• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 598
  • 148
  • 145
  • 49
  • 40
  • 37
  • 21
  • 14
  • 13
  • 10
  • 8
  • 7
  • 7
  • 5
  • 2
  • Tagged with
  • 1301
  • 1301
  • 144
  • 109
  • 108
  • 107
  • 105
  • 91
  • 90
  • 87
  • 84
  • 83
  • 82
  • 74
  • 71
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1011

Engineering PSMA-targeted nanoparticles co-encapsulating mitoxantrone and indocyanine green for precise combinatory therapy in prostate cancer

Khalid, Hafiza J., Khan, Sobia, Hussain, Danyaal, Obinyima, Amarachi, Pina, Clara, Walker, Harriet R., Fox, Stuart, Elies, Jacobo, Ruiz, Amalia 31 October 2024 (has links)
Yes / Prostate cancer is the 2nd most common cancer in men worldwide. Chemotherapeutic treatment of prostate cancer with mitoxantrone (MTX) has limited efficacy due to severe side effects in which cardiotoxicity and myelosuppression are the two major causes of its dose-limiting toxicity. This study aimed to obtain a poly (lactic-co-glycolic acid) (PLGA) nanoparticle that can precisely deliver MTX to the prostate cancer cells overexpressing the Prostate-specific membrane antigen (PSMA) receptor-sparing healthy tissues and co-loading Indocyanine green (ICG) as a fluorescent photothermal/photodynamic agent for precise combinatory therapy in prostate cancer. The biocompatible polymer PLGA was covalently modified with the peptide of sequence (WQPDTAHHWATL) to actively target the PSMA receptor. Factors like the peptide-to-polymer ratio or the peptide's orientation during the polymer's chemical modification were investigated to enhance the active targeting of the nanoparticles (NPs). NPs were characterised using dynamic light scattering, scanning electron microscopy, and UV–vis spectroscopy to determine their morphological and colloidal properties and optimal MTX and ICG encapsulation efficiency. Quantitative FACS analysis of LNCaP and PC-3 cells incubated with Nile Red-labelled non-targeted PLGA or PLGA-PSMA targeted NPs was assessed to identify the best formulation that bound selectively to PSMA. The orientation of the peptide conjugated to the polymer, which has the C-terminal end of the peptide sequence accessible for interaction with the cell receptor, maximises the targeting capacity of the system. Photothermal experiments using 808 nm near-infrared laser irradiation were conducted, and cytotoxicity was assessed using the resazurin viability assay. Remarkably, our results confirmed the safety and efficacy of a targeted and activatable therapy using polymeric NPs functionalised with the peptide and co-loaded with MTX and ICG. This pioneer nanosystem opens new perspectives for exploring advanced targeted delivery in prostate cancer. It offers a straightforward methodology for functionalising drug delivery systems with bioactive peptides that can be applied to different types of cancer. / Royal Society Research Grant (RGS\R1\221399); MRC Confidence in Concept grant (RM0039); University of Bradford. This work was partially supported by a grant to I.H. (PID2021-122216OB-I00) funded by the Spanish Ministry of Economy, Industry and Competitiveness at the European Regional Development Fund
1012

Amélioration du calcul de dose TG-43 en curiethérapie à bas débit par un algorithme de dose primaire et diffusée sur processeur graphique

Bourque, Alexandre 19 April 2018 (has links)
Les calculs de dose en curiethérapie à bas débit reposent depuis 1995 sur un formalisme qui considère le milieu irradié comme étant homogène et constitué d’eau afin de mieux accommoder les temps de calcul clinique. Ce travail présente une amélioration de ce formalisme dosimétrique issu du protocole TG-43 de l’AAPM (American Association of Physicists in Medicine), utilisé actuellement dans les systèmes de planification de traitement (SPT) clinique. Avec l’ajout d’un tracé radiologique pour tenir compte des hétérogénéités et en séparant la dose primaire de la dose diffusée, il est possible de raffiner les calculs dosimétriques. Or, cette modification au calcul le rendant plus complexe était coûteuse en temps d’exécution jusqu’à très récemment. Elle se voit matérialisée dans ce travail avec l’arrivée récente de la technologie GPGPU, les calculs scientifiques sur périphériques graphiques. En exploitant le parallélisme des calculs de dose en curiethérapie à bas débit pour les implants permanents, l’algorithme baptisé TG-43-RT pour TG-43 avec tracé de rayons (Ray-Tracing en anglais) permet d’obtenir des facteurs d’accélération de l’ordre de 103 par rapport au CPU. Seulement 0.5 s par source est requis dans une géométrie de 1003 voxels, et les dosimétries d’anatomies hétérogènes sont sensiblement améliorées. Le TG-43-RT corrige les dépôts de dose en aval des hétérogénéités et réduit les effets indésirables de l’atténuation inter-sources. Des écarts de dose de plus de 80% au-delà d’une calcification avaient de quoi influencer les HDV, or, le TG-43-RT ramène ces déviations en-deçà de l’incertitude de 8.7% (2σ) concédée par les SPT, tel qu’établi dans le TG-138. Les simulations Monte Carlo ont été employées pour servir de référence absolue à la méthode développée et quantifier les améliorations dosimétriques relatives à l’actuel calcul de dose. L’algorithme a été testé d’un point de vue clinique dans un fantôme de prostate avec des sources d’125I et dans un fantôme de sein avec des sources de 103Pd pour unifier les corrections apportées. / Brachytherapy dose calculations have been relying since 1995 on a formalism that considers the whole geometry as a homogeneous water tank. This gives the opportunity to compute dose distributions within a reasonable clinical timeframe, but with considerable approximations that can influence or even change the treatment. This work presents an upgraded version of this formalism derived from the TG-43 protocol (AAPM), currently used in actual treatment planning systems. The new algorithm includes a primary and scatter dose separation using ray-tracing operation to account for heterogeneities through the medium. These modifications to the dose calculation are very power consuming and too long for the clinical needs when executed on modern CPUs. With the GPGPU technology, a GPU-driven algorithm allows a complex handling of the anatomic heterogeneities in the dose calculation and keeps execution times below 0.5 s/seed. The algorithm was named TG-43-RT for TG-43 with Ray-Tracing and accelerations factors of three order of magnitude were obtained over a regular CPU implementation. The TG-43-RT algorithm adequatly corrects dose deposition along heterogeneities and it reduces interseed attenuation effects. Dose is scored in the medium instead of water, which also applies a severe correction for high heterogeneous medium like the breast. Deviations of more than 80% in dose deposition were obtained over calcification inside the prostate when compared to Monte Carlo simulations. This kind of deviation influences DVH shape. However, the TG-43-RT was keeping those deviations within the 8.7% uncertainty range (2σ) associated with a regular TG-43 evaluation as stated in the TG-138. Monte Carlo simulations were used as a gold standard to get an absolute dose calculation reference. The algorithm was also tested in a prostate phantom with 125I seeds and in a breast phantom with 103Pd seeds to mimic real anatomic geometries and unify the applied corrections.
1013

Synthèse de dérivés stéroïdiens et évaluation de leur capacité inhibitrice sur les enzymes de la stéroïdogenèse pour le traitement de la maladie d’Alzheimer et /ou du cancer de la prostate

Boutin, Sophie 27 January 2024 (has links)
No description available.
1014

Effets des acides gras oméga-3 sur le cancer de la prostate

Gevariya, Nikunj 05 October 2024 (has links)
Le cancer de la prostate (CaP) est le cancer le plus fréquemment diagnostiqué chez les hommes canadiens, avec 21 300 nouveaux cas et est la troisième cause de mortalité par cancer au Canada avec 4100 décès en 2017. Des études épidémiologiques ont montré que les populations ayant un régime riche en acides gras oméga (ω) 3 (e.g. les populations asiatiques côtières) ont une faible incidence de CaP alors que les populations des pays occidentaux ayant une diète riche en acides gras ω6 ont une incidence plus élevée (près de 60 fois) de CaP. Les graisses alimentaires influencent de nombreux processus biologiques, dont l'inflammation associée au développement et à la progression du CaP. Notamment, les acides gras ω6 à longues chaînes (LCω6) ont des propriétés pro-inflammatoires et pourraient contribuer à la progression du CaP. À l'inverse, les LCω3, tels que l'acide eicosapentaénoïque (EPA) et l'acide docosahexanénoïque (DHA), ont des propriétés anti-inflammatoires et pourraient inhiber la progression du CaP. J'ai donc émis l'hypothèse que les acides gras ω3 seraient bénéfiques contre la croissance et la progression du CaP principalement par leurs propriétés anti-inflammatoires. En utilisant le modèle murin de CaP TRAMP-C2, j'ai constaté qu'un régime enrichi en acides gras ω3 réduisait la croissance du CaP par rapport à un régime enrichi en acide gras ω6 chez les souris non-dépourvues et dépourvues d'androgènes, en induisant une réponse immune antitumorale locale de type Th1-, Th2- et associée aux éosinophiles. Dans le but d’étudier plus en détails les effets de différents sous-types d’acides gras ω3, j’ai constaté que la supplémentation alimentaire en monoacylglycéride (MAG)-EPA réduisait la croissance tumorale en inhibant le facteur de croissance endothélial vasculaire (VEGF) et le gène du récepteur 2 de ce facteur de croissance (VEGFR2), ainsi que la taille des vaisseaux sanguins dans les tumeurs TRAMP-C2. J'ai également observé un effet similaire sur le système vasculaire tumoral des patients participant à un essai clinique visant à analyser les effets de la supplémentation en MAG-EPA sur le CaP avant une prostatectomie radicale. Enfin, dans le but d'analyser l'inflammation et de découvrir des biomarqueurs de la progression du CaP, j'ai analysé les effets d'une intervention alimentaire enrichie en acides gras ω3 versus un traitement avec un inhibiteur de la 5α-réductase (5ARI) sur des patients atteints deCaP de faible risque sous surveillance active. J'ai observé que 6 mois de régime alimentaire riche en acides gras ω3 ont entraîné une réduction des taux plasmatiques de cytokines pro-inflammatoires et pro-angiogeniques, ainsi que des cytokines liées à la réponse immunitaire Th2 et Th17. Afin d'évaluer les effets de ces interventions sur les protéines du tissu prostatique, j'ai effectué des dosages de cytokines et des analyses par spectrométrie de masse (MS) dans l'urine clarifiée obtenue après un toucher rectal (urine TR). Je n'ai pas réussi à identifier des variations significatives dans la teneur en protéines, mais j'ai conclu que l’urine TR non clarifiée, contenait deux fois plus de protéines que l'urine clarifiée, suggérant que ce type d’échantillon devrait être utilisé pour les prochaines analyses. Dans l'ensemble, mes résultats confirment l'importance des acides gras ω3 pour la prévention de la progression du CaP et appuient une étude plus approfondie de leurs effets sur la réponse immunitaire, l'angiogenèse et la progression tumorale chez les patients atteints de CaP. / Prostate cancer (PCa) is the most frequently diagnosed cancer in Canadian men with 21,300 new cases and is the third-largest cause of cancer mortality with 4100 deaths in 2017. Epidemiological studies have shown that populations with a diet rich in omega (ω)-3 fatty acids(FA) (e.g. coastal Asian populations) have a low incidence of PCa while populations in Western countries with a diet rich in ω6 FA have higher (almost 60 times) incidence of PCa. Dietary fats influence many biological processes including inflammation which is associated with PCa development and progression. Notably, long-chain ω6 FA (LCω6) have pro-inflammatory properties and could contribute to PCa progression. On the opposite, LCω3 such as eicosapentaenoic acid (EPA) and docosahexanenoic acid (DHA) have anti-inflammatory properties and could inhibit PCa progression. I hypothesized that dietary ω3 FA are beneficial against PCa growth and progression mainly via their anti-inflammatory properties. Using the TRAMP-C2 mouse model of PCa, I found that an ω3 FA-enriched diet reduced PCa growth compared to an ω6 FA-enriched diet in both androgen-deprived and non-deprived mice by inducing local antitumor Th1-, Th2-and eosinophil-related immune response. In the quest to further study the effects of individual ω3 FA subtype, I found that dietary supplementation with monoacylglyceride (MAG)-EPA reduced tumor growth by inhibiting vascular endothelial growth factor (VEGF)and vascular endothelial growth factor receptor-2gene (VEGFR2)expression as well as reducing the size of blood vessels in TRAMP-C2 tumors. I also observed that higher level of EPA reduced the size of blood vessels in prostate in a clinical trial testing MAG-EPA supplementation on PCa patients undergoing radical prostatectomy. Finally, I analyzed the effects of an ω3 FA-rich diet intervention versus treatment with a 5α- reductase inhibitor (5ARI) on low-risk PCa patients under active surveillance. I found that 6 months of ω3 FA-rich diet intervention resulted in a reduction of plasma level of pro-inflammatory and pro-angiogenesis cytokines as well as Th2 and Th17 immune response-related cytokines. In order to assess the effects of these interventions on the prostate tissue, I used cytokines assay and mass spectrometry (MS ) assay to analyze proteins in clarified urine obtained after digital rectal examination (DRE urine). I did not succeed at identifying significant variation in protein levels following the interventions in this sample type but I found that crude (non-clarified) DRE urine contained twice the amount of proteins compared to clarified urine, suggesting that this type of sample should be used for further analysis. Overall, my results confirmed the importance of ω3 FA for prevention of PCa progression and provide the rationale to further investigate their effects on immune response, tumor vasculature and tumor progression in PCa patients.
1015

Intervention psychologique pour les hommes ayant reçu une prostatectomie radicale pour un diagnostic de cancer de la prostate localisé : une étude préliminaire

Gaudreau, Pierre-Olivier 16 April 2021 (has links)
La présente étude vise à vérifier l'efficacité d'un traitement cognitif-comportemental multimodal pour réduire la détresse psychologique (ie., anxiété et dépression) et certains symptômes psychophysiologiques (i.e., difficultés érectiles, insomnie et fatigue) auprès d'hommes ayant subi une prostatectomie radicale pour un cancer de la prostate localisé. Un protocole expérimental A-B à niveaux de base multiples avec réplications directes et suivis est utilisé. Six participants complètent le traitement. Les analyses de séries chronologiques effectuées sur des indices de détresse psychologique suggèrent des améliorations significatives au post-traitement pour deux des participants sur au moins deux variables et qui se maintiennent au suivi de trois mois. Des tests non-paramétriques effectués sur les questionnaires d'auto-évaluation appuient généralement ces résultats. D'autre part, des bénéfices au niveau de la fatigue et du fonctionnement érectile apparaissent au suivi trois mois. En somme, l'intervention telle qu'administrée dans cette étude semble être efficace pour certains patients, mais pourrait l'être davantage si l'emphase était mise sur le fonctionnement sexuel qui constitue le problème primordial chez cette population.
1016

Simulations Monte Carlo sur processeur graphique en curiethérapie à bas débit de dose pour le cancer de la prostate

Bonenfant, Éric 19 April 2018 (has links)
Ce mémoire porte sur l’étude d’un algorithme Monte Carlo en curiethérapie à bas débit de dose sur processeur graphique. Avec le développement de cette plate-forme de calcul, l’application de la méthode Monte Carlo fait un pas en avant quant à son utilisation clinique dans un département de radio-oncologie. Le travail se déroule en deux parties. Premièrement, le développement d’un algorithme Monte Carlo sur processeur graphique, bGPUMCD, est poursuivi dans le but d’en améliorer les performances. Deuxièmement, une source de curiethérapie à bas débit de dose, la SelectSeed de Nucletron, est simulée et étalonnée pour être en accord avec les données du rapport du Task Group 43 de l’American Association of Physicists in Medicine. Avec cette source, quatre cas cliniques sont ensuite simulés pour montrer la concordance des résultats avec un autre algorithme Monte Carlo bien établi et évaluer les temps de calcul pour une éventuelle utilisation clinique de l’algorithme.
1017

Localisation of kallikreins in the prostate and association with prostate cancer progression

Bui, Loan Thuy January 2006 (has links)
At present, prostate cancer is a significant public health issue throughout the world and is the second leading cause of cancer deaths in older men. The prostate specific antigen or PSA (which is encoded by the kallikrein 3/KLK3 gene) test is the current most valuable tool for the diagnosis and management of prostate cancer. However, it is insufficiently sensitive and specific for early diagnosis, for staging of prostate cancer or for discriminating between benign prostatic hyperplasia (BPH) and prostate cancer. Recent research has revealed another potential tumour marker, glandular kallikrein 2 (KLK2 gene/hK2 protein), which may be used alone or in conjunction with PSA to overcome some of the limitations of the PSA test. Twelve new kallikrein gene family members have been recently identified and, like hK2 and PSA, many of these genes have been suggested to be involved in carcinogenesis. In this study, the cellular localisation and level of expression of several of these newer kallikreins (KLK4, KLK5, KLK7, KLK8 and KLK11) was examined in prostate tissue, to provide an understanding of the association of their expression with prostatic diseases and their potential as additional biomarkers. Like PSA and hK2, the present observation indicated that each of these proteins, hK4, hK5, hK7, hK8 and hK11, was detected within the cytoplasm of the secretory cells of the prostate glands. For the first time, all of these newly-identified proteins were shown to be expressed in prostatic intraepithelial neoplasia (PIN) lesions, in comparison to normal glands and cancer lesions. In addition to cytoplasmic secretory cell expression, the localisation of hK4 to the basal cells and nuclei in prostatic lesions was intriguing. The intensity of hK4 staining in prostate tissue was strongest in comparison to the other newly-identified kallikrein proteins (hK5, hK7, hK8 and hK11). Therefore, KLK4/hK4 expression was characterised further to define this cellular localisation and examined in non-prostatic tissue and also in a larger number of prostate tissues in an attempt to determine its potential value as a biomarker for prostate disease. Three hK4 antipeptide polyclonal antibodies, derived against N-terminal, mid-region and C-terminal hK4 amino acid sequences, were used. The hK4 N-terminal antipeptide antibody was used to demonstrate the cellular localisation of hK4 in kidney, salivary glands, liver, testis, colon carcinoma, heart, endometrium and ovarian cancer, for the first time. The presence of hK4 in these non-prostate tissues was consistent with the previous reports using RT-PCR. The dual cytoplasmic and nuclear localisation of hK4 observed in the prostate above was also seen in these tissues. Although hK4 was found widely expressed in many human tissue types, indicating that it is not prostate specific in its expression, the highest expression level of hK4 was seen in the prostate. Therefore, detailed expression patterns and levels of KLK4 mRNA and hK4 protein in the normal prostate and prostatic diseases and histopathological lesions were investigated and reported for the first time in this study. Twelve benign prostatic hyperplasia (BPH), 19 adenocarcinoma (Gleason grade 2-5) and 34 bone metastases from prostate cancer were analysed. Using in situ hybridisation, the expression of KLK4 mRNA was detected in the cytoplasm of the secretory cells of both normal and diseased prostate tissue. KLK4 mRNA was also noted in both secretory and basal cells of PIN lesions, but the basal cells of normal glands were negative. Using the hK4 N-terminal and mid-region antipeptide antibodies, hK4 was predominantly localised in the cytoplasm of the secretory cells. The intensity of hK4 staining appeared lowest in normal and BPH, and increased in PIN lesions, high Gleason grade prostate cancer and bone metastases indicating the potential of hK4 as a histopathological marker for prostatic neoplasias. Further studies are required with a larger cohort to determine its utility as a clinical biomarker. Small foci of atypical cells, which were found within normal glands, were also intensely stained. Surprisingly, hK4 protein was found in the nucleus of the secretory cells (but not the basal cells) of high grade PIN and Gleason grade 3 prostate cancer. The detection of KLK4 mRNA and hK4 protein in PIN lesions and small foci of atypical cells suggests that up-regulation of KLK4 expression occurs early in the pathology of prostate carcinogenesis. The finding of basal cell expression is not typical for the kallikreins and it is not clear what role hK4 would play in this cell type. With the use of the hK4 C-terminal antipeptide antibody, the staining was mainly localised in the nuclei of the secretory cells of the prostate glands. Although the nuclear localisation was readily noted in more than 90% of epithelial cells of the prostate gland with the C-terminal antibody, no difference in staining intensity was observed among the histopathological lesions of the prostate. The prominent nuclear localisation with the C-terminal antipeptide antibody was also shown to be distributed throughout the nucleus by using confocal microscopy. Further, by using gold-labelled particles for electron microscopy, the intracellular localisation of these hK4 antipeptide antibodies was reported here for the first time. Similar to the immunohistochemical results, the cytoplasm was the major site of localisation with the N-terminal and mid-region antipeptide antibodies. To further characterise the involvement of KLK4/hK4 in human prostate cancer progression, the transgenic adenocarcinoma mouse prostate (TRAMP) model was used in this study. In this study, mouse KLK4 (also known as enamel matrix serine protease -1, EMSP-1) was shown to be expressed in the TRAMP prostate for the first time. Previous studies had only shown the developing tooth as a site of expression for EMSP-1. The level of EMSP-1 mRNA expression was increased in PIN and prostate cancer lesions of the TRAMP model, while negative or low levels of EMSP-1 mRNA were seen in normal glands or in control mouse prostate tissue. The normal mouse prostate did not stain with any the three hK4 antipeptide antibodies. hK4 N-terminal and mid-region antipeptide antibodies showed positive staining in the cytoplasm of the epithelial cells of PIN and cancer lesions of the mouse prostate. The C-terminal antipeptide antibody showed distinctively nuclear staining and was predominantly localised in the nuclei of the glandular cells of PIN and cancer lesions of the mouse prostate. The expression patterns of both the mRNA and protein level for mouse KLK4 strongly supported the observations of KLK4/hK4 expression in the human prostate and further support the utility of the TRAMP model. Overall, the findings in this thesis indicate a clear association of KLK4/hK4 expression with prostate cancer progression. In addition, several intriguing findings were made in terms of cellular localisation (basal as well as secretory cells; nuclear and cytoplasmic) and high expression in atypical glandular cells and PIN, perhaps indicating an early involvement in prostate disease progression and, additionally, utility as basal cell and PIN histological markers. These findings provide the basis for future studies to confirm the utility of hK4 as a biomarker for prostate cancer progression and identify functional roles in the different cellular compartments.
1018

Resilience in families of husbands with prostate cancer

Thiel, Colleen 12 1900 (has links)
Thesis (MA (Psychology))--Stellenbosch University, 2005. / Family resilience is an increasingly visible concept in the field of family psychology. The aim of the present study was to identify family resilience qualities associated with the successful adaptation of families with a husband diagnosed with prostate cancer. The Resiliency Model of Family Stress, Adjustment and Adaptation (McCubbin & Thompson, 1991) served as the theoretical framework in the design and the execution of the research. Both qualitative and quantitative measures were used in this cross-sectional survey research design. Twenty-one husbands and their spouses independently completed seven questionnaires, a biographical questionnaire and answered an open-ended question. Qualitative findings revealed the importance of intrafamilial support, spiritual/religious beliefs and professional support and knowledge in families coping with prostate cancer. Quantitative results indicated that family adaptation to prostate cancer was fostered by family hardiness (the family's internal strengths and durability), affirmative communication and social support.
1019

Hur män med prostatacancer upplever sin livskvalitet efter en prostatektomi / How men with prostate cancer experience their quality of life after a prostatectomy

Capanov, Mitko, Lindström, John January 2010 (has links)
Bakgrund- Prostatacancer är en av de vanligaste cancerformerna i Sverige och nästan 34 % av alla fall av cancer hos män är prostatacancer. Radikal prostatektomi är en behandling som innebär att hela prostatan och intilliggande körtlar tas bort. Prostatektomi kan ha negativ påverkan på livskvaliteten p.g.a. ingreppets komplikationer. Syfte- att belysa hur män upplever sin livskvalitet efter att ha genomgått en prostatektomi. Metod- En systematisk litteraturstudie. Artiklar har sökts fram i elektroniska databaser. Tio artiklar har granskats enligt kriterier för kvalitetsgranskning där nio kvalificerats och används i resultatet. Inspireras av kvalitativ analys och identifierat olika teman i texten. Vi kom fram till fyra kategorier som vi redovisar resultaten ifrån: fysiska, psykiska, sociala och omvårdnadsaspekter. Resultat- Sexualitet, relationer, männens upplevelse av självkänsla och kontroll över sin kropp samt informationsbrist var de viktigaste områdena där livskvaliteten påverkades negativt. Slutsats- Radikal prostatektomi innebar en stor förändrig för männens livskvalitet och deras liv. Vi tror att mer forskning behövs inom ämnesområdet för att få en djupare förståelse för hur männen upplever sin livskvalitet efter operationen.
1020

The prostatic tumour stroma

Bonda, Ulrich 12 August 2016 (has links) (PDF)
The majority of cancer research projects mainly focus on the epithelial cancer cell, while the role of the tumour stroma has been largely neglected. Conventional 2D techniques, such as well plates and other kinds of tissue culture plastic, and animal models are mainly used to broaden our understanding of how tumours arise, develop, and induce metastasis. However, there is accumulating evidence suggesting a tremendous impact of the non‐cancerous tumour stroma on carcinogenesis, while other publications illustrate the great importance of advanced 3D in vitro models for cancer research. The overall goal of this work was to investigate how cancer associated fibroblasts (CAFs; the most abundant component in the tumour stroma) and normal prostate fibroblasts (NPFs), isolated from patients diagnosed with aggressive forms of prostate cancer, contribute to angiogenesis, an important hallmark of cancer progression. For this purpose, a 3D in vitro angiogenesis co‐culture model was established. At first, two (semi‐) synthetic hydrogel platforms, gelatine methacrylate (GelMA) and star‐shaped (star)PEG‐heparin hydrogels were characterised and their physicochemical properties were compared with each other. Interestingly, GelMA gels shrank while starPEG‐heparin gels swelled in cell culture medium over the course of 24 hours. The cell concentration, in addition to the stiffness, was critical for the formation of endothelial networks, and the knowledge of swelling behaviour enabled the adjustment of initial cell density to ensure the density between both gel types was comparable. Moreover, preliminary tests with mesenchymal stem cells demonstrated that the hydrogel can be actively remodelled, as evaluated by stiffness parameters at day one and seven of incubation. Growth factors (GFs) affect cellular fate and behaviour, and storage, presentation and administration of such chemokines can be critical for certain cellular applications. Due to the high anionic charge density of heparin, starPEG‐heparin hydrogels are known to reversibly immobilise several GFs and thereby might mimic the GF reservoir of the extra cellular matrix. Thus, transport processes of GFs with low and high heparin affinity inside these hydrogels were analysed by fluorescence correlation spectroscopy and a bulk diffusion approach. Results indicated that diffusion constants were synergistically decreased with increasing size and heparin affinity of the diffusant. Next, the capability of endothelial cells (ECs) to self‐assemble and organise into 3D capillary networks was tested in GelMA, starPEG‐heparin and Matrigel hydrogels. Only starPEG‐heparin hydrogels allowed the formation of interconnected capillaries in macroscopic hydrogel samples. However, as it is widely used to test for pro‐ and anti‐angiogenic agents, the 2D Matrigel angiogenesis assay was included for subsequent co‐culture experiments of ECs and fibroblasts in order to investigate how the stromal cells influence the formation of endothelial networks. For a detailed characterisation of 3D structures, a conventionally applied 2D method (Maximum Intensity Projection for 3D reconstructed images, MIP) was compared to an optimised 3D analysing tool. As a result, it was discovered that MIP analysis did not allow for an accurate determination of 3D endothelial network parameters, and can result in misleading interpretations of the data set. Indirect co‐cultures of hydrogel‐embedded ECs with a 2D layer of fibroblasts showed that fibroblast‐derived soluble factors, including stromal cell‐derived factor 1 and interleukin 8, affected endothelial network properties. However, only co‐encapsulation of ECs and fibroblasts in starPEG‐heparin hydrogel discs revealed remarkable changes in endothelial network parameters between CAF and NPF samples. In detail, the total length and branching of the capillaries was increased. For two donor pairs, the diameter of capillaries was decreased in CAF samples compared to NPF samples, underlining the high physiological relevance of this model. In contrast, significant differences in 2D Matrigel assays were not detected between, CAF, NPF and control (ECs only) samples. In summary, a 3D angiogenesis co‐culture system was successfully developed and used to characterise stromal‐endothelial interactions in detail. The combination of advanced biomaterials (starPEG‐heparin) and 3D analysing techniques goes beyond conventional 2D in vitro cancer research, and opens new avenues for the development of more complex models to further improve the acquisition of more biologically relevant data.

Page generated in 0.1107 seconds