage colony-forming units). AA also inhibited growth of the bcr-abl-transformed cell line H7.bcr-abl A54. In contrast, a minimal effect of AA on inhibition of cell growth was observed in the parental nontransformed NSF/N1.H7 cell line. The antiproliferative effect of AA was associated with apoptosis. Gamma-linolenic acid, a precursor of AA, also inhibited cell growth, whereas other unsaturated and saturated fatty acids had no effect. Pharmacological inhibition of cyclooxygenase, lipooxygenase, and cytochrome P450 monooxygenase enzymes prior to exposure to AA did not rescue cells from the inhibitory effect of AA. Moreover, 5,8,11,14-eicosatetraynoic acid, a nonmetabolizable arachidonate analogue, also inhibited cell growth, suggesting that the effect of AA did not require further metabolism. Treatment with antioxidants prior to stimulation with AA was also ineffective in preventing its antiproliferative effect. Thus, AA inhibited proliferation of CML cells by inducing apoptotic cell death. The signaling mechanisms of AA-induced inhibition of cell growth appeared to be independent of its conversion into eicosanoids or free radical generation.

Clonogenic potential and phenotypic analysis of CD34+ cells mobilized by different chemotherapy regimens.

BACKGROUND AND OBJECTIVE: Since limited data concerning quantitative and qualitative differences of CD34+ cells collected after different mobilization schedules are available, we investigated phenotype, proliferative capacity and primitive progenitor cell content of CD34+ cells mobilized with four different regimens. DESIGN AND METHODS: The number, phenotype, and progenitor cell content of CD34+ cells were investigated in 46 patients mobilized with cyclophosphamide (CY) 7 g/m(2) plus granulocyte colony-stimulating factor (G-CSF, 5 microg/kg) (CY7+G-CSF) (n=16), CY 4 g/m(2) plus G-CSF (CY4+G-CSF) (n=8), IVE [ifosphamide (2.5 g/m(2) for 3 d), etoposide (150 mg/m(2) for 3 d), epirubicin (100 mg/m(2) on day 1)] plus G-CSF (IVE+G-CSF) (n=9), or G-CSF (10 microg/kg) alone (n=13). RESULTS: The number of CD34+ cells collected per liter of processed blood was significantly higher in the CY7+G-CSF group than in the CY4+G-CSF and G-CSF groups (p

Effects of the tyrosine kinase inhibitor AG957 and an Anti-Fas receptor antibody on CD34(+) chronic myelogenous leukemia progenitor cells.

The hallmark of chronic myelogenous leukemia (CML) is the Philadelphia (Ph) chromosome that fuses genetic sequences of the BCR gene on chromosome 22 with c-ABL sequences translocated from chromosome 9. BCR/ABL fusion proteins have a dysregulated protein tyrosine kinase (PTK) activity exerting a key role in malignant transformation. Targeting the tyrosine kinase activity of BCR/ABL or using agents capable of triggering apoptosis might represent attractive therapeutic approaches for ex vivo purging. AG957, a member of the tyrphostin compounds, exerts a selective inhibition of p210(BCR/ABL) tyrosine phosphorylation. We report here that preincubation of CML or normal CD34(+) cells with graded concentration of AG957 (1 to 100 micromol/L) resulted in a statistically significant, dose-dependent suppression of colony growth from multipotent, erythroid, and granulocyte-macrophage progenitors as well as the more primitive long-term culture-initiating cells (LTC-IC). However, AG957 doses causing 50% inhibition (ID50) of CML and normal progenitors were significantly different for multilineage colony-forming units (CFU-Mix; 12 v 64 micromol/L; P =.008), burst-forming unit-erythroid (BFU-E; 29 v 89 micromol/L; P =.004), colony-forming unit-granulocyte-macrophage (CFU-GM; 34 v 85 micromol/L; P =.004), and LTC-IC (43 v 181 micromol/L; P =.004). In 5 of 10 patients, analysis of BCR/ABL mRNA on single progenitors by reverse transcription-polymerase chain reaction showed that AG957 at 50 micromol/L significantly reduced the mean (+/-SD) percentage of BCR/ABL-positive progenitors (92% +/- 10% v 33 +/- 5%; P =.001). Because AG957 treatment resulted in significantly higher percentages of apoptotic cells (30% v 9%) in the BCR/ABL-transfected 32DLG7 cells as compared with 32D-T2/93 cells (BCR/ABL-negative), we investigated the combined effects of AG957 with the anti-Fas receptor (Fas-R) monoclonal antibody CH11 that triggers apoptosis. As compared with AG957 alone, the sequential treatment of CML CD34(+) cells with AG957 (1 micromol/L) and CH11 (1 microgram/mL) increased CFU-Mix, BFU-E, and CFU-GM growth inhibition by 1.6-fold, 3-fold, and 4-fold, respectively. In contrast, the treatment of normal CD34(+) cells with AG957 and CH11 failed to enhance AG957-induced colony growth inhibition. We conclude that (1) AG957 inhibits in a dose-dependent manner CML CD34-derived colony formation by both primitive LTC-IC as well as committed CFU-Mix, BFU-E, and CFU-GM; (2) this growth inhibition is associated with the selection of a substantial amount of BCR/ABL-negative progenitors; and (3) the antiproliferative effect of AG957 is dramatically increased by combining this compound with the anti-Fas-R antibody CH11. These data may have significant therapeutic applications.

Primitive hematopoietic progenitors within mobilized blood are spared by uncontrolled rate freezing.

Uncontrolled-rate freezing techniques represent an attractive alternative to controlled-rate cryopreservation procedures which are time-consuming and require high-level technical expertise. In this study, we report our experience using uncontrolled-rate cryopreservation and mechanical freezer storage at -140 degrees C. Twenty-eight PBPC samples (10 cryovials, 18 freezing bags) from 23 patients were cryopreserved in a cryoprotectant solution composed of phosphate-buffered saline (80%, v/v) supplemented with human serum albumin (10%, v/v) and dimethylsulfoxide (10%, v/v). The cryopreservation procedure required on average 1.5 h. The mean (+/- s.e.m.) storage time of cryovials and bags was 344+/-40 and 299+57 days, respectively. Although cell thawing was associated with a statistically significant reduction of the absolute number of nucleated cells (vials: 0.3x10(9) vs. 0.2x10(9), P< or =0.02; bags: 14x10(9) vs. 11x10(9), P< or =0.0003), the growth of committed progenitors was substantially unaffected by the freezing-thawing procedure, with mean recoveries of CFU-Mix, BFU-E, and CFU-GM ranging from 60+/- 29% to 134+/-15%. Mean recoveries of LTC-IC from cryovials and bags were 262+/-101% and 155+/-27% (P< or =0.2), respectively. In 14 out of 23 patients who underwent high-dose chemotherapy and PBPC reinfusion, the pre-and post-freezing absolute numbers of hematopoietic progenitors cryopreserved in bags were compared. A significant reduction was detected for CFU-Mix (11 vs. 7.4x10(5)), but no significant loss of BFU-E (180 vs. 150x10(5)), CFU-GM (400 vs. 290x10(5)) and LTC-IC (15 vs. 16x10(5)) could be demonstrated. When these patients were reinfused with uncontrolled-rate cryopreserved PBPC, the mean number of days to reach 1x10(9)/l white blood cells and 50x10(9)/l platelets were 9 and 13, respectively. In conclusion, the procedure described here is characterized by short execution time, allows a substantial recovery of primitive and committed progenitors and is associated with prompt hematopoietic recovery following myeloablative therapy even after long-term storage.