Defining biomarkers in oral cancer according to smoking and drinking status

Introduction

Oral Squamous Cell Carcinomas (OSCC) are mostly related to tobacco consumption eventually associated to alcohol (Smoker/Drinker patients: SD), but 25-30% of the patients have no identified risk factors (Non-Smoker/Non-Drinker patients: NSND). We hypothesized that these patients have distinguishable immune profiles that could be useful for prognosis.

Materials and Methods

Cells present in immune tumor microenvironment (TME) and blood from 87 OSCC HPV-negative patients were analyzed using a multiparameter flow cytometry assay, in a prospective case-control study. Cytokine levels in tumor supernatants and blood were determined by a cytometric bead array (CBA) assay.

Results

Normal gingiva and blood from healthy donors (HD) were used as controls. A significant increase of granulocytes (p<0.05 for blood), of monocytes-macrophages (p<0.01 for blood) and of CD4⁺ T cells expressing CD45RO and CCR6 (p<0.001 for blood; p<0.0001 for TME) as well as higher levels of IL-6 (p<0.01 for sera, p<0.05 for tumor supernatant) were observed in SD patients as compared to NSND OSCC patients and HD. High percentages of CD4⁺ T cells expressing CD45RO and CCR6 cells in tumor tissue (p=0.05) and blood (p=0.05) of SD OSCC patients were also associated with a poorer prognosis while a high percentage of regulatory T cells (Treg) in tumor tissue was associated with a more favorable prognostic factor (p=0.05). Also, a higher percentage of blood CD8⁺ T lymphocytes among CD45⁺ cells in NSND patients was associated with a better disease-free survival (p=0.004).

Conclusion

Granulocytes, monocytes-macrophages, and CD4⁺ T cells expressing CD45RO and CCR6 in blood and TME as well as serum IL-6 can therefore distinguish OSCC SD and NSND patients. Quantifying the proportion of CD4⁺ T cells expressing CD45RO and CCR6 and of Treg in SD patients and CD8⁺ T cells in NSND patients could help defining the prognostic of OSCC patients.

Cigarette smoking induces human CCR6+Th17 lymphocytes senescence and VEGF-A secretion

Chronic exposure to environmental pollutants is often associated with systemic inflammation. As such, cigarette smoking contributes to inflammation and lung diseases by inducing senescence of pulmonary cells such as pneumocytes, fibroblasts, and endothelial cells. Yet, how smoking worsens evolution of chronic inflammatory disorders associated with Th17 lymphocytes, such as rheumatoid arthritis, psoriasis, Crohn’s disease, and multiple sclerosis, is largely unknown. Results from human studies show an increase in inflammatory CD4⁺ Th17 lymphocytes at blood- and pulmonary level in smokers. The aim of the study was to evaluate the sensitivity of CD4⁺ Th17 lymphocytes to cigarette smoke-induced senescence. Mucosa-homing CCR6⁺ Th17- were compared to CCR6^neg -and regulatory T peripheral lymphocytes after exposure to cigarette smoke extract (CSE). Senescence sensitivity of CSE-exposed cells was assessed by determination of various senescence biomarkers (β-galactosidase activity, p16^Ink4a- and p21 expression) and cytokines production. CCR6⁺ Th17 cells showed a higher sensitivity to CSE-induced senescence compared to controls, which is associated to oxidative stress and higher VEGFα secretion. Pharmacological targeting of ROS- and ERK1/2 signalling pathways prevented CSE-induced senescence of CCR6⁺Th17 lymphocytes as well as VEGFα secretion. Altogether, these results identify mechanisms by which pro-oxidant environmental pollutants contribute to pro-angiogenic and pathogenic CCR6⁺Th17 cells, therefore potential targets for therapeutic purposes.

Preclinical evaluation of mRNA trimannosylated lipopolyplexes as therapeutic cancer vaccines targeting dendritic cells

Clinical trials with direct administration of synthetic mRNAs encoding tumor antigens demonstrated safety and induction of tumor-specific immune responses. Their proper delivery to dendritic cells (DCs) requires their protection against RNase degradation and more specificity for dose reduction. Lipid-Polymer-RNA lipopolyplexes (LPR) are attractive mRNA delivery systems and their equipment with mannose containing glycolipid, specific of endocytic receptors present on the membrane of DCs is a valuable strategy. In this present work, we evaluated the capacity of LPR functionalized with a tri-antenna of α-d-mannopyranoside (triMN-LPR) concerning (i) their binding to CD209/DC-SIGN and CD207/Langerin expressing cell lines, human and mouse DCs and other hematopoietic cell populations, (ii) the nature of induced immune response after in vivo immunization and (iii) their therapeutic anti-cancer vaccine efficiency. We demonstrated that triMN-LPR provided high induction of a local inflammatory response two days after intradermal injection to C57BL/6 mice, followed by the recruitment and activation of DCs in the corresponding draining lymph nodes. This was associated with skin production of CCR7 and CXCR4 at vaccination sites driving DC migration. High number of E7-specific T cells was detected after E7-encoded mRNA triMN-LPR vaccination. When evaluated in three therapeutic pre-clinical murine tumor models such as E7-expressing TC1 cells, OVA-expressing EG7 cells and MART-1-expressing B16F0 cells, triMN-LPR carrying mRNA encoding the respective antigens significantly exert curative responses in mice vaccinated seven days after initial tumor inoculation. These results provide evidence that triMN-LPR give rise to an efficient stimulatory immune response allowing for therapeutic anti-cancer vaccination in mice. This mRNA formulation should be considered for anti-cancer vaccination in Humans.

Intra-cheek immunization as a novel vaccination route for therapeutic vaccines of head and neck squamous cell carcinomas using plasmo virus-like particles

Despite current therapy, head and neck squamous cell carcinomas (HNSCCs) arising from various mucosal sites of the upper aero-digestive tract frequently relapse in a loco-regional manner and have a poor prognosis. Our objective was to validate an innovative mucosal route of vaccination using plasmo virus-like particles (pVLPs) in a pre-clinical orthotopic model of HNSCCs. For this purpose, we used pVLP-E7, that are plasmid DNA encoding retroviral virus-like particles carrying a truncated E7 oncoprotein from HPV-16 as antigen model, to vaccinate mice bearing pre-established TC-1 tumors implanted into the buccal mucosa. pVLP-E7 were combined with clinical grade TLR agonists (Imiquimod and CpG-ODN). In this pre-clinical orthotopic model, whose tumor microenvironment resembles to those of human HNSCCs, different mucosal vaccination routes were tested for their ability to elicit efficient immune and antitumoral responses. Results showed that mucosal intra-cheek (IC) vaccinations using pVLP-E7, comparatively to intradermic vaccinations (ID), gave rise to higher mobilization of mucosal (CD49a(+)) CD8(+) specific effector T cells in both tumor draining lymph nodes (TdLNs) and tumor microenvironment resulting in better antitumor effects and in a long-term protection against tumor rechallenge. In vivo CD8(+) depletion demonstrated that antitumoral effects were fully dependent upon the presence of CD8(+) T cells. Validation of IC mucosal vaccinations with pVLPs combined with adjuvants using a pre-clinical orthotopic model of HNSCC provides valuable pre-clinical data to rapidly envision the use of such therapeutic vaccines in patients with HNSCCs, inasmuch as vaccinal components and adjuvants can be easily obtained as clinical grade reagents.

Generation of Human Alloantigen-Specific Regulatory T Cells under Good Manufacturing Practice-Compliant Conditions for Cell Therapy

Natural regulatory T cells (Tregs) may have a great therapeutic potential to induce tolerance in allogeneic cells and organ transplantations. In mice, we showed that alloantigen-specific Tregs (spe-Tregs) were more efficient than polyclonal Tregs (poly-Tregs) in controlling graft-versus-host disease (GVHD). Here we describe a clinical-grade compliant method for generating human spe-Tregs. Tregs were enriched from leukapheresis products with anti-CD25 immunomagnetic beads, primed twice by allogeneic mature monocyte-derived dendritic cells (mDCs), and cultured during 3 weeks in medium containing interleukin 2 (IL-2), IL-15, and rapamycin. After 3 weeks of culture, final cell products were expanded 8.3-fold from the initial CD25+ purifications. Immunophenotypic analyses of final cells indicate that they were composed of 88 ± 2.6% of CD4+ T cells, all expressing Treg-specific markers (FOXP3, Helios, GARP, LAP, and CD152). Spe-Tregs were highly suppressive in vitro and also in vivo using a xeno-GVHD model established in immunodeficient mice. The specificity of their suppressive activity was demonstrated on their ability to significantly suppress the proliferation of autologous effector T cells stimulated by the same mDCs compared to third-party mDCs. Our data provide evidence that functional alloantigen Tregs can be generated under clinical-grade compliant conditions. Taking into account that 130 × 106 CD25+ cells can be obtained at large scale from standard leukapheresis, our cell process may give rise to a theoretical final number of 1 × 109 spe-Tregs. Thus, using our strategy, we can propose to prepare spe-Tregs for clinical trials designed to control HLA-mismatched GVHD or organ transplantation rejection.

A suicide gene therapy combining the improvement of cyclophosphamide tumor cytotoxicity and the development of an anti-tumor immune response

Gene-directed enzyme prodrug therapy (GDEPT) consists in targeted delivery to tumor cells of a suicide gene responsible for in situ conversion of a prodrug into cytotoxic metabolites. One of the major limitations of this strategy in clinical application was the poor prodrug activation capacity of suicide gene. We built a highly efficient suicide gene capable of bioactivating the prodrug cyclophosphamide (CPA) by fusing a CYP2B6 triple mutant with NADPH cytochrome P450 reductase (CYP2B6TM-RED). Expression of this fusion gene via a recombinant lentivirus (LV) vector converted resistant human (A549) and murine (TC1) pulmonary cell lines into CPA-susceptible cell lines. We tested the efficiency of our GDEPT strategy in C57Bl/6 immunocompetent mice, using TC1 cells expressing the HPV-16 E6/E7 oncoproteins. In mice bearing tumors composed only of TC1-CYP2B6TM-RED cells, four CPA injections (140 mg/Kg once a week) completely eradicated the tumors for more than two months. Tumors having only 25% of TC1-CYP2B6TM-RED cells were also completely eradicated by five CPA injections, demonstrating a major in vivo bystander effect. Moreover, surviving mice were rechallenged with parental TC1 cells. The tumors regressed spontaneously 7 days after cell inoculation or grew more slowly than in control naive mice due to a strong immune response mediated by anti-E7CD8(+)T cells. These data suggest that combining the CYPB6TM-RED gene with CPA may hold promise as a highly effective treatment for solid tumors in humans.

Efficacy of DNA vaccines forming e7 recombinant retroviral virus-like particles for the treatment of human papillomavirus-induced cancers

Human papillomavirus (HPV) is involved in the development of anogenital tumors and also in the development of oropharyngeal head and neck carcinomas, where HPV-16, expressing the E6 and E7 oncoproteins, is the most frequent serotype. Although vaccines encoding L1 and L2 capsid HPV proteins are efficient for the prevention of HPV infection, they are inadequate for treating established tumors. Hence, development of innovative vaccine therapies targeting E6/E7 is important for controlling HPV-induced cancers. We have engineered a nononcogenic mutated E7-specific plasmo-retroVLP vaccine (pVLP-E7), consisting of plasmid DNA, that is able to form recombinant retrovirus-based virus-like particles (VLPs) that display E7 antigen into murine leukemia virus Gag proteins pseudotyped with vesicular stomatitis virus envelope glycoprotein (VSV-G). pVLP-E7 vaccinations were studied for their ability to generate specific immune responses and for induction of protective immunity against tumor cell challenge in preventive and therapeutic models. The produced VLPs induce the maturation of human dendritic cells in vitro and mount specific E7 T cell responses. Intradermic vaccinations of mice with pVLP-E7 show their efficacy to generate antigen-specific T cell responses, to prevent and protect animals from early TC-1 tumor development compared with standard DNA or VLP immunizations. The vaccine efficacy was also evaluated for advanced tumors in mice vaccinated at various time after the injection of TC-1 cells. Data show that pVLP-E7 vaccination can cure mice with already established tumors only when combined with Toll-like receptor-7 (TLR7) and TLR9 agonists. Our findings provide evidence that pVLPs, combining the advantages of DNA and VLP vaccines, appear to be a promising strategy for the treatment of HPV-induced cancers.

Abstract 3315: Synergistic direct and distant bystander effects contribute to the efficiency of a new suicide gene therapy against cancer

Gene-directed enzyme prodrug therapy (GDEPT) systems have been developed for killing cancer cells by introducing a gene coding for a protein able to convert a harmless prodrug into a cytotoxic one. We built a highly efficient therapeutic suicide gene which metabolizes the prodrug cyclophosphamide (CPA) into cytotoxic metabolites. This gene was formed by the fusion of two human genes: a triple mutant of CYP2B6 (CYP2B6TM) modified by site-directed mutagenesis and the soluble part of NADPH cytochrome P450 reductase (RED). Moreover the linker between both genes was optimized to express a high RED activity to improve electron transfer required for CYP2B6TM catalytic activity. Expression of this fusion gene (CYP2B6TM-RED), by a recombinant lentivirus (LV), allowed switching of a resistant human pulmonary cell line (A549) into a sensitive cell line to CPA. After 48 hours of CPA treatment, cytotoxic tests showed that A549 cells expressing CYP2B6TM-RED had an IC50 of about 0.5 mM approximately 13-fold lower than that of cells expressing CYP2B6 wild type-RED. Our strategy was tested in tumor models using immunocompetent C57Bl/6 mice and the mouse epithelial pulmonary cell line (TC1). In vitro, this CPA resistant cell line became sensitive to CPA after expression of CYP2B6TM-RED gene with an IC50 comparable to that observed in transduced A549 cells.TC1 cells previously infected or not by LV-CYP2B6TM-RED were injected sub-cutaneously into C57Bl/6 mice. CPA was intraperitonealy administered each week at a dose of 140 mg/Kg when the tumor volume reached about 500 mm3. Mice with TC1-CYP2B6TM-RED tumors presented an important decrease of the tumor volume immediately after the first injection of CPA and only four injections of CPA were necessary to observe a complete disappearance of the tumors. Similar results were obtained when the tumor cells were composed of 25% of TC1 expressing CYP2B6TM-RED and 75% of non-infected cells demonstrating in vivo the contribution of a direct bystander effect to the efficiency of our strategy. Moreover cured mice were rechallenged with uninfected TC1 cells. In some cases a complete eradication of the tumor that was related to a specific cellular immune response against tumor cells was observed 7 days after cell inoculation. This result demonstrated an efficient distant bystander effect that would lead to a long-term protection against potential metastases. We are now testing CYP2B6TM-RED fusion gene either by intratumoral lentiviral injection or by infection of mesenchymal stem cells used as delivery strategy, in view of clinical human trials.

Citation Format: Walid Touati, Johanne Seguin, Thi Tran, Eric Tartour, Claude Baillou, François M. Lemoine, Philippe Beaune, Isabelle de Waziers. Synergistic direct and distant bystander effects contribute to the efficiency of a new suicide gene therapy against cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3315. doi:10.1158/1538-7445.AM2013-3315

Waldenström's macroglobulinemia harbors a unique proteome where Ku70 is severely underexpressed as compared with other B-lymphoproliferative disorders

Waldenström's macroglobulinemia (WM) is a clonal B-cell lymphoproliferative disorder (LPD) of post-germinal center nature. Despite the fact that the precise molecular pathway(s) leading to WM remain(s) to be elucidated, a hallmark of the disease is the absence of the immunoglobulin heavy chain class switch recombination. Using two-dimensional gel electrophoresis, we compared proteomic profiles of WM cells with that of other LPDs. We were able to demonstrate that WM constitutes a unique proteomic entity as compared with chronic lymphocytic leukemia and marginal zone lymphoma. Statistical comparisons of protein expression levels revealed that a few proteins are distinctly expressed in WM in comparison with other LPDs. In particular we observed a major downregulation of the double strand repair protein Ku70 (XRCC6); confirmed at both the protein and RNA levels in an independent cohort of patients. Hence, we define a distinctive proteomic profile for WM where the downregulation of Ku70—a component of the non homologous end-joining pathway—might be relevant in disease pathophysiology.

Human CD90 identifies Th17/Tc17 T cell subsets that are depleted in HIV-infected patients

By revisiting CD90, a GPI-anchored glycoprotein, we show that CD90 is expressed by a subset of CD4(+) and CD8(+) human T cells. CD4(+)CD90(+) cells share similarities with Th17 cells because they express the Th17-specific transcription factor RORC2 and produce IL-17A. CD4(+)CD90(+) cells are activated memory T cells that express the gut mucosal markers CCR6, CD161, and the α(4) and β(7) integrins. Compared with CD90-depleted CCR6(+) memory Th17 cells, CD4(+)CD90(+) cells express higher levels of IL-22 and proinflammatory cytokines (IL-6, TNF-α and GM-CSF), but they produce lower levels of IL-21 and no IL-9. Analyses of CD8(+)CD90(+) cells reveal that they express RORC2 and are able to produce higher levels of IL-17A, IL-22, and CCL20 compared with CD90-depleted CD8(+) cells. These data show that CD90 identifies Th17 and Tc17 cells with a peculiar cytokine profile. Studies of circulating CD90(+) cells in HIV patients show that CD90(+) cells are decreased with an imbalance of the CD4(+)CD90(+)/regulatory T cell ratio in nontreated patients compared with treated patients and healthy donors. Overall, human CD90 identifies a subset of Th17 and Tc17 cells within CD4(+) and CD8(+) T cells, respectively, which are depleted during HIV infection.

High diversity of the immune repertoire in humanized NOD.SCID.gamma c-/- mice

The diversity of the human immune repertoire and how it relates to a functional immune response has not yet been studied in detail in humanized NOD.SCID.gammac(-/-) immunodeficient mice. Here, we used a multiplex PCR on genomic DNA to quantify the combinatorial diversity of all possible V-J rearrangements at the TCR-beta chain and heavy chain Ig locus. We first show that the combinatorial diversity of the TCR-beta chain generated in the thymus was well preserved in the periphery, suggesting that human T cells were not vastly activated in mice, in agreement with phenotypic studies. We then show that the combinatorial diversity in NOD.SCID.gammac(-/-) mice reached 100% of human reference samples for both the TCR and the heavy chain of Ig. To document the functionality of this repertoire, we show that a detectable but weak HLA-restricted cellular immune response could be elicited in reconstituted mice after immunization with an adenoviral vector expressing HCV envelope glycoproteins. Altogether, our results suggest that humanized mice express a diversified repertoire and are able to mount antigen-specific immune responses.

Characteristics of hybrid cells obtained by dendritic cell/tumour cell fusion in a T-47D breast cancer cell line model indicate their potential as anti-tumour vaccines

Many strategies have been proposed to circumvent cancer development or prevent its growth. One of the promising strategies is to direct the immune response toward tumour antigens. This can be achieved by loading dendritic cells, the most potent antigen presenting cells, with tumour antigens. Fusion of dendritic cells (DC) with tumour cells is an attractive way to load the DC with all tumour antigens regardless of their immunogenicity status and the fact that they have, or not, been identified. The aim of our study was to characterise the immunophenotype of fused cells, monitor the evolution of the fusion interface and the distribution of surface antigens over time and assess for their maturation status and functionality in vitro. We used polyethylene glycol to fuse DC with Her2/neu positive breast cancer cell line T-47D. We demonstrate that false positive events accounted in flow cytometry can be identified using confocal microscopy to avoid an overestimation of fusion efficiency and to distinguish clearly hybrid cells from aggregated or phagocytosed cells. We used imaging means to demonstrate the conservation of presentation molecules (MHC II, CD1a), co-stimulatory molecules (CD40, CD80, CD86), as well as tumour antigens (Her2/neu, cytokeratins) in optimised conditions. Fused cells were only recognisable for 48 h as assessed by membrane staining and membranous antigen distribution. Fusion was necessary for their maturation to be accompanied by functional activity such as secretion of cytokines and perforin. These results suggest that hybrid cells generated by the fusion of DC and tumour cells can be easily identified and characterised using imaging techniques, and that, regarding functionality and cytokine secretion, they appear to be good candidates for anti-tumour therapies namely in breast cancer.

GFP-transduced CD34+ and Lin− CD34− hematopoietic stem cells did not adopt a cardiac phenotype in a nonhuman primate model of myocardial infarct

OBJECTIVE

Studies in mice have reported contradictory results on the contribution of bone marrow cells to myocardial regeneration. This study aims to evaluate their ability to differentiate into cells of cardiac lineage in a nonhuman primate mode of myocardial infarct.

MATERIALS AND METHODS

Lin(-)CD34(-) and CD34(+)-enriched bone marrow cells or mobilized peripheral blood cells were transduced with green fluorescent protein (GFP) and injected directly into ischemic myocardium. The fate of the transplanted cells was evaluated using quantitative reverse transcription polymerase chain reaction (QRT-PCR) and immunohistology. Animals were followed-up using echocardiography.

RESULTS

QRT-PCR analysis detected from 3% to 10% of the original number of administered GFP(+) cells after 7 days. These GFP(+) cells did not express cardiac tissue-specific markers, but were immunophenotypically consistent with undifferentiated hematopoietic cells. The local production of vascular endothelial growth factor, measured by QRT-PCR, was approximately doubled as compared to the untreated infarcted control heart. Three months after hematopoietic stem cell (HSC) administration, no GFP(+) cells were detected and no evidence of regeneration of the infarcted region was found by histological examination. In contrast, a high level of matrix metalloproteinase 2 was measured in infarct and peri-infarct area. At this time, an improved ejection fraction and decreased left ventricular chamber dimension, which might be also related to a natural course after reperfusion, were observed.

CONCLUSIONS

Our data show that GFP(+) CD34(+) and Lin(-)CD34(-)-enriched HSC do not differentiate into cardiomyocytes or into endothelial cells in the infarcted myocardium and that the local production of some growth factors had no positive effect on myocardial regeneration after 3 months.

CD4 regulation in human lymphoid non-T-cells: A role for the silencer element

In humans, the CD4 molecule is expressed on a subset of T-cells and at various levels on myeloid and lymphoid cells. The mechanisms regulating human CD4 gene expression are yet poorly understood. We speculated that the CD4 silencer, which operates in CD8+ T-cells to repress CD4 expression, could be responsible for CD4 repression in human lymphoid non-T-cells. To test this possibility, we used lentiviral vectors carrying CD4 regulatory sequences, with or without the silencer element, to express an eGFP reporter gene. We observed that (i) in the absence of the silencer element, eGFP expression was detected in CD34+-derived B- and NK-cells that otherwise lacked endogenous CD4 mRNA, indicating active repression of the CD4 regulatory sequences and (ii) the addition of the CD4 silencer could repress eGFP expression in these same cells, as well as in human B-cells generated in vivo in NOD/SCID mice. Collectively, our results suggest that beyond its well-characterized function in T-cells, the CD4 silencer also regulates CD4 gene expression in human lymphoid non-T-cells.

Lentiviral transduction of human hematopoietic cells by HIV-1- and SIV-based vectors containing a bicistronic cassette driven by various internal promoters

BACKGROUND

Lentiviral gene transfer into hematopoietic cells has been mostly optimized with vectors carrying a single reporter gene. For many clinical applications, lentiviral vectors should contain more than one gene because transduced cells should be enriched by a selectable marker or killed for safety reasons after use. Thus, we compared various vectors containing a bicistronic cassette driven by different ubiquitous promoters for their ability to transduce human T-lymphocytes, CD34+-cells, and dendritic cells (DCs) derived from CD34+-cells or monocytes.

METHODS

We designed HIV or SIV constructs containing a bicistronic cassette composed of two reporter genes (thy1/GFP) linked by an internal ribosome entry site sequence and driven by the cytomegalovirus (CMV) or elongation factor 1alpha (EF1alpha) promoters. The woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) was or not inserted within the constructs, the Vpx accessory protein was or not used for SIV vectors. Target cells were infected at the same multiplicity of infection, transduction efficiency was analyzed both by flow cytometry and vector integration.

RESULTS

For T-cells, HIV-based vectors/WPRE+ in which the thy1/GFP cassette was driven by the EF1alpha promoter were more efficient than SIV-based vectors. For CD34+-cells and CD34+-derived DCs, better thy1/GFP expression was achieved when the CMV promoter drove the cassette inserted into HIV-based vectors/WPRE+. Conversely, for monocyte-derived DCs, the cassette yielded better thy1/GFP expression when inserted into SIV-based vectors/WPRE+ and driven by the CMV or EF1alpha promoters, the use of Vpx significantly improving the expression levels.

CONCLUSIONS

Our results provide guidelines for improving the transduction of T-cells, CD34+-cells or DCs with lentiviral bicistronic vectors designed for clinical applications.

Molecular characterization of early human T/NK and B-lymphoid progenitor cells in umbilical cord blood

The early stages of human lymphopoiesis are poorly characterized. Here, we compared the lymphoid potential of a novel umbilical cord blood CD34(+)CD45RA(hi)CD7(+) hematopoietic progenitor cell (HPC) population with that of CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs, previously proposed as candidate common lymphoid progenitors. Limiting-dilution and clonal analysis, fetal thymic organ cultures, and culture onto Notch ligand Delta-like-1-expressing OP9 cells, showed that although CD34(+)CD45RA(hi)CD7(+) HPCs could generate cells of the 3 lymphoid lineages, their potential was skewed toward the T/natural killer (T/NK) lineages. In contrast, CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs predominantly exhibited a B-cell potential. Gene expression profiling with DNA microarrays confirmed that CD34(+)CD45RA(hi)CD7(+) HPCs selectively expressed T-lymphoid and NK lineage-committed genes while retaining expression of genes affiliated to the granulomonocytic lineage, whereas CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs displayed a typical pro-B-cell transcription profile and essentially lacked genes unrelated to the B lineage. In addition, both populations could be generated in vitro from CD34(+)CD45RA(int)CD7(-) and CD34(+)CD45RA(hi)Lin(-) HPCs with mixed lymphomyeloid potential, from which they emerged independently with different growth/differentiation factor requirements. These findings indicate that CD34(+)CD45RA(hi)CD7(+) and CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs correspond to multipotent early lymphoid progenitors polarized toward either the T/NK or B lineage, respectively.

Highly active antiretroviral therapy corrects hematopoiesis in HIV-1 infected patients: interest for peripheral blood stem cell-based gene therapy

OBJECTIVES

To study, in asymptomatic HIV-1-infected (HIV+) patients, whether peripheral blood hematopoietic progenitor/stem cells (PBPC) mobilized by granulocyte colony stimulating factor (G-CSF), can be used as a source of cells for retroviral gene therapy.

DESIGN

PBPC from two groups of HIV+ patients (treated or untreated by highly active antiretroviral therapy) and from seronegative donors were mobilized with G-CSF.

METHODS

PBPC collected by leukapheresis were enriched for CD34 cells, immunophenotypically and functionally characterized, cultured and infected with retroviral vectors. HIV proviral integration was studied on fresh and cultured cells.

RESULTS

G-CSF moderately and transiently increased the viral load in untreated patients only, and induced in both groups of HIV+ patients mobilization of percentages and numbers of CD34 cells comparable to those of seronegative volunteers. The most immature CD34 cell subset, the clonogenic progenitor and long-term culture initiating cells were significantly decreased in leukapheresis products and CD34-enriched fractions from untreated HIV+ patients but not in those from treated HIV+ patients. Cell cycle activation and growth factor responses of CD34 cells from both groups of HIV+ patients were not different from those of the control group. Culture and retroviral infection of CD34 cells from HIV+ patients did not enhance HIV replication, and yielded transduction levels similar to those obtained using CD34 cells from seronegative donors.

CONCLUSIONS

G-CSF-mobilized PBPC can be safely used for HIV retroviral gene therapy in asymptomatic treated patients while highly active antiretroviral therapy would control the G-CSF-induced increase in viral load and correct the defective hematopoiesis observed in untreated patients, without inhibiting the retroviral transduction of PBPC.

High level of retrovirus-mediated gene transfer into dendritic cells derived from cord blood and mobilized peripheral blood CD34+ cells

Dendritic cells (DCs), the most potent antigen-presenting cells, can be generated from CD34+ hematopoietic stem cells and used for generating therapeutic immune responses. To develop immunotherapy protocols based on genetically modified DCs, we have investigated the conditions for high-level transduction of a large amount of CD34+-derived DCs. Thus, we have used an efficient and clinically applicable protocol for the retroviral transduction of cord blood (CB) or mobilized peripheral blood (MPB) CD34+ cells based on infection with gibbon ape leukemia virus (GALV)-pseudotyped retroviral vectors carrying the nls-LacZ reporter gene. Infected cells have been subsequently cultured under conditions allowing their dendritic differentiation. The results show that using a growth factor combination including granulocyte-macrophage colony-stimulating factor plus tumor necrosis factor alpha plus interleukin 4 plus stem cell factor plus Flt3 ligand, more than 70% of DCs derived from CB or MPB CD34+ cells can be transduced. Semiquantitative PCR indicates that at least two proviral copies per cell were detected. Transduced DCs retain normal immunophenotype and potent T cell stimulatory capacity. Finally, by using a semisolid methylcellulose assay for dendritic progenitors (CFU-DCs), we show that more than 90% of CFU-DCs can be transduced. Such a highly efficient retrovirus-mediated gene transfer into CD34+-derived DCs makes it possible to envision the use of this methodology in clinical trials.

High-level gene transfer to cord blood progenitors using gibbon ape leukemia virus pseudotype retroviral vectors and an improved clinically applicable protocol

The best methods for transducing hematopoietic progenitor cells usually involve either direct co-cultivation with virus-producing cells or human stromal supportive cells. However, these methods cannot be safely or easily applied to clinical use. Therefore, we aimed at improving retrovirus-mediated gene transfer into hematopoietic progenitors derived from cord blood CD34+ cells using viral supernatant to levels achieved at least with direct co-cultivation and under conditions that are suitable for clinical applications. In a first set of experiments, CD34+ cells were infected with supernatant containing amphotropic retroviral particles carrying the nls-lacZ reporter gene and the effects of centrifugation, cell adhesion to fibronectin, and Polybrene on the transduction of both clonogenic progenitors (CFC) and long-term culture initiating cells (LTC-IC) were studied. Transduction efficiency was evaluated on the percentage and total number of progenitors expressing the beta-galactosidase activity. Results show that a 48-hr infection of CD34+ cells with viral supernatant combining centrifugation at 1000 x g for 3 hr followed by adhesion to fibronectin allows transduction levels for both CFC and LTC-IC to be reached that are as good as using direct co-cultivation. In a second set of experiments, CD34+ cells were infected using this optimized protocol with pseudotyped retroviral particles carrying the gibbon ape leukemia virus (GALV) envelope protein. Under these conditions, between 50 and 100% of CFC and LTC-IC were transduced. Thus, we have developed a protocol capable of highly transducing cord blood progenitors under conditions suitable for a therapeutical use.

Comparison of the effects of AcSDKP, thymosin beta4, macrophage inflammatory protein 1alpha and transforming growth factor beta on human leukemic cells

We have compared the effects of AcSDKP, Thymosin beta4 (Tbeta4), MIP1alpha and TGFbeta on acute myeloid leukemia (AML) and B-lineage acute lymphoid leukemia (B-ALL) cells using liquid cultures in the presence of GM-CSF, IL-3 and SCF for AML cells and IL-3 and IL-7 for ALL cells. Each molecule was added daily and cell proliferation was evaluated on day 3 by thymidine incorporation. Whereas TGFbeta was found inhibitory in all the AML and B-ALL cases studied, MIP1alpha was inhibitory in 6/12 AML cases and had no effect on B-ALL cells. AcSDKP and Tbeta4 showed an inhibitory effect in a few cases but only at high doses which were inactive on normal cells. Thus, our study not only confirms the effect of TGFbeta, MIP1alpha and AcSDKP on AML cells but also provides new data concerning their effect on B-ALL and the possible inhibitory effect of AcSDKP at high doses. Furthermore, we show for the first time the effect of Tbeta4 on leukemic cells. Altogether, our data indicate differences of sensitivity of leukemic cells to negative regulators, some leukemias being inhibited by one or several of these molecules whereas others were unresponsive to all used. The clinical relevance of these observations still remains to be determined.

Optimization of the cycling of clonogenic and primitive cord blood progenitors by various growth factors

The cycling status of cord blood progenitors and the culture conditions triggering their activation into S-phase have been studied using flow cytometry and a 3H-thymidine suicide assay. Mononuclear cells cultured either in Iscove's modified Dulbecco's medium (IMDM) +/- 10% fetal calf serum ([FCS]; IMDM + FCS) or in Dulbecco's modified Eagle's medium (DMEM) +/- 10% newborn bovine serum ([NBS]; DMEM + NBS) were stimulated by various growth factors (GFs). Results showed that CD34+ cells, clonogenic progenitors (colony forming cells [CFCs]) and long-term culture initiating cells (LTC-IC) present in freshly harvested cord blood were quiescent. CFC numbers were maintained without cycling after 48-h cultures in serum-containing media without GFs. Addition of interleukin 3 (IL-3) + IL-6 + stem cell factor stimulated into S-phase approximately 40% of CFCs within 24-48 h, without modifying their number except in DMEM + NBS where erythroid progenitors decreased. When cells were stimulated in IMDM + FCS by these three GFs + insulin-like growth factor I and basic fibroblast growth factor used at high concentration, more than 50% of CFCs were in S-phase and their total number was maintained. The latter culture conditions also recruited up to 66% of LTC-IC into S-phase. Our data underline the importance of the combination of GFs and culture media used for optimizing the cycling and maintenance of CFCs and LTC-IC within two days.

Direct infection of CD34+ progenitor cells by human cytomegalovirus: evidence for inhibition of hematopoiesis and viral replication

We successfully infected fluorescence-activated cell-sorted CD34+ cells from normal cord blood by the human cytomegalovirus (HCMV) laboratory strain Towne. An inhibitory effect of HCMV on clonogenic myeloid progenitors was observed in primary methylcellulose cultures. After an initial 7-day liquid culture of CD34(+)-infected cells, this inhibition was further amplified in secondary methylcellulose cultures, then involving both the myeloid and erythroid lineages. Under these conditions, viral DNA was detected both in erythroid and myeloid colonies using the polymerase chain reaction (PCR), but reverse transcription PCR (RT-PCR) failed to detect viral RNA. In contrast, when CD34(+)-infected cells were maintained in liquid suspension, both immediate, early, and late transcripts were detected as soon as day 3. In addition, viral production was demonstrated in the culture supernatants, thus confirming that a complete viral cycle occurred under liquid conditions. Furthermore, by resorting cells into CD34+ and CD34- fractions, we showed by RT-PCR that viral replication took place in cells still expressing CD34 antigen, whereas no RNA was found in more differentiated cells that had subsequently lost their CD34 antigen. These findings suggest that HCMV replication can occur at the early steps of progenitor differentiation and may be involved in the viral-induced myelosuppression.

Thymosin beta4, inhibitor for normal hematopoietic progenitor cells

Thymosin beta4 (Tbeta4), isolated from the calf thymus fraction 5, has a ubiquitous localization and plays a pleiotropic role in both the immune and nonimmune systems. Because it contains at its N-terminal end the sequence of a known inhibitor of hematopoiesis, the acetylated tetrapeptide Ac-N-Ser-Asp-Lys-Pro (AcSDKP, Goralatide), we have assayed Tbeta4 on human hematopoietic cells. We demonstrate that it inhibits normal bone marrow progenitor cell growth; indeed, it decreased the growth of both granulo-macrophagic and erythroid progenitors and reduces their percentage in S phase. Furthermore, we show that Tbeta4 reduces both the clonogenicity and the cell proliferation of purified CD34+ cells induced by a combination of seven growth factors. Although Tbeta4's inhibitory effect is very similar to that of AcSDKP, we demonstrate, using neutralizing antibodies and a truncated form of Tbeta4 devoid of the AcSDKP sequence, that the inhibitory effect of Tbeta4 is not mediated by the sequence AcSDKP. These data indicate that Tbeta4 is a novel inhibitor for human normal hematopoietic progenitors.

Heterogeneity of B lineage acute lymphoblastic leukemias (B-ALL) with regard to their in vitro spontaneous proliferation, growth factor response and BCL-2 expression

The spontaneous proliferation and the effects of 8 various growth factors (GF) were evaluated on leukemic cells from 27 patients with B-lineage ALL. Two groups of ALLs were distinguished. ALLs from group I (21 patients) exhibited a low spontaneous proliferative rate and were stimulated by IL-3 + IL-7 +/- SCF and/or LIF, while ALLs from group II (6 patients) had a high spontaneous proliferative rate and did no longer require this combination of GFs for proliferation. No effect of bFGF, IGF-I, IL-10 and IL-11 alone or in combination, was observed. Such differences in the behaviour of B-ALLs indicated that the GF requirement of ALL blasts was not related to the presence of serum in the culture nor to the pattern of reactivity of ALL blasts for B lymphoid markers or CD34 antigen. Furthermore, we showed in 1/9 cases that high proliferation might be due to an overexpression of the bcl-2 proto-oncogene and to the acquisition of an autocrine secretion.

Highly purified primitive hematopoietic stem cells are PML-RARA negative and generate nonclonal progenitors in acute promyelocytic leukemia

The hierarchical level of stem cell involvement in acute promyelocytic leukemia (APL) characterized by the pathognomonic PML-RARA fusion gene is unknown. To determine if the cells of the primitive hematopoietic stem cell compartment are involved in the leukemic process, we have used molecular and cell sorting techniques in peripheral blood and bone marrow (BM) cells at diagnosis from three patients with APL and t(15; 17). In two of them, clonality analysis was also possible using the BstXI polymorphic site of the PGK gene. The PML-RARA fusion gene was readily identified by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of BM cells obtained at diagnosis in all three patients. These same samples were then used to sort CD34+ cells and their CD38+ and CD38- subsets by fluorescence-activated cell sorting. In both female patients, CD34+/CD38+ and CD34+/CD38- cell fractions were polyclonal using PCR, whereas a monoclonal pattern was identified at the BM sample obtained at diagnosis either by Southern blotting or by PCR. Because of the high sensitivity of the PCR analysis, the polyclonal pattern of these cell populations could mask the presence of a minor clone. To detect this clone, we preformed RT-PCR analysis for t(15; 17). In one female patient, the abnormal PML-RAR fusion gene was found only in the more mature CD34+/CD38+ cell fraction using a nested PCR approach, whereas the polyclonal CD34+/CD38- fraction was PML-RARA negative. These findings were confirmed in a third patient with APL in whom the PML-RARA transcripts were absent in the CD34+/CD38- cell fraction. To study the clonality at the level of clonogenic progenitors, we used in one patient PGK analysis by PCR of individual burst-forming units-erythroid and colony-forming units-granulocyte-macrophage obtained from the CD34+/CD38- and CD34+/CD38+ cell populations at diagnosis and from the BM sample obtained during remission. The two highly purified cell populations gave rise to morphologically normal colonies clonal for both the BstXI site containing (A) and the BstXI site lacking (B) PGK allelles, indicating their polyclonal content, a pattern that was also found in clonogenic progenitors obtained at remission. These findings strongly suggest that the primitive hematopoietic stem cells as defined by the CD34+/CD38- antigens are not involved by the neoplastic process in APL. These results may have important implications for autografting strategies of retinoic acid/chemotherapy-resistant or relapsed patients.

In vitro transformation of murine pro-B and pre-B cells by v-mpl, a truncated form of a cytokine receptor

v-mpl is a constitutively activated, truncated form of a cytokine receptor that has been transduced in a murine retrovirus, the myeloproliferative leukemia virus (MPLV). Expression of this oncogene results in the factor-independent proliferation of myeloid, erythroid, megakaryocytic, and mast precursor cells, which retain the ability to differentiate. However, no lymphoid disease was ever reported. To determine whether MPLV could infect and transform very early B cells and their precursors (BCPs), lymphoid long-term bone marrow cultures were infected with a helper-free MPLV. Within 3 wk after infection, highly proliferating BCPs could be isolated. These cells were able to clone spontaneously in semi-solid cultures, grown in the absence of feeder cell layer or exogenous growth factor and rapidly produced tumors after s.c. injection into synegic irradiated mice. In addition, MPLV transformation of pre-B cells led to the induction of an autocrine activity. Immunophenotypic and molecular analysis indicated that MPLV transformed early pro-B, pro-B, and pre-B cells, according to the expression of HSA, CD43, B220, Thy1, s-IgM and BP1 Ags, and to the rearrangements of Ig genes. Interestingly, MPLV-transformed BCPs expressed Mac1 Ag without acquiring further characteristics of macrophagic differentiation. Although the v-mpl cytoplasmic domain is devoid of tyrosine kinase consensus sequence, MPLV-transformed pre-B cells contained a major approximately 105-kDa tyrosine-phosphorylated protein that was not detected in uninfected cells or in cells transformed by the Abelson viral oncogene (v-abl). These results demonstrate that, like v-abl, the truncated cytokine receptor v-mpl is able to transform BCPs in vitro and suggest that the oncogenic transformation of BCPs by either v-mpl or v-abl use different pathways.

In vitro transformation of murine pro-B and pre-B cells by v-mpl, a truncated form of a cytokine receptor

v-mpl is a constitutively activated, truncated form of a cytokine receptor that has been transduced in a murine retrovirus, the myeloproliferative leukemia virus (MPLV). Expression of this oncogene results in the factor-independent proliferation of myeloid, erythroid, megakaryocytic, and mast precursor cells, which retain the ability to differentiate. However, no lymphoid disease was ever reported. To determine whether MPLV could infect and transform very early B cells and their precursors (BCPs), lymphoid long-term bone marrow cultures were infected with a helper-free MPLV. Within 3 wk after infection, highly proliferating BCPs could be isolated. These cells were able to clone spontaneously in semi-solid cultures, grown in the absence of feeder cell layer or exogenous growth factor and rapidly produced tumors after s.c. injection into synegic irradiated mice. In addition, MPLV transformation of pre-B cells led to the induction of an autocrine activity. Immunophenotypic and molecular analysis indicated that MPLV transformed early pro-B, pro-B, and pre-B cells, according to the expression of HSA, CD43, B220, Thy1, s-IgM and BP1 Ags, and to the rearrangements of Ig genes. Interestingly, MPLV-transformed BCPs expressed Mac1 Ag without acquiring further characteristics of macrophagic differentiation. Although the v-mpl cytoplasmic domain is devoid of tyrosine kinase consensus sequence, MPLV-transformed pre-B cells contained a major approximately 105-kDa tyrosine-phosphorylated protein that was not detected in uninfected cells or in cells transformed by the Abelson viral oncogene (v-abl). These results demonstrate that, like v-abl, the truncated cytokine receptor v-mpl is able to transform BCPs in vitro and suggest that the oncogenic transformation of BCPs by either v-mpl or v-abl use different pathways.

Tumor necrosis factor alpha (TNF alpha) downregulates c-kit proto-oncogene product expression in normal and acute myeloid leukemia CD34+ cells via p55 TNF alpha receptors

Tumor necrosis factor alpha (TNF alpha), as a modulator of hematopoiesis, interacts with many growth factor receptors, such as interleukin-3, granulocyte-macrophage colony-stimulating factor (CSF), and granulocyte-CSF receptors. Here, we studied the interactions between TNF alpha and the stem cell factor (SCF) receptor, c-kit, in normal CD34+ hematopoietic progenitors and their leukemic counterpart, ie, acute myeloid leukemic (AML) CD34+ cells coexpressing c-kit antigen. The results showed that (1) incubation of normal bone marrow mononuclear cells with 200 U/mL rhTNF alpha for 20 hours induced a diminution of 31.2% +/- 5.2% of CD34+ cells coexpressing c-kit; (2) the same decrease was observed using purified CD34+ cells and, furthermore, their proliferative response to SCF was inhibited by 31.5% +/- 7.3% after exposure to TNF alpha; (3) similar experiments performed on CD34+ c-kit+ AML cells from 11 patients gave comparable results. Further analysis at the mRNA level indicated that TNF alpha decreased c-kit mRNA transcripts. Moreover, using monoclonal antibodies against the two types of TNF alpha receptors, p75 and p55, we showed that the downregulation of c-kit proto-oncogene product by TNF alpha, on normal and leukemic CD34+ cells, was exclusively mediated by the TNF alpha p55 receptor. Therefore, we conclude that TNF alpha acts as a downregulator of the SCF receptor expression.

Efficacy of recombinant human erythropoietin in the treatment of refractory anemias without excess of blasts in myelodysplastic syndromes

To determine the efficacy of recombinant human erythropoietin at pharmacological doses in myelodysplastic syndromes (MDS) without excess of blasts, 20 patients with refractory anemias (RA) or refractory anemias with ring sideroblasts (RARS) were treated in an open study with escalating doses from 40 U/kg to 300 U/kg three times a week subcutaneously during a period of 3 months. Maintenance therapy at the lowest effective dose was continued in responders. A dose response of CFU-E and BFU-E to Epo was analysed at the entry. Bone marrow examination with an in vitro study of hematopoietic progenitors was performed before and after the first three months. Seven of 20 patients responded: a total recovery was observed in 3 patients; one became transfusion independent and a reduction of 50% of the transfusion requirement was achieved in 3 others. 3 patients are still receiving treatment for 2, 3 and 4 years. No significant correlation was found between the in vitro and clinical response. A non parametric analysis of responders and non responders emphasised the importance of a long delay between the diagnosis and the treatment, (p = 0.024) and an endogenous Epo level less than 100 mU/ml (p = 0.025) in order to predict the efficacy of rhEpo. This study offers evidence that patients with refractory anemias without excess of blasts in the bone marrow respond to rhEpo at pharmacological doses. Larger studies are required in order to define the patients who may respond and to elucidate the mechanism of the positive effect of rhEpo.

Direct and reversible inhibitory effect of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (Seraspenide) on the growth of human CD34+ subpopulations in response to growth factors

The tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP, Seraspenide; Ipsen-Biotech, Paris, France), an inhibitor of murine spleen colony-forming units reduces the number and the percentage in DNA synthesis of progenitors from human unfractionated bone marrow. To determine whether AcSDKP may directly affect the growth potential of purified progenitors even at the most primitive level, CD34+HLA-DRhigh and CD34++HLA-DRlow cells were highly purified by cell sorting. Then, CD34+ subsets were stimulated in liquid culture with combinations of growth factors (GFs) and AcSDKP was added for 20 hours or 6 days and cells plated in methylcellulose. After a 20-hour incubation, we show that AcSDKP (at 10(-10) mol/L) significantly inhibits the colony formation of both CD34+ subsets. Moreover, when added daily for 6 days, AcSDKP: (1) reduces the proliferation of both CD34+ cell fractions stimulated by 3 or 7 GFs, and (2) decreases the number of progenitors generated from the CD34+HLA-DRhigh and CD34++HLA-DRlow cell fractions. Furthermore, we show for the first time, using both high proliferative potential cell and long-term culture initiating cell assays, that AcSDKP inhibits the most primitive cells contained in the CD34++HLA-DRlow subpopulation. Finally, by using limiting dilution assays we demonstrated that AcSDKP acts directly at a single cell level and that its inhibitory effect is reversible and dose dependent.

Characterization and functional analysis of adult human bone marrow cell subsets in relation to B-lymphoid development

To study the frontiers between pluripotent stem cells and committed progenitors and to further define the B-cell pathway in adult bone marrow (BM), CD34+ subpopulations and CD34- B-lineage cells were analyzed by multiparameter flow cytometry, studied by light and electron microscopy, and in short-term and long-term cultures (LTC). While the total CD34+ cells represent 4.9% +/- 0.8 of BM mononuclear cells within the lymphoid-blast window, 73.8 +/- 3.5%, 14.4 +/- 1.8% and 8.8 +/- 2.9% of them were CD34+ CD10- CD19-, CD34+ CD10+ CD19+, and CD34+ CD10+ CD19-, respectively. CD34+ CD10+ CD19+ cells represent a smal homogeneous TdT4 c micro-blast population. Although expressing CD38 and high level of HLA-DR antigens, like myeloid committed progenitors, they did not generate LTC, myeloid, and T lymphoid colonies suggesting that the CD34+ CD10+ CD19+ population represents exclusively B lymphoid committed progenitors. By contrast, all myeloid progenitors and LTC-initiating cells were found in the CD34+ CD10- CD19- cell fraction. This fraction appeared more heterogeneous and contained CD38- HLA-DRlow small cells, larger blasts, and promonocyte-like cells exhibiting small peroxidase-positive granules. Interestingly, CD10 was also present on CD34+ CD19- cells. This population mainly coexpressed CD33 and gave rise to macrophagic colonies.

Tumor necrosis factor alpha in human long-term bone marrow cultures: distinct effects on nonadherent and adherent progenitors

Although tumor necrosis factor alpha (TNF alpha) exerts a variety of activities on hematopoietic cells, suggesting it may have some potential therapeutic applications, its long-term effects on hematopoiesis are not well defined. Therefore, we took the advantage of long-term bone marrow cultures (LTBMCs) to evaluate the long-term role of TNF alpha on both the microenvironment and the hematopoietic progenitors. LTBMCs were inoculated with 100 U/ml of recombinant human TNF alpha (rhTNF alpha) either at the onset of the cultures (d0) or at day 21 (d21) when the adherent layer (AL) was already established. Then TNF alpha was added at each weekly medium change. The cellularity and the content of progenitors in both the nonadherent layer (NAL) and AL, the formation of the AL, and the presence of various cytokines in the supernatants were examined weekly. The data showed 1) a strong and durable inhibitory effect on total nonadherent cells; 2) a rapid and transient inhibition of NA progenitors, whereas adherent progenitors were lately affected; and 3) microenvironmental changes consisting of the disappearance of adipocytes and the secretion of high levels of interleukin 6. The results suggest that the inhibitory effects of TNF alpha on the NAL are in part counterbalanced by stromal modifications that in turn lead to a faster exhaustion of hematopoiesis.

Secretion of tumor necrosis factor-alpha by fresh human acute nonlymphoblastic leukemic cells: role in the disappearance of normal CFU-GM progenitors

The disappearance of normal hematopoiesis during acute nonlymphoblastic leukemia (ANLL) is poorly understood. Several reports indicate that conditioned medium obtained from leukemic cells might inhibit the formation of normal hematopoietic progenitors. However, these blast-conditioned medium (BCM) inhibitory activities are not well characterized. In order to evaluate whether BCM might contain an activity inhibiting the growth of normal marrow progenitors, BCM from 13 consecutive patients with ANLL were tested on normal bone marrow in methylcellulose assays. In all the cases, a significant inhibition of the growth of granulocyte-macrophage colony-forming unit (CFU-GM) progenitors was observed, whereas erythroid burst-forming unit (BFU-E) progenitors were not affected. Further characterization of the BCM inhibitory activity showed using both a biological assay and RIA, the presence of tumor necrosis factor-alpha (TNF-alpha) in 10 out of 13 BCM. Northern blot analysis performed in six patients showed a correlation between the expression of TNF-alpha mRNA by leukemic cells and the presence of TNF-alpha in BCM. Moreover, the BCM inhibitory activity could be neutralized with an anti-TNF-alpha antiserum. These data indicate that leukemic cells express and release frequently TNF-alpha, which may therefore play an important role in the inhibition of granulopoiesis during leukemia.

Human liquid bone marrow culture in serum-free medium

Prolonged in vitro maintenance of human bone marrow progenitor cells was achieved using a serum-free (SF) liquid culture system. Culture medium was based on Iscove's medium supplemented with bovine serum albumin, human transferrin, bovine insulin, soybean lecithin, cholesterol, hydrocortisone and alpha-thioglycerol. Under these standardized culture conditions, CFU-GM were maintained for up to 4 weeks, as is the case when using conventional serum-dependent medium. Erythropoiesis exhibited a slower decline than that found using serum containing medium. Development of normal haematopoiesis was effective in spite of poor stromal cell development--a confluent adherent layer as classically described in serum conditions was never achieved. Our newly defined system provides a reliable technique for studying human haematopoietic stem cell proliferation and differentiation in vitro; it allows for rational utilization of currently available purified recombinant growth factors. It may be a promising tool in the clinical use of cultured haematopoietic stem cells.

B-lymphocytes as a source of cell surface growth-promoting factors for hematopoietic progenitors

Although B cells reside in the bone marrow, little is known concerning their functional role in hematopoiesis. We have measured the effects of surface membrane factors released from unstimulated, circulating B cells of normal donors and patients with chronic lymphocytic leukemia on human hematopoiesis in vitro. Leukemic cells augment erythroid burst formation by allogeneic blood cells (p less than 0.05). The stimulatory effect is increased in cultures containing a high B-cell seeding density, and is decreased in those with a high peripheral blood mononuclear cell seeding density. Medium conditioned by B cells (CM) from the circulation or bone marrow stimulates the formation of erythroid bursts, granulocyte-macrophage colonies, and mixed colonies containing granulocytes, erythroblasts, monocytes, and megakaryocytes (GEMM) in serum-free cultures of allogeneic and autologous marrow (p less than 0.05). This effect is localized primarily to surface membrane vesicle-rich pellets of CM. Screening of several hematopoietic and nonhematopoietic cell types reveals that membrane vesicle-associated activity is released from B cells and mitogen-stimulated, circulating T cells. In contrast, vesicles shed from freshly isolated, resting T cells, continuous T-cell leukemia cell lines, erythrocytes, and endothelial cells do not express the activity (p greater than 0.10). The stimulatory activity is augmented in cultures of marrow cells that are depleted of B4 antigen-positive lymphocytes but not of T-lymphocytes, suggesting that endogenous release of the factor(s) occurs during incubation. Furthermore, membranes partially purified from leukemic B cells also express the activity. Together with our findings that (1) the growth enhancing factor(s) is solubilized by octylglucoside, and that (2) the factor can be immunoprecipitated with BPA-neutralizing, antimembrane IgG, our results suggest that the erythropoietic activity is an integral membrane protein that may be immunologically related to BPA. The relationship of the erythroid burst stimulatory factor to other hematopoietic activities found in CM pellets is unknown.

Polycythemia in chronic obstructive pulmonary disease. A study of serum and urine erythropoietin and medullary erythroid progenitors

In order to investigate the mechanism of polycythemia in chronic obstructive pulmonary disease (COPD), serum and urinary levels of erythropoietin and medullary erythroid progenitors were studied in 21 patients; nine were nonpolycythemic (hematocrit, 39 +/- 4 percent; red blood cell [RBC] mass, 28 +/- 5 ml/kg; forced expiratory volume in one second [FEV1], 0.6 +/- 0.1 L), and 12 patients were polycythemic (hematocrit, 52 +/- 7 percent; RBC mass, 46 +/- 7 ml/kg; FEV1, 0.9 +/- 0.3 L). Hypoxia was severe in both groups, with mean arterial oxygen pressure of 47 mm Hg. The following parameters of tissue oxygenation were not significantly different between the two groups: arterial and mixed-venous oxygen saturations; cardiac output; oxygen utilization coefficient; 2, 3-diphosphoglycerate, and carboxyhemoglobin level. The level of erythropoietin was measured by bioassay in vitro. The level was increased in the serum of 85 percent (18) and in the urine of 38 percent (8) of the patients. There was no significant difference between the nonpolycythemic and polycythemic groups. Without exogenous erythropoietin, none of the subjects showed spontaneous colonies of erythroid progenitors. The addition of one unit of erythropoietin induced a similar normal proliferation of erythroid progenitors in both groups. The absence of adaptative polycythemia in the nonpolycythemic group with severe hypoxia was seemingly related neither to a quantitative deficit of erythropoietin nor to a lack of sensitivity of erythroid progenitors to its action.

A prospective study of the value of bone marrow erythroid progenitor cultures in polycythemia

The diagnostic value in polycythemia of the presence of endogenous erythroid colonies derived from bone marrow cells (EECs) was assessed in a prospective study on 108 patients referred for polycythemia (Hb greater than g/dL in men, greater than 16 g/dL in women) with normal plasma volume by comparison with the standard criteria, the bone marrow grade, and the serum erythropoietin (Epo) level. Total red cell volume (TRCV) was high (greater than 36 mL/kg in men, 32 mL/kg in women) in 87 cases (group A) and slightly increased in 21 cases (group B). Standard criteria were applicable in 63 of 108 cases (57%); 46 were PV and 17 were secondary polycythemia (SP). Standard criteria were nonapplicable in 45 cases. EECs were present in 65 cases (60%) with a ratio of EEC/Epo-stimulated colonies of 39.5% +/- 18% (extremes 10% to 80%). EECs were noted in 43 of 46 polycythemia vera (PV) and 0 of 17 SP. Among the 45 unclassified cases, EECs were noted in 22: 18 of 29 cases from group A (10 with 2 major and 1 minor criteria; 8 with 2 major criteria) and 4 of 16 cases from group B (with variable standard criteria, 2 belonging to a PV family). In group A, there was a positive significant correlation between EECs and the presence of two major and 1 minor criteria (P less than .0001). In group B, there was a positive significant correlation between EECs and the presence of at least 1 major criterion and 2 minor criteria or a family background (P less than .0001). The unclassified polycythemias with EECs in the bone marrow are characterized by a bone marrow grade and a mean serum Epo level not different from that of patients with PV and an active course of the disease. The unclassified polycythemias without EECs in the bone marrow are a heterogeneous group corresponding in some cases to SPs of unknown origin (slightly increased bone marrow grade and/or high serum Epo level), and in others cases to spurious polycythemias (normal bone marrow grade and/or normal Epo level). In conclusion, EECs were of great value in differentiating PV from SP (P less than .001), and in allowing the diagnosis of PV in the absence of all the standard criteria even when TRCV was slightly increased. In our study, EEC improved the classification of polycythemia by 22%. The recommended diagnostic steps for the evaluation of polycythemia must be reconsidered.

Recovery of CFU-GM from cryopreserved marrow and in vivo evaluation after autologous bone marrow transplantation are predictive of engraftment

In 18 patients with non-Hodgkin's lymphomas or solid tumors treated with intensive chemotherapy and/or total-body irradiation followed by autologous bone marrow transplantation (ABMT), we assessed the value of granulocyte-macrophage progenitor cells (CFU-GM) monitoring to predict engraftment. We studied CFU-GM in cryopreserved marrow and attempted to settle whether detection of CFU-GM in vivo after ABMT has a predictive value on engraftment. Our data showed: The absence of linear correlation linking recovery of hematopoiesis to the dose of CFU-GM/kg infused. The existence of a CFU-GM threshold in respect to engraftment. Patients receiving doses of CFU-GM greater than 10(3)/kg had significantly faster recovery kinetics for hematopoiesis than did patients receiving doses below this threshold, with median recoveries to 0.5 and 1.0 X 10(9) neutrophils/liter, respectively, on days 14 and 15 versus days 29 and 31.5 (p less than 0.05 and p less than 0.02) and median recoveries to 1.0 and 2.5 X 10(9) leukocytes/liter respectively, on days 12.5 and 16 versus days 28 and 30.5 (p less than 0.05 and p less than 0.02). Considering the entire course of events during the first four weeks, we were able to show that white blood cell recovery was significantly faster in the group of patients receiving doses of CFU-GM greater than 10(3)/kg (p less than 0.001). Sequential studies of the reappearance of CFU-GM in marrow and peripheral blood indicated that the kinetics of CFU-GM recovery in vivo after ABMT predict engraftment. By day 7 after the graft, CFU-GM were already detectable in the marrow at a level of 10% of the dose infused for patients with optimal engraftment--median time to recovery to 1.0 and 2.5 X 10(9) leukocytes/liter and 1.0 X 10(9) neutrophils/liter on days 11, 15, and 14.5 versus days 18, 23, and 23 (p less than 0.02, less than 0.05, and less than 0.05), respectively after. On day 10 after ABMT, a 15% CFU-GM level in bone marrow confirmed engraftment, with a significant correlation of all parameters studied--1.0 and 2.5 X 10(9) leukocytes/liter (p less than 0.02 and less than 0.01), 0.5 and 1.0 X 10(9) neutrophils/liter (p less than 0.05), 50.0 and 100.0 X 10(9) platelets/liter (p less than 0.05). On day 14, a 50% CFU-GM level was reached in all patients with optimal engraftment; p less than 0.01 on 1.0, and 2.5 X 10(9) leukocytes on 0.5 and 1.0 X 10(9) neutrophils/liter. The detection of circulating CFU-GM in the blood by day 10 or 14 indicated engraftment.(ABSTRACT TRUNCATED AT 400 WORDS)

Human granulocyte colony growth: differences between serum-free and serum-dependent cultures

Human granulocyte colony formation has been observed in serum-free methylcellulose cultures with Iscove medium, delipidated bovine serum albumin, iron-saturated transferrin, alpha-thioglycerol, oleylpalmitoyl lecithin, cholesterol, and linoleic acid using serum-free human placental-conditioned medium (SF-HPCM) as the source of colony stimulating factor (CSF). Dose-response curves for SF-HPCM indicated a lower sensitivity to colony-stimulating activity in serum-free cultures than in serum-dependent cultures. Gel filtration of SF-HPCM revealed that CSF fractions with molecular weights in the range of 30 kD are inefficient in serum-free cultures, while fractions with molecular weights in the range of 40 kD stimulate granulocyte colony formation in both types of cultures. These results demonstrate that serum constituents modulate the effects of one of the stimulating factors for granulocyte colony formation, and that serum-free culture conditions are essential for establishing the growth factor requirements of the granulocyte lineage.

Polycythemia and the Budd-Chiari syndrome: study of serum erythropoietin and bone marrow erythroid progenitors

The mechanism of polycythemia associated with the Budd-Chiari syndrome is unknown. Erythropoiesis in 10 patients with Budd-Chiari syndrome was studied in an attempt to distinguish prior unrecognized polycythemia vera from secondary polycythemia. Serum erythropoietin was assayed using a mouse fetal liver erythroblast assay. High concentrations of serum erythropoietin were observed in 6 of 7 patients with acute primary Budd-Chiari syndrome. Levels were normal in four patients who were investigated during the chronic phase and were increased in one with persisting polycythemia. In one patient, erythropoietin concentration in the hepatic vein was twice the level measured in peripheral, caval and renal venous blood. Bone marrow erythroid progenitors developed in vitro in the absence of exogenous erythropoietin in all polycythemia vera cases studied in acute and chronic phases, whether polycythemia persisted or not. These findings indicate that hepatic erythropoietin production occurs in the acute phase of Budd-Chiari syndrome and suggest that, in some cases of Budd Chiari syndrome, polycythemia which resolves after the acute phase may be secondary to liver disease.

Regulation of human peripheral blood BFU-E growth in vitro by leukaemic B-lymphocytes

We report a stimulating effect of leukaemic B-lymphocytes from anaemic and non-anaemic patients with CLL on the proliferation of normal peripheral blood BFU-E. Coculture of leukaemic B-cells at various concentrations (2.5 X 10(3)-10(6)) with 2.5 X 10(5) mononuclear cells from normal peripheral blood increased the number of BFU-E derived erythroid colonies. The same effect was observed when the number of target cells was varied in the presence of a fixed number of B-lymphocytes, with a clear linear relationship. B-cell conditioned medium gave a similar increase when added to the culture instead of B-cells. At high concentration of B-cells from anaemic patients, the size of the colonies was increased and a large number of macroscopic colonies was seen. The place of the B-cells in the regulation of erythroid progenitors in relation to monocytes and T-lymphocytes has still to be established.

Evidence for absence of toxicity of T101 immunotoxin on human hematopoietic progenitor cells prior to bone marrow transplantation

T101-ricin A-chain immunotoxin is a hybrid molecule made up of the T101 monoclonal antibody bound to the A-chain of ricin. It specifically destroys cells expressing the cell surface T65 antigen. We have designed a preclinical study to evaluate its possible use for the in vitro treatment of T-cell hematological cancers prior to autologous bone marrow transplantation. The data presented here show that conditions previously defined to produce high tumor cell killing, i.e., a 20-hr incubation at 37 degrees in the presence of T101-ricin A-chain immunotoxin up to 10(-7) M in a 10 mM ammonium chloride solution, do not affect the in vitro proliferative capacity of human hematopoietic stem cells studied by means of semisolid medium cultures (granulocyte-macrophage progenitors, burst-forming units-erythrocyte) and continuous liquid cultures (pre-granulocyte-macrophage progenitors). Therefore, autologous bone marrow transplantation with T101-ricin A-chain immunotoxin-treated graft should be feasible.

The role of serum lipoproteins on the in vitro proliferative potential of human hematopoietic progenitors CFUC and CFUE

The influence of various lipoprotein fractions on the proliferation of normal human hematopoietic progenitors, CFUC and CFUE, was studied in vitro. The lipoprotein fractions, very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), low density lipoproteins (LDL), high density lipoproteins (HDL2 and HDL3), were isolated by sequential ultracentrifugation. The addition of each subfraction to lipoprotein deficient medium allowed us to distinguish two categories of lipoproteins: firstly, those with density d greater than 1.030, LDL, HDL2 and HDL3 which showed a marked inhibitory activity on CFUC and CFUE proliferation and, secondly, those with density d less than 1.030, VLDL and IDL which did not show any inhibitory activity. The regulatory role of lipoproteins on progenitor cell proliferation is discussed.