Η αιμοποιητική φωλαιά (hematopoietic stem cell niche) περιέχει οστεοβλάστες, οι οποίοι ρυθμίζουν τη φυσιολογική αιμοποίηση. Ωστόσο, λίγα στοιχεία είναι γνωστά, έως τώρα, για το ρόλο των οστεοβλαστών στη διαδικασία της αιμοποίησης σε ασθενείς με Μυελοδυσπλαστικό Σύνδρομο (ΜΔΣ). Το ΜΔΣ, αποτελεί μια ετερογενή ομάδα κλωνικών αιματολογικών διαταραχών, με αυξημένο κίνδυνο εκτροπής προς Οξεία Μυελογενή Λευχαιμία (ΟΜΛ). Μελέτες σε ex-vivo συστήματα καλλιεργειών (co-cultures) περιγράφουν την επίδραση των μεσεγχυματικών κυττάρων (“feeder cells”) στο δυναμικό πολλαπλασιασμού, στη μεταναστευτική ικανότητα, καθώς και στη διατήρηση (stemness) των αρχέγονων αιμοποιητικών κυττάρων (HSCs) φυσιολογικών δοτών. Η μελέτη αυτή στοχεύει στη διερεύνηση των βιολογικών χαρακτηριστικών των οστεοβλαστών από ασθενείς με ΜΔΣ καθώς και τις αλληλεπιδράσεις φυσιολογικών HSCs και οστεοβλαστών ασθενών με ΜΔΣ. Για το σκοπό αυτό δημιουργήθηκε ένα σύστημα δισδιάστατης καλλιέργειας (2-D culture system) χρησιμοποιώντας οστεοβλάστες που παρήχθησαν από μεσεγχυματικά κύτταρα μυελού των οστών (human marrow mesenchymal stem cells-MSCs). Τα MSCs απομονώθηκαν από το μυελό των οστών ασθενών με ΜΔΣ και υγιών δοτών και καλλιεργήθηκαν σε κατάλληλο θρεπτικό μέσο. Ακολούθησε επαγωγή της διαφοροποίησης των MSCs, μετά από συνεχόμενες καλλιέργειες σε οστεοβλάστες. Στη μελέτη χρησιμοποιήθηκαν 13 δείγματα μυελού των οστών από ασθενείς με ΜΔΣ (6 RA, 3 RAEBI, 2 RAEBII, 1 5q- και 1 υποπλαστικό MDS) και 8 δείγματα μυελού φυσιολογικών μαρτύρων όμοιας ηλικίας. Για τη μελέτη της επίδρασης των οστεοβλαστών από ασθενείς με ΜΔΣ στην αιμοποίηση χρησιμοποιήθηκαν φυσιολογικά HSCs από κινητοποιημένο περιφερικό αίμα υγιών δοτών (mPB, n=4), τα οποία τοποθετήθηκαν πάνω στους ήδη εγκατεστημένους οστεοβλάστες (osteoblast confluent monolayer cultures). Τα MSCs και οι οστεοβλάστες που αναπτύχθηκαν ελέγχθηκαν μορφολογικά και ανοσοφαινοτυπικά, με τη χρήση μικροσκοπίας και κυτταρομετρίας ροής αντίστοιχα. Μονοπύρηνα κύτταρα από δείγματα κινητοποιημένου περιφερικού αίματος υγιών δοτών τοποθετήθηκαν στο δισδιάστατο καλλιεργητικό σύστημα, σε καλλιεργητικό υλικό αιμοποιητικών κυττάρων, χωρίς την εξωγενή προσθήκη κυτταροκινών. Με τη χρήση κυτταρομετρίας ροής ελέγχθηκε η έκφραση των μορίων που σχετίζονται με την προσκόλληση των αιμοποιητικών κυττάρων στην αιμοποιητική φωλαιά καθώς και την εγκατάσταση και διατήρησή τους σε αυτή. Ο έλεγχος έγινε στις 36 ώρες και τις 7 ημέρες συγκαλλιέργειας και αφορούσε τα μόρια CXCR4, το οποίο ρυθμίζει την άμεση πρόσδεση των HSCs στην φωλαιά κατά τη διαδικασία του “homing”, CD49d (Very Late Antigen-4- VLA4) και CD49e (Very Late Antigen-5- VLA5), τα οποία παρέχουν σήματα επιβίωσης ή προάγουν την ενεργοποίηση μιας φάσης ηρεμίας (quiescence) στα HSCs μετά την είσοδο τους στη φωλαιά (localization). Η έκφραση των μορίων αυτών μελετήθηκε στους υποπληθυσμούς των CD34+, CD34+/CD38+ και CD34+/CD38- κυττάρων. Παράλληλα εκτιμήθηκε το ποσοστό (συχνότητα) των CD34+ αιμοποιητικών κυττάρων καθώς επίσης και η προσκόλλησή τους στους οστεοβλάστες. Μετά τη συγκαλλιέργεια, οι οστεοβλάστες που προήλθαν από υγιείς δότες προκάλεσαν τον πολλαπλασιασμό των CD34+ κυττάρων των φυσιολογικών αιμοποιητικών κυττάρων που τοποθετήθηκαν πάνω στο εγκατεστημένο στρώμα των οστεοβλαστών (3-fold και 9-fold αύξηση στις 36ώρες και τις 7ημ., αντίστοιχα). Αύξηση επίσης, παρατηρήθηκε (2 fold αύξηση) στα CD34+ κύτταρα στις συγκαλλιέργειες των 36h, φυσιολογικών HSCs με οστεοβλάστες που παρήχθησαν από ασθενείς με ΜΔΣ, ενώ καμία διαφορά δεν παρατηρήθηκε μεταξύ των διαφορετικών υποτύπων ΜΔΣ. Στις 7 ημέρες συγκαλλιέργειας από την άλλη, δεν 12 παρατηρήθηκε καμία διαφορά στη συχνότητα εμφάνισης ενός πιο άωρου φαινοτύπου των φυσιολογικών HSCs που αναπτύχθηκαν σε οστεοβλάστες από ασθενείς με χαμηλού κινδύνου ΜΔΣ (low risk MDS). Αντιθέτως, τα CD34+ κύτταρα αυξήθηκαν κατά πολύ (16- fold αύξηση), όταν φυσιολογικά HSCs, τοποθετήθηκαν σε οστεοβλάστες ασθενών με υψηλού κινδύνου ΜΔΣ (high risk MDS). Επιπλέον, παρατηρήθηκε αύξηση της έκφρασης των μορίων CXCR4, CD49d και CD49e στα CD34+ κύτταρα μετά από συγκαλλιέργεια φυσιολογικών HSCs και οστεοβλαστών από υγιείς δότες, συγκριτικά με τα επίπεδα έκφρασης των μορίων αυτών πριν την τοποθέτηση τους στο σύστημα συγκαλλιέργειας. Η αύξηση της έκφρασης του μορίου CXCR4 ήταν λιγότερο εμφανής στην περίπτωση συγκαλλιέργειας των φυσιολογικών HSCs με οστεοβλάστες από ασθενείς με ΜΔΣ, όπου η μεγαλύτερη διαφορά παρατηρήθηκε στο σύστημα που περιείχε τους οστεοβλάστες από ασθενείς χαμηλού κινδύνου ΜΔΣ (3- και 1,7- fold αύξηση στις 7ημέρες καλλιέργειας με οστεοβλάστες από υγιείς δότες και χαμηλού κινδύνου ΜΔΣ ασθενείς, αντίστοιχα). Το πρότυπο έκφρασης των μορίων CD49d και CD49e ήταν όμοιο στα κύτταρα που τοποθετήθηκαν τόσο σε οστεοβλάστες προερχόμενους από υγιείς δότες, όσο και οστεοβλάστες από ΜΔΣ ασθενείς. Ο φαινότυπος, τόσο όσον αφορά τα μορφολογικά όσο και τα ανοσοφαινοτυπικά χαρακτηριστικά, των MSCs ήταν ίδιος και στις δυο ομάδες μελέτης, ενώ η διαφοροποίηση των MSCs προς οστεοβλάστες ήταν όμοια τόσο στα MSCs που προήλθαν από φυσιολογικούς δότες όσο και σε αυτά που προήλθαν από ασθενείς με ΜΔΣ, δείχνοντας παρόμοια έκφραση των ειδικών οστεοβλαστικών πρωτεϊνών αλλά και της διαδικασίας της ενασβεστοποίησης. Σύμφωνα με τα αποτελέσματα που λάβαμε, οι οστεοβλάστες από υγιείς δότες προώθησαν την αύξηση του ποσοστού των προγονικών αιμοποιητικών κυττάρων και οδήγησαν στην επαγωγή της έκφρασης του μορίου CXCR4, ενός πολύ σημαντικού μορίου για τη μετανάστευση, την εγκατάσταση αλλά και την ανάπτυξη. Ωστόσο, η διαφορετική δραστηριότητα, τόσο όσον αφορά το ποσοστό των CD34+ όσο και την έκφραση του μορίου CXCR4, όταν τα φυσιολογικά αιμοποιητικά κύτταρα συγκαλλιεργήθαν με οστεοβλάστες που προήλθαν από ασθενείς με ΜΔΣ, οδηγεί στην υπόθεση ότι υπάρχει μεταβολή στη λειτουργία των οστεοβλαστών, οπότε προβλέπεται και μια επακόλουθη αλλαγή στη ρύθμιση της εγκατάστασης των HSC στην αιμοποιητική φωλαιά, στους ασθενείς με ΜΔΣ. / The hematopoietic stem cell niche contains osteoblasts that regulate normal hematopoiesis. However, little is known about the role of osteoblasts in MDS hematopoiesis so far. Myelodysplastic syndrome comprises a heterogeneous group of clonal stem cell disorders with dismal prognosis and difficulty in their therapeutic approach, which is characterized by ineffective hematopoiesis. It appears with dysplastic hematopoietic cells, peripheral blood cytopenias and high risk of evolution to acute myeloid leukemia (AML). Data derived from ex vivo co-culture systems using mesenchymal stromal cells as a feeder cell layer suggest that cell-cell contact has a significant impact on the expansion, migratory potential and “stemness” of hematopoietic stem cells. In this study, we investigated the biological characteristics of osteoblasts from MDS patients and the interactions between these cells and normal hematopoietic stem cells (HSCs). Osteoblasts were differentiated from marrow MSCs from 13 MDS patients (6 RA, 3 RAEBI, 2 RAEBII, 1 5q- and 1 hypoplastic MDS) and 8 age-matched healthy individuals. To study the effect of MDS osteoblasts on hematopoiesis, normal HSCs from mobilized peripheral blood from healthy individuals (n=4) were seeded onto osteoblast confluent monolayer cultures using a culture medium appropriate for the culture of HSCs, without the exogenous addition of cytokines. We studied the morphology and immunophenotype of MSCs and osteoblasts by microscopy and flow cytometric analysis, respectively. Cytometric analyses of homing associated molecules were performed 36h and 7d later. These molecules are CXCR4, which regulates the direct adhesion of HSCs to the bone marrow niche during “homing”, CD49d (Very Late Antigen-4- VLA4) and CD49e (Very Late Antigen-5- VLA5), which produce survival signals or promote the maintenance of a quiescent state for HSCs after entering the stem cell niche (localization). We investigated the expression of these molecules in CD34+, CD34+/CD38+ and CD34+/CD38- cell populations. Furthermore we studied the frequency of CD34+ hematopoietic cells and also their ability to adhere osteoblasts.Osteoblasts from healthy individuals increased the frequency of CD34+ cells by 3- and 9-fold increase in normal hematopoietic cells after 36h and 7d co-cultures respectively. A 2-fold increase was also seen in CD34+ cells when normal HSCs grown on MDS-osteoblasts for 36h and no difference was seen between the MDS subtypes. When the culture period was extended to 7d, there was no change in the frequency of immature phenotype of normal HSCs in osteoblast cultures from low-risk MDS patients. In contrast, CD34+ cells increased several fold (16-fold increase) when normal HSCs were cultured on high-risk MDS 14 osteoblasts, twice the values obtained in osteoblast co-cultures from healthy individuals and low risk patients. The expression of adhesion molecules CXCR4, CD49d and CD49e on CD34+ cells from normal HSCs was increased in co-cultures with osteoblasts from healthy individuals compared to the values obtained before culture (3-fold increase at 7d). The increase in CXCR4 expression was less pronounced in the presence of osteoblasts from MDS patients with the largest difference being found in low-risk MDS patients (1,7-fold increase at 7d). The expression pattern of CD49d and CD49e was identical between cells grown on MDS- and normal- osteoblast co-cultures.The morphological and immunophenotypical analysis of MSCs show the same results for the two study groups, while the differentiation of MSCs to osteoblasts was similar for both healthy individuals and MDS patients, after having similar expression of bone specific proteins and mineralization activity. According to our data, osteoblasts from healthy individuals promoted the expansion of immature hematopoietic progenitors and induced the cell surface expression of CXCR4, an important molecule in HSCs homing, retention and development. However, the different expression of CXCR4 and the change in frequency of CD34+ cells that were detected when normal HSCs co-operated with MDS-osteoblasts, suggests alteration in osteoblast function and the subsequent regulation of the HSC residency in the niche in MDS patients compared with healthy individuals.

Les Cellules Souches Hématopoïétiques sont à l’origine de la production de toutes les cellules sanguines et immunitaires, grâce à leur double capacité à s’auto-renouveler et se différencier en progéniteurs puis en cellules matures fonctionnelles. Du fait de leur importance, leur physiologie est contrôlée par de nombreux signaux qui assurent un équilibre entre quiescence, prolifération, auto-renouvellement et différenciation. Mes travaux s’intéressent au rôle du facteur de transcription PLZF dans la régulation des CSH grâce à l’utilisation du modèle murin Zbtb16lu/lu, qui porte une mutation spontanée inactivant PLZF. En cas de stress régénératif, les souris Zbtb16lu/lu présentent des défauts de reconstitution de l’hématopoïèse caractérisés par un biais myéloïde, une forte expansion des LT-HSC et des dérégulations du cycle cellulaire, un phénotype similaire au vieillissement physiologique des CSH. De plus, lors d'expositions répétées au Lipopolysaccharide, un composant des bactéries à Gram négatif, les souris Zbtb16lu/lu montent une réponse pro-inflammatoire excessive qui induit un remodelage du compartiment CSH, ce qui suggère qu’elles ne parviennent pas à mettre en place de tolérance au LPS. Ainsi, nos résultats semblent positionner PLZF comme un régulateur central du destin des CSH. / Hematopoietic stem cells (HSCs) are responsible for the production of all blood cells and possess the dual ability to self-renew and differentiate into progenitor and into mature cells. Given their importance, their physiology is tightly controlled by a plethora of signals that balance quiescence, proliferation, self-renewal and differentiation. In the present Phd work, I focused on the role of the transcription factor PLZF in HSC fate using the Zbtb16lu/lu mouse model, harbouring a spontaneous mutation inactivating PLZF. In a context of regenerative stress, Zbtb16lu/lu mice showed a decreased repopulation capacity characterized by a myeloid bias, expansion of LT-HSC and cell cycle dysregulation, features that seem to recapitulate HSC physiological aging. Furthermore, repeated injections of LPS, a component of Gram Negative bacteria, induced a strong pro-inflammatory response in Zbtb16lu/lu mice, that resulted in the reshaping of the HSC compartment and the failure to induce endotoxin tolerance. Taken together, our results suggest that PLZF is a central regulator of HSC fate.

Umbilical cord blood (UCB) is a source of hematopoietic stem and progenitor cells (HSPC) used for allogeneic transplantation. Ex vivo expansion of HSPC can improve the slow platelet and neutrophil engraftment associated with UCB transplants. HSPCs reside in niches, some of which are near the endosteal bone surface, where they can associate with immature osteoblasts. Interestingly, osteoblasts can enhance the growth of HSPC in culture and their platelet engraftment activity. Using a proteomics approach, I identified 47 differentially expressed proteins between mesenchymal stem cells and immature osteoblasts. Several of these were previously implicated in HSPC maintenance such as IGF2, IGFBP2, DCN, GAS6 and VCAM1. Moreover, several other proteins belong to the alternative and classical complement pathways. Finally, I discovered that microvesicles found in osteoblast conditioned medium may also modulate the growth of HSPC, at least in ex vivo cultures.

Les cellules souches (CS) se démarquent des progéniteurs et cellules différenciées à de nombreux égards. Notamment, les CS présentent des caractéristiques particulières dans des processus cellulaires fondamentaux, et il a été récemment proposé que la biogenèse des ribosomes (BiRi) participe à la régulation des CS. Pendant ma thèse, j’ai utilisé diverses approches pour étudier le rôle et la régulation de la BiRi dans des populations de CS, in vivo et ex vivo dans des modèles murins.Grâce à un modèle d’inactivation génétique du facteur de BiRi Notchless (Nle), j’ai participé à l’étude de son rôle dans le lignage hématopoïétique et l’épithélium intestinal adultes, et cours du développement embryonnaire précoce. In vivo, la perte constitutive de Nle entraîne une létalité embryonnaire, et j’ai montré ex vivo que l’inactivation de Nle dans des CS embryonnaires induit une réponse au stress ribosomique médiée par le suppresseur de tumeur p53, et des défauts de prolifération/survie. L’induction de la perte de Nle chez l’adulte active également p53 dans les CS hématopoïétiques et intestinale, entraînant leur rapide élimination.En parallèle, j’ai utilisé plusieurs méthodes pour mesurer l’activité de BiRi des progéniteurs immatures et CS hématopoïétiques (CSH) à l’homéostasie, in vivo chez la souris adulte. J’ai ainsi mis en évidence des variations de l’activité de BiRi dans ces populations, révélant notamment une activité de BiRi des CSH jusqu’ici insoupçonnée du fait de leur quiescence.Dans l’ensemble, mon travail renforce l’idée d’un rôle de la BiRi dans la régulation des CS, et apporte une meilleure compréhension de la régulation de ce processus dans le lignage hématopoïétique. / Stem cells (SCs) differ from progenitors and differentiated cells on many aspects. Notably, SCs display particular characteristics in fundamental cellular processes, and ribosome biogenesis (RiBi) has recently been proposed to play an important role in the regulation of SCs. During my thesis, I have used various approaches to study the role and regulation of RiBi in SC populations, using in vivo and ex vivo mouse models.Using genetic inactivation of the RiBi factor Notchless (Nle), I have participated to the analysis of its role in the adult hematopoietic system and intestinal epithelium, and in the establishment of the first cell lineages during early embryogenesis. In vivo, constitutive Nle deficiency causes early embryonic lethality, and I showed ex vivo that Nle inactivation in embryonic SCs induces a ribosomal stress response mediated by the tumor suppressor p53, and proliferation/survival defects. Conditional Nle inactivation in the adult mouse also induces activation of p53 in hematopoietic and intestinal SCs in vivo, leading to their rapid elimination.In parallel, I have used different methods to analyze the RiBi activity of hematopoietic SCs (HSCs) and immature progenitors at homeostasis, in vivo in the adult mouse. Thus, I have unraveled variations in the RiBi activity of these populations, and notably uncovered previously unsuspected RiBi activity in HSCs despite their quiescent state.Altogether, my work supports the hypothesis of a role for RiBi in the regulation of SCs and provides better understanding of the activity of this process during hematopoietic differentiation.

INTRODUÇÃO: O Transplante de Células-tronco Hematopoéticas (TCTH) alogênico é uma modalidade de tratamento com capacidade de curar várias doenças hematológicas benignas e malignas. Os progressos nesta área aumentaram o número e melhoraram os desfechos dos procedimentos realizados, porém sua morbimortalidade permanece elevada. Em 2009, o escore de risco do EBMT foi validado como um método simples para predizer, com dados pré-transplante, os desfechos de um paciente após o TCTH alogênico. OBJETIVOS: O objetivo deste estudo foi validar a aplicabilidade do escore de risco do EBMT em pacientes brasileiros do Hospital de Cínicas de Porto Alegre (HCPA), submetidos a TCTH alogênico. MÉTODOS: Foi realizado um estudo retrospectivo, observacional, com dados coletados de prontuários de 278 pacientes (156 homens (56%) com mediana de idade de 32 anos) submetidos ao TCTH alogênico no HCPA para doenças malignas e anemia aplástica severa, entre 1994 e 2010. Foi aplicado o escore de risco do EBMT e analisados os desfechos sobrevida global (OS), mortalidade não relacionada à recaída (NRM) e taxa de recaída (RR). RESULTADOS: OS, NRM e RR em cinco anos foram de 53,4%, 39% e 30,7%, respectivamente. A OS em pacientes com risco 0 foi significativamente maior (81,8%) do que os de risco 6 (20%) (p<0,001). Da mesma forma, pacientes com risco 0 tiveram menor NRM (13,6%) do que os com risco 6 (80%) (p=0,001). O estágio avançado da doença foi associado com aumento de RR em todas as patologias neoplásicas avaliadas. CONCLUSÃO: O escore de risco do EBMT pode ser utilizado como um dado adicional na avaliação de pacientes com doenças malignas e anemia aplástica severa com indicação de TCTH alogênico no nosso centro. / BACKGROUND: Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) is a treatment modality able to cure many hematological disorders. Although utilized with increasing frequency and success, it is still associated with a high transplant related mortality rate. In 2009, the EBMT risk score was validated as a simple tool to predict outcome after allogeneic HSCT for acquired hematological disorders. OBJECTIVES: The aim of this study was to validate the applicability of the EBMT risk score for allogeneic HSCT on south Brazilian patients, from a single center. METHODS: A retrospective observational study was performed based on patients’ records and data base of Hematology and Bone Marrow Transplantation Department at Hospital de Clínicas de Porto Alegre, including all allogeneic transplants for malignant and severe aplastic anemia from 1994 to 2010. Patients were categorized according to EBMT risk score and overall survival (OS), non-relapse mortality (NRM) and relapse rate (RR) were analyzed. RESULTS: There were 278 evaluable patients, of whom 56% were male, and the median age was 32 years. OS, NRM, and RR at five years median follow up, were 53,4%, 39%, and 30,7%, respectively. The OS was 81,8% for risk score 0 and 20% for score 6 (p<0,001), and NRM 13,6% and 80% for risk score 0 and 6, respectively (p=0,001). Advanced disease stage was associated with an increased RR in all evaluated neoplastic disorders. CONCLUSION: The EBMT risk score can be utilized as a tool for clinical decision-making before allogeneic HSTC for malignant hematological diseases and severe aplastic anemia at a single center, in Brazil.

Infecções fúngicas invasivas têm emergido como causa de alta morbimortalidade entre pacientes com neoplasia hematológicas, principalmente os submetidos a transplante de células-tronco hematopoéticas (TCTH). Fungos estão onipresentes na natureza, logo, medidas com o objetivo de reduzir a carga fúngica em ambientes hospitalares têm sido preconizadas. No presente estudo, foi realizada coleta de fungos no ar em dois centros de referência em TCTH do sul do Brasil, que possuem instalações distintas, assim como diferentes formas de controle de ar. Todos os quartos do hospital 2 são equipados com filtro de partículas de ar de alta eficiência (HEPA), enquanto no hospital 1 não há sistema específico de filtragem do ar; além disso, os pacientes internados no hospital 2 são de maior risco para doença fúngica invasiva, em função de fatores relacionados ao hospedeiro. Foram realizadas 130 coletas de ar no período de dezembro de 2009 a janeiro de 2011, sendo as amostras provenientes de quartos, banheiros e corredor. Para fins de análise, os fungos pertencentes ao gênero Aspergillus, Rhizopus e Fusarium foram considerados como fungos filamentosos potencialmente patogênicos, enquanto os demais fungos foram classificados como ambientais. A comparação entre os corredores dos hospitais 1 e 2 não mostrou diferença quanto a quantidade de fungos isolados (p=0,114 para fungos ambientais e p=0,622 para fungos filamentosos potencialmente patogênicos). Já os quartos de ambos os hospitais apresentaram redução significativa na quantidade de fungos filamentosos potencialmente patogênicos, quando comparados com os corredores (p<0,0001). Comparando-se os quartos dos hospitais 1 e 2, observou-se menor quantidade de fungos ambientais no hospital 2 (p<0,0001); contudo, para fungos filamentosos potencialmente patogênicos não se encontrou diferença (p=0,7145). Durante o período de estudo, a incidência de doença fúngica invasiva por fungos filamentosos foi de 2,1% no hospital 1 e 7,6% no hospital 2. A baixa carga fúngica nos quartos do hospital 1 poderia ser explicadas pelo uso de medidas protetoras adicionais, incluindo janelas e portas fechadas, reforçando-se a importância de tais medidas no cuidados em ambientes protegidos. / Invasive fungal infections have emerged as a cause of high morbidity and mortality among patients with hematologic malignancies, especially among those undergoing hematopoietic stem cell transplantation. Fungi are ubiquitous in nature, therefore measures aimed at reducing fungal burden in hospitals have been emphasized. In this study air samples were collected in two HSCT centers in Southern Brazil, which have distinct facilities, as well diferent air control systems. All rooms of hospital 2 are equipped with HEPA filters. In addition, patients hospitalized in this unit are at a higher risk for invasive fungal diseases. A total of 130 samples were obtained during December 2009 to January 2011 from rooms, restrooms and corridors. For analysis, all fungi belonging to the genus Aspergillus, Rhizopus and Fusarium were considered filamentous fungi potentially pathogenic, while others were considered environmental fungi. The comparison between corridors of hospital 1 and 2 showed no difference in fungal concentration (p=0.114 for environmental fungi and p=0.622 for potentially pathogenic). The rooms of both hospitals showed a significant lower concentration in PPF, as compared to corridors (p<0.0001). Comparing rooms of hospital 1 e 2 there was a lower amount of environmental fungi in hospital 2 (p<0.0001) – however no difference was observed for potentially pathogenic (p=0.714). During the period of study, the incidence of invasive mold infection was 2.1% in hospital 1 and 7.6% in hospital 2. The low fungal burden in rooms in hospital 1 may be explained by the implementation of additional protective measures, emphasizing the importance of such measures in protected environments.

xi, 38 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / A critical question for developmental biology is the mechanism by which cells make fate decisions. In the hematopoietic system, stem cells differentiate into several different cell types, but the mechanisms that affect this process are incompletely known. Understanding these mechanisms is important because abnormal regulation of hematopoiesis can result in disease. STAT1 protein plays crucial roles in mediating innate immunity by transducing interferon signals, but recent results have also related STAT1 to hematopoietic cell differentiation. Here we cloned a previously uncharacterized zebrafish co-ortholog of the human STAT1 gene we call stat1b and investigated the functions of two zebrafish Stat1 proteins in hematopoiesis. The advantage of the zebrafish model is that, due to a whole genome duplication (WGD), some human genes have two co-orthologs in zebrafish. During evolution, co-orthologs have retained or acquired similar, complimentary, or new functions. Both stat1a and stat1b encode all four characteristic domains of the human STAT1 protein. Phylogenetic and conserved synteny analyses showed that stat1b and stat1a arose as duplicates in the teleost genome duplication event, and these analyses clarified the historical origin of the entire vertebrate STAT gene family. RT-PCR demonstrated maternal expression of both stat1a and stat1b . Expression of stat1b, but not stat1a, was detected in hematopoietic domains of embryos by in situ hybridization. Morpholino knockdown of stat1b , but not stat1a, mRNA expression resulted in a decrease in expression of the myeloid cell marker genes spi and mpx and an increase in expression of the hematopoietic progenitor marker gene scl and the erythrocyte marker gene gatal. These results show that in zebrafish, Stat1b protein functions in the commitment of hematopoietic cells to a myeloid cell fate. / Committee in charge: William Cresko, Chairperson, Biology; John Postlethwait, Advisor, Biology; Judith Eisen, Member, Biology; Jan Spitsbergen, Member, Not from U of O; J. Andrew Berglund, Outside Member, Chemistry

INTRODUÇÃO: As infecções causadas pela neutropenia severa são as causas mais frequentes de morbidade em pacientes submetidos à quimioterapia e Transplante de Células Tronco Hematopéticas (TCTH). Além da neutropenia prolongada vários fatores como o uso de dispositivos intravenosos, mucosite, condições clinicas prévias, tipo de tratamento e tempo de internação também contribuem para o desenvolvimento de infecções. A classe socioeconômica parece influenciar em uma série de desfechos no tratamento do câncer. A análise destas correlações é importante para determinar um melhor desfecho clinico para estes pacientes. OBJETIVO: verificar a relação entre perfil clinico e condições econômicas com o desenvolvimento de complicações infecciosas em pacientes submetidos a quimioterapia e TCTH. MÉTODO: Foi realizado um estudo de coorte prospectivo com 89 pacientes adultos e crianças submetidos a quimioterapia e/ou TCTH que internaram na Unidade de Ambiente Protegido (UAP) do Hospital de Clinicas de Porto Alegre (HCPA). O período de coleta de dados foi de Abril de 2011 a Maio de 2012, e o método foi através de acompanhamento clínico diário e análise de prontuário eletrônico. Foram analisados os desfechos de infecções correlacionados com o perfil clinico e status econômico. RESULTADO: Pacientes com comorbidades foram 35(39,3%). A classe econômica foi classificada A+B igual (37) 41,6% e classe C+D igual (52) 58,6%. Dos pacientes analisados 85,4% apresentaram algum tipo de infecção, sendo as bacterianas as mais frequentes (37) 41,6% e mucosite verificada em (79) 88,8%. Em relação à classe econômica, o grupo C+D apresentou RR 1,2 e P 0,005 para o desfecho infecção. CONCLUSÃO: constatamos que pacientes submetidos à quimioterapia e/ou TCTH com comorbidades apresentam maior risco para infecções, e que o grupo de classe econômica A+B foi associada a menor incidência de infecções e de tempo de internação que a classe C + D durante o período de tratamento. / INTRODUCTION: The infections caused by severe Neutropenia are the most frequent causes of morbidity and mortality in patients undergoing chemotherapy and Hematopoietic Stem Cell Transplantation (HSCT). Besides the extended Neutropenia, other factors like the use of intravenous devices, mucositis, previous clinical conditions, kind of treatment, economic class and length of stay in hospital contribute to the development of infections. The present analysis of these correlations is important to establish the best clinical outcome for these patients. OBJECTIVE: The objective of this study is to verify the clinical profile, the economic conditions and the infectious complications in patients undergoing chemotherapy and HSCT. METHOD: A prospective cohort study was performed with 89 patients, adults and children, undergoing chemotherapy and/or HSCT admitted at the Unit of Protected Environment (UAP) at the Hospital de Clínicas de Porto Alegre (HCPA). The data were collected from April 2011 to May 2012, through the method of a daily monitoring and analysis of the electronic medical records. The outcomes of infections correlated to the clinical profile and economic status were analyzed. RESULT: Patients with comorbidity represented 39,3%. The economic class was ranked as: A+B equal to 41,6% and class C+D equal to 58,6%. From the analyzed patients, 84,5 % presented some kind of infection, with more frequency to the bacterial infection (41,6%) and mucositis representing 88,8%. In relation to the economic class the C+D group presented RR 1,2 and P 0,005 to the outcome of the infection. CONCLUSION: We concluded that patients undergoing chemotherapy and/or HSCT with comorbidities presented a higher risk of infection, and that the A+B economic class was associated to a lower incidence of infections and length of stay in hospital than the class C+D during the period of treatment.

O objetivo deste estudo foi avaliar a evolução do estado nutricional, a ingestão alimentar por via oral (VO) e a utilização de terapias nutricionais complementares durante a internação de crianças e adolescentes submetidos ao transplante de células-tronco hematopoéticas (TCTH) alogênico em um hospital terciário. Estudo retrospectivo, com revisão de prontuários de pacientes submetidos ao TCTH, com idade entre 0 e 19 anos incompletos, entre janeiro de 2009 e dezembro de 2014. Foram coletados dados referentes a dados antropométricos, ingestão alimentar por VO, terapias nutricionais utilizadas (nutrição enteral (NE) e/ou parenteral (NP)); e sinais e sintomas clínicos em seis momentos: Internação, D0 (dia da infusão de células), D+7, D+14, D+21 e D+ 28. Foram avaliados 63 pacientes, 56% do sexo masculino, com uma mediana de idade de 10 anos. No momento da internação 100% dos pacientes tiveram suas necessidades energéticas atingidas pela VO, diminuindo a partir do D0 (cerca de 30%), com maior prevalência de utilização de NP e NE a partir do D+7. Inapetência, mucosite e náusea foram os sinais e sintomas mais frequentes. A partir do D+21 foi possível observar um aumento do aporte calórico por VO. Os pacientes apresentaram diminuição da ingestão alimentar ao longo da internação, porém, neste hospital, já se está conseguindo atingir um aporte calórico mais próximo do ideal, com auxílio de terapias nutricionais complementares. / The aim of this study was to describe the nutritional aspects relevant to the maintenance of a nutritional status during hospitalization of children and adolescents undergoing allogeneic hematopoietic stem cell transplantation (HSCT) at a tertiary hospital. A retrospective study with a review of medical records of patients undergoing HSCT, aged between 0 and 19 years of age (incomplete) between January 2009 and December 2014. Data were collected regarding food intake, nutritional therapies used, and clinical signs and symptoms in six times: Hospitalization, D0 (day of cell infusion), D+7, D+14, D+21 and D+28. Sixty-three patients were evaluated, being 56% males, with a median age of 10 years. At the time of hospitalization, 100% of patients had their energy needs met by mouth, decreasing from D0 (about 30%), with more prevalent use of PN (parenteral nutrition) and EN (enteral nutrition) from D+7. Loss of appetite, mucositis and nausea were the most frequent signs and symptoms. From D+21 it was possible to observe an increase in caloric intake by mouth. Patients showed decreased food intake throughout hospitalization, but in this hospital it has been already possible to get calorie intake closer to the ideal one with the help of complementary nutritional therapies.

O câncer constitui um problema de saúde pública para o mundo desenvolvido e também para nações em desenvolvimento. Segundo a estimativa realizada pelo Inca para o ano de 2012, a partir dos dados dos Registros de Câncer de Base Populacional (RCBP), o percentual mediano dos tumores pediátricos encontrava-se próximo de 3%. Para o ano de 2012, com exceção dos tumores da pele não melanoma, estavam previstos 384.340 casos novos de câncer. Destes, ocorrerão cerca de 11.530 casos novos de câncer em crianças e adolescentes até os 19 anos. Este estudo teve por objeto as expectativas de vida do adolescente frente ao transplante de células tronco hematopoiéticas (TCTH) e como objetivos: descrever as expectativas dos adolescentes que se submeteram ao TCTH e analisar compreensivamente as expectativas de vida destes jovens que se submeteram ao TCTH. Trata-se de estudo de natureza qualitativa, pautado no referencial teórico-metodológico da fenomenologia sociológica de Alfred Schutz. O cenário para sua realização foi uma unidade de Transplante de Medula Óssea, localizada em um hospital federal de referência nacional, localizado na cidade do Rio de Janeiro. Os participantes do estudo foram oito adolescentes, na faixa etária entre 12 e 18 anos de idade, que se encontravam em fase pós-TCTH, em acompanhamento no hospital diariamente ou já de alta hospitalar da unidade. Para a realização do trabalho de campo, foi utilizada a entrevista fenomenológica como instrumento de captação das falas, as quais foram guiadas pelas seguintes questões orientadoras: fale para mim como foi esse período de adoecimento para você. Quais as suas expectativas em relação ao transplante de células tronco hematopoiéticas? O que você espera da sua vida diária/cotidiana agora após a realização do transplante de células tronco hematopoiéticas? As falas foram transcritas, analisadas para então serem categorizadas. A partir da análise compreensiva, emergiram quatro categorias: Ser curado; Ter uma vida normal; Ter uma profissão; Constituir família; e Apresentando o motivo porque. O estudo possibilitou através dos relatos dos adolescentes mergulhar e adentrar no seu universo de significados sobre o que eles esperam do TCTH para a apreensão do que pensam sobre a sua inserção no mundo da vida após a sua realização, como também remeteu para a ação profissional que vislumbra a atuação multidisciplinar na perspectiva do nós, na qual o adolescente, sua família e a equipe sejam parte integrantes desse processo. / Cancer is a public health problem for the developed world and also to developing nations. According to the estimate done by Inca to 2012, from data of Cancer Registries of Population Based (CRPB), the average percentage of pediatric tumors was around 3%. For 2012, with the exception of non-melanoma skin tumors, 384,340 new cases of cancer were estimated. Of these, around 11,530 new cases of cancer occurred in children and adolescents up to 19 years old. The aim of this study was adolescents life expectations facing the hematopoietic stem-cell transplantation (HSCT) and as objectives: to describe the expectations of adolescents who have undergone the HSCT and analyze comprehensively the life expectancy of these young people who have undergone the HSCT. This is a qualitative study, based on theoretical-methodology reference of the sociological phenomenology of Alfred Schutz. The scenario for its realization was a Bone Marrow Transplant Unit, located in a federal national reference hospital, located in the city of Rio de Janeiro. Study participants were eight adolescents, aged between 12 and 18 years old, who were undergoing HSCT, monitoring in the hospital daily or already discharged from the unit. For the completion of fieldwork, the phenomenological interview was used as an instrument to capture lines, which were guided by the following guiding questions: tell me how this period of illness to you was. What are your expectations for the hematopoietic stem cell transplant? What do you expect from your daily life now, after completion of hematopoietic stem cell transplantation? The lines were transcribed, analyzed to then be categorized. From the comprehensive analysis, four categories emerged: Be cured; Have a normal life; Have a profession; Constitute a family; and Showing the reason why. Through the reports of the adolescents, the study was able to enter in their universe of meanings about what they expect from HSCT to understand what they think about their insertion in the world of life after its realization, but also referred to the professional action that see the multidisciplinary activities in the perspective of the us, in which the adolescent, his family and the team are integral part of this process.