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Biomedical subjects

D Thierry

Publications and source records attributed to D Thierry.

At least 19 recordsLinked to original sources
PubMed2004

Feasibility and limits of bone marrow mononuclear cell expansion following irradiation.

PURPOSE: To define the ability of bone marrow mononuclear cells (BMMNC) to expand after irradiation and to determine the amount of apoptosis in irradiated expanded cells. MATERIALS AND METHODS: Non-human primate BMMNC were irradiated in vitro at doses ranging from 0 to 4 Gy and were cultured during 1 week in the presence of interleukin 3, interleukin 6, stem cell factor, thrombopoietin and fms-like tyrosine kinase-3 ligand. The expansion yield of BMMNC, colony-forming cells and CD34(+) cells were compared with non-irradiated control cultures. Apoptosis in expanded cells was also defined by annexin V/propidium iodine staining. RESULTS: Irradiation of BMMNC up to 1 Gy did not modify the ability of haematopoietic cells to expand. At higher doses, expansion of haematopoietic cells is reduced as compared with non-irradiated cultures but it remains significant. This reduction in expansion of BMMNC was related to radiation-induced apoptosis. CONCLUSION: The results suggest that it is possible to expand haematopoietic cells after irradiation doses at least up to 2 Gy. This suggests a possible use of cell therapy for the treatment of radiation accident victims.

Animals↗
PubMed2000

Absence of the effects of 50 Hz magnetic fields on the progression of acute myeloid leukaemia in rats.

PURPOSE: As the most recent epidemiological studies provide no definite conclusions about the effects of 50/60 Hz magnetic fields (MFs) on the incidence of leukaemia in humans, animal models in a well-controlled environment are useful for evaluating the possibility of an association between MFs and leukaemia. The present study was designed to determine whether 50 Hz magnetic fields can alter the progression of leukaemia. MATERIALS AND METHODS: A well-characterized model of transplantable acute myeloid leukaemia in rats was used for the first time. This model is closely related to human acute myeloid leukaemia, the type most frequently reported in epidemiological studies of adults. After leukaemic cell implantation, rats were exposed to a sinusoidal 50 Hz MF of 100 microT for 18 h a day, 7 days a week, throughout leukaemia progression. The parameters investigated were: survival time, body weight, haematologic parameters, infiltration of blood, bone marrow, spleen and liver by leukaemic cells. RESULTS: The results showed no significant changes (p > 0.05) in leukaemic MF-exposed versus unexposed rats for any of the parameters involved in leukaemia progression. CONCLUSION: These data do not support the hypothesis that 50 Hz magnetic fields influence leukaemia progression in humans.

Adult↗
PubMed2000

Transplantation of gene-modified human bone marrow stromal cells into mouse-human bone chimeras.

Transplantation of BM stromal cells engineered to secrete therapeutic factors could represent a treatment for a large array of hematologic disorders. The aim of this study was to evaluate the susceptibility of human BM stromal cell precursors to retroviral gene transfer, then the ability of those to be transplanted in vivo. We have transduced a recombinant retrovirus encoding the mouse CD2 antigen into STRO-1+ cells selected from adult and fetal BM. Gene-modified stromal cells were injected intravenously into NOD-SCID mice engrafted previously with pieces of human fetal hematopoietic bone. Using nested PCR, transgenic human cells were detected both in the marrow of human bone grafts and in the BM, liver, and spleen of host mice 7 weeks after grafting. These data indicate that BM stromal progenitor cells are targets for retrovirus-mediated gene transfer and can home to hematopoietic tissues on engraftment through the bloodstream of nonconditioned hosts.

Adult↗
PubMed1999

Targeted transfection of the IL-3 gene into primary human hematopoietic progenitor cells through the c-kit receptor.

We recently showed that an antibody-mediated gene transfer procedure termed antifection can be used for targeted gene delivery into lymphoid cells in vitro and in vivo. We here report that antifection also is effective for targeted gene transfer to immature hematopoietic cells. A human IL3-expressing plasmid was chemically linked to an anti-human CD117 antibody. Delivery of the IL3 plasmid into IL-3-dependent myeloid TF-1 cells (bearing the CD117 antigen) was specific and resulted in the transient proliferation of the targeted cells in the absence of exogenous IL-3. Transfection of primary human CD34+ hematopoietic stem/progenitor cells led to transient production of IL-3 and transient proliferation of the target cells. Interestingly, by using a semisolid progenitor cell assay, we found that transfected primary CD34+ cells were able to generate normal numbers of cell colonies in the absence of exogenous IL-3. Polymerase chain reaction analysis confirmed the presence and expression of the IL-3 transgene in the progenitor-derived colonies. In conclusion, our data show that CD117 is a suitable cell surface target to specifically transfer gene by antifection into primary CD34+ cells and that delivery of IL-3 gene in these cells resulted in the expression of a functional IL-3 able to support cell growth in absence of exogenous cytokine. Thus, antifection may provide new therapeutic modality relying on the transient production of appropriate growth factors acting via autocrine and/or paracrine mechanisms.

Antigens, CD34↗
PubMed1999

Interleukine-8 acts as a strong peripheral blood granulocyte-recruiting agent rather than as a hematopoietic progenitor cell-mobilizing factor.

Intravenous infusion of Interleukine-8 has been shown to lead to a rapid mobilization of hematopoietic cells in mice and rhesus monkeys. We report in this study that the IL-8-mediated mobilizing effect results in low levels of circulating CD34+ cells, whereas a rapid and strong recruitment of mature granulocytes occurs. This would be of great interest for harvesting large numbers of functional granulocytes to fight infection in immunodepressed patients. We performed a kinetic study of the mobilization in a nonhuman primate model (Papio ursinus), mobilized with a single or double infusion of IL-8 with a dose range of 30-50 microg/kg of body weight. Blood was sampled every 15 min after the IL-8 infusion, and IL-8 plasma levels, complete blood counts, differential WBCC, colony-forming unit assays, and CD34+ cell evaluation assays were performed. At the same time, leukapheresis was performed on the anesthetized animal to collect either hematopoietic stem and progenitor cells (HSPC) or peripheral blood granulocytes (PBG) according to different collection settings. IL-8 induced a rapid increase of PBG (7-12-fold the basal values). The HSPC leukapheresis concentrate showed poor ex vivo expansion abilities. IL-8-mobilized peripheral blood polymorphonuclear cells showed normal oxidative, chemotactic, phagocytic, and adherence abilities. We suggest that IL-8-induced neutrophilia could be used as an allogeneic source of granulocytes for transfusion in neutropenic patients or in granulocyte dysfunction.

Animals↗
PubMed1999

Evaluation of an rDNA Listeria probe for Listeria monocytogenes typing.

A Listeria monocytogenes DNA fragment, identified as part of the 23S rRNA gene and called B17, was used to type 266 L. monocytogenes strains and 43 strains of other Listeria species. Results were compared with those obtained: i) with pBA2 (which consists of a 2.3 kb Bacillus subtilis DNA fragment encoding 16S rRNA, inserted into the HindIII site of pBR322), a probe previously used for Listeria and L. monocytogenes ribotyping, and ii) with DNA macrorestriction profiles analysis. Twenty profiles were identified for L. monocytogenes using pB 17, three of which accounted for 87% of strains. This new rDNA probe had greater discriminatory power for serogroups 1/2 or 3 strains than for serogroup 4 strains. The number of varieties and the discrimination index were higher with this new probe than with pBA2, but DNA macrorestriction patterns analysis gave better discrimination between strains.

Animals↗
PubMed1998

Importance of Extracellular Polymeric Substances from Thiobacillus ferrooxidans for Bioleaching.

Leaching bacteria such as Thiobacillus ferrooxidans attach to pyrite or sulfur by means of extracellular polymeric substances (EPS) (lipopolysaccharides). The primary attachment to pyrite at pH 2 is mediated by exopolymer-complexed iron(III) ions in an electrochemical interaction with the negatively charged pyrite surface. EPS from sulfur cells possess increased hydrophobic properties and do not attach to pyrite, indicating adaptability to the substrate or substratum.

Journal Article↗
PubMed1998

Variation of oxide films on titanium induced by osteoblast-like cell culture and the influence of an H2O2 pretreatment.

Variations of titanium oxide films induced by osteoblast-like cells in a rat calvaria culture system and the influence of an H2O2 pretreatment have been investigated by using X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. For abraded titanium, the results revealed that phosphate and calcium ions may incorporate into the surface oxide film during the cell culture, forming a precipitate with a Ca/P ratio near that of hydroxyapatite. Oxidized carbon also was found in the surface layer, most likely precipitated hydroxylcarbonated apatite (HCA). The H2O2 pretreatment of titanium in a phosphate-buffered saline solution results in a 10-fold thickened porous oxide film and large amounts of surface hydroxyl groups as well as a certain amount of phosphate ions inside the oxide film. During the cell culture, the H2O2-treated titanium surface favors the ion incorporation and precipitation of the HCA-like compound, which probably is inlaid into the oxide film. Osteoblast-like cells on the H2O2-treated titanium showed a more active morphology during the initial stage compared with cells on abraded titanium. Moreover, bone-like nodule formation and mineralization appear to be related to the precipitation of the HCA-like compound on the surface. The results are discussed with respect to corrosion resistance, ion incorporation and precipitation of the HCA-like compound on the surface, osseointegration, and bioactivity of titanium implants.

Animals↗
PubMed1998

Flank matrix attachment regions (MARs) from chicken, bean, yeast or tobacco do not prevent homology-dependent trans-silencing in transgenic tobacco plants.

The effect of flanking matrix attachment regions (MARs) on homology-dependent trans-silencing was tested using two strong trans-silencing loci. The transgenic tobacco line 271 carries at a single locus a p35S-RiN-tNos transgene which is able to silence, in trans and at the transcriptional level, the expression of any p35S-driven transgene irrespective of its position. The transgenic tobacco line 6b8 carries at a single locus a p35S-uidA-tRbcS transgene which is able to silence in trans, at the post-transcriptional level, the expression of any uidA-expressing transgene irrespective of its position. Various transgenic tobacco lines carrying a target p35S-uidA-tNos transgene, flanked on each side by MARs from chicken, bean, yeast or tobacco, were crossed with lines carrying the 271 and 6b8 loci. Expression of the target transgene was silenced in all hybrids, irrespective of the presence or absence of MAR sequences. These results therefore demonstrate that MARs are not able to protect transgene expression from strong silencing loci that act in trans.

Animals↗
PubMed1998

Cell culture bags allow a large extent of ex vivo expansion of LTC-IC and functional mature cells which can subsequently be frozen: interest for a large-scale clinical applications.

The aim of this study was to evaluate the ex vivo expansion of normal CD34+ cells in gas-permeable polypropylene bags suitable for clinical use. Cells were cultured for 14 days in serum-free medium supplemented with SCF, IL3, IL6, FLT3-1, G-CSF + MGDF or Epo. The bags supported the expansion of hematopoietic cells in a similar manner to small scale well or flask systems, allowing mean expansions of up to 2193-fold for total nucleated cells, 140-fold for CFU-GM and 66-fold for LTC-IC. Increasing the initial cell concentration from 5 x 10(3) to 1 x 10(5)CD34+ cells/ml induced the production of granulocytic cells with terminal differentiation while simultaneously decreasing the overall extent of expansion of the white blood cells produced. We tested the phagocytic activity and oxidative metabolism of the white blood cells produced. The percentage of phagocytic cells was 39+/-0.5% in expanded cultures derived from fractions initiated at 5 x 10(3), 10(4) or 10(5) cells/ml and 45+/-6% in cultured cells obtained from starting fractions containing 5 x 10(4) cells/ml, as compared to 58+/-4% in normal controls. A study of the potential for oxygen-dependent microbe killing showed that the expanded cells produced H2O2, although in lesser quantities than control cells. We subsequently investigated the possibility of freezing expanded cells. Total cell recovery after thawing was 45+/-4%, while recoveries of progenitors and stem cells ranged from 65 to 90%, without any influence of the initial cell concentration. This new approach could be of major interest for clinical practice, as it would allow evaluation of the quality of a graft prior to its infusion and employs experimental conditions which meet the criteria for potential clinical use.

Blood Preservation↗
PubMed1998

Transplantation of stromal cells transduced with the human IL3 gene to stimulate hematopoiesis in human fetal bone grafts in non-obese, diabetic-severe combined immunodeficiency mice.

The non-obese diabetic-severe combined immunodeficiency (NOD-SCID) mouse is a convenient host for human hematopoietic tissues and cells. Human fetal bone fragments engrafted subcutaneously in NOD-SCID mice sustain human hematopoiesis for several months. MS5 murine bone marrow stromal cells were transfected by electroporation with a plasmid containing the human interleukin-3 gene. As expected, stably transfected hu-IL3-MS5 cells supported human hematopoiesis in vitro more efficiently than MS5 cells. hu-IL3-MS5 cells were then injected intravenously into hu-NOD-SCID mice to test their ability to home to the mouse and/or human bone marrow, and to evaluate the role of hu-IL3 secretion on human hematopoiesis in vivo. hu-IL3 was detected in the mouse serum for up to an observation time of 8 weeks. hu-IL3-MS5 cells engrafted the bone marrow, spleen, liver and lungs of the mice but also the human bone graft. The presence of hu-IL3-MS5 cells in the human bone significantly stimulated local human hematopoiesis. This setting could be used to model the bone marrow homing of intravenously injected stromal cells or stromal cell precursors. The same experimental principle could also be applied in a therapeutic perspective to malignant human bone marrow hematopoiesis.

Animals↗
PubMed1998

Gamma-irradiation does not impair ATRA-induced maturation of myeloid leukaemic cells: implication for combined radiation and differentiation therapy.

In the present study we investigated the effects of various doses of gamma-irradiation, followed by induction of granulocytic differentiation with all-trans-retinoic acid (ATRA), on proliferative rate, differentiation capability and oxidative metabolism of leukaemic cells from two different myeloid leukaemia cell lines, HL-60 and PLB-985. Regarding the effects of such combined treatment on the proliferative capabilities of HL-60 and PLB-985 cell lines, we showed that their growth kinetics were similar after 2 Gy gamma-irradiation combined with ATRA. However, with doses >2 Gy, the behaviour of the cell lines differed largely. Indeed, HL-60 appeared to be more radiosensitive than PLB-985 regarding cell viability and proliferation. Besides, whatever dose of irradiation (2, 5 or 10 Gy) was applied, ATRA was still able to induce differentiation of HL-60 and PLB-985 into granulocytes that retained the capacity to produce superoxide anion. The results of these in vitro studies suggest that leukaemia cell lines retain their ability to respond to ATRA, a granulocytic-differentiating inducer following high doses of irradiation. This may have implications for the use of radiation therapy in combination with ATRA for the treatment of extramedullary infiltrations of myeloid leukaemias in humans.

Cell Differentiation↗
PubMed1998

Functional studies of maturing myeloid cells during ex vivo expansion for treatment of aplasia: feasibility of ex vivo expansion from cryopreserved bone marrow cell samples.

Ex vivo expanded CD34+ progenitor cells from fresh or cryopreserved primate bone marrow, induced to granulocytic differentiation with growth factors, were investigated to determine whether myeloid cells produced in liquid cultures have the normal biologic functions needed for the treatment of patients with neutropenia following high-dose chemotherapy or therapeutic or accidental radiation exposure. Human and simian (baboons or macaques) CD34+ cells were cultured with granulocyte-colony stimulating factor (G-CSF), stem cell factor (SCF), interleukin-1 (IL-1), IL-3, and IL-6, and assessed at 14 days of culture for their capacity to respond to different functional tests. Immunostaining revealed that human ex vivo expanded cells contained myeloperoxydase (MPO, 82% +/- 8%) and lactoferrin (LF, 30% +/- 6%) in their granules. Maturation of cultured cells was associated with stimulated chemotactic responsiveness and respiratory burst activity (superoxide anion and hydrogen peroxide production) in expansions from human, baboon, and macaque CD34+ progenitor cells. Mature cells obtained from ex vivo expansion of selected cryopreserved human bone marrow CD34+ cells presented reduced but significant functional activities (chemotactic responsiveness and hydrogen peroxide production) when compared with human peripheral blood neutrophils. The validation of nonhuman primate ex vivo expansion systems may permit their use as models of irradiation. The feasibility of ex vivo expansion from cryopreserved bone marrow cell samples may offer considerable opportunity for banking bone marrow for autologous transfusion.

Anemia, Aplastic↗
PubMed1997

Corrosion resistance for biomaterial applications of TiO2 films deposited on titanium and stainless steel by ion-beam-assisted sputtering.

The high corrosion resistance and good biocompatibility of titanium and its alloys are due to a thin passive film that consists essentially of titanium dioxide. There is increasing evidence, however, that under certain conditions extensive titanium release may occur in vivo. An ion-beam-assisted sputtering deposition technique has been used to deposit thick and dense TiO2 films on titanium and stainless steel surfaces. In this study, using the following measurements these TiO2 films have been investigated in a phosphate-buffered saline solution: (1) open-circuit potential versus time of exposure, (2) electrochemical impedance spectroscopy, (3) potentiodynamic polarization, and (4) Mott-Schottky plot. A higher electrical film resistance, lower passive current density, and lower donor density (in the order of 10(15) cm-3) have been measured for the sputter-deposited oxide film on titanium in contrast to the naturally formed passive oxide film on titanium (donor density in the order of 10(20) cm-3). The improved corrosion protection of the sputter-deposited oxide film can be explained by a low defect concentration and, consequently, by a slow mass transport process across the film. As opposed to TiO2 on titanium, a deviation from normal n-type semiconducting Mott-Schottky behavior was observed for TiO2 on stainless steel.

Biocompatible Materials↗
PubMed1996

Hydrogen peroxide toward enhanced oxide growth on titanium in PBS solution: blue coloration and clinical relevance.

Oxide films formed on titanium exposed to a phosphate-buffered saline solution with and without hydrogen peroxide (H2O2) addition were investigated by means of electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The oxide growth at the titanium/electrolyte interface was monitored in situ by daily EIS measurements during periods of several weeks. The results suggest that the oxide film can be described by a two-layer model with a barrier inner layer and a porous outer layer. H2O2 addition results in an increased dissolution/oxidation rate that leads to an enhanced oxide growth of the porous outer layer. As a result, the total oxide film can reach a thickness corresponding to an interference blue color. Based on XPS results, H2O2 addition furthermore seems to facilitate the incorporation of phosphate ions into the thicker porous layer. This observation may be related to the so-called osseointegration properties of titanium.

Buffers↗
PubMed1996

Sequence homology requirements for transcriptional silencing of 35S transgenes and post-transcriptional silencing of nitrite reductase (trans)genes by the tobacco 271 locus.

The transgene locus of the tobacco plant 271 (271 locus) is located on a telomere and consists of multiple copies of a plasmid carrying an NptII marker gene driven by the cauliflower mosaic virus (CaMV) 19S promoter and the leaf-specific nitrite reductase Nii1 cDNA cloned in the antisense orientation under the control of the CaMV 35S promoter. Previous analysis of gene expression in leaves has shown that this locus triggers both post-transcriptional silencing of the host leaf-specific Nii genes and transcriptional silencing of transgenes driven by the 19S or 35S promoter irrespective of their coding sequence and of their location in the genome. In this paper we show that silencing of transgenes carrying Nii1 sequences occurs irrespective of the promoter driving their expression and of their location within the genome. This phenomenon occurs in roots as well as in leaves although root Nii genes share only 84% identity with leaf-specific Nii1 sequences carried by the 271 locus. Conversely, transgenes carrying the bean Nii gene (which shares 76% identity with the tobacco Nii1 gene) escape silencing by the 271 locus. We also show that transgenes driven by the figwort mosaic virus 34S promoter (which shares 63% identity with the 35S promoter) also escape silencing by the 271 locus. Taken together, these results indicate that a high degree of sequence similarity is required between the sequences of the silencing locus and of the target (trans)genes for both transcriptional and post-transcriptional silencing.

Fabaceae↗
PubMed1996

Decreased IL-1 beta and TNF alpha secretion in long-term bone marrow culture supernatant from Fanconi's anaemia patients.

Recent studies have shown that abnormalities of cytokine and lymphokine secretion are involved in the pathophysiology of Fanconi's anaemia (FA). In the present study, we quantified IL-1 beta, IL-1 receptor antagonist (IL-1Ra), IL-6 and TNF alpha protein levels in the supernatant of long-term cultures generated from BM cells of FA patients. Cell-free conditioned medium from long-term bone marrow culture was harvested every week at confluence and tested for interleukin secretion. IL-1 beta, IL-1Ra, TNF alpha and IL-6 protein secretion was assessed using immunoassays. IL-6 secretion was similar between controls and FA supernatants from wk 1 to wk 4. TNF alpha released from FA cells was consistently found at very low levels compared to control cells during the first 3 wk. Furthermore, secretion of IL-1 beta by cells from FA was always more than 2 standard deviations below the value of IL-1 beta found in normal donor cells from wk 1 to wk 4. In conclusion, in addition to a stem cell defect, a marked decrease in IL-1 beta and TNF alpha secretion may be one of the mechanisms leading to bone marrow failure in individuals with Fanconi's anaemia.

Adolescent↗