Academic literature on the topic 'Mesenchyme Cytology'

Lipoma is one of the most common soft tissue tumor arising from the mesenchyme. It is slow growing, encapsulated, and usually benign in nature. Tumors over the back, shoulder, and neck region have a high propensity to assume large size thereby getting redefined as a giant lipoma when they exceed 10 cm in width or weigh more than 1000 grams. MRI is the investigation of choice for evaluating giant lipomas. Fine needle aspiration cytology (FNAC) or frozen section may be pertinent in suspected cases of liposarcoma. Complete surgical incision is the treatment of choice. A case of a giant lipoma on the back of a 64-year-old lady is presented with a view to revisit conceptual understanding of the clinical evaluation, investigation, and management of giant lipomas.

AbstractSertoli-Leydig cell tumor of ovary is a gonadal tumour of the sex cord-stromal type. It is a rare tumor comprising 0.1 to 0.5% of all ovarian tumours. Peritoneal cytology has been well established as a diagnostic and staging tool in the management of the common epithelial tumours of ovary. Germ cell, mesenchymal, and sex-cord stromal tumours are much less frequently encountered in peritoneal specimens, often with cytologic features that may pose diagnostic difficulty and dilemma. We report a case of peritoneal fluid cytology of sertoli leydig cell tumor of ovary in a 20 year old female who presented with virilising symptoms. On removal of ovarian tumor, her virilising symptoms regressed, with regaining of menstruation.

Mesenchymal origin of primary thyroid angiosarcomas (TAS) is extremely rare and comprises less than 1% of primary thyroid cancer worldwide. While TAS are most commonly occurring in the Alpine region, there are multiple reported cases of TAS in non-Alpine regions. Diagnosis of TAS is commonly made after thyroidectomy as cytologic diagnosis can be challenging due to paucity of cells, presence of necrosis and unawareness of the disease due to rarity. We report a case of primary TAS diagnosed by cytology in a 56-year-old man who presented with a sudden onset of left neck pain, swelling and haemoptysis. He was later noted to have suspicious nodules on both lobes of thyroid on ultrasound. Fine needle aspiration of thyroid nodules showed malignant epithelioid cells. The diagnosis of TAS was made based on positive endothelial markers such as thrombomodulin and CD31, with many pertinent negatives, including negative cytokeratins,thyroid transcription factor (TTF1), thyroglobulin, calcitonin and carcinoembryonic antigen (CEA).

Abstract Casestudy Gastroblastoma is a rare tumor with biphasic components showing epithelial and mesenchymal differentiation. To date, <15 cases have been reported, with molecular confirmation of the recently identified MALAT1-GLI1 translocations only in a subset. Aspiration cytologic and small biopsy findings have not yet been reported. We present a case of gastroblastoma, arising in a 22-year-old female. Results A CT scan was performed, showing a 7 cm heterogeneous mass in the distal stomach and pancreas, clinically suspected to represent at gastrointestinal stromal tumor (GIST). She underwent two preoperative samples, including endoscopic ultrasound guided-fine needle aspiration and core biopsy, followed by a distal gastrectomy. Diff- Quik stained touch preparations performed on the core needle biopsy during rapid on-site evaluation showed a hypercellular neoplasm composed of large, three-dimensional aggregates of neoplastic cells in a background of numerous isolated single cells and bare nuclei. The neoplastic cells were bland with spindled to epithelioid nuclei, occasional nuclear grooves, and small nucleoli. Immunostains were only helpful in excluding GIST (CD117 and DOG1 negative). Distal gastrectomy showed a nodular/plexiform tumor with variably epithelioid to spindle cell cytology and solid to focally myxoid/microcystic architecture. Pancytokeratins CAM5.2 (patchy) and AE1/AE3 (very focal) were positive, with negative S100, SMA, Desmin, Melan-A, Inhibin, Calretinin, and Synaptophysin. Based on the age, location, histology and immunophenotype, gastroblastoma was suspected, and multiplex NGS-based fusion sequencing identified a MALAT1-GLI1 fusion. Staging studies were negative for metastasis at presentation. Conclusion Based on this experience, we recommend consideration of gastroblastoma for a gastric tumor in a young patient, especially if encountering a cytologic sample showing non-pleomorphic epithelioid and spindle cell cytology. Lack of expression of GIST, smooth muscle, neuroendocrine, and neural sheath-associated markers should particularly raise consideration of this rare neoplasm. While in this case molecular studies clinched the diagnosis upon resection, increasingly used GLI1 immunostain may be of use prospectively for diagnosis of limited samples.

Objectives: Fine-needle aspiration cytology (FNAC), a well-accepted minimally invasive diagnostic technique utilized in adults, is gradually gaining ground for pediatric patients as well. However, there are very few comprehensive reports in the literature on utility of FNA in pre-operative diagnosis of pediatric tumors. Material and Methods: An observational study was conducted at a cancer research center and a pediatric tertiary care hospital over a 5-year period. A cytologic-histologic correlation was performed for FNACs performed in pediatric patients for a clinical diagnosis of neoplastic lesions at both the centers. Relevant clinical details and histopathology, wherever available, were retrieved. Sensitivity, specificity, and accuracy of FNAC in diagnosis of malignant lesion were calculated from the cases with available histologic correlation. Results: Of the 266 cases included, there was a slight male predominance with lymphadenopathy being the most common presentation and non-Hodgkin’s lymphoma as the most frequent diagnosis in cases clinically suspected to have a neoplasm. Histologic correlation was available in 112 cases with 100% concordance in liver and kidney tumors. Few rare cytologic diagnoses such as papillary renal cell carcinoma, mesenchymal hamartoma of the liver, and thymolipoma could be accurately rendered on FNAC smears in conjunction with the clinic-radiologic features. The sensitivity, specificity, and accuracy of FNA in diagnosing malignant pediatric tumors were found to be 100%, 92.6%, and 97.7%, respectively. Conclusion: The present study underscores the high sensitivity and accuracy of FNAC in diagnosis of pediatric tumors, both in superficial and deep-seated locations. Awareness of the cytomorphologic features and clinic-radiologic correlation may assist the cytopathologists in rendering a precise diagnosis of rare pediatric tumors as well.

Abstract In this study, we compared the cytological, histopathological, and immunohistochemical diagnoses of 71 canine cutaneous and subcutaneous masses. Cytological diagnoses included 56 tumors (21 mesenchymal, 15 epithelial, 16 round cell, four melanocytic), 13 inflammatory reactions, and two cysts. Of the 21 cytologically diagnosed mesenchymal tumors, three were later confirmed non-tumoral (hematoma, granulation tissue, fibroepithelial polyp). Thirteen out of 15 epithelial tumors were correctly diagnosed cytologically, whereas two cases were confirmed to be non-tumoral (fibroepithelial polyp, granulation tissue) after histopathological examination. One mast cell tumor was later confirmed as fibrous hyperplasia; diagnoses were correct in other round cell tumors. Cytological diagnoses were correct for all melanocytic tumors and cystic lesions. Five cases which had been cytologically diagnosed as inflammatory reactions were diagnosed as tumors (lymphoma, papilloma, sebaceous adenoma, and squamous cell carcinoma) after histopathological examination. Immunohistochemistry confirmed the histopathological diagnoses of all epithelial and round cell tumors, while the diagnoses of six mesenchymal tumors were changed after the immunohistochemical examination. The total accuracy of cytology in the diagnosis of tumoral/non-tumoral masses was 84.5%, and the accuracy in the determination of benign/malignant behavior was 83%. Diagnostic accordance between histopathology and immunohistochemistry was 86.6%. High success rates obtained with cytological diagnoses prove that cytology is a reliable diagnostic tool. The main diagnostic challenge remains with mesenchymal tumors and tumors accompanied by inflammatory reactions. The results suggest that immunohistochemistry is fundamental for diagnoses of most mesenchymal tumors.

Infrared thermography is a safe and non-invasive method of research used to aid the diagnosis of inflammation, infectious diseases and muscle damage, as well as in reproductive control. The images captured by thermography convert infrared radiation emanating from the body in a temperature gradient, represented by a pattern of visible colors. Aspiration cytology, on the other hand, is an easily applicable research tool that offers excellent preliminary results and directs the clinical case towards a diagnosis. A male jaguar (Panthera onca) presenting a tumor in the abdominal region was examined with the aid of a thermal imager and later a fine needle aspiration cytology was performed. These methods disclosed a mesenchymal malignant neoplasm; later histopathological analysis confirmed the diagnosis of fibrosarcoma. The combination of thermography with fine needle aspiration cytology provided excellent results, showing efficiency, speed and convenience as a diagnostic aid.

Primary ovarian neoplasms constitute a heterogenous group of benign and malignant tumors of epithelial, sex cord–stromal, mesenchymal and germ cell origin. Secondary tumors constitute a minority. The management of benign and malignant ovarian neoplasms varies and it is here that imprint cytology plays a crucial role in diagnosis. It provides a rapid intraoperative diagnosis which will decide further treatment course for the patient. Imprint cytology of ovarian neoplasms is simple, inexpensive, challenging and provides a rapid diagnosis with excellent cellular details. The aim of the present study is to determine the role of imprint cytology in the diagnosis of ovarian neoplasms. A retrospective study was conducted in the department of pathology. A total of 53 cases were included in the study. In 48 cases, the imprint cytology findings correlated with the histopathological diagnosis. 5 cases did not correlate. Epithelial ovarian tumors accounted for the majority, (85%) followed by germ cell tumors (9.4%) and sex cord stromal tumors (5.6%). The sensitivity and specificity were 93.75% and 100% respectively. Thus imprint cytology is an effective cytological method in the diagnosis of ovarian neoplasms. Knowledge of specific cytological features for each tumor type helps in accurate diagnosis which in turn is valuable in immediate appropriate treatment and management of patients with benign or malignant neoplasms.

In order to establish the diagnosis and prognosis of tumors of the oral cavity, a comparative study was carried out in 130 dogs considering age, sex, breed, clinical aspects, exfoliative cytology as well as histopathology. Exfoliative cytology revealed: 100% negative for benign non-odontogenic tumors, 97.91% negative benign odontogenic tumors and 77.92% positive for malignant tumors. Histopathology showed: 59.23% malignant tumors (33.08% malignant melanoma, 9.23% squamous cell carcinoma, 5.38% osteosarcoma, 2.31% fibrosarcoma, 2.31% angiosarcoma, 1.54% malignant mesenchymal tumors, 1.54% malignant fibrohistiocytoma, 1.54% lymphoma, 0.77% leyomyosarcoma, 0.77%% epithelioid sarcoma and 0.77% angiofibrosarcoma); 36.92% benign odontogenic tumors (25.38% peripheral odontogenic fibroma, 10.0% ossifyng fibroma and 1.54% odontoma) in addition to 3.85% benign non-odontogenic tumors (1.54% fibroma, 0.77% plasmocytoma, 0.77% pilomatrixoma and 0.77% giant tumor cells). These results permit us to conclude that exfoliative cytology was an efficient, safe, quick and noninvasive method and could be used for early evaluation of oral cancer.

Hemopoiesis is thought to be regulated in part by specific, but as yet undefined, interactions between primitive hemopoietic cells and fixed, non-hemopoietic marrow elements collectively referred to as the stroma. Recently, a marrow culture system has been described that allows the maintenance of primitive human hemopoietic progenitor cells for many weeks in the absence of exogenously added hemopoietic growth factors. The formation of a heterogeneous adherent layer in which many stromal elements are found appears to be important to the maintenance of hemopoiesis in this system. As part of the overall goal of delineating the cellular and molecular interactions involved, my first objective was to develop an experimental system for assessing the hemopoiesis-sustaining function of the adherent layer of long-term human marrow cultures. This required the identification of a suitable procedure for separating the hemopoietic and non-hemopoietic regulatory components so that the former could be used to quantitate the function of the latter. This was achieved using irradiation to selectively inactivate residual hemopoietic cells in long-term culture adherent layers, and using a medium containing cis-4-hydroxy-L-proline to selectively inactivate stromal cells and their precursors present in suspensions of unseparated human marrow which were then added back in co-culture experiments. My second objective was to develop a strategy for obtaining purified populations of cells corresponding to the various mesenchymal cell types in long-term adherent layers. I therefore prepared a high titre SV-40 virus stock and used it to establish permanent, cloned lines from human marrow "fibroblast" colonies, long-term culture adherent layers, and umbilical cord endothelial cells. Characterization of the transformants generated showed that they were all positive for SV-40, and in general expressed the phenotypic characteristics of the cells originally infected. Functional studies showed that these transformants, like their normal counterparts, respond to activation by producing two types of hemopoietic growth factors. These studies suggest that marrow mesenchymal cells may regulate the growth and maintenance of primitive hemopoietic cells by producing hemopoietic growth factors in response to appropriate perturbation. The availability of permanent cloned lines of human marrow stromal cells should facilitate future analysis of these events at the molecular level.
Medicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate

Reactive Oxygen Species (ROS) are known as important intracellular signaling molecules. These are also well known for their role in oxidative stress and cellular damage, leading to their involvement in several pathologies. Despite the widespread postulation of ROS mechanisms, little is actually known about the immediate response in living cells to the generation of these highly reactive compounds. The development of nanoplatforms incorporating photosensitizers would permit the generation of ROS at specific sub-cellular locations and determine the in situ cellular response. The work presented in this thesis describes the development of porphyrinic nanoplatforms for the controlled generation of ROS and investigates their impact on the surface marker expression of human Mesenchymal Stem Cells (hMSCs). Surface tailoring of polyacrylamide nanoparticles with alkyne and amine functionalities were exploited to achieve stable reactive chemical groups for further conjugation. Nanoplatforms surface was also modulated with trimethylammonium functionalities for the development of nanosystems for sub-cellular targeting and facilitated uptake. Physicochemical characterization of alkyne and alkyne/trimethylammonium functionalised constructs showed sizes in the range of 40 nm with a positive surface charge. Alkyne/trimethylammonium nanosystemswere found to be stable over long periods of time, whilst amino functionalized nanosystems were found to be prone to aggregation. Mechanisms of conjugation were exploited to create covalent linkage of porphyrinic photosensitizers to mono and dually functionalised constructs. Conjugation through "click chemistry" allowed stable coupling with alkyne and alkyne/trimethylammonium nanosystems. To overcome aggregation associated with amino functionalised nanoplatforms, porphyrin conjugated monomers were synthesised which resulted in stable polyacrylamide nanoparticles. The developed conjugated nanosystems showed final sizes in the range 40-100 nm, while conjugates with surface charges greater than + 20 mV have led to sizes higher than 100 nm. The effect of surface charge on cellular delivery was investigated and nanosystems with a surface charge in the range + 13 mV to + 18 mV proved optimal in terms of cell delivery and viability. It was found that highly charged nanosystems (above + 20 mV) remained attached to the cellular membrane and had a negative effect on cell viability. In addition, intracellular co-localisation studies showed preferential mitochondrial targeting of the delivered nanosystems. Production of ROS in nanoparticle treated hMSCs was achieved by exposure to light at wavelength of 575 nm. For porphyrin conjugated nanosystems a single light dosage resulted in a "blast zone" in the irradiated area where significant production of hydrogen peroxide was also observed. Titration of the amount of porphyrin conjugated at the surface of nanoparticles resulted in systems with different levels of ROS production. Control of ROS generation allowed development of a nanoplatform that was used to expose cells to repeated exposure of ROS over a time period of 100 minutes. The surface marker expression of hMSCs treated with porphyrin conjugated nanosystems was investigated. In the absence of light the surface marker expression of hMSCs was maintained, positive for CD29 and CD105 and negative for CD34 and CD45. Increased generation ROS in hMSCs did not produce alterations in the surface marker expression of cells, and over two generations of treated cells (light and nanoparticles) no changes were detected in surface marker expression. The developed nanoplatforms have the potential to be applied as a tool to investigate the cellular mechanisms and metabolism associated with different levels of oxidative stress. In addition, these nanosystems could also represent an innovative platform for theranostic applications (drug delivery/diagnostic).

The Wharton’s Jelly (WJ) of human umbilical cord (HU) contains multipotent stem cells (WJ-MSC) which express mesenchymal markers but not hematopoietic markers. WJ-MSC are increasingly being tested for use in stem cell therapy, with intravenous delivery being the preferred route. Fetal stem cells from embryonic germ layers are present in maternal blood and can home to damaged maternal tissues. This study investigates how WJ-MSC cross the fetal and adult endothelial barriers; including the cellular and molecular mechanisms employed. WJ-MSC were isolated from HU (n=27) which were taken from normal term pregnancies after elective Caesarean section. Flow cytometry and immunofluorescence were used to check presence/absenc of mesenchymal versus haematopoietic markers. Cells were induced to become adipocytes, chondrocytes and osteocytes by using specific induction medium. Isolated WJ-MSC were added after labelling with PKH26 to confluent monolayers of isolated human umbilical vein endothelial cells (HUVEC) or commercially bought human uterine microvascular endothelial cells (HUtMEC) at a 1:5 ratio. Cell-cell interactions were monitored with real time microscopy for 24 to 40h. Fluorescence and confocal scanning microscopy, after vascular endothelial (VE) cadherin immunocytochemistry were used for detailed analysis of VE-cadherin junctional occupancy and spatio-temporal location of stem cells. Tyrosine phosphorylation status of VE-cadherin, whether at Tyr685 or Tyr731, at different time points were investigated by immunoblotting whilst levels of vascular endothelial growth factor (VEGF) in the conditional media (CM) were measured by ELISA. Three different isolates were tested, with 3 experimental repeats for all expermints. Statistical analyses were performed with ANOVA (One or Two way). Cells (>95%) from each passage were positive for the mesenchymal markers CD 29, CD 105, CD 90, CD 73 and CD 44. <2% cells showed positivity to the haematopoietic markers CD 34, HLA-DR, CD 14, CD 19 and CD 45. WJ-MSC differentiated into adipocytes, osteocytes and chondrocytes. WJ-MSC displayed exploratory behaviour for a minimum of 30 min on HUtMEC or 60 min on HUVEC with interrogation of paracellular openings before crossing rather than replacing endothelial cells. By 2h, half were found at sub-endothelial positions, with a majority reaching this within 16-22h. There was accompanying loss of junctional VE-cadherin (64.9 + 3.7 %; p<0.001 in HUVEC; 63 + 4.6%; p< 0.001 in HUtMEC) in the endothelial monolayers followed by a return at 16h and increased continuity by 22h (p<0.01 in HUVEC; p<0.001 in HUtMEC). Junctional disruptions were found close to overlying or migrating WJ-MSC. Confocal microscopy confirmed paracellular extravasation. VE-cadherin protein levels matched controls in the early hours (0-2h) and increased after 22h co-culture in both fetal and uterine endothelium. VE-cadherin showed a 2-fold increase in phosphorylation at Tyr685 from 30 min to 2h. P-Tyr731 remained unchanged, similar to untreated endothelial layers, then decreased at 2h and 22h. VEGF levels in WJ-MSC – HUtMEC co-culture supernatants was highest at 2h (88 + 3 pg/ml) and decreased by 22h, reaching negligible levels by 48h. Anti-VEGF blocked Tyr685 phosphorylation but did not affect the decrease in P-Tyr731; this was accompanied by a 25% decrease in transmigration of cells in the first two hours and a 43% decrease in total by 22h. in WJ-MSC – HUtMEC co-cultures. However, in HUVEC-WJ-MSC co-cultures, no VEGF were detected and anti-VEGF did not block Tyr685 phosphorylation and Tyr731 de-phosphorylation. WJ-MSC from term umbilical cords can be easily isolated and expanded in culture. They retain mesenchymal stem cell properties for the passages tested (up to P5) making them a valuable model for studies into mechanisms underlying extravasation. The data obtained suggest that WJ-MSC can influence expression of VE-cadherin, with perturbation during transmigration followed by upregulation and repair once the adlumenal side is reached. There was a similarity in the cellular and molecular mechanisms employed by WJ-MSC in their paracelluar migration across fetal and uterine endothelium, although VEGF may not be the key player in HUVEC interactions. For both endothelial types, WJ-MSC appear to induce phosphorylation events linked with paracellular permeability and de-phosphorylation events normally associated with leukocyte extravasation. The data from the uterine endothelial investigations suggests that fetal stem cells are able to influence paracellular junctional dynamics and strengthens the growing hypothesis that they may also play a role in re-modelling the uterine circulation for fetal advantage. The extra-embryonic WJ-MSC holds the promise of use in restoring junctional maturity and vascular repair in future therapeutic applications.

La glycylation, une modification post-traductionnelle des microtubules, est cruciale dans le maintien des cils primaires. Notre groupe a précédemment identifié un rôle inattendu de la tubuline glycylase TTLL3 dans la régulation de l'homéostasie du colon et de la tumorigénèse. Plus précisément, une diminution du nombre de cils primaires a été observée chez les souris déficientes pour la glycylase TTLL3, qui est la seule glycylase exprimée dans le côlon. Les souris TTLL3 - / - ne présentent pas d'anomalie évidente à l'état stationnaire. Cependant, lorsqu'elles sont exposées à une carcinogenèse du côlon chimiquement induite, les souris TTLL3 - / - sont plus sensibles à la formation de tumeurs. Il est important de noter que les niveaux d'expression de TTLL3 sont significativement réduits dans les carcinomes primaires et métastases colorectales chez l'homme comparativement au tissu de côlon sain, ce qui suggère un lien entre la régulation des cils primaires par TTLL3 et le développement du cancer colorectal.L'objectif de mon projet de thèse était d'explorer l’effet de la modulation des cils primaires sur la carcinogenèse du côlon. J’ai ainsi démontré que le nombre de cils primaires diminue lors de la carcinogenèse du côlon chimiquement induite chez la souris. Notamment, j'ai découvert que les cils primaires du côlon sont principalement exprimés par les cellules mésenchymateuses. Pour mieux caractériser le rôle des cils primaires dans le côlon murin, j'ai étudié les conséquences de leur perte dans les cellules mésenchymateuses intestinaux. Pour cela, j'ai utilisé deux modèles de souris KO conditionnelles, pour la kinesin-3A (Kif3A) et le transport intra-flagellaire 88 (Ift88), deux molécules essentielles pour la formation des cils. Leur délétion spécifique dans les cellules mésenchymateuses intestinaux est obtenue par croisement des souches de souris Kif3Afl/fl et Ift88fl/fl des souris transgéniques collagène VI-cre. Bien que le promoteur colllagène VI ne soit actif que dans un sous-ensemble de cellules mésenchymateuses coliques, j'ai constaté que la diminution du nombre de cils primaires dans ces derniers favorise la colite chimiquement induite et la carcinogenèse. L'analyse par séquençage ARN des cellules mésenchymateuses coliques isolés de souris mutantes suggère un déclenchement de la signalisation Wnt et Notch chez les souris ColVIcre-Kif3Afl/fl. Nous confirmons actuellement ces résultats par qPCR et immunohistochimie
Glycylation, a posttranslational modification of microtubules, is crucial in the maintenance of PC. Our group previously identified an unexpected role of the tubulin glycylase TTLL3 in the regulation of colon homeostasis and tumorigenesis. Specifically, a decreased number of primary cilia (PC) was observed in mice deficient for the glycylase TTLL3, which is the only glycyclase expressed in the colon. TTLL3-/- mice display no obvious abnormalities in the steady state. However, when exposed to chemically induced colon carcinogenesis, TTLL3-/- mice are more susceptible to tumor formation. Importantly, TTLL3 expression levels were significantly downregulated in human primary colorectal carcinomas and metastases as compared to healthy colon tissue, suggesting a link between TTLL3 regulation of PC and colorectal cancer development.The aim of my thesis project was to explore the relation of PC and colon carcinogenesis. In fact, I could demonstrate that the number of PC decreases during chemically induced colon carcinogenesis in mice. Notably, I discovered that PC in the colon are mostly expressed by fibroblasts. To better characterize the role of PC in murine colon, I studied the consequences of a loss of PC in intestinal fibroblasts. For this, I used two independent ciliary conditional knockout mice, kinesin-3A (Kif3A) and intraflagellar transport 88 (Ift88), both essential for cilia formation. Specific deletion in intestinal fibroblasts is obtained by crossing with colVI-cre transgenic mice. Though the colVI promoter is only active in a subset of colonic mesenchymal cells I found that the decreased number of PC in colonic mesenchymal cells promotes chemically induced colitis and carcinogenesis. RNAseq on isolated colonic mesenchymal cells of mutant mice suggests a triggering of Wnt and Notch signaling in ColVIcre-Kif3aflx/flx mice. We are presently validating these findings by qPCR and immunohistochemistryTaken together, I discovered that PC are expressed by at least a subset of colonic mesenchymal cells, which has not been described before. Decreased numbers of those PC renders mice more susceptible to colitis and colitis associated carcinogenesis

Bone marrow mesenchymal stem cells (BM-MSCs) are pluripotent cells that can differentiate into a variety of non-hematopoietic tissues. They also maintain healthy heamatopoiesis by providing supportive cellular microenvironment into BM. In this thesis, MSCs were characterized in terms of their morphological, immunophenotypical and differentiation properties. Then, they were examined by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy together with hierarchical clustering, and FTIR microspectroscopy. In the first part of this study, global structural and compositional changes in BM-MSCs during beta thallasemia major (

Les vésicules extracellulaires nanométriques (nEVs) issues de cellules souches mésenchymateuses (CSMs) et les nanovésicules synthétiques sont au centre de nombreuses recherches pour le développement de nouvelles stratégies thérapeutiques en médecine régénérative. La mise en place d’une méthode standardisée pour isoler les nEVs à partir de milieu conditionné de CSMs et de pouvoir les caractériser a été nécessaire. Nous nous sommes concentrés sur leur taille qui se situe entre 30 et 150 nm ainsi que la présence de certains de leur marqueurs membranaires (CD9, CD63 et CD81). Durant ce travail, deux méthodes d’isolement ont été testées. Les résultats obtenus par les analyses physiques (Nanosight®, microscopie électronique à transmission) et biologiques (cytométrie en flux) des différents échantillons ont permis de standardiser la méthode d’isolement des nEVs par centrifugations et ultracentrifugations successives. Ensuite, nous nous sommes intéressés à l’utilisation de ces nEVs sécrétées par les CSMs en culture cellulaire. Il a été mis en évidence que des interactions existent entre ces nEVs et des cellules endothéliales (CEs) in vitro. Ces interactions vont entraîner des modifications dans le comportement cellulaire des CEs en augmentant leur potentiel de formation de réseaux vasculaires. En parallèle de ces travaux sur les nEVs, une étude a été réalisée sur l’utilisation de nanovésicules synthétiques, des nanoliposomes (NLPs), élaborées à partir de lécithine d’agro-ressource (saumon) comme transporteur de TGF-ß1 pour une application en médecine régénérative. Après leur caractérisation physico-chimique, cette étude préliminaire a montré que ces NLPs ne présentent pas de cytotoxicité pour les CSMs in vitro. Il existe un potentiel important d’utilisation des nEVs de CSMs ainsi des NLPs pour développer de nouvelles stratégies innovantes en thérapie « cell-free » dans le domaine de la médecine régénérative
Nanoscale extracellular vesicles (nEVs) derived from mesenchymal stem cells (MSCs) and synthetic nanovesicles are at the centre of many research studies for the development of new therapeutic strategies in regenerative medicine. A standardized method was used to isolate nEVs from conditioned media of CSMs and to characterize them. We focused on their size with a range of 30 to 150 nm and the presence of some of their membrane markers (CD9, CD63 and CD81). During this work, two isolation methods were tested. The results obtained by the physical (Nanosight®, transmission electron microscopy) and biological (flow cytometry) analyses of the different samples allowed to standardize the method of isolation of the nEVs by successive centrifugation and ultracentrifugation. Then, we studied the use of these nEVs derived from MSCs in cell culture. Interactions between these nEVs and endothelial cells (ECs) have been demonstrated in vitro. These interactions lead to changes in the cellular behaviour of ECs by increasing their potential to form vascular networks. In parallel of this work on nEVs, we studied the use of synthetic nanovesicles, called nanoliposomes (NLPs) prepared from agro-resource derived lecithin (salmon) as TGF-β1 transporters for applications in regenerative medicine. After their physicochemical characterization, this preliminary study showed that these NLPs do not exhibit cytotoxicity for MSCs in vitro. There is an important potential for the use of nEVs derived from MSCs as well as NLPs to develop new cell-free therapy innovative strategies in the field of regenerative medicine

Notre équipe a développé un protocole d'ingénierie de l'organe dentaire basé sur la biomimétique et l'utilisation de cellules dentaires embryonnaires dissociées. La recherche de ressources cellulaires permettant d'éviter le recours aux cellules embryonnaire reste un défi majeur, et nécessite une meilleure connaissance des paramètres limitants. Nous avons testé les potentialités odontogènes de lignées cellulaires, dentaires ou non, embryonnaires ou adultes. Le développement dentaire étant contrôlé par des interactions réciproques entre ectomésenchyme dérivé des crêtes neurales et épithélium, ces cellules ont été réassociés à un épithélium dentaire compétent. Nous avons recherché la formation de dents in vitro et/ou après implantation chez la souris adulte et étudié un certain nombre de paramètres biologiques et techniques. Ainsi, nous avons étudié l'impact de l'âge, de la mise en culture, et de l'hétérogénéité cellulaire sur les potentialités odontogènes des cellules mésenchymateuses. Nos résultats montrent que le potentiel odontogène des différentes lignées mésenchymateuses testées pouvait être lié à l'âge des cellules et qu'il est perdu lorsque les cellules mésenchymateuses sont cultivées avant d'être ré-associées. Ceci pouvant s'expliquer par un changement phénotypique, nous avons testé un certain nombre de gènes essentiels au développement dentaire, et suivi l'expression de marqueurs de surface. Les changements observés peuvent être liés à une sélection cellulaire in vitro pouvant conduire à des modifications de l'hétérogénéité des cellules en monocouche.

The work of my thesis is the cumulative result of 6 years of research in Prof. Michael P. Sheetz laboratory at the Biological Sciences Department of Columbia University, within the collaborative framework of the Nanotechnology Center for Mechanobiology, an interdisciplinary and multi-institutional center for the study of cell mechanics, involving, among other institutions, the Applied Physics department at Columbia University, and the Schools of Medicine of University of Pennsylvania, New York University, and Mt Sinai. In Chapter 1, I provide an overview of the field of mechanobiology, with an emphasis on the implications of cell-extracellular matrix and cell-cell attachment on cell function. In Chapter 2, I present the aims of the thesis, with a focus on the two cell systems used in the projects described: human mesenchymal stem cells, and T cells. Then, Chapters 3-5 represent the main body of my thesis, where I present detailed descriptions of the projects that I worked on and that successfully made it into scientific publications or that are in preparation for publication. In Chapter 3, I analyze how matrix chemistry and substrate rigidity affect human mesenchymal stem cell morphology in the context of lineage differentiation, and speculate on potential mechanisms that cells use to sense local rigidity. In Chapter 4, I present a new substrate design that facilitates live visualization of the interface formed between a T cell and an antigen presenting cell, i.e. the immunological synapse, and discuss the impact of intercellular forces on T cell activation. In Chapter 5, I explore the molecular mechanism of Cas-L mechanical activation at the immunological synapse of T cells, and demonstrate how Cas-L regulates T cell activation in the context of an immune response. Finally, in Chapter 6, I lay down the main conclusions of the thesis, and discuss ongoing projects that directly follow up on the results of this thesis.

Mesenchymal stem cells (MSCs) are promising candidates for treating diverse inflammatory disorders due to their capacity to be immunosuppressive. This phenotype is not present at baseline but develops in response to instructive cues. To date, clinical trials use cells grown in basic culture conditions, anticipating the cells will acquire a useful phenotype in response to in vivo cues. This strategy has failed to produce any FDA approved therapies, based on inconsistent efficacy. This thesis explores whether priming MSCs prior to administration can lead to a more uniformly therapeutic phenotype, and it details the design of an optimal in vitro priming regimen. Because interferon gamma (IFN-γ) is known to induce an anti-inflammatory state in MSCs, hypoxia can confer survival benefits, and both cues coexist in known situations of immune tolerance, we hypothesized dual IFN-γ/hypoxia priming would yield a superior immunosuppressive MSC therapy. We show that priming MSCs with hypoxia or IFN-γ alone improves their ability to inhibit T-cells in vitro, but combining these cues results in additive improvements. We next characterize the proteomic and metabolomic changes MSCs undergo when exposed to single or dual IFN-γ/hypoxia priming. While IFN-γ induces MSCs to suppress inflammation and fibrosis, hypoxia leads to cell adaptations to low oxygen, including upregulation of proteins involved in anaerobic metabolism, autophagy, angiogenesis, and cell migration. Dual priming results in additive effects, with many instances of synergy. Finally, we show initial evidence that dual primed MSCs are better able to inhibit disease progression in a mouse model of acute graft-vs-host disease (GvHD).

前言：間充質幹細胞容易擴增並且能分化為成骨細胞、軟骨細胞和脂肪細胞，並且能對炎症、感染和損傷做出反應，並且遷移到相應的組織部位。這些特性使間充質幹細胞成為骨骼組織工程學中非常重要的細胞來源。外周血間充質幹細胞是一種存在於血液中的間充質幹細胞，而主要的間充質幹細胞存在與骨髓中，被稱之為骨髓間充質幹細胞。在我們實驗室之前的研究中通過DNA微陣列發現外周血間充質幹細胞中很多基因的表達與骨髓間充質幹細胞有很大區別。這其中的一些基因可能參與調控間充質幹細胞的分化和歸巢，我們從中挑選了三個變化比較明顯的基因--CRBP1, N-cadherin和 SOX11做進一步研究。本研究的目的在於研究CRBP1, N-cadherin和 SOX11在骨髓間充質幹細胞分化和遷移中的作用及相關機理。
方法：培養的骨髓間充質幹細胞來源於6-8周大小的SD大鼠。細胞的表型經過多分化潛能測試（成骨分化，成脂分化和成軟骨分化）和流式細胞儀檢驗。克隆大鼠的CRBP1, N-cadherin和SOX11基因到慢病毒載體。而且還設計了針對CRBP1和 N-cadherin的shRNA及非特異性對照shRNA。慢病毒由暫態轉染293FT細胞產生。細胞遷移實驗採用了BD Falcon的細胞遷移系統（cell culture insert）。實驗採用了定量PCR、免疫共沉澱、western雜交和雙螢光報告檢驗。對於體內實驗，細胞經感染帶有不同基因的病毒後，種植到Si-TCP材料並移植到裸鼠皮下。8周後，收集樣品進行組織學和免疫組織學分析。最後，我們建立了大鼠的股骨開放式骨折模型，並在4天后將SOX11基因修飾的間充質幹細胞通過心臟注射打到大鼠體內。4周後，收集股骨骨折樣品並進行microCT、力學測試和組織學分析。
結果：CRBP1過表達能夠促進骨髓間充質幹細胞的成骨分化潛能，並能抑制其成脂分化。進一步的機理研究表明CRBP1可以通過與RXRα的蛋白相互作用抑制RXRα誘導的β-catenin降解，從而維持β-catenin和磷酸化-ERK1/2在較高的水準，導致間充質幹細胞成骨能力增強；N-cadherin過表達可以促進間充質幹細胞的遷移，但是卻通過下調β-catenin和磷酸化ERK1/2抑制其成骨分化。過表達SOX11可以通過增強BMP信號通路促進三系分化。SOX11還可以通過啟動CXCR4的表達來促進細胞遷移。最後，在大鼠的股骨開放骨折模型上通過系統注射，我們證明穩定過表達SOX11的間充質幹細胞遷移到骨折部位的數量明顯增加。這些細胞到達骨折部位以後可以起始骨痂的鈣化，促進骨折的修復。
結論：本研究證明CRBP1, N-cadherin 和SOX11具有調節骨髓間充質幹細胞遷移和/或分化的功能。這些基因也許會成為幹細胞治療的新靶點。系統注射SOX11基因修飾的骨髓間充質幹細胞對於骨折修復可能具有較好的療效。本研究初步研究了CRBP1, N-cadherin 和SOX11在間充質幹細胞中的作用，為探討以間充質幹細胞為基礎的組織工程的某些新臨床應用提供了一些線索。
Introduction: Mesenchymal stem cells (MSCs) can be easily harvested, expanded, and have the capability of differentiating into osteoblasts, chondrocytes and adipocytes, and they can home to various tissues in response to stimuli such as inflammation, infection and injuries. MSCs are therefore valuable cell source for musculoskeletal tissue engineering. Peripheral blood-derived MSCs (PB-MSCs) are one kind of MSCs that reside in peripheral blood, whereas the main source of MSCs is bone marrow-derived MSCs (BM-MSCs). In our previous study, we found many genes were differentially expressed in the PB-MSCs compared to their counterpart BM-MSCs demonstrated by microarray analysis, among which the effects of CRBP1, SOX11 and N-cadherin on MSCs in terms of migration and differentiation are studied.
Methods: BM-MSCs and PB-MSCs were cultured from 6-8 weeks SD rats. The phenotypes of MSCs were characterized by tri-lineage (adipo-, osteo- and chondrogenic) differentiation and flow cytometry analysis. The genes encoding rat CRBP1, SOX11 and N-cadherin were cloned into lentiviral vectors respectively. shRNAs targeting CRBP1, N-cadherin, and one nonspecific shRNA were designed. Pseudo-lentivirus was produced by transient transfection of 293FT cells. Cell migration was examined using transwell insert culture system. Quantitative RT-PCR, CO-IP, western blot and dual-luciferase assay were employed in the studies. For in vivo study, MSCs transduced with different genes were seeded on Si-TCP scaffolds and implanted subcutaneously in nude mice. 8 weeks later, the samples were collected for histological and immunohistological analysis. Finally, an open femoral fracture model was established in 8-week old SD rats, SOX11-modified MSCs were injected at four days after fracture. At 4-week after MSCs injection, the femurs were collected for microCT, mechanical test and histological analysis.
Results: For CRBP1gene, our results showed that CRBP1 overexpression promoted osteogenic differentiation of BM-MSCs, while inhibited their adipogenic differentiation. We demonstrated that CRBP1 promoted osteogenic differentiation by inhibiting RXRα-induced β-catenin degradation through physical interactions, and maintaining β-catenin and pERK1/2 at higher levels. For N-cadherin gene, we found that N-cadherin overexpression promoted MSCs migration, and suppressed osteogenic potential of MSCs through inhibiting ERK and β-catenin signaling pathways. For SOX11 gene, we demonstrated that SOX11 overexpression enhanced the adipo-, osteo- and chondrogenic differentiation of BM-MSCs, through enhancing BMP signaling pathways. The migration capacity of BM-MSCs was also enhanced when Sox-11 was overexpressed, through activating CXCR4 expression. Finally, in the open femur fracture model we demonstrated that a larger number of SOX11-overexpressing BM-MSCs migrated to the fracture site, initiated earlier callus ossification and improved bone fracture healing quality.
Conclusions: This study demonstrated that CRBP1, N-cadherin and SOX11 gene can regulate the migration and/or differentiation potentials of BM-MSCs. These genes may become new therapeutic targets in stem cell therapy applications. Systemic administration of genetically modified SOX11-overexpressing BM-MSCs may be useful in promoting fracture healing. Overall, this study defined some unknown functions of CRBP1, N-cadherin and SOX11 in MSCs and shed the lights on some novel therapeutic implications for MSCs-based tissue engineering.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Xu, Liangliang.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 128-144).
Abstract also in Chinese.
Declaration --- p.i
Abstract --- p.ii
摘要 --- p.v
Acknowledgements --- p.vii
Chapter 1 --- p.1
Introduction --- p.1
Chapter 1.1 --- Mesenchymal stem cells --- p.2
Chapter 1.1.1 --- Characteristics of mesenchymal stem cells --- p.2
Chapter 1.1.2 --- Bone marrow- and peripheral blood-derived MSCs --- p.4
Chapter 1.1.3 --- Other tissue-derived MSCs --- p.5
Chapter 1.2 --- Adipogenesis of MSCs --- p.6
Chapter 1.3 --- Chondrogenesis of MSCs --- p.7
Chapter 1.4 --- Osteogenesis of MSCs --- p.8
Chapter 1.4.1 --- Regulators of osteogenesis --- p.9
Chapter 1.4.2 --- Stratergies for improving bone tissue engineering --- p.11
Chapter 1.5 --- Signaling pathways involved in osteogenesis --- p.13
Chapter 1.5.1 --- ERK signaling pathway --- p.14
Chapter 1.5.2 --- Wnt signaling pathway --- p.15
Chapter 1.5.3 --- BMP signaling pathway --- p.17
Chapter 1.6 --- Migration of MSCs --- p.20
Chapter 1.7 --- Fracture healing --- p.22
Chapter 1.8 --- Clinical application of MSCs --- p.23
Chapter 1.8.1 --- BM-MSCs vs. PB-MSCs --- p.24
Chapter 1.8.2 --- Autologous vs. Allogeneic MSCs transplantation --- p.25
Chapter 1.9 --- Scope of the present study --- p.26
Chapter 1.9.1 --- CRBP1 --- p.26
Chapter 1.9.2 --- N-cadherin --- p.27
Chapter 1.9.3 --- SOX11 --- p.27
Chapter 1.10 --- Experimental scheme --- p.29
Chapter 2 --- p.31
Comparison between PB-MSCs and BM-MSCs --- p.31
Chapter 2.1 --- Chapter introduction --- p.32
Chapter 2.2 --- Materials and methods --- p.33
Chapter 2.2.1 --- Cell culture --- p.33
Chapter 2.2.2 --- Flow cytometry --- p.33
Chapter 2.2.3 --- Adipogenic differentiation --- p.34
Chapter 2.2.4 --- Osteogenic differentiation --- p.34
Chapter 2.2.5 --- RNA Extraction and Real-time PCR --- p.34
Chapter 2.3 --- Results --- p.35
Chapter 2.3.1 --- Morphology of PB-MSCs --- p.35
Chapter 2.3.2 --- Cellular surface markers of BM-MSCs and PB-MSCs --- p.36
Chapter 2.3.3 --- Multi-differentiation potential of BM-MSCs and PB-MSCs --- p.38
Chapter 2.3.4 --- Target genes expression in BM-MSCs and PB-MSCs --- p.39
Chapter 2.4 --- Discussion and future work --- p.40
Chapter 3 --- p.41
Role of CRBP1 in Differentiation and Migration of MSCs --- p.41
Chapter 3.1 --- Chapter introduction --- p.42
Chapter 3.2 --- Materials and methods --- p.46
Chapter 3.2.1 --- Chemicals --- p.46
Chapter 3.2.2 --- Isolation and culture of BM-MSCs --- p.46
Chapter 3.2.3 --- RNA Extraction and Real-time PCR --- p.47
Chapter 3.2.4 --- Plasmid construction, transfection, production of lentivirus and infection --- p.48
Chapter 3.2.5 --- Osteogenic differentiation --- p.50
Chapter 3.2.6 --- Adipogenic differentiation --- p.50
Chapter 3.2.7 --- Western blot --- p.51
Chapter 3.2.8 --- Immunofluorescence labeling and fluorescence microscopy --- p.52
Chapter 3.2.9 --- Cell migration assay --- p.52
Chapter 3.2.10 --- Ectopic bone formation assay --- p.52
Chapter 3.2.11 --- Statistical analysis --- p.53
Chapter 3.3 --- Results --- p.53
Chapter 3.3.1 --- Transducing BM-MSCs with lentivirus carrying CRBP1 or shRNAs --- p.53
Chapter 3.3.2 --- CRBP1 accelerates osteogenesis of BM-MSCs via enhancing ERK1/2 and β-catenin pathways --- p.56
Chapter 3.3.3 --- CRBP1 stabilizes β-catenin by inhibiting RXRα-induced degradation --- p.58
Chapter 3.3.4 --- CRBP1 inhibits adipogenesis of BM-MSCs --- p.61
Chapter 3.3.5 --- CRBP1 overexpression has no effect on MSCs migration potential --- p.63
Chapter 3.3.6 --- CRBP1 promotes ectopic bone formation in vivo --- p.64
Chapter 3.4 --- Discussion --- p.66
Chapter 3.5 --- Future work --- p.73
Chapter 4 --- p.74
Role of N-cadherin in Differentiation and Migration of MSCs --- p.74
Chapter 4.1 --- Chapter introduction --- p.75
Chapter 4.2 --- Materials and methods --- p.78
Chapter 4.2.1 --- Chemicals --- p.78
Chapter 4.2.2 --- Isolation and culture of BM-MSCs --- p.78
Chapter 4.2.3 --- Plasmid construction, transfection, production of lentivirus and infection --- p.79
Chapter 4.2.4 --- Osteogenic differentiation and ALP activity assay --- p.81
Chapter 4.2.5 --- Western blot --- p.81
Chapter 4.2.6 --- Ectopic bone formation assay --- p.82
Chapter 4.2.7 --- Statistical analysis --- p.82
Chapter 4.3 --- Results --- p.83
Chapter 4.3.1 --- Expression of N-cadherin during osteogenesis in MSCs --- p.83
Chapter 4.3.2 --- N-cadherin overexpression inhibits osteogenesis through suppressing β-catein and ERK1/2 signaling pathways --- p.84
Chapter 4.3.3 --- N-cadherin silencing increases osteogenesis through enhancing β-catenin and ERK1/2 signaling pathways --- p.86
Chapter 4.3.4 --- N-cadherin promotes migration of MSCs --- p.87
Chapter 4.3.5 --- Cellular surface markers of SV40-immortalized MSCs --- p.89
Chapter 4.3.6 --- N-cadherin inhibits ectopic bone formation in vivo --- p.89
Chapter 4.4 --- Discussion --- p.91
Chapter 4.5 --- Future work --- p.94
Chapter 5 --- p.96
Role of SOX11 in Differentiation and Migration of MSCs --- p.96
Chapter 5.1 --- Chapter introduction --- p.97
Chapter 5.2 --- Materials and methods --- p.105
Chapter 5.2.1 --- Plasmid construction, transfection, production of lentivirus and infection --- p.105
Chapter 5.2.2 --- Cell culture --- p.106
Chapter 5.2.3 --- Luciferase reporter gene assay --- p.106
Chapter 5.2.4 --- Osteogenic differentiation and ALP activity assay --- p.106
Chapter 5.2.5 --- Adipogenic differentiation --- p.107
Chapter 5.2.5 --- Chondrogenic diffferentiation --- p.107
Chapter 5.2.6 --- Western blot --- p.108
Chapter 5.2.7 --- RNA Extraction and Real-time PCR --- p.108
Chapter 5.2.8 --- Cell migration --- p.110
Chapter 5.2.9 --- Ectopic bone formation --- p.110
Chapter 5.2.10 --- Fracture healing model and analysis --- p.111
Chapter 5.2.11 --- Statistical Analysis --- p.112
Chapter 5.3 --- Results --- p.112
Chapter 5.3.1 --- SOX11 is upregulated during osteogenesis of BM-MSCs --- p.112
Chapter 5.3.2 --- SOX11 promotes adipogenesis in BM-MSCs --- p.113
Chapter 5.3.3 --- SOX11 promotes migration of BM-MSCs --- p.114
Chapter 5.3.4 --- SOX11 promotes osteogenesis in BM-MSCs --- p.115
Chapter 5.3.5 --- SOX11 promotes chondrogenesis of MSCs --- p.117
Chapter 5.3.6 --- Mechanisms of how SOX11 regulates differentiation and migration of MSCs --- p.118
Chapter 5.3.7 --- SOX11-modified MSCs promote bone fracture healing in an open femur fracture rat model --- p.122
Chapter 5.4 --- Discussion --- p.126
Chapter 5.5 --- Future work --- p.131
Appendix --- p.153