RESUMO
Graft-versus-host disease (GVHD) is a major cause of toxicity after allogeneic hematopoietic cell transplantation (allo-HCT). While rapamycin (RAPA) is commonly used in GVHD prophylaxis in combination with a calcineurin inhibitor (CNI), the understanding of its mechanism of action on human T cells is still incomplete. Here, we performed an extensive analysis of RAPA effects on human T cells in a humanized mouse model of GVHD, in ex-vivo T cell cultures and in patients given RAPA plus tacrolimus as GVHD prophylaxis after nonmyeloablative allo-HCT. We demonstrate that RAPA mitigates GVHD by decreasing T cell engraftment and differentiation, inhibiting CD8+ T cell activation and increasing the long-term IL-2 secretion, thereby supporting regulatory T cell (Treg) proliferation. In contrast, graft-versus-leukemia effects were not abrogated, as RAPA-treated T cells had increased resistance to apoptosis and retained their effector function and proliferative capacity upon re-stimulation. Importantly, we found that RAPA impact on Treg and CD8+ T cells was closely dependent upon IL-2 signaling and that therapeutic options interfering with IL-2, such as calcineurin inhibitors, antagonize the IL-2-dependent promotion of Treg mediated by RAPA. Our results suggest that RAPA immunological efficacy could be improved in combination with drugs having possible synergistic effects such as the hypomethylating agent 5-azacytidine.
Assuntos
Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Linfócitos T CD8-Positivos , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Sirolimo/farmacologia , TacrolimoRESUMO
PURPOSE: The proportion of older populations living with cancer is on the increase. Maintaining or improving their quality of life (QoL) has become an important goal in the treatment of cancer and has become an endpoint in clinical trials. Melatonin regulates a wide variety of physiological functions and is involved in the initiation of sleep and the improvement of QoL. With age, the secretion of melatonin decreases and could lead to a deterioration in QoL. METHODS: Literature searches were conducted using the PubMed database. The search terms and derivatives of "metastatic cancer", "older patients", "quality of life" and "melatonin" were used. Titles and abstracts were screened to identify whether studies were relevant for full-text screening. RESULTS: There is major concern about the symptoms older cancer patients encounter during treatment because they can impact their QoL. Melatonin supplementation presents several benefits for older patients: improvement in survival, decrease in symptoms induced by cancer and cancer treatment, and also improvements in quality of life. CONCLUSION: It therefore seems appropriate to study the impact of melatonin supplementation during cytotoxic therapy on QoL among elderly patients with metastatic cancer. The use of melatonin as a therapeutic strategy seems particularly suitable for elderly patients, a population known to secrete significantly less melatonin. However, to date, no studies have been conducted in this population.
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Neoplasias , Idoso , Humanos , Melatonina/uso terapêutico , Neoplasias/tratamento farmacológico , Qualidade de Vida , SonoRESUMO
Acute graft-versus-host disease (aGVHD) is a severe complication of allogeneic hematopoietic stem cell transplantation. The role of Th17 cells in its pathophysiology remains a matter of debate. In this study, we assessed whether enrichment of human peripheral blood mononuclear cells (PBMCs) with in vitro Th17-polarized CD4+ T cells would exacerbate xenogeneic GVHD (xGVHD) into NOD-scid IL-2Rγ null (NSG) mice. Naive human CD4+ T cells were stimulated under Th17-skewing conditions for 8 to 10 days and then coinjected in NSG mice with fresh PBMCs from the same donor. We observed that Th17-polarized cells engrafted and migrated toward xGVHD target organs. They also acquired a double-expressing IL-17A+IFNγ+ profile in vivo. Importantly, cotransfer of Th17-polarized cells (1â¯×â¯106) with PBMCs (1â¯×â¯106) exacerbated xGVHD compared with transplantation of PBMCs alone (2â¯×â¯106). Furthermore, PBMC cotransfer with Th17-polarized cells was more potent for xGVHD induction than cotransfer with naive CD4+ T cells stimulated in nonpolarizing conditions (Th0 cells, 1â¯×â¯106â¯+â¯1â¯×â¯106 PBMCs) or with Th1-polarized cells (1â¯×â¯106â¯+â¯1â¯×â¯106 PBMCs). In summary, our results suggest that human Th17-polarized cells can cooperate with PBMCs and be pathogenic in the NSG xGVHD model.
Assuntos
Doença Enxerto-Hospedeiro/imunologia , Células Th17/imunologia , Células Th17/transplante , Doença Aguda , Adulto , Animais , Feminino , Doença Enxerto-Hospedeiro/patologia , Xenoenxertos , Humanos , Interferon gama/imunologia , Masculino , Camundongos , Camundongos Endogâmicos NOD , Células Th17/patologiaRESUMO
Americium (Am) biodistribution data obtained after wound contamination in rats were analysed to evaluate and quantify the influence of different physicochemical forms of Am in the presence or absence of plutonium (Pu). The biodistribution data were individual Am daily urinary excretion and tissue retention. The data were analysed with STATBIODIS, a statistical tool developed in the laboratory and based on the R language. Non-parametric methods were selected to comply with the data characteristics. Am systemic tissue retention and urinary excretion data were much greater for contamination with soluble physicochemical forms than insoluble forms. Meanwhile, Am relative biodistribution between the main retention tissues (skeleton, liver and kidney) remained the same. Hence, after absorption into blood the radionuclide behaviour was independent of the physicochemical form. The presence of Pu did not change the Am biodistribution. Comparisons of the biodistribution data from the laboratory with mean values published by other laboratories showed that soluble to moderately soluble forms of Am resulted in similar urine excretion after contamination, whether it was intravenous, intramuscular, subcutaneous injection or incision. Findings from this work will contribute to improve the understanding and interpretation of wound contamination cases with different physicochemical forms and mixtures of actinides including Am.
Assuntos
Amerício/farmacocinética , Plutônio/farmacocinética , Lesões Experimentais por Radiação/metabolismo , Distribuição Tecidual/efeitos da radiação , Animais , Interpretação Estatística de Dados , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Multiple myeloma bone disease is characterized by an uncoupling of bone remodeling in the multiple myeloma microenvironment, resulting in the development of lytic bone lesions. Most myeloma patients suffer from these bone lesions, which not only cause morbidity but also negatively impact survival. The development of novel therapies, ideally with a combined anti-resorptive and bone-anabolic effect, is of great interest because lesions persist with the current standard of care, even in patients in complete remission. We have previously shown that MELK plays a central role in proliferation-associated high-risk multiple myeloma and its inhibition with OTSSP167 resulted in decreased tumor load. MELK inhibition in bone cells has not yet been explored, although some reports suggest that factors downstream of MELK stimulate osteoclast activity and inhibit osteoblast activity, which makes MELK inhibition a promising therapeutic approach. Therefore, we assessed the effect of OTSSP167 on bone cell activity and the development of myeloma-induced bone disease. OTSSP167 inhibited osteoclast activity in vitro by decreasing progenitor viability as well as via a direct anti-resorptive effect on mature osteoclasts. In addition, OTSSP167 stimulated matrix deposition and mineralization by osteoblasts in vitro This combined anti-resorptive and osteoblast-stimulating effect of OTSSP167 resulted in the complete prevention of lytic lesions and bone loss in myeloma-bearing mice. Immunohistomorphometric analyses corroborated our in vitro findings. In conclusion, we show that OTSSP167 has a direct effect on myeloma-induced bone disease in addition to its anti-multiple myeloma effect, which warrants further clinical development of MELK inhibition in multiple myeloma.
Assuntos
Doenças Ósseas/tratamento farmacológico , Mieloma Múltiplo/tratamento farmacológico , Naftiridinas/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Animais , Doenças Ósseas/etiologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Feminino , Xenoenxertos , Humanos , Camundongos , Mães , Mieloma Múltiplo/complicações , Mieloma Múltiplo/patologia , Naftiridinas/uso terapêutico , Osteoblastos/efeitos dos fármacos , Osteoclastos/efeitos dos fármacos , Osteólise/tratamento farmacológico , Osteólise/prevenção & controle , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêuticoRESUMO
The constant development of health technologies, combined with the increase in the cost of treatment, means that States must continually make choices about the introduction of new technologies into their healthcare system and how they are to be funded. In France, the systematic participation of patients in these processes is one of the targets to be met in terms of healthcare democracy. Although, on an international level, patient involvement in these assessments is constantly growing, it is difficult to define due to the presence of unstabilised elements in terms of both terminology and assessment methods. As a result, patient and public involvement in health technology assessments varies considerably from one country to the next, from one field to the next and even from one type of technology to the next. Several types of involvement exist, ranging from studies conducted to collect patient "insight" (experience, perception, needs, preferences, attitudes to treatment and health, etc.) to processes aimed at including patients in assessments (as individuals, as representatives of associations, etc.). Given the scope and complexity of the subject, and the difficulty involved in understanding all the different aspects of health technologies and innovations, the members of the Round Table chose to concentrate on health technology assessments (medicinal products and medical devices) to develop national recommendations on all possible types of patient involvement in the health technology assessment processes conducted by the health authorities in France.
Assuntos
Participação da Comunidade , Avaliação da Tecnologia Biomédica , HumanosRESUMO
Genetic diversity is crucial for species' maintenance and persistence, yet is often overlooked in conservation studies. Species diversity is more often reported due to practical constraints, but it is unknown if these measures of diversity are correlated. In marine invertebrates, adults are often sessile or sedentary and populations exchange genes via dispersal of gametes and larvae. Species with a larval period are expected to have more connected populations than those without larval dispersal. We assessed the relationship between measures of species and genetic diversity, and between dispersal ability and connectivity. We compiled data on genetic patterns and life history traits in nine species across five phyla. Sampling sites spanned 600 km in the northwest Mediterranean Sea and focused on a 50-km area near Marseilles, France. Comparative population genetic approaches yielded three main results. (i) Species without larvae showed higher levels of genetic structure than species with free-living larvae, but the role of larval type (lecithotrophic or planktotrophic) was negligible. (ii) A narrow area around Marseilles, subject to offshore advection, limited genetic connectivity in most species. (iii) We identified sites with significant positive contributions to overall genetic diversity across all species, corresponding with areas near low human population densities. In contrast, high levels of human activity corresponded with a negative contribution to overall genetic diversity. Genetic diversity within species was positively and significantly linearly related to local species diversity. Our study suggests that local contribution to overall genetic diversity should be taken into account for future conservation strategies.
Assuntos
Distribuição Animal , Biodiversidade , Variação Genética , Genética Populacional , Invertebrados/classificação , Animais , Organismos Aquáticos/classificação , Geografia , Larva , Mar MediterrâneoRESUMO
In France, market access for innovative drugs (level I, II & III improvement of medical service rendered having significant impact on health insurance expenditure) involves medico-economic evaluation. In addition to cost-effectiveness analysis (CEA), budget impact analysis (BIA) can be performed, especially since the sustainability of the health insurance system has become a growing concern for all stakeholders. The members of the Giens 2016 round table discussed the contribution of BIA based on a review of the literature on distribution models, the participants' experiences including experience related to the modalities of hospital assessments, and examples from other countries. The round table established recommendations on four elements of interest: 1: the use of BIA from a contractual point of view - between manufacturers and the French Economic Committee for Health Products - during the price negotiations process, and from a prospective point of view within the framework of the annual review of budget expenditures; the definition of the target population and the rhythm of a health product's distribution are also major elements; 2: the interpretation of BIA results in light of CEA results: for what products and at what moment in the life cycle of these products; 3: the integration of the rhythm of a health product's distribution into the BIA; 4: preoccupations about how the level of health product implementation is integrated into the BIA in terms of opportunity cost and organisational quality for the promoter.
Assuntos
Tecnologia Biomédica/economia , Orçamentos , Preparações Farmacêuticas/economia , Garantia da Qualidade dos Cuidados de Saúde/economia , Análise Custo-Benefício , França , HumanosRESUMO
Lyme disease is caused by spirochetes of the Borrelia burgdorferi sensu lato complex. They are transmitted mainly by Ixodes ricinus ticks. After a few hours of infestation, neutrophils massively infiltrate the bite site. They can kill Borrelia via phagocytosis, oxidative burst, and hydrolytic enzymes. However, factors in tick saliva promote propagation of the bacteria in the host even in the presence of a large number of neutrophils. The neutrophil extracellular trap (NET) consists in the extrusion of the neutrophil's own DNA, forming traps that can retain and kill bacteria. The production of reactive oxygen species is apparently associated with the onset of NETs (NETosis). In this article, we describe NET formation at the tick bite site in vivo in mice. We show that Borrelia burgdorferi sensu stricto spirochetes become trapped and killed by NETs in humans and that the bacteria do not seem to release significant nucleases to evade this process. Saliva from I. ricinus did not affect NET formation by human neutrophils or its stability. However, it greatly decreased neutrophil reactive oxygen species production, suggesting that a strong decrease of hydrogen peroxide does not affect NET formation. Finally, round bodies trapped in NETs were observed, some of them staining as live bacteria. This observation could help contribute to a better understanding of the early steps of Borrelia invasion and erythema migrans formation after tick bite.
Assuntos
Vetores Aracnídeos/imunologia , Mordeduras e Picadas , Grupo Borrelia Burgdorferi/fisiologia , Glossite Migratória Benigna/imunologia , Ixodes/imunologia , Doença de Lyme/imunologia , Neutrófilos/imunologia , Saliva/imunologia , Animais , Vetores Aracnídeos/microbiologia , DNA/imunologia , Feminino , Glossite Migratória Benigna/complicações , Glossite Migratória Benigna/microbiologia , Glossite Migratória Benigna/patologia , Humanos , Ixodes/microbiologia , Doença de Lyme/complicações , Doença de Lyme/microbiologia , Doença de Lyme/patologia , Masculino , Camundongos , Infiltração de Neutrófilos , Neutrófilos/metabolismo , Coelhos , Espécies Reativas de Oxigênio/imunologia , Saliva/químicaRESUMO
Beneficial polyphenols in apples can reach the stomach as complexes formed with salivary proteins. The present study aimed at documenting the interactions between salivary proteins and cider apple polyphenols and the fate of complexes during gastric digestion. A polyphenolic extract was mixed with human saliva, and interactions were characterized by analyzing proteins and polyphenols in the insoluble and soluble fractions of the mixtures, before and after in vitro gastric digestion. Results confirmed that proline-rich proteins can efficiently precipitate polyphenols and suggested that two zinc-binding proteins can also form insoluble complexes with polyphenols. The classes of polyphenols involved in such complexes depended on the polyphenol-to-protein ratio. In vitro gastric digestion led to extensive proteolysis of salivary proteins, and we formulate the hypothesis that the resulting peptides can interact with and precipitate some procyanidins. Saliva may therefore partly modulate the bioaccessibility of at least procyanidins in the gastric compartment.
RESUMO
BACKGROUND AIMS: Graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation caused by donor T cells reacting against host tissues. Previous studies have suggested that mesenchymal stromal cells (MSCs) could exert potent immunosuppressive effects. METHODS: The ability of human bone marrow derived MSCs to prevent xenogeneic GVHD in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice and in NOD/SCID/interleukin-2Rγ(null) (NSG) mice transplanted with human peripheral blood mononuclear cells (PBMCs) was assessed. RESULTS: Injection of 200 × 10(6) human PBMCs intraperitoneally (IP) into sub-lethally (3.0 Gy) irradiated NOD/SCID mice also given anti-asialo GM1 antibodies IP 1 day prior and 8 days after transplantation induced lethal xenogeneic GVHD in all tested mice. Co-injection of 2 × 10(6) MSCs IP on day 0 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs. Similarly, injection of 30 × 10(6) human PBMCs IP into sub-lethally (2.5 Gy) irradiated NSG mice induced a lethal xenogeneic GVHD in all tested mice. Injection of 3 × 10(6) MSCs IP on days 0, 7, 14 and 21 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs. CONCLUSIONS: Injection of MSCs did not prevent xenogeneic GVHD in these two humanized mice models.
Assuntos
Doença Enxerto-Hospedeiro/fisiopatologia , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Animais , Células da Medula Óssea/citologia , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/genética , Humanos , Leucócitos Mononucleares/transplante , Camundongos , Camundongos SCID , Linfócitos T/imunologia , Linfócitos T/transplante , Transplante Homólogo/efeitos adversosRESUMO
The Balkans are known to have a high level of biodiversity and endemism. No less than 15 taxa have been recorded in salmonids of the Salmo genus. Among them, the Prespa trout is found in only four river systems flowing into Lake Macro Prespa, three in the Former Yugoslav Republic of Macedonia and one in Greece. This is the first comprehensive survey of all streams located within the Macro Prespa Basin, encompassing the whole taxon range. A large genetic sample of 536 Prespa trout was collected mainly between 2005 and 2007. The sampling included 59 individuals from the Golema river system, 93 from the Kranska, 260 from the Brajcinska, 119 from the Agios Germanos, and five individuals from the lake itself. These specimens were analyzed with six microsatellite markers and by sequencing the mitochondrial control region. Nuclear data were examined through multidimensional analysis and assignment tests. Five clusters were detected by assignment: Golema, Kranska, Brajcinska upstream, Rzanska Brajcinska tributary and Brajcinska downstream. Most of these river systems thus hosted differentiated Prespa trout populations (with past gene flows likely dating before the construction of dams), except Agios Germanos, which was found to be composed of 5% to 32% of each cluster. Among the five trout individuals from the lake, four originated from Kranska River and one was admixed. Supported parsimonious hypotheses are proposed to explain these specificities. Conservation of this endemic taxon should take these results into account. No translocation should be performed between different tributaries of the lake and preservation of the Brajcinska populations should address the upstream-downstream differentiation described.
Assuntos
Variação Genética , Truta/genética , Alelos , Animais , Península Balcânica , DNA/análise , DNA Mitocondrial/análise , Genótipo , Haplótipos , Repetições de Microssatélites , Filogenia , Reação em Cadeia da Polimerase , Polimorfismo Genético , Truta/classificaçãoRESUMO
Graft-versus-host disease (GVHD) remains a serious limitation of allogeneic hematopoietic cell transplantation (allo-HCT). While post-transplant administration of cyclophosphamide (PTCy) is increasingly used as GVHD prophylaxis, its precise mechanisms of action and its impact on graft-versus-leukemia effects have remained debated. Here, we studied the mechanisms of xenogeneic GVHD (xGVHD) prevention by PTCy in different humanized mouse models. We observed that PTCy attenuated xGVHD. Using flow cytometry and single-cell RNA-sequencing, we demonstrated that PTCy depleted proliferative CD8+ and conventional CD4+ T cells but also proliferative regulatory T cells (Treg). Further, T-cell receptor ß variable region sequencing (TCRVB) analyses demonstrated that highly xenoreactive T-cell clones were depleted by PTCy. Although Treg frequencies were significantly higher in PTCy-treated than in control mice on day 21, xGVHD attenuation by PTCy was not abrogated by Treg depletion. Finally, we observed that PTCy did not abrogate graft-versus-leukemia effects.
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Polypharmacy in elderly is a public health problem with both clinical (increase of adverse drug events) and economic issues. One solution is medication review, a structured assessment of patients' drug orders by the pharmacist for optimizing the therapy. However, this task is tedious, cognitively complex and error-prone, and only a few clinical decision support systems have been proposed for supporting it. Existing systems are either rule-based systems implementing guidelines, or documentary systems presenting drug knowledge. In this paper, we present the ABiMed research project, and, through literature reviews and brainstorming, we identified five candidate innovations for a decision support system for medication review: patient data transfer from GP to pharmacists, use of semantic technologies, association of rule-based and documentary approaches, use of machine learning, and a two-way discussion between pharmacist and GP after the medication review.
Assuntos
Sistemas de Apoio a Decisões Clínicas , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Idoso , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/prevenção & controle , Humanos , Revisão de Medicamentos , Farmacêuticos , PolimedicaçãoRESUMO
Amylose-free and wild-type cassava starches were fermented for up to 30 days and oven- or sun-dried. The specific volume (ν) after baking was measured in native and fermented starches. The average ν (across treatments) for waxy starch was 3.5 times higher than that in wild-type starches (17.6 vs. 4.8 cm3 g-1). The best wild-type starch (obtained after fermentation and sun-drying) had considerably poorer breadmaking potential than native waxy cassava (8.4 vs. 16.4 cm3 g-1, respectively). The best results were generally obtained through the synergistic combination of fermentation (for about 10-14 days) and sun-drying. Fermentation reduced viscosities and the weight average molar mass led to denser macromolecules and increased branching degree, which are linked to a high loaf volume. The absence of amylose, however, was shown to be a main determinant as well. Native waxy starch (neutral in taste, gluten-free, and considerably less expensive than the current alternatives to cassava) could become a new ingredient for the formulation of clean label-baked or fried expanded products.
Assuntos
Manihot , Amilopectina , Amilose , Dieta Livre de Glúten , AmidoRESUMO
Flavan-3-ols (catechin monomers and procyanidins) are the main class of polyphenols in apples and are found in high concentrations in cider apple varieties. They are known to be involved in bitterness and astringency in apple-based beverages, and also contribute to polyphenol nutritional intake.Therefore, highly purified flavan-3-ol fractions isolated from raw materials are needed to study their various properties. For this purpose, a gentle strategy combining pH-zone-refining centrifugal partition chromatography (pH-ZRCPC) and preparative reversed-phase liquid chromatography (Prep-RPLC) was developed to recover one hundred milligrams of a high purity apple flavan-3-ol fraction. First, pH-ZRCPC fractionation in descending mode was optimized to remove hydroxycinnamic acid derivatives using a biphasic mixture composed of ethyl acetate/n-butanol/water (3/2/5, v/v). Trifluoroacetic acid and sodium hydroxide were used as retainer and eluter, in the upper and lower phases, respectively. Secondly, Prep-RPLC separation was carried out in isocratic mode at 20% ACN to remove dihydrochalcones. Finally, from one gram of a crude polyphenol extract, four hundred and nine milligrams of a highly purified fraction of flavan-3-ols with an average degree of polymerization close to 3.1 was obtained with 73% recovery.
Assuntos
Cromatografia Líquida , Cromatografia de Fase Reversa , Flavonoides , Malus , Flavonoides/química , Flavonoides/isolamento & purificação , Concentração de Íons de Hidrogênio , Malus/químicaRESUMO
We assessed the impact of the Janus Kinase (JAK) 1 inhibitor itacitinib on xenogeneic graft-versus-host disease (xGVHD). XGVHD was induced by i.v. injection 20 × 106 human peripheral blood mononuclear cells (hPBMC) in NSG mice on day 0. Itacitinib (3 mg, ≈120 mg/kg) or methylcellulose was administered by force-feeding twice a day from day 3 to day 28. Mice were followed for xGVHD score and survival. In addition, human T-cell engraftment and as well as human T-cell subtypes were monitored in blood on days 14, 21, and 28 after transplantation. We observed that itacitinib-treated mice had significantly longer survival than control mice (median 45 versus 33 days; P < 0.001). Further, they also had lower absolute numbers of human CD4+ T cells on days 21 and 28 after transplantation as well as of human CD8+ T cells on days 14, 21, and 28 after transplantation. In addition, itacitinib-treated mice had higher frequencies of human regulatory T cells (Treg) on days 21 and 28 after transplantation. In summary, our data indicate that itacitinib decreases human T-cell engraftment, increases Treg frequencies and attenuates xGVHD in NSG mice transplanted with hPBMC.
Assuntos
Doença Enxerto-Hospedeiro , Acetonitrilas , Animais , Linfócitos T CD8-Positivos , Doença Enxerto-Hospedeiro/prevenção & controle , Leucócitos Mononucleares , Camundongos , Camundongos SCID , Pirazóis , Pirimidinas , PirróisRESUMO
BACKGROUND: Bone marrow mesenchymal stem cells support proliferation and differentiation of hematopoietic progenitor cells in vitro. Since these cells constitute a rare subset of bone marrow cells, mesenchymal stem cell preparations for clinical purposes require a preparative step of ex vivo multiplication. The aim of our study was to analyze the influence of culture duration on mesenchymal stem cell supportive activity. DESIGN AND METHODS: Mesenchymal stem cells were expanded for up to ten passages. These cells and CD34+ cells were seeded in cytokine-free co-cultures after which the phenotype, clonogenic capacity and in vivo repopulating activity of harvested hematopoietic cells were assessed. RESULTS: Early passage mesenchymal stem cells supported hematopoietic progenitor cell expansion and differentiation toward both B lymphoid and myeloid lineages. Late passage mesenchymal stem cells did not support hematopoietic progenitor cell and myeloid cell outgrowth but maintained B-cell supportive ability. In vitro maintenance of NOD/SCID mouse repopulating cells cultured for 1 week in contact with mesenchymal stem cells was effective until the fourth passage of the mesenchymal cells and declined thereafter. The levels of engraftment of CD34(+) cells in NOD/SCID mice was higher when these cells were co-injected with early passage mesenchymal stem cells; however mesenchymal cells expanded beyond nine passages were ineffective in promoting CD34(+) cell engraftment. Non-contact cultures indicated that mesenchymal stem cell supportive activity involved diffusible factors. Among these, interleukins 6 and 8 contributed to the supportive activity of early passage mesenchymal stem cells but not to those of late passage cells. The phenotype, as well as fat, bone and cartilage differentiation capacity, of mesenchymal stem cells did not change during their culture. Conclusions Extended culture of mesenchymal stem cells alters the ability of these cells to support hematopoietic progenitor cells without causing concomitant changes in their phenotype or differentiation capacity.