De onderwijscommissie Biomedische Wetenschappen wil jullie graag welkom heten op de Dag van de Biomedici

Beste studenten en participanten,

De onderwijscommissie Biomedische Wetenschappen wil jullie graag welkom heten op de ‘Dag van de Biomedici’. Met dit initiatief willen wij alle studenten Biomedische Wetenschappen de kans geven om kennis te maken met het onderzoek dat verricht wordt op de VUB campus Jette. Een breed spectrum van onderwerpen zal aan bod komen, waaronder diabetes, epilepsie, multiple myeloma en nog veel meer. Deze dag is een geschikt moment voor de jongere generatie om al eens na te denken over hun toekomstige stages. We beginnen deze dag met de presentaties van de 2de master studenten over het ‘biomedisch' onderzoek dat ze verrichten ter voorbereiding van hun thesis. Tijdens de middag kunnen jullie genieten van een lunch in het Forum/Atrium, waar ook een postersessie georganiseerd wordt om jullie de mogelijke stageplaatsen op de campus Jette voor te stellen. Kom gerust even langs als je met vragen zit, vooral studenten van 3de bachelor krijgen tijdens deze postersessie een uitgelezen kans om na te denken waar ze eventueel hun korte en lange stages willen lopen. In de namiddag mag je sprekers verwachten uit een brede waaier van het beroepenveld. Wij hebben het plezier om je enkele VUB-alumni van onze richting voor te stellen: Christophe Empsen als onderwijsdeskundige aan de VUB, Lien Thoen als doctoraatstudente aan de VUB, Nele De Medts als leerkracht in het Koninklijk Atheneum van Asse en Kevin Ariën werkzaam als postdoctoraal medewerker aan het Tropisch Instituut voor Geneeskunde. Daarnaast zal ook de bedrijfswereld aan jullie voorgesteld worden door Galapagos, een biotechnologiebedrijf en Valesta, een outsourcingbedrijf in de klinische research. Aan het einde van deze gevulde dag willen wij jullie graag uitnodigen om deel te nemen aan de labdrink in de practicumzaal Fysiologie. Tijdens de labdrink kan je als jonge student een praatje slaan met de master studenten.

Happy Meeting

Programma: Deel I 08.00 – 08.30

Registratie

08.30 – 08.45

Welkomstwoord door prof. Karin Vanderkerken

08.45 – 09.00

Asmah Aberkane: Gene expression in frozen-thawed versus fresh human preimplantation embryos

09.00 – 09.15

Lise Barbé: The (in)stability of X-chromosome inactivation in female VUB human embryonic stem cell lines

09.15 – 09.30

Joy Eliaerts: Microbiological tests to assist the medico-legal diagnosis of death by drowning

09.30 – 09.45

Mérédis Favreau : Noradrenerge therapie voor antiepileptogenese: impact op hemikanalen en de bloed-hersenbarrière functionaliteit

09.45 – 10.00

Wim Leonard: Immunosuppressive functions and survival of myeloidderived suppressor cells in multiple myeloma

10.00 – 10.15

Fatimazzahra Moustaghfir: Epigenetische modificaties in tweecellige embryo’s en nakomelingen bekomen na spermatogoniale stamceltransplantatie

10.15 – 10.45

Frisdrank – Pauze

10.45 – 11.00

Laurence Simon : Identification and validation of prognostic and predictive molecular markers towards individual management of breast cancer patients

11.00 – 11.15

Silke Smeets: De rol van astrocytaire beta2-adrenoreceptoren in de pathofysiologie van multiple sclerose

11.15 – 11.30

Leslie Stradiot: The role of PW1 in pancreas development and adult islet cells

11.30 – 11.45

Kevin Van der Jeught : Characterization of cancer stem cells in a syngenic mouse model

11.45 – 12.00

Stefaan Verhulst: Aldehyde dehydrogenase positive cells during liver injury

Dag van de Biomedici - Biomedische Research Week 2012

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Programma: Deel II 12.00 – 14.00

Lunch

14.00 – 14.15

Christophe Empsen (BMW Alumnus) – Onderwijsdeskundige VUB: Kwaliteitszorg in het Universitair Onderwijs

14.15 – 14.30

Nele De Medts (BMW Alumnus) – Onderwijs: Onderzoek en Onderwijs

14.30 – 14.45

Hilde Bex – Valesta: Staffing in Clinical Research

14.45 – 15.00

Wim Leonard en Lise Barbé (2de Master BMW): Stage in het buitenland, van aanvraag tot getuigenissen

15.00 – 15.30

Frisdrank – Pauze

15.30 – 15.45

Sara Musch – Galapagos: Werken als Scientist in een biotechnologiebedrijf

15.45 – 16.00

Lien Thoen (BMW Alumnus) – PhD student VUB: Hoe een IWT aanvragen ?

16.00 – 16.15

Kevin Ariën (BMW Alumnus) – Instituut voor Tropische Geneeskunde: Van student tot zelfstandig onderzoeker

16.15 – 16.30

Christophe Empsen (BMW Alumnus) – Onderwijsdeskundige VUB: Toekomst voor Biomedici !

16.30 – 16.45

Slotwoord

16.45 – 18.30

Labdrink (Practicumzaal Fysiologie B018)


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Abstracts 2de Master BMW voor het Maastricht Medical Students Research Conference 2012 (MMSRC)

Sinds 2003 nemen de studenten tweede master Biomedische Wetenschappen deel aan het Maastricht Medical Students Research Conference. Op dit internationale congres krijgen (bio)medische studenten de mogelijkheid om hun eigen wetenschappelijk onderzoek voor te stellen. De auteurs met de beste ingezonden abstracts krijgen de mogelijkheid tot een orale presentatie en de andere auteurs stellen hun onderzoek voor met een poster presentatie. Zowel de orale als de poster presentatie wordt beoordeeld door een internationale jury. De afgelopen jaren behaalden verschillende van onze studenten prijzen op het MMSRC:

2011 - Bart Legein kreeg de publieksprijs voor de beste posterpresentatie met ‘Tamoxifen Inhibits Beta Cell Proliferation and Biases Beta Cell Neogenesis Mechanisms in Mouse Pancreas’.

2010 – Lien Thoen behaalde de prijs van beste orale presentatie met ‘The role of lipolysis in hepatic stellate cell activation’. Liesbeth Bieghs kaapte de publieksprijs voor de beste poster presentatie weg met ‘Forodesine reduces proliferation and induces apoptosis in multiple myeloma’. 2009 – Violette Coppens behaalde de prijs van de beste orale presentatie met ‘Human endothelial cells improve the outcome of the experimental islet transplantation’. Sander Van Lint kaapte de publieksprijs voor de beste poster presentatie weg met ‘Development of a multiplex PCR for occurence of uniparental disomy in all chromosomes of human embryonic stem cell lines’. 2007 – Inge Neels kreeg de prijs voor de beste poster presentatie en Miguel Lemaire ontving de publieksprijs voor de beste poster. 2005 – Christelle Orlando kreeg de prijs voor de beste mondelinge presentatie en Mieke Geens ontving de publieksprijs voor beste poster. Tessa Dieltjens nam in deze categorie de tweede plaats voor haar rekening. 2003 – An Verloes behaalde met de mondelinge presentatie van haar eindwerk de eerste prijs. Pieter Goossens behaalde de eerste prijs voor de beste poster presentatie.


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Gene expression in frozen-thawed versus fresh human preimplantation embryos Authors: Asma Aberkane 1, Caroline De Paepe 1, Hilde Van de Velde 1,2 1 2

Department of Reproduction and Genetics (REGE), Vrije Universiteit Brussel, Belgium Centre for Reproductive Medicine (CRG), Universitair Ziekenhuis Brussel, Belgium

Aim: Human preimplantation embryos cultured in IVF centres show lower implantation rates post cryopreservation using either slow freezing or vitrification protocols (20%) as compared to fresh embryos (30%). This is unexpected because fresh embryos are transferred in a stimulated cycle which is known to compromise the endometrium whereas frozen-thawed embryos are transferred in a natural cycle. We hypothesize that the impaired implantation capacity is due to an altered gene expression after freezing-thawing. In order to investigate the vitality of cryopreserved embryos, we retrospectively analysed the survival and developmental rates of a set of embryos that had been thawed for research. Moreover, we investigated the expression of a set of 20 candidate genes playing a major role during preimplantation embryo development and implantation in frozen-thawed versus fresh human embryos. Material and Methods: We performed a statistical evaluation on the survival and in vitro blastocyst development until day 5 of 400 day 3 embryos that had been thawed in 2011 for several research projects. The gene expression study was approved by the Local and Federal Ethical Committee for research on human embryos in vitro. Day 3 cryopreserved embryos became available for research after 5 years storage with informed consent of the patients. They were thawed and cultured in vitro until day 5. Fresh day 3, 4 and 5 human preimplantation embryos (mainly embryos affected after preimplantation genetic diagnosis) were donated for research after informed consent of the patients. Quantification of gene expression on single embryos was performed by real-time polymerase chain reaction (qRTPCR). Results: Our retrospective analysis of 400 day 3 frozen-thawed embryos revealed that 243 (60,75%) survived the procedure, of which 80 (32,9%) developed further to the blastocyst stage on day 5 (this corresponds with 20% of the total number of thawed embryos). Setting up standard curves for qRT-PCR, we observed inhibition of the reaction if we used a low dilution of cDNA. We have shown that this is neither caused by the lysisbuffer nor DNase. Removing the zona pellucida did not resolve the inhibition either, but gave lower cycle thresholds (CT’s). Conclusion: Our retrospective analysis on frozen-thawed embryos confirmed that they have a poor survival and in vitro developmental rate. In order to compare the gene expression in frozen-thawed versus fresh embryos, we optimized the qRT-PCR reaction. For the following experiments, cDNA will be diluted 25 times to avoid inhibition. Corresponding to the better CT’s achieved, the zona pellucida will be removed from all the embryos used for qRT-PCR. Experiments on gene expression are still ongoing. The results will be evaluated on the protein level by fluorescent immunostaining.


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The (in)stability of X-chromosome inactivation in female VUB human embryonic stem cell lines Authors: Lise Barbé, Mieke Geens, Kimberly Dee, Karen Sermon Department of Reproduction and Genetics (REGE), Vrije Universiteit Brussel, Belgium Introduction: hESC are considered as a valuable in vitro model to study human development and for disease modelling as well as a promising cell source for regenerative medicine. However, (epi)genetic changes during long-term culture raise concerns about the applicability and safety of hESC. Therefore, characterisation and monitoring of (epi)genetic (in)stability is necessary. This study focuses X-chromosome inactivation (XCI) as an epigenetic gene regulation. Recent literature describes variable XCI patterns in female hESC, ranging from cell lines with two active X chromosomes to cell lines with random or completely skewed XCI. We will determine the XCI pattern in female VUB hESC lines, the heritability upon cell division and the stability during longterm culture. Material and Methods: hESC were cultured on inactivated mouse embryonic fibroblasts in standard SR-medium with bFGF addition, in 5% CO2 and atmospheric O2 concentrations. Undifferentiated hESC were collected at day 4 to 6 after passaging, using collagenase. DNA was extracted by phenol-chloroform. XCI was studied in 16 female VUB hESC lines and clonal sublines of 3 hESC lines. To determine the methylation pattern on the X chromosome, methylationsensitive restriction with HapII and PCR for the polymorphic aristaless related homeobox (ARX) gene was performed. XIST expression was determined by real-time PCR after reconversion of the mRNA to double stranded cDNA. Results: We found a variable XCI pattern for the 16 female hESC lines: 4 lines (25%) displayed 2 active X chromosomes, even at later passages (up to P50). The remaining 12 lines all displayed XCI, however, with different patterns. Only two lines (13%) displayed the expected random XCI pattern at different passages, while nine lines (56%) showed a completely skewed XCI pattern. For the cell lines with a skewed XCI pattern, we identified 4 cell lines with an active maternal Xchromosome, and 4 with an active paternal X-chromosome. The lines with skewed XCI displayed this pattern already at early passages, e.g. P3 or P10. One line (6%) was not informative. Within 3 female VUB hESC lines, and in their clonal sublines, no difference in XIST expression was detected. Moreover, the XIST expression was more than a hundred times lower compared to female amniocytes, which were used as control. Unexpectedly, the XIST expression in female hESC lines was comparable to the expression in male hESC lines. Discussion: It has already been reported that XCI in hESC is highly variable. This study is the first to show the high degree of preferential inactivation of a specific X chromosome in hESC. In fact, only 13% of the hESC lines in this study displayed the expected random XCI pattern, while most lines had either no or skewed XCI. The low XIST expression in female hESC lines can be explained by the late stage of XCI where XIST expression is almost lost but epigenetic marks such as methylation are retained on the inactivated X-chromosome to suppress activation. This is in contrast with the XIST regulated XCI in amniocytes.To confirm this hypothesis of a late XCI state in hESC, further research on the accumulation of epigenetic marks, such as histon 3 lysine 27 trimethylation (H3K27me3) and macroH2A, on the inactivated X-chromosome will be performed. Our finding of skewed XCI patterns warrants further research into its effect on differentiation capacity and efficiency. Furthermore, it raises the question of selective advantage of the culture that shows skewed XCI and the still outstanding question of how many embryonic cells it takes to make a hESC line. Dag van de Biomedici - Biomedische Research Week 2012

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Microbiological tests to assist the medico-legal diagnosis of death by drowning Authors: Joy Eliaerts1,3, Vera Coopman1, Geert Huys2, Jan Cordonnier1, Dirk Van Varenbergh3 1 Department of Analytical Toxicology, Chemiphar N.V., Bruges, Belgium 2 BCCM/LMG Bacteria Collection & Laboratory of Microbiology, Faculty of Sciences, Ghent University, Belgium 3 Department of Forensic Medicine, Vrije Universiteit Brussel, Belgium Introduction: The diagnosis of death by drowning remains one of the most challenging issues in forensic medicine. In search of an alternative to the conventional diatom test, a few studies have examined the use of aquatic bacteria as diagnostic markers of drowning. The aim of this study was to explore the potential of the bacterial genus Aeromonas in this respect. Aeromonads are gram-negative bacteria present in aquatic environments and absent in the normal microbiota of healthy persons. In order to detect these bacteria in water and tissue samples, a new microbiological test based on selective culturing and genus-specific PCR detection was developed and evaluated. Moreover, to investigate the validity of this method to aid the diagnosis of death by drowning, the possibility of post-mortem bacterial invasion in submerged bodies of piglets was studied. The presence of aeromonads in tissue samples of human water bodies (drowned and non-drowned) will also be investigated, provided that these samples are available. Material and Methods: Surface and deep water samples were collected from thirty places (including freshwater, brackish water and seawater environments) in East and West Flanders, during four months. These samples were quantitatively analyzed by cultivation using the selective medium Ampicillin Dextrin Agar (ADA), in order to detect aeromonads. To study the post-mortem bacterial invasion, piglets which have died a natural death were submerged in water barrels exposed to the open air. After different periods of submersion, the piglets were dissected to document the post-mortem colonization interval of aeromonads. The control group consisted of piglets that were not submerged in water. Several organs were swabbed in an aseptic manner and these swabs were incubated overnight at 37°C in buffered peptone water for bacterial enrichment. The detection of Aeromonas in these tissue samples was again performed by selective culturing on ADA medium. Positive culture plates were confirmed by genus-specific PCR. Results: A sensitive, inexpensive and rapid screening and confirmation method for Aeromonas species was developed. The genus Aeromonas is present in all selected aquatic environments, although in varying concentrations. The presence of Aeromonas in seawater, certain freshwaters and brackish waters is extremely low and may limit its potential as marker in these cases of drowning. Concerning the colonization experiments with the piglets, post-mortem bacterial invasion was demonstrated. Determination of the post-mortem interval of colonization is ongoing. The results of the human water bodies are still under investigation. Discussion and Conclusion: This study is the first to reveal that post-mortem bacterial invasion does occur and therefore may cause false positive results in the diagnosis of drowning. The preliminary results show that the detection of Aeromonas species in tissue samples from drowning cases can assist the diagnosis of death by drowning, but probably limited to a postmortem period of immersion.


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Noradrenerge therapie voor antiepileptogenese: impact op hemikanalen en de bloedhersenbarrière functionaliteit Authors: Mérédis Favreau, Katia Vermoesen, Mathieu Vinken, Luc Leybaert, Ilse Smolders, Ralph Clinckers Departement Farmaceutische Chemie en Analyse van Geneesmiddelen, Center for Neurosciences, Vrije Universiteit Brussel, België Departement Toxicologie, Dermato-Cosmetologie en Farmacognosie, Vrije Universiteit Brussel, België Departement Medische Basiswetenschappen, Universiteit Gent, België

Inleiding: Neurodegeneratie en neuroinflammatie spelen een belangrijke rol in de pathogenese van epilepsie. Volgens preliminaire onderzoeksresultaten van het onthaallabo heeft noradrenerge therapie een antiepileptogene activiteit. Niet enkel de gekende neuroprotectieve en anti-inflammatoire effecten van deze therapie maar mogelijk ook het stabiliserend effect op bloed-hersen barrière (BHB) en hemikanaal dysfunctie liggen hier potentieel aan de basis. Het huidige onderzoekswerk is gericht op de bevestiging van de BHB stabiliserende activiteit tijdens epileptogenese. Parallel wordt ook de rol van hemikanalen in epilepsie en epileptogenese bestudeerd. Materiaal en Methoden: Epileptische post status epilepticus (SE) ratten werden gedurende de latente (dag 1-14 post-SE) en de daarop volgende chronische fase opgevolgd met videoradiotelemetrische EEG monitoring. De ratten werden ad random opgedeeld in 2 groepen: sham en reboxetine behandeling (noradrenaline heropname inhibitor, behandeling dag 0-10, 40mg/kg/dag). Op dag 4 en 10 post-SE werd met behulp van Evans Blue (i.v. bolusinjectie 0.5%) als standaard impermeabele tracer de permeabiliteit van de BHB bekeken met behulp van fluorescentiemicroscopie. Op dag 1, 4, 10 en 31 werd via Western Blot de expressieniveaus van de hemikanalen connexin (Cx) 30, 32, 36 en 43 en pannexin 1, 2 en 3 bepaald. In een ander experiment werd het effect van Cx43 blocker Gap-19 op acute epileptische aanvalsactiviteit bestudeerd. Simultaan werd met intracerebrale microdialyse het effect van Gap19 op de cerebrale neurochemie (glutamaat, D-serine) en het cerebraal metabolisme (glucose, lactaat) in vivo gekarakteriseerd. Resultaten: Tot dusver kunnen enkel de resultaten van het tweede experiment worden vrijgegeven. Gap-19 onderdrukt op een significante wijze (p<0.01; ANOVA) limbische aanvalsactiviteit. Simultaan zorgt het voor een significante toename (p<0.05; ANOVA) van de extracellulaire glutamaat, D-serine en glucose concentraties. Discussie en Conclusie: We kunnen concluderen dat Gap19 anticonvulsieve eigenschappen bezit en een significante impact heeft op de cerebrale neurochemie en metabole activiteit. In tegenstelling met wat werd geconcludeerd op basis van in vitro gegevens wijzen de huidige in vivo gegevens op het feit dat het Cx43 hemikannaal eerder betrokken is in de opname van glutamaat en D-serine. Dag van de Biomedici - Biomedische Research Week 2012

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Immunosuppressive functions and survival of myeloid-derived suppressor cells in multiple myeloma Authors: Wim Leonard, Marie Joos de ter Beerst, Eline Menu, Haneen Nur, Elke De Bruyne, Karin Vanderkerken, Els Van Valckenborgh Department of Hematology and Immunology, Myeloma Center Brussels, Vrije Universiteit Brussel, Belgium

Introduction: Myeloid-derived suppressor cells (MDSC) are a heterogeneous population that suppress T-cell proliferation in pathological conditions such as cancer. Multiple myeloma (MM) is a monoclonal, malignant proliferation of plasma cells in the bone marrow. MM cells are known to suppress the immune system, partly caused by activating MDSC. Lenalidomide (LEN) has important immunomodulatory capacities and is currently used in the treatment of MM. The aim of this study is to investigate the effect of LEN on MDSC in MM. Material and Methods: Human myeloma cell lines and the 5TMM mouse models, were used. MDSC were obtained from the BM of naive or 5T33MM-diseased mice and sorted by MACS in two subsets, MO- and PMN-MDSC. Viability and apoptosis were measured with CellTitter-Glo and annexinV. For T-cell proliferation assays, splenocytes from naive mice or OT-1 mice were labelled with CFSE and cocultured with MDSC subsets. Results: In first instance, MDSC were cultured in 5T33MMvt-conditioned medium (CM) or with 5T33MMvt cells to measure MDSC survival. There was a significant better survival of MDSC when cocultured with MM cells or MM CM compared to medium alone. There was no difference in survival in the cocultures with contact or with CM, indicating that a soluble factor is responsible for the survival of MDSC. Furthermore, the suppressive capacity of myeloma MO- and PMN-MDSC was investigated. MDSC have a suppressive activity on CD3/CD28 stimulated splenocytes (antigen-nonspecific T-cell stimulation and on antigenspecific T-cell proliferation (ovalbumin-stimulated OT-1 splenocytes). Next, the effect of LEN on the immunosuppressive capacity of MDSC and viability of MDSC and MM cells, was investigated. Myeloma PMN-MDSC from mice treated with LEN (100mg/kg, daily) have a decreased capacity to suppress T-cell proliferation compared to MM PMN-MDSC from vehicle-treated mice. Also, in vitro a mild effect of LEN (0,1-100 µM) on the suppressive capacities of both myeloma PMN- and MO-MDSC was seen. LEN had no effect on MDSC viability and apoptosis, but affected the viability of human and mouse MM cells. Discussion and Conclusions: MM conditioned medium contains survival factors for MDSC. Myeloma MDSC have the capacity to suppress T-cell proliferation that can be inhibited by treatment with LEN. Furthermore, LEN has no effect on MDSC viability, but affects MM cell viability.


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Epigenetische modificaties in tweecellige embryo’s en nakomelingen bekomen na spermatogoniale stamceltransplantatie Authors: Fatima Zzahra Moustaghfir Departement Embryologie en Genetica, Biology of the testis, Vrije Universiteit Brussel, België

Introductie: Naar schatting 1 op 650 kinderen ontwikkelt kanker tijdens de kinderjaren. De spermatogoniale stamceltransplantatie (SSCT) is een veel belovende fertiliteitpreserverende techniek voor prepubertaire jongens, die een gonadotoxische therapie dienen te ondergaan. Hoewel de efficiëntie van SSCT reeds bewezen is in een muismodel, moet de veiligheid ervan onderzocht worden alvorens klinische toepassing mogelijk is. Genetisch materiaal wordt ook doorgegeven naar de volgende generatie, waardoor fouten tijdens de spermatogenese absoluut vermeden moeten worden. Het doel van onze studie is gericht op het evalueren van de epigenetische modificaties ter hoogte van de pre-implantatie embryo’s en de impact hiervan op nakomelingen bekomen na SSCT. Methoden: Prepubertaire GFP+ donorcellen werden geïnjecteerd in de tubuli van een GFPacceptormuis. Twee maanden na transplantatie werden de muizen gepaard met vrouwtjesmuizen om de fertiliteit te evalueren. Embryo’s werden verkregen via in vitro fertilisatie en gefixeerd op tweecellig stadium. Via immunohistochemie werden zowel het algemene DNA methylatiepatroon (5-methylcytosine, 5-MC) als histonacetylatie (H4ac8) geanalyseerd in tweecellig embryo. Bovendien, werd naast de histonacetylatie de expressie van DNA methyltransferases (DNMTs) nagegaan in de nakomelingen. Resultaten: Momenteel worden de immunokleuringen nog op punt gesteld op controle embryo’s en testisweefsel. DNMT3A werd enkel tot uitdrukking gebracht in spermatogonia maar vertoonde veel achtergrondkleuring. DNMT1, 5-MC en H4ac8 zijn nog volop in de optimalisatie fase. H4ac8 werd gedetecteerd in de nucleus van tweecellige embryo’s. De immunokleuing wordt geoptimaliseerd via verschillende incubatietijden en blocking sera. Discussie: Onze bevindingen op controle tweecellige embryo’s voor H4ac8 nucleaire detectie is vergelijkbaar met de studie van Worrad et al. (1995) waar de geacetyleerde histon 4 op lysine 8 gedetecteerd werd in de kern van het tweecellig muisembryo. In een recente studie van der Heijden et al. (2006) werd ook aangetoond dat H4ac8 overerfbaar is van de vader met een detectie in zowel de mannelijke pre-pronucleus als de pronucleus in de zygote.


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Identification and validation of prognostic and predictive molecular markers towards individual management of breast cancer patients Authors: Laurence Simon, J. De Grève (VUB), C. Desmedt and C. Stiriou (ULB- Bordet) Introduction: Breast cancer is by the most frequent cancer among women. As for prognostic factors, the currently used factors for predicting response to chemotherapy are suboptimal and insufficient to explain the differences in survival and response observed in the clinical practice. The BCTL, the lab in which I am doing my thesis, developed last year an “anthracycline-based score (A-Score)” (Desmedt et al. J Clin Oncol 2011). The A-Score could potentially identify a significant proportion of the breast cancer population who would not benefit from anthracyclines and who could then be spared the non-negligible side-effects from this chemotherapy. One limitation of these results is that they are based on gene expression profiling using Affymetrix microarrays which require frozen samples, which are not available for every patient as opposed to paraffin embedded (FFPE) tumor samples. It is therefore crucial to convert the A-Score into a new A-score as a gene expression assay applicable on FFPE tumor samples and then further validate it in clinical trials. The conversion of the original A-Score into a new A-Score assessable on FFPE tissues using RT-PCR is the main objective of my thesis. Material and Methods: We compared 5 different RNA extraction kits for FFPE samples available on the market. We chose the one with the best elution recovery out of 6 FFPE cell lines and 24 FFPE tumor samples from different ages.The A-Score was built by combining the 3 gene signatures (the immune (STAT1), the stroma (PLAU) and the TOP2A signature) representing 179 genes together. Given the fact that RT-PCR can only investigate a limited number of genes, we selected for each subsignature those genes which were most correlated with the prototype. A first selection of reference genes has been made based on the literature and based on a meta-analysis of gene expression data, in which we were looking for genes whose expression was very stable across the different samples and datasets. During Taqman RT-PCR tests, we target short amplicons (<100 bp) to maximize the chance of detecting short fragments in degraded FFPE samples. We used primers spanning exons to eliminate the detection of residual genomic DNA. We will validate the gene expression levels of the individual genes and the A-Score by comparing the obtained RT-PCR values with the matched Affymetrix expression values on the corresponding frozen (n~80). The relative expression values of each gene per sample will be calculated with delta-Ct method normalized to the reference genes. Results: We could make a conclusion for the comparison of RNA extraction protocols for FFPE samples. For the RNA extraction on tumor samples, we selected Qiagen miRNeasy® FFPE kit out of the 5 kits that we evaluated. To make a selection of the genes from the A-Score to be tested by RTPCR, we first have identified bio-informatically the individual genes which had a minimum Spearman correlation of 0.8 with the signature prototypes. Next, we performed an extensive research work on GeneSigDB and Pubmed to select the genes which have been poorly described until now, to allow to potentially patent the new A-Score (strongly recommended by the funding source of the project). The normalization of the gene expression of the genes of the new A-score will be done by those whose expression stay stable through different breast cancer samples. We identified 6 genes which we are currently testing by RT-PCR: B2M, GUSB, MRPL19, PUM1, TBP, TFRC. We already did some Taqman RT-PCR tests using cell lines samples and those showed, as expected that the Ct-values for FFPE samples were higher compared to the matched frozen samples. We are currently extracting RNA from ~80 FFPE samples. We will accomplish soon the RT-PCR reactions to make the final selection of the reference and test genes for the new A-Score. Conclusion: The ability to work with FFPE samples is critical for the clinical applicability and success of a prognostic/predictive test in breast cancer as this is the standard method for tumor preservation and storage. In this project, we intend to transfer the A-score obtained with microarray procedures into a new A-score by RT-PCR assays, in order to bring this molecular predictor closer to clinical practice. This new A-score will then to be validated in large clinical trials.


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De rol van astrocytaire beta2-adrenoreceptoren in de pathofysiologie van multiple sclerose Authors: Smeets Silke, Demol Frauke1, Kooijman Ron2, Aerts Joeri3, Jensen Cathy1, Massie Ann4, Clinckers Ralph5, De Keyser Jacques1 1 Departement Neurologie, UZ Brussel, Vrije Universiteit Brussel, België 2 Departement Farmacologie, Vrije Universiteit Brussel, België 3 Departement Fysiologie, Vrije Universiteit Brussel, België 4 Departement Farmaceutische Biotechnologie en Moleculaire Biologie, Vrije Universiteit Brussel, België 5 Departement Farmaceutische Chemie en Analyse van Geneesmiddelen, Vrije Universiteit Brussel, België Inleiding: Multiple sclerose is een chronisch progressieve aandoening van het centraal zenuwstelsel waarbij axonen demyeliniseren. Uit onderzoek is gebleken dat de beta2adrenoreceptoren (B2AR) op astrocyten bij patiënten ondetecteerbaar zijn. Deze deficiëntie kan een immuunrespons veroorzaken die zorgt voor beschadiging van de myelineschede. Het verantwoordelijke mechanisme is ongekend, maar mogelijk liggen virale infecties hier aan de basis. Immers, canine distemper virus (CDV) veroorzaakt een demyeliniserende ziekte bij honden, eveneens gekarakteriseerd door het ontbreken van de astrocytaire B2AR. Het onderzoeksdoel is tweeledig. Enerzijds zal in vitro op primaire muisastrocyten het mechanisme (transcriptie/translatie) worden nagegaan van het verdwijnen van de B2AR ten gevolge van een CDV infectie. Anderzijds zullen in vivo de functionele consequenties van een B2AR deficiëntie worden nagegaan in een induceerbare astrocytaire B2AR knock-out (KO) muis. Materiaal & Methoden: In vitro: Primaire muisastrocyten worden geïsoleerd, in cultuur gebracht en geïnfecteerd met eGFP-CDV (rgA75/17-V). Na 7 dagen worden de geïnfecteerde astrocyten (i.e. eGFP postieve cellen) door middel van FACS analyse gescheiden van nietgeïnfecteerde astrocyten. B2AR expressie wordt op mRNA (reverse transcriptase PCR) en eiwitniveau (Western Blot) vergeleken tussen beide gecollecteerde fracties. In vivo: Tamoxifen injecties (1mg/2x daags gedurende 5 dagen) in 8 weken oude GLAST:CreERT2+/- ADRB2 floxed+/+ muizen. Op dag 9, 15 en 31 na KO inductie worden de muizen gefenotypeerd in vergelijking met niet-geïnduceerde KO muizen en tamoxifenbehandelde controle muizen (Cre+/-Flox-/- en Cre-/-Flox+/+). De geblindeerde fenotypering gebeurt op basis van de in-house gemodificeerde SHIRPA methode. De gegevens worden afhankelijk van de test statistisch verwerkt met repeated measures ANOVA, Kruskal-Wallis en Mann-Whitney. Resultaten & Discussie: In vitro: Momenteel wordt de CDV infectie van primaire astrocyten en de daaropvolgende FACS-scheidingsmethode geoptimaliseerd. De eerste resultaten wijzen erop dat de primaire astrocyten succesvol kunnen geïnfecteerd worden en gescheiden worden met de FACS-methode. In vivo: Voorlopig zijn er geen statistisch significante verschillen gevonden tussen de verschillende genotypes. Bijkomende experimenten om het aantal dieren per conditie te verhogen zijn lopende. Dag van de Biomedici - Biomedische Research Week 2012

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The role of PW1 in pancreas development and adult islet cells Authors: Leslie Stradiot, Paola Bonfanti, Harry Heimberg Beta Cell Neogenesis, Vrije Universiteit Brussel, Belgium

Introduction: Diabetes is a chronic disease characterized by elevated blood sugar levels with increased risk for cardiovascular diseases. It is caused by a relative or absolute shortage of insulin due to loss of insulin producing beta cells or insulin resistance of peripheral tissues respectively. Besides obvious benefits, the current insulin therapy has many disadvantages. A true cure could be by transplantation of endocrine cells from donor organs that, unfortunately, are too scarce for routine treatment. Consequently, an alternative cell source is one of the main foci in the field. To address this objective, a better understanding of key transcription factors and signaling pathways involved in development and regeneration of the endocrine pancreas, is required. Pw1 is a patternally expressed gene encoding a zinc finger protein, and has not been studied in pancreas. In other tissues Pw1 regulates proliferation, differentiation and cell death. Furthermore it has been described as a stem cell marker in different adult tissues such as skin, intestine, testis and muscle. Material and Methods: The purpose of my thesis is to describe the expression pattern and the role of Pw1 in both developing and adult pancreas. Using mainly immunohistochemistry and RT-qPCR, we analyzed Pw1 expression in mouse pancreas. Results: Pw1 is detected as early as embryonic day 9.5 (E9.5) in all pancreatic progenitors and is co-expressed with the pancreatic progenitor marker Pdx1. During development Pw1 expression is down-regulated but re-expressed at high level in early differentiating endocrine cells. At E11.5 Pw1 is expressed in early alpha cells, while it is detected in beta cells only at later stages. In the adult pancreas, Pw1 protein is restricted to the endocrine alpha, beta and delta cells. To determine its role in pancreas development, we aim to locate Pw1 in the transcription factor hierarchy. Using knock-out embryos for specific transcription factors, we conclude that Pw1 expression is not directly affected in the pancreas of Pax4, Pax6, Lgr5 and p53 null-mice. Discussion and Conclusion: Therefore our preliminary conclusion is that Pw1 is expressed in early pancreatic progenitors and becomes restricted to endocrine cells later in development and in adult. We suggest that similarly to Pdx1, Pw1 might serve a dual function, maintaining early pancreas progenitors and stimulate endocrine function. Functional assays are currently being performed.


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Characterization of cancer stem cells in a syngenic mouse model Authors: Kevin Van der Jeught, Sarah Maenhout, Łukasz Białkowski , Kris Thielemans, Joeri Aerts Department Immunology - Physiology, Vrije Universiteit Brussel, Belgium

Introduction: Recently, the “cancer stem cell (CSC) hypothesis” has gained prominence as a possible explanation for treatment resistance and disease relapse. So far, the vast majority of the studies were performed in immune compromised mouse models. In order to characterize the interactions between CSCs and immune cells in vivo, we decided to study CSCs in an autologous, immune competent mouse model. Material and Methods: Side population (SP) discrimination is a commonly used method for identification of stem cells. We used Vybrant DyeCycle Violet (DCV), a dye that can be excited by a violet laser for the SP staining. Results: First we optimized the DCV staining technique using mouse bone marrow cells. The bone marrow SP correlated with hematopoietic stem cells based on the expression of the surface markers c-kit and sca-1. Next, we detected a SP in different mouse (B16 melanoma, 5T33vt multiple myeloma, Lewis Lung Carcinoma) and human (1087-mel melanoma) tumor cell lines. Those tumor SP-cells were then further characterized based on the expression of cell surface markers such as CD133, sca-1, c-kit and CD138. No clear correlation was found between SP and any of the stem cell markers we evaluated. We further evaluated the effect of different parameters related to the tumor microenvironment on B16 SP cells in vitro. When cells were maintained under hypoxic conditions for 24 hours followed by reoxygenation for 24 hours, in order to mimic intermittent hypoxia, an increase in the SP was observed. Treatment of cells with interleukin-6 for 4 days also led to an increased SP. Finally, we characterized the tumor-growth of B16 SP cells in vivo. For this experiment, B16 cells transduced with a lentiviral vector encoding Fluc was used to follow up tumor growth via bio-luminescence imaging. B16 SP cells were able to induce tumor formation when only 10000 cells were injected. In contrast, the bulk population was not able to form a tumor. B16 SP cells induced tumor-formation much faster in comparison with non-SP and bulk cells. Discussion and Conclusions: Our in vitro experiments show that a SP can be detected in most tumor cell lines and that extrinsic factors, such as hypoxia and the presence of inflammatory cytokines influence the extent of SP formation. In vivo experiments showed that SP cells have a tumor-initiating capacity corresponding to that described for CSCs.


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Aldehyde dehydrogenase positive cells during liver injury Authors: Stefaan Verhulst, Laurent Dollé, Leo van Grunsven Department of Cell Biology, Liver Cell Biology lab Background: Many chronic liver diseases can lead to hepatic dysfunction with organ failure, of which the prevalence in Europe is estimated to be approximately 29 million. The only way to rescue such patients is the orthotopic liver transplantation, but especially liver shortage and cost and risks of a lifelong immunosuppression have prompted the search for alternative treatments. The discovery of Liver Progenitor Cell (LPCs) has also given hope to the potential use of such adult stem cells to treat chronic liver patients. Recently, methods to isolate these LPCs, such as the Aldehyde dehydrogenase (ALDH) activity based method, have been optimized that facilitate their further characterisation. Aim: Characterisation of ALDH+ cells in livers of mice during DDC injury. Methods: Male C57B1/6J mice were treated with 3,5-diethoxycarbonyl-1,4-dihydro-collidine (DDC) and sacrificed at different time points (day 0, 3, 7, 10 and 14). We also investigated mice that were put on normal diet after 14 days of DDC (recovery). After each time point we digested the liver using in vivo perfusion with pronase and collagenase. We removed the red blood cells and haematopoietic stem cells from the non-parenchymal fraction by using red blood cell lysis buffer and magnetic-activated cell sorting (MACS). ALDH substrate was incubated for 40 min on 37°C and was analysed on a fluorescence-activated cell sorter (FACS). After sorting ALDH+ cells, we characterized these cells by using qPCR. Blood was also taken to measure liver damage by alanine aminotransferase (ALT) levels. Results: Upon DDC injury, elevated ALT levels clearly indicated that the liver was damaged. After 4 days of recovery, ALT levels were down, similar to the untreated situation. Moreover, tissue analysis from DDC-treated animals illustrated that the LPCs became activated upon this injury. The ALDH+ population was increasing during time of DDC treatment and decreasing in recovery. Gene expression analysis (qPCR) on ALDH+ fractions for LPC-markers revealed that EpCAM and CK19 expression during DDC-treatment did not change. However, in recovery (day 4), they both increased 3 fold in ALDH+ cells, which could indicate that the LPC or cholangiocyte population increases during recovery. In addition, other markers like HNF4α, AFP, TTR (for hepatocytes) and secretin receptor (for cholangiocytes) are also increasing in the ALDH+ population. Further analysis on biological repeats needs to be done to be able to perform statistics. Immunocytochemistry for these markers on the freshly isolated populations is ongoing to confirm these changes at the protein level. Conclusion: Our results indicate that LPCs only differentiate to hepatocytes and cholangiocytes during recovery phase. Another possibility is that LPC-derived cells (hepatocytes and cholangiocytes) are dying during chronic injury. Further experiments like measurement of apoptosis in vivo and detection of other genes in isolated populations need to be performed to confirm our conclusion.


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