Stem cell-related "self-renewal" signature and high epidermal growth factor receptor expression associated with resistance to concomitant chemoradiotherapy in glioblastoma

PURPOSE: Glioblastomas are notorious for resistance to therapy, which has been attributed to DNA-repair proficiency, a multitude of deregulated molecular pathways, and, more recently, to the particular biologic behavior of tumor stem-like cells. Here, we aimed to identify molecular profiles specific for treatment resistance to the current standard of care of concomitant chemoradiotherapy with the alkylating agent temozolomide. PATIENTS AND METHODS: Gene expression profiles of 80 glioblastomas were interrogated for associations with resistance to therapy. Patients were treated within clinical trials testing the addition of concomitant and adjuvant temozolomide to radiotherapy. RESULTS: An expression signature dominated by HOX genes, which comprises Prominin-1 (CD133), emerged as a predictor for poor survival in patients treated with concomitant chemoradiotherapy (n = 42; hazard ratio = 2.69; 95% CI, 1.38 to 5.26; P = .004). This association could be validated in an independent data set. Provocatively, the HOX cluster was reminiscent of a "self-renewal" signature (P = .008; Gene Set Enrichment Analysis) recently characterized in a mouse leukemia model. The HOX signature and EGFR expression were independent prognostic factors in multivariate analysis, adjusted for the O-6-methylguanine-DNA methyltransferase (MGMT) methylation status, a known predictive factor for benefit from temozolomide, and age. Better outcome was associated with gene clusters characterizing features of tumor-host interaction including tumor vascularization and cell adhesion, and innate immune response. CONCLUSION: This study provides first clinical evidence for the implication of a "glioma stem cell" or "self-renewal" phenotype in treatment resistance of glioblastoma. Biologic mechanisms identified here to be relevant for resistance will guide future targeted therapies and respective marker development for individualized treatment and patient selection.

Role of plerixafor in autologous stem cell mobilization with vinorelbine chemotherapy and granulocyte-colony stimulating factor in patients with myeloma: a phase II study (PAV-trial)

Current practice in Switzerland for the mobilization of autologous stem cells in patients with myeloma is combining vinorelbine chemotherapy and granulocyte-colony stimulating factor (G-CSF) cytokine stimulation. We prospectively investigated adding intravenous plerixafor to the vinorelbine/G-CSF combination (VGP), and compared it with vinorelbine/plerixafor (VP) and G-CSF/plerixafor (GP) combinations. In a final cohort (VP-late), plerixafor was given on the first day of CD34 + cells increasing to > 15 000/mL peripheral blood. Four consecutive cohorts of 10 patients with myeloma were studied. We observed that intravenously administered plerixafor can be safely combined with vinorelbine/G-CSF. VGP was superior in mobilizing peripheral stem and progenitor cells compared to the three double combinations (VP, GP and VP-late), and GP mobilized better than VP. Our data indicate that the triple combination of VGP is an efficient strategy to collect autologous CD34 + cells, with G-CSF contributing predominantly in this concept. Plerixafor can be safely added to G-CSF and/or vinorelbine chemotherapy.

Donor pretreatment with progenipoietin-1 is superior to granulocyte colony-stimulating factor in preventing graft-versus-host disease after allogeneic stem cell transplantation

The granulocyte colony-stimulating factor (G-CSF) and Fit-3 receptor agonist progenipoietin-1 (ProGP-1) has potent effects on dendritic cell (DC) expansion and may be an alternative to G-CSF for the mobilization of stem cells for allogeneic stem cell transplantation (SCT). We studied the ability of stem cell grafts mobilized with this agent to induce graft-versus-host disease (GVHD) to minor and major histocompatibility antigens in the well-described B6 --> B6D2F1 SCT model. ProGP-1, G-CSIF, or control diluent was administered to donor B6 mice. ProGP-1 expanded all cell lineages in the spleen, and unseparated splenocytes from these animals produced large amounts of interleukin 10 (IL-10) and transforming growth factor beta (TGFbeta) whereas the expression of T-cell adhesion molecules was diminished. Transplantation survival was 0%, 50%, and 90% in recipients of control-, G-CSF-, and ProGP-1-treated allogeneic donor splenocytes, respectively (P < .0001). Donor pretreatment with ProGP-1 allowed a 4-fold escalation in T-cell dose over that possible with G-CSF. Donor CD4 T cells from allogeneic SCT recipients of ProGP-1 splenocytes demonstrated an anergic response to host antigen, and cytokine production (interferon gamma [IFNγ], IL-4, and IL-10) was also reduced while CD8 T-cell cytotoxicity to host antigens remained intact. Neither CD11c(hi) DCs nor CD11c(dim)/B220(hi) DCs from ProGP-1-treated animals conferred protection from GVHD when added to control spleen. Conversely, when equal numbers of purified T cells from control-, G-CSF-, or ProGP-1-treated allogeneic donors were added to allogeneic T-cell-depleted control spleen, survival at day 60 was 0%, 15%, and 90%, respectively (P < .0001). The improved survival in recipients of ProGP-1 T cells was associated with reductions in systemic tumor necrosis factor alpha generation and GVHD of the gastrointestinal tract. We conclude that donor pretreatment with ProGP-1 is superior to G-CSIF for the prevention of GVHD after allogeneic SCT, primarily due to incremental affects on T-cell phenotype and function

Chronic graft-versus-host disease after granulocyte colony-stimulating factor-mobilized allogeneic stem cell transplantation: The role of donor T-cell dose and differentiation

The use of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood as a source of stem cells has resulted in a high incidence of severe chronic graft-versus-host disease (cGVHD), which compromises the outcome of clinical allogeneic stem cell transplantation. We have studied the effect of G-CSF on both immune complex and fibrotic cGVHD directed to major (DBA/2 --> B6D2F1) or minor (B10.D2 --> BALB/c) histocompatibility antigens. In both models, donor pretreatment with G-CSF reduced cGVHD mortality in association with type 2 differentiation. However, after escalation of the donor T-cell dose, scleroderma occurred in 90% of the recipients of grafts from G-CSF-treated donors. In contrast, only 11% of the recipients of control grafts developed scleroderma, and the severity of hepatic cGVHD was also reduced. Mixing studies confirmed that in the presence of high donor T-cell doses, the severity of scleroderma was determined by the non-T-cell fraction of grafts from G-CSF-treated donors. These data confirm that the induction of cGVHD after donor treatment with G-CSF is dependent on the transfer of large numbers of donor T cells in conjunction with a putatively expanded myeloid lineage, providing a further rationale for the limitation of cell dose in allogeneic stem cell transplantation. (C) 2004 American Society for Blood and Marrow Transplantation.

Granulocyte-colony-stimulating factor mobilizes bone marrow stem cells in patients with subacute ischemic stroke: the Stem Cell Trial of Recovery EnhanceMent After Stroke (STEMS) Pilot Randomized, Controlled Trial (ISRCTN 16784092)

Background and Purpose - Loss of motor function is common after stroke and leads to significant chronic disability. Stem cells are capable of self-renewal and of differentiating into multiple cell types, including neurones, glia, and vascular cells. We assessed the safety of granulocyte-colony-stimulating factor (G-CSF) after stroke and its effect on circulating CD34 stem cells. Methods - We performed a 2-center, dose-escalation, double-blind, randomized, placebo-controlled pilot trial (ISRCTN 16784092) of G-CSF (6 blocks of 1 to 10 g/kg SC, 1 or 5 daily doses) in 36 patients with recent ischemic stroke. Circulating CD34 stem cells were measured by flow cytometry; blood counts and measures of safety and functional outcome were also monitored. All measures were made blinded to treatment. Results - Thirty-six patients, whose mean SD age was 768 years and of whom 50% were male, were recruited. G-CSF (5 days of 10 g/kg) increased CD34 count in a dose-dependent manner, from 2.5 to 37.7 at day 5 (area under curve, P0.005). A dose-dependent rise in white cell count (P0.001) was also seen. There was no difference between treatment groups in the number of patients with serious adverse events: G-CSF, 7/24 (29%) versus placebo 3/12 (25%), or in their dependence (modified Rankin Scale, median 4, interquartile range, 3 to 5) at 90 days. Conclusions - ”G-CSF is effective at mobilizing bone marrow CD34 stem cells in patients with recent ischemic stroke. Administration is feasible and appears to be safe and well tolerated. The fate of mobilized cells and their effect on functional outcome remain to be determined. (Stroke. 2006;37:2979-2983.)

Sinonasal Disorders In Hematopoietic Stem Cell Transplantation.

hematopoietic stem cell transplantation (HSCT) is associated with more respiratory infections due to immunosuppression. this study aimed to verify the frequency of rhinosinusitis after HSCT, and the association between rhinosinusitis and chronic graft vs. host disease (GVHD) and type of transplantation, clinical treatment, surgical treatment, and survival. this was a retrospective study in a tertiary university hospital. A total of 95 patients with hematological diseases undergoing HSCT between 1996 and 2011 were selected. chronic myeloid leukemia was the most prevalent disease. The type of transplant most often performed was the allogenic type (85.26%). The frequency of rhinosinusitis was 36%, with no difference between the autologous and the allogenic types. Chronic GVHD occurred in 30% of patients. Patients with GVHD had a higher frequency and recurrence of rhinosinusitis, in addition to more frequent need for endoscopic sinusectomy and decreased overall survival. there was a higher frequency of rhinosinusitis in HSCT and GVHD. The type of transplant does not appear to predispose to the occurrence of rhinosinusitis. GVHD seems to be an aggravating factor and requires a more stringent treatment.

Influence Of Cyclosporine On The Occurrence Of Nephrotoxicity After Allogeneic Hematopoietic Stem Cell Transplantation: A Systematic Review.

Cyclosporine, a drug used in immunosuppression protocols for hematopoietic stem cell transplantation that has a narrow therapeutic index, may cause various adverse reactions, including nephrotoxicity. This has a direct clinical impact on the patient. This study aims to summarize available evidence in the scientific literature on the use of cyclosporine in respect to its risk factor for the development of nephrotoxicity in patients submitted to hematopoietic stem cell transplantation. A systematic review was made with the following electronic databases: PubMed, Web of Science, Embase, Scopus, CINAHL, LILACS, SciELO and Cochrane BVS. The keywords used were: bone marrow transplantation OR stem cell transplantation OR grafting, bone marrow AND cyclosporine OR cyclosporin OR risk factors AND acute kidney injury OR acute kidney injuries OR acute renal failure OR acute renal failures OR nephrotoxicity. The level of scientific evidence of the studies was classified according to the Oxford Centre for Evidence Based Medicine. The final sample was composed of 19 studies, most of which (89.5%) had an observational design, evidence level 2B and pointed to an incidence of nephrotoxicity above 30%. The available evidence, considered as good quality and appropriate for the analyzed event, indicates that cyclosporine represents a risk factor for the occurrence of nephrotoxicity, particularly when combined with amphotericin B or aminoglycosides, agents commonly used in hematopoietic stem cell transplantation recipients.

Association of drug metabolism gene polymorphisms with toxicities, graft-versus-host disease and survival after HLA-identical sibling hematopoietic stem cell transplantation for patients with leukemia

Individual differences in drug efficacy or toxicity can be influenced by genetic factors. We investigated whether polymorphisms of pharmacogenes that interfere with metabolism of drugs used in conditioning regimen and graft-versus-host disease (GvHD) prophylaxis could be associated with outcomes after HLA-identical hematopoietic stem cell transplantation (HSCT). Pharmacogenes and their polymorphisms were studied in 107 donors and patients with leukemia receiving HSCT. Candidate genes were: P450 cytochrome family (CYP2B6), glutathione-S-transferase family (GST), multidrug-resistance gene, methylenetetrahydrofolate reductase (MTHFR) and vitamin D receptor (VDR). The end points studied were oral mucositis (OM), hemorrhagic cystitis (HC), toxicity and venoocclusive disease of the liver (VOD), GvHD, transplantation-related mortality (TRM) and survival. Multivariate analyses, using death as a competing event, were performed adjusting for clinical factors. Among other clinical and genetic factors, polymorphisms of CYP2B6 genes that interfere with cyclophosphamide metabolism were associated with OM (recipient CYP2B6*4; P=0.0067), HC (recipient CYP2B6*2; P=0.03) and VOD (donor CYP2B6*6; P=0.03). Recipient MTHFR polymorphisms (C677T) were associated with acute GvHD (P=0.03), and recipient VDR TaqI with TRM and overall survival (P=0.006 and P=0.04, respectively). Genetic factors that interfere with drug metabolisms are associated with treatment-related toxicities, GvHD and survival after HLA-identical HSCT in patients with leukemia and should be investigated prospectively.

A Pilot Randomized Trial Comparing CD-34Selected Versus Unmanipulated Hemopoietic Stem Cell Transplantation for Severe, Refractory Rheumatoid Arthritis

Objective. Evidence from animal studies, case reports, and phase I studies suggests that hemopoietic stem cell transplantation (HSCT) can be effective in the treatment of rheumatoid arthritis (RA). It is unclear, however, if depletion of T cells in the stem cell product infused after high-dose chemotherapy is beneficial in prolonging responses by reducing the number of infused autoreactive T cells. This pilot multicenter, randomized trial was undertaken to obtain feasibility data on whether CD34 selection (as a form of T cell depletion) of an autologous stem cell graft is of benefit in the HSCT procedure in patients with severe, refractory RA. Methods. Thirty-three patients with severe RA who had been treated unsuccessfully with methotrexate and at least 1 other disease-modifying agent were enrolled in the trial. The patients received high-dose immunosuppressive treatment with 200 mg/kg cyclophosphamide followed by an infusion of autologous stem cells that were CD34 selected or unmanipulated. Safety, efficacy (based on American College of Rheumatology [ACR] response criteria), and time to recurrence of disease were assessed on a monthly basis for up to 12 months. Results. All patients were living at the end of the study, with no major unexpected toxicities. Overall, on an intent-to-treat basis, ACR 20% response (ACR20) was achieved in 70% of the patients. An ACR70 response was attained in 27.7% of the 18 patients who had received CD34-selected cells and 53.3% of the 15 who had received unmanipulated cells (P = 0.20). The median time to disease recurrence was 147 days in the CD34-selected cell group and 201 days in the unmanipulated cell group (P = 0.28). There was no relationship between CD4 lymphopenia and response, but 72% of rheumatoid factor (RF)-positive patients had an increase in RF titer prior to recurrence of disease. Conclusion. HSCT can be performed safely in patients with RA, and initial results indicate significant responses in patients with severe, treatment-resistant disease. Similar outcomes were observed in patients undergoing HSCT with unmanipulated cells and those receiving CD34-selected cells. Larger studies are needed to confirm these findings.

Immune reconstitution after autologous hematopoietic stem cell transplantation

Abstract The investigation of the web of relationships between the different elements of the immune system has proven instrumental to better understand this complex biological system. This is particularly true in the case of the interactions between B and T lymphocytes, both during cellular development and at the stage of cellular effectors functions. The understanding of the B–T cells interdependency and the possibility to manipulate this relationship may be directly applicable to situations where immunity is deficient, as is the case of cancer or immune suppression after radio and chemotherapy. The work presented here started with the development of a novel and accurate tool to directly assess the diversity of the cellular repertoire (Chapter III). Contractions of T cell receptor diversity have been related with a deficient immune status. This method uses gene chips platforms where nucleic acids coding for lymphocyte receptors are hybridized and is based on the fact that the frequency of hybridization of nucleic acids to the oligonucleotides on a gene chip varies in direct proportion to diversity. Subsequently, and using this new method and other techniques of cell quantification I examined, in an animal model, the role that polyclonal B cells and immunoglobulin exert upon T cell development in the thymus, specifically on the acquisition of a broader repertoire diversity by the T cell receptors (Chapter IV and V). The hypothesis tested was if the presence of more diverse peptides in the thymus, namely polyclonal immunoglobulin, would induce the generation of more diverse T cells precursors. The results obtained demonstrated that the diversity of the T cell compartment is increased by the presence of polyclonal immunoglobulin. Polyclonal immunoglobulin, and particularly the Fab fragments of the molecule, represent the most diverse self-molecules in the body and its peptides are presented by antigen presenting cells to precursor T cells in the thymus during its development. This probably contributes significantly to the generation of receptor diversity. Furthermore, we also demonstrated that a more diverse repertoire of T lymphocytes is associated with a more effective and robust T cell immune function in vivo, as mice with a more diverse T cell receptors reject minor histocompatiblility discordant skin grafts faster than mice with a shrunken T cell receptor repertoire (Chapter V). We believe that a broader T cell receptor diversity allows a more efficient recognition and rejection of a higher range of external and internal aggressions. In this work it is demonstrated that a reduction of TCR diversity by thymectomy in wild type mice significantly increased survival of H-Y incompatible skin grafts, indicating decrease on T cell function. In addiction reconstitution of T-cell diversity in mice with a decreased T cell repertoire diversity with immunoglobulin Fab fragments, lead to a increase on TCR diversity and to a significantly decreased survival of the skin grafts (Chapter V). These results strongly suggest that increases on T cell repertoire diversity contribute to improvement of T cell function. Our results may have important implications on therapy and immune reconstitution in the context of AIDS, cancer, autoimmunity and post myeloablative treatments. Based on the previous results, we tested the clinical hypothesis that patients with haematological malignancies subjected to stem cell transplantation who recovered a robust immune system would have a better survival compared to patients who did not recover such a robust immune system. This study was undertaken by the examination of the progression and overall survival of 42 patients with mantle cell non-Hodgkin lymphoma receiving autologous hematopoietic stem cell transplantation (Chapter VI). The results obtained show that patients who recovered higher numbers of lymphocytes soon after autologous transplantation had a statistically significantly longer progression free and overall survivals. These results demonstrate the positive impact that a more robust immune system reconstitution after stem cell transplantation may have upon the survival of patients with haematological malignancies. In a similar clinical research framework, this dissertation also includes the study of the impact of recovering normal serum levels of polyclonal immunoglobulin on the survival of patients with another B cell haematological malignancy, multiple myeloma, after autologous stem cell transplantation (Chapter VII). The relapse free survival of the 110 patients with multiple myeloma analysed was associated with their ability to recover normal serum levels of the polyclonal compartment of immunoglobulin. These results suggest again the important effect of polyclonal immunoglobulin for the (re)generation of the immune competence. We also studied the impact of a robust immunity for the response to treatment with the antibody anti CD20, rituximab, in patients with non- Hodgkin’s lymphoma (NHL) (Chapter VIII). Patients with higher absolute counts of CD4+ T lymphocytes respond better (in terms of longer progression free survival) to rituximab compared to patients with lower number of CD4+ T lymphocytes. These observations highlight again the fact that a competent immune system is required for the clinical benefit of rituximab therapy in NHL patients. In conclusion, the work presented in this dissertation demonstrates, for the first time, that diverse B cells and polyclonal immunoglobulin promote T cell diversification in the thymus and improve T lymphocyte function. Also, it shows that in the setting of immune reconstitution, as after autologous stem cell transplantation for mantle cell lymphoma and in the setting of immune therapy for NHL, the absolute lymphocyte counts are an independent factor predicting progression free and overall survival. These results can have an important application in the clinical practice since the majority of the current treatments for cancer are immunosuppressive and implicate a subsequent immune recovery. Also, the effects of a number of antineoplastic treatments, including biological agents, depend on the immune system activity. In this way, studies similar to the ones presented here, where methods to improve the immune reconstitution are examined, may prove to be instrumental for a better understanding of the immune system and to guide more efficient treatment options and the design of future clinical trials. Resumo O estudo da rede de inter-relações entre os diversos elementos do sistema immune tem-se mostrado um instrumento essencial para uma melhor compreensão deste complexo sistema biológico. Tal é particularmente verdade no caso das interacções entre os linfócitos B e T, quer durante o desenvolvimento celular, quer ao nível das funções celulares efectoras. A compreensão da interdependência entre linfócitos B e T e a possibilidade de manipular esta relação pode ser directamente aplicável a situações em que a imunidade está deficiente, como é o caso das doenças neoplásicas ou da imunossupressão após radio ou quimioterapia. O trabalho apresentado nesta dissertação iniciou-se com o desenvolvimento de um novo método laboratorial para medir directamente a diversidade do reportório celular (Capítulo III). Reduções da diversidade do reportório dos receptores de células T têm sido relacionadas com um estado de imunodeficiência. O método desenvolvido utiliza “gene chips”, aos quais hibridizam os ácidos nucleicos codificantes das cadeias proteicas dos receptores linfocitários. A diversidade é calculada com base na frequência de hibridização do ácido nucleico da amostra aos oligonucleótidos presentes no “gene chip”. De seguida, e utilizando este novo método e outras técnicas de quantificação celular examinei, num modelo animal, o papel que as células policlonais B e a imunoglobulina exercem sobre o desenvolvimento linfocitário T no timo, especificamente na aquisição de um reportório diverso de receptores T (Capítulos IV e V). Testei, então, a hipótese de que a presença no timo de péptidos mais diversos, como a imunoglobulna policlonal, induzisse a génese de precursores T mais diversos. Demonstrámos que a diversidade do compartimento T é aumentado pela presença de imunoglobulina policlonal. A imunoglobulina policlonal, e particularmente os fragmentos Fab desta molécula, representam as moléculas autólogas mais diversas presentes nos organismos vertebrados. Estes péptidos são apresentados por células apresentadoras de antigénio às células precursoras T no timo, durante o desenvolvimento celular T. Tal, provavelmente, contribui para a génese da diversidade dos receptores. Também demonstrámos que a presença de um reportório mais diverso de linfócitos T se associa a um incremento da função imunológica T in vivo. Uma diversidade de receptores T mais extensa parece permitir um reconhecimento e rejeição mais eficientes de um maior número de agressores internos e externos. Demonstrámos que ratinhos com receptores de células T (RCT) com maior diversidade rejeitam transplantes cutâneos discordantes para antigénios minor de histocompatibilidade mais rapidamente do que ratinhos com um menor reportório T (Capítulo V). Por outro lado, uma redução da diversidade do RCT, causada por timectomia de ratinhos de estirpes selvagens, mostrou aumentar significativamente a sobrevivência de transplantes cutâneos incompatíveis para o antigénio H-Y (antigénio minor de histocompatibilidade), indicando uma diminuição da função linfocitária T. Além disso, a reconstituição da diversidade dos linfócitos T em ratinhos com uma diversidade de reportório T diminuída, induzida pela administração de fragmentos Fab de imunoglobulina, conduz a um aumento da diversidade dos RCT e a uma diminuição significativa da sobrevivência dos enxertos cutâneos (Capítulo V). Estes resultados sugerem que o aumento do reportório de células T contribui para uma melhoria das funções celulares T e poderão ter implicações importantes na terapêutica e reconstitutição imunológica em contexto de SIDA, neoplasias, autoimunidade e após tratamentos mieloablativos. Baseado nos resultados anteriores, decidimos testar a hipótese clínica de que doentes com neoplasias hematológicas sujeitos a transplantação de precursores hematopoiéticos e com recuperação imunológica precoce após transplante teriam uma sobrevivência mais longa do que doentes que não recuperassem tão bem a sua imunidade. Analisámos a sobrevivência global e sobrevivência sem doença de 42 doentes com linfoma não Hodgkin de células do manto sujeitos a transplante autólogo de precursores hematopoiéticos (Capítulo VI). Os resultados obtidos mostraram que os doentes que recuperaram contagens mais elevadas de linfócitos imediatamente após o transplante autólogo, apresentaram uma sobrevivência global e sem progressão mais longa do que doentes que não recuperaram contagens linfocitárias tão precocemente. Estes resultados demonstram o efeito positivo de uma reconstitutição imunológica robusta após transplante de presursores hematopoiéticos, sobre a sobrevivência de doentes com neoplasias hematológicas. Do mesmo modo, estudámos o efeito que a recuperação de níveis séricos normais de imunoglobulina policlonal tem na sobrevivência de doentes com outras neoplasias hematológicas de linfócitos B, como o mieloma múltiplo,após transplante autólogo de precursos hematopoiéticos (Capítulo VII). A sobrevivência livre de doença dos 110 doentes com mieloma múltiplo analizados está associada com a sua capacidade de recuperar níveis séricos normais do compartmento policlonal de imunoglobulina. Estes resultados pioneiros indicam a importância da imunoglobulina policlonal para a génese de competência imunológica. Também estudámos o impacto de um sistema imunitário eficiente sobre a resposta ao tratamento com o anticorpo anti CD20, ituximab, em doentes com linfoma não Hodgkin (LNH) (Capítulo VIII). Os resultados mostram que doentes com valores mais elevados de linfócitos T CD4+ respondem melhor (em termos de maior sobrevida livre de doença) ao rituximab, do que doentes com valores mais baixos. Estas observações ilustram a necessidade de um sistema imunitário competente para o benefício clínico da terapêutica com rituximab em doentes com LNH. Em conclusão, o trabalho apresentado nesta dissertação demonstra que as células B e a imunoglobulina policlonal promovem a diversidade das células T no timo e melhoram a função linfocitária T periférica. Concomitantemente, também demonstrámos que, no contexto de reconstituição imune, por exemplo, após transplante autólogo de precursores hematopoiéticos em doentes com linfomas de células do manto, o número absoluto de linfócitos é uma factor independente da sobrevivência. Os resultados demonstram, também, a importância dos valores de linfocitos T na resposta ao tratamento com rituximab no caso de doentes com LNH. O mesmo princípio se prova pelo facto de que doentes com mieloma múltiplo sujeitos a transplante autólogo de precursores hematopoiéticos que recuperam valores normais séricos de imunoglobulinas policlonais, terem melhores taxas de resposta em comparação com doentes que não recuperam valores normais de imunoglobulinas policlonais. Estes resultados podem ter importantes aplicações na prática clínica dado que a maioria dos tratamentos de doenças neoplásicas implica imunossupressão e, subsequente, recuperação imunológica. Estes estudos podem ser um instrumento fundamental para uma melhor compreensão do sistema imune e guiar uma escolha mais eficiente de opções terapêuticas bem como contribuir para a concepção de futuros estudos clínicos.

Stem Cell Transplantation for Retinal Degenerations

Within the last few years, several reports have revealed that cell transplantation can be an effective way to replace lost neurons in the central nervous system (CNS) of patients affected with neurodegenerative diseases. Concerning the retina, the concept that newborn photoreceptors can integrate the retina and restore some visual functions was univocally demonstrated recently in the mouse eye (MacLaren et al. 2006) and remains to be achieved in human. These results pave the way to a standard approach in regenerative medicine aiming to replace lost photoreceptors. With the discovery of stem cells a great hope has appeared towards elaborating protocols to generate adequate cells to restore visual function in different retinal degeneration processes. Retinal stem cells (RSCs) are good candidates to repair the retina and are present throughout the retina development, including adulthood. However, neonatal mouse RSCs derived from the radial glia population have a different potential to proliferate and differentiate in comparison to adult RSCs. Moreover, we observed that adult mouse RSCs, depending on the culture conditions, have a marked tendency to transform, whereas neonatal RSCs show subtle chromosome abnormalities only after extensive expansion. These characteristics should help to identify the optimal cell source and culture conditions for cell transplantation studies. These results will be discussed in light of other studies using RSCs as well as embryonic stem cells. Another important factor to consider is the host environment, which plays a crucial role for cell integration and which was poorly studied in the normal and the diseased retina. Nonetheless, important results were recently generated to reconsider cell transplantation strategy. Perspectives to enhance cell integration by manipulating the environment will also be presented.

Stem cell transplantation in brain tumors: a new field for molecular imaging?

Neural stem cells have been proposed as a new and promising treatment modality in various pathologies of the central nervous system, including malignant brain tumors. However, the underlying mechanism by which neural stem cells target tumor areas remains elusive. Monitoring of these cells is currently done by use of various modes of molecular imaging, such as optical imaging, magnetic resonance imaging and positron emission tomography, which is a novel technology for visualizing metabolism and signal transduction to gene expression. In this new context, the microenvironment of (malignant) brain tumors and the blood-brain barrier gains increased interest. The authors of this review give a unique overview of the current molecular-imaging techniques used in different therapeutic experimental brain tumor models in relation to neural stem cells. Such methods for molecular imaging of gene-engineered neural stem/progenitor cells are currently used to trace the location and temporal level of expression of therapeutic and endogenous genes in malignant brain tumors, closing the gap between in vitro and in vivo integrative biology of disease in neural stem cell transplantation.

Comparable Survival Between HIV+ and HIV- non-Hodgkin and Hodgkin Lymphoma Patients Undergoing Autologous Peripheral Blood Stem Cell Transplantation.

Autologous stem cell transplantation (ASCT) has been successfully used in HIV-related lymphoma (HIV-Ly) patients on highly active antiretroviral therapy. We report the first comparative analysis between HIV-Ly and a matched cohort of HIV(-) lymphoma patients. This retrospective European Group for Blood and Marrow Transplantation study included 53 patients (66% non-Hodgkin and 34% Hodgkin lymphoma) within each cohort. Both groups were comparable except for the higher proportion of males, mixed-cellularity Hodgkin lymphoma and patients receiving granulocyte colony-stimulating factor before engraftment and a smaller proportion receiving total body irradiation-based conditioning within the HIV-Ly cohort. Incidence of relapse, overall survival, and progression-free survival were similar in both cohorts. A higher nonrelapse mortality within the first year after ASCT was observed in the HIV-Ly group (8% vs 2%), predominantly because of early bacterial infections, although this was not statistically significant and did not influence survival. Thus, within the highly active antiretroviral therapy era, HIV patients should be considered for ASCT according to the same criteria adopted for HIV(-) lymphoma patients.

Manipulating keratinocyte stem cell proliferation and differentiation using RNA interference

ABSTRACT : The epidermis, the outermost compartment of the skin, is a stratified and squamous epithelium that constantly self-renews. Keratinocytes, which represent the main epidermal population, are responsible for its cohesion and barrier function. Epidermal renewal necessitates a fine equilibrium between keratinocyte proliferation and differentiation. The keratinocyte stem cell, located in the basal cell layer, is responsible for epidermal homeostasis and regeneration during the wound healing process. The transcription factor p63 structurally belongs to the p53 superfamily. It is expressed in the basal and supra-basal cell layers of stratified epithelia and is thought to be important for the renewal or the differentiation of keratinocyte stem cells (Yang et al., 1999; Mills et al., 1999). In order to better understand its function, we established an in vitro model of p63 deficient human keratinocyte stem cells using a shp63 mediated RNA interference. Knockdown of endogenous p63 induces downregulation of cell-adhesion genes as previously described (Carroll et al., 2006). Interestingly, the replating of attached p63-knockdown keratinocytes on a feeder layer results in a loss of attachment and proliferation. They are no longer clonogenic. However, if the same population are replated in a fibrin matrix, extended fibrinolysis is reported, a common process in wound healing, suggesting that p63 regulates the fibrinolytic pathway. This result was confirmed by Q-PCR and shows that the urokinase pathway, which mediates fibrinolysis, is upregulated. Altogether, these findings suggest a mechanism in which the fine tuning of p63 expression promotes attachment or release of the keratinocyte stem cell from the basement membrane by inducing genes of adhesion and/or of fibrinolysis. This mechanism may be important for epidermal self-renewal, differentiation as well as wound healing. Its misregulation may be partly responsible for the p63 knockout phenotype. The downregulation of p63 also induces a decrease in LEKTI expression. LEKTI (lymphoepithelial Kazal-type serine protease inhibitor) is a serine protease inhibitor encoded by the Spink5 gene. It is expressed and secreted in the uppermost differentiated layers of stratified epithelia and plays a role in the desquamation process. When this gene is disrupted, humans develop the Netherton syndrome (Chavanas et al., 2000b). It is a dermatosis characterized by hair dysplasias, ichtyosiform erythroderma and impairment in epidermal barrier function promoting inflammation similarly as in psoriasis with inflammatory infiltrate in excess. TNFα (tumor necrosis factor alpha) and EDA1 (ectodysplasin A1) are two transmembraneprecursors that belong to the TNF superfamily, which is involved in immune and inflammation regulation (Smahi et al., 2002). We suggest that the secreted serine protease inhibitor LEKTI plays a role in the regulation of TNFα and EDA1 precursor cleavage and absence of LEKTI induces excess of inflammation. To investigate this hypothesis, we induced downregulation of Spink5 expression in rat keratinocyte stem cells by using a shSpink5 mediated RNA interference approach. Interestingly, expression of TNFα and EDA1 is modified after knockdown of Spink5 by Q-PCR. Moreover, downregulation of Spink5 induces loss of cohesiveness between keratinocytes and colonies adopt a scattered phenotype. Altogether, these preliminary data suggest that downregulation of LEKTI may play a role in the inflammatory response in Netherton syndrome patients, by regulating TNFα expression.

Pseudoprogression after high-dose busulfan-thiotepa with autologous stem cell transplantation and radiation therapy in children with brain tumor: impact on survival

Objective: To demonstrate the incidence, time course, predisposing factor and reversibility of neurotoxicity in children with brain tumors treated with high dose busulfan-thiotepa with autologous stem cell transplantation (ASCT) and radiation therapy in our institutional experience.Materials and Methods: We performed a retrospective analysis of prospectively collected data. Between May 1988 and May 2007, 110 patients, median age 3.6 years (range, 1 months-15.3 years), with brain tumors were treated with surgical intervention and conventional chemotherapy. All patients received one course of high-dose busulfan-thiotepa with stem cell rescue, followed or preceded by radiotherapy.Results: Twenty-three patients (21%) developed neuroradiological abnormalities on follow-up imaging studies at a median time of 9.2 months (range, 5.6-17.3 months) after day 0 of ASCT. All MRI-lesions appeared in patients receiving radiotherapy after ASCT and were localized inside the 50-55 Gy isodoses. They disappeared in 14 of 23 patients with a median time of 8 months (range, 3-17 months). The presence of MRI-abnormalities was a favorable prognostic factor for overall survival on univariate analysis (hazard ratio: 0.12, 95% confidence interval [0.04, 0.33]), with a 5-year overall survival in patients with MRI-abnormalities of 84% (95% CI, 62-94), comparedto 27% (95% CI, 19-37) in those without lesions. On multivariate analysis, the presence of MRI-abnormalities was an independent prognostic factor for overall survival.Conclusion: MRI-detectable brain abnormalities are common early findings in children treated with high-dose busulfan-thiotepa followed by radiation therapy, and may mimic early tumor recurrence. They are correlated with a better outcome.