Ischaemic stroke is a major cause of mortality and chronic disability for which there is no effective treatment. The subventricular zone (SVZ) is an adult neurogenic niche which mediates limited endogenous repair following stroke. To harness this phenomenon for therapy, it is important to understand how the SVZ niche is altered in stroke, and the processes that recruit neural precursors to the site of injury, which becomes a de facto neurogenic niche. Galectin-3 (Gal-3) is a β-galactoside binding protein involved in cellular adhesion, inflammation and tumour metastasis. Gal-3 is specifically expressed in the SVZ and maintains neuroblast migration to the olfactory bulb, although its role in post-stroke neurogenesis is not well-understood. Therefore, this project aimed to (1) characterise the cytoarchitecture of the SVZ in response to stroke, and (2) examine the role of Gal-3 in stroke outcome and tissue remodelling, and test the hypothesis that Gal-3 is required for neuroblast ectopic migration into the ischaemic striatum. Using the intraluminal filament model of middle cerebral artery occlusion (MCAO) in mice, and whole mounts of the lateral ventricular wall, significant SVZ reactive astrocytosis and increased vascular branching were observed, thereby disrupting the neuroblast migratory scaffold. Stroke increased SVZ cell proliferation without increase in cell death. Post-stroke ependymal cells were enlarged and non-proliferative, and assumed a reactive astroglial phenotype, expressing de novo high levels of glial fibrillary acidic protein. This was associated with focal planar cell polarity misalignment, and turbulent and decreased rate of cerebrospinal fluid flow. These findings demonstrate significant changes in multiple SVZ cell types which are positioned to influence post-stroke neurogenesis and regulation of the neural stem cell niche Gal-3 was up-regulated in the ischaemic brain and ipsilateral SVZ. To elucidate the role of Gal-3 after stroke, MCAO was performed in wildtype and Gal-3 null (Gal-3^-/-) mice, and parameters of stroke outcome and post-stroke neurogenesis compared. The deletion of Gal-3 did not affect infarct volumes or neurological outcomes, although neuroblast migration into the ischaemic striatum was increased in Gal-3^-/- brains. Gal-3^-/- mice failed to mount an angiogenic response in the ischaemic striatum, and this was associated with lower levels of vascular endothelial growth factor (VEGF) and increased anti-angiogenic protein levels. Loss of Gal-3 further disrupted the pro-proliferative neural-vascular interaction at the basement membrane. The current data indicate that Gal-3 is a pleiotropic molecule which has distinct roles in both the SVZ and the post-stroke striatum as niches of adult neurogenesis.

A Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree Of Master of Science in Medicine, 2016. / Dental stem cells (DSCs) have been identified in teeth and their supporting tissues. They represent an exclusive source of adult stem cells, easily isolated and manipulated for tissue repair and regeneration. This research project evaluated the neurogenic potential of the dental pulp stem cells (DPSCs) and stem cells from the pulp of human exfoliated deciduous teeth (SHEDs) in a South African cohort. Sixty non-carious permanent and deciduous teeth were extracted from healthy patients aged between 18 and 30 years and 5 and 10 years, at the University of the Witwatersrand's Oral Health Clinic in Johannesburg Charlotte Maxeke Academic Hospital, South Africa. The cells, isolated from the extracted pulp tissue were cultured, counted and then phenotyped by flow cytometry analysis. The cells were further expanded in a neural induction medium and immunocytochemistry analysis for Ki-67, doublecortin (DCX) and nestin were performed. Large colonies of both DPSCs and SHEDS were harvested from the extracted pulp tissues and positively cultured. Flow cytometry analysis confirmed the presence of CD44+ and CD29+ cells as well as the known mesenchymal stem cell markers CD90 and CD105. Both DPSCs and SHEDs demonstrated successful proliferation and neural differentiation. This study confirmed that DPSCs and SHEDs are highly proliferative human adult stem cells that exhibit a neurogenic potential that may contribute in the treatment of neurological disorders. / AC2017

Introdução. A possiblidade de restauração do Sistema Nervoso Central representa um desafio em Neurociências, e a integração bem sucedida de células-tronco no cérebro adulto tem se tornado um importante objetivo. Objetivo. Testar a hipótese de que a sobrevivência e diferenciação de células-tronco mesenquimais (CTMs) sejam dependentes de condições microambientais de acordo com o alvo de implante no cérebro. Métodos. CTMs foram isoladas de ratos adultos e geneticamente modificadas por meio de transfecção lentiviral para expressarem GFP. O fenótipo neuronal foi satisfatoriamente induzido in vitro. Uma suspensão de células foi implantada estereotaxicamente no cérebro de 40 ratos da mesma linhagem, em uma área neurogênica (hipocampo) e outra não-neurogênica (estriado). Os animais foram sacrificados 6 e 12 semanas após a cirurgia, e os cérebros foram corados com marcadores de neurônios maduros. Células co-expressando NeuN e GFP foram contadas estereologicamente nos dois alvos. Resultados. A população de célula isolada foi capaz de gerar 14,5 ± 1,1 % de neurônios NF200-positivos in vitro. Uma vez implantados no hipocampo, as células migraram além do enxerto e geraram neurônios maduros (1634±231 células GFP/NeuN+). Por outro lado, maciça degeneração celular foi vista no estriado, onde não ocorreu migração significativa, sendo que somente 108±24 NeuN/GFP+ neurônios (p<0.001) foram contados. Conclusão. Nossos dados demonstraram que a sobrevivência e diferenciação de CTMs são altamente dependentes do sítio de implante no cérebro hospedeiro, indicando assim a importância de um microambiente permissivo. Futuros estudos para identificação dos fatores pró-neurogênicos presentes no hipocampo poderão subsequentemente permitir a integração de células-tronco em áreas do SNC nãopermissivas, assim contribuindo para se alcançar o objetivo de introduzir a restauração do SNC na prática clínica. / The possibility of CNS restoration represents a challenge in Neuroscience, and the successful integration of stem cells in adult brain has become an important goal. The working hypothesis of the present study is that survival and neurodifferentiation of mesenchymal stem cells (MSCs) may be dependent upon microenvironmental conditions according to the site of implant in the brain. Methods: MSCs were isolated from adult rats and labeled with eGFP lentivirus. The neuronal phenotype was successfully induced in vitro. A cell suspension was implanted stereotactically into the brain of 40 young rats of the same strain, in neurogenic (hippocampus) and non-neurogenic (striatum) areas. Animals were sacrificed six or twelve weeks after surgery, and brains were stained for mature neuronal markers. Cells co-expressing NeuN-GFP were counted stereologically at both targets. Results: The isolated cell population was able to generate 14.5±1.1% of NF200+-neurons in vitro. Once implanted into the hippocampus, cells migrated away from the graft and gave rise to mature neurons (1634±231 cells GFP/NeuN+). By contrast, massive cell degeneration was seen in the striatum, with no significant migration, while only 108±24 NeuN/GFP+ neurons (p<0.001) were counted. Conclusions: Our data demonstrated that survival and differentiation of MSCs are strongly dependent upon the site of implant in the brain, thus indicating the importance of a permissive microenvironment. Future studies for identification of the pro-neurogenic factors present in the hippocampus could subsequently allow the integration of stem cells into non-permissive areas of the CNS and thus contribute for the challenging goal of introducing CNS repair in the clinical practice.

A regeneração óssea é um processo fisiológico que promove a neoformação de tecido ósseo saudável e funcional com características idênticas antes da lesão. Entretanto, frente a defeitos críticos, o osso é incapaz de se regenerar espontaneamente. Diante destas deficiências, a bioengenharia de tecidos ósseos (BTO) é uma opção promissora para a regeneração deste tipo de defeito. A maioria das abordagens de BTO utiliza as células-tronco mesenquimais da medula óssea (BMSC), porém, a coleta de BMSC dos pacientes é um processo bastante invasivo e doloroso. Por estas desvantagens, a busca por abordagens acessíveis e menos invasivas de novas fontes de células-tronco (CT) se tornou necessária. Neste contexto, as células-tronco de polpa de dentes decíduos (SHED) foram identificadas e sua aplicação na BTO, desde então, vem sendo amplamente estudada devido ao seu potencial osteogênico e por se tratar de uma fonte não invasiva. A obtenção de células-tronco do músculo orbicular do lábio (OOMDSC) também não causa dor adicional aos indivíduos, pois os fragmentos deste tecido são rotineiramente descartados durante as cirurgias de reconstrução do lábio. No presente trabalho investigamos o potencial de diferenciação osteoblástico in vitro e in vivo das OOMDSC e comparamos com as SHED, além disto, associamos estas células a biomateriais de HA/&beta;-TCP e investigamos a sua contribuição na neoformação óssea in vivo. O imunofenótipo de cada amostra de SHED e OOMDSC foi verificado para certificar a identidade de CT mesenquimais. Em seguida, as células em cultura foram submetidas à diferenciação osteoblástica in vitro. Em 9 e 14 dias de diferenciação as OOMDSC apresentaram menor atividade de fosfatase alcalina (p<0,0001) e menor marcação de matriz extracelular mineralizada, comparado às SHED (p<0,001), enquanto que em 21 dias estas diferenças não foram mais observadas. Quando associadas a biomateriais e implantadas em defeitos críticos calvariais bilaterais em ratos Wistar, tanto OOMDSC e SHED foram capazes de induzir neoformação óssea após 50 dias de cirurgia, conforme evidenciado pela análise morfológica e por micro-CT. Todavia, as células ósseas encontradas nos sítios da neoformação óssea não eram de origem humana. A avaliação da neoformação óssea in vivo induzida por SHED assim como a sua distribuição no enxerto foi verificada também em 07, 15 e 30 dias pós-cirúrgicos. Nestes períodos não há evidência de neoformação óssea, entretanto, as SHED estão localizadas no tecido conjuntivo que se forma e preenche o enxerto. Além disto, os dados sugerem que estas células estão relacionadas à modificações na microarquitetura do biomaterial e ainda à modulação dos números dos osteoclastos, também verificada nestas amostras. Portanto, podemos concluir que as OOMDSC são tão capazes de se diferenciar em osteoblastos quanto às SHED in vitro, porém esta diferenciação é mais lenta. Os experimentos in vivo indicam que as SHED possuem maior capacidade de indução à neoformação óssea quando comparadas às OOMDSC e que, em nosso modelo, as CT humanas não se diferenciam em osteoblastos in vivo. De qualquer forma a adição das CT ao biomaterial favorece a neoformação óssea, variações de microarquitetura e modulação dos osteoclastos. O fato de as ilhas ósseas não serem de origem humana indica que as células-tronco possam estar secretando fatores de indução à osteogênese, estimulando a neoformação óssea a partir das células do hospedeiro. / Bone regeneration is a physiological process, which promotes the growth of tissue at the site of injury, with the same characteristics of the original bone. However, when faced with critical defects the bone is unable to regenerate spontaneously. Bone tissue engineering (BTE) is a promising option for regenerating this type of defect. The majority of the approaches in BTE use Bone Marrow derived Mesenchymal Stem Cells (BMSC); however, the aspiration of bone marrow is a very invasive and painful procedure. Due to these disadvantages, the search for new, affordable and less invasive sources of stem cells (SC) has become necessary. In this context, stem cells from exfoliated deciduous teeth (SHED) have been identified and their application in BTE, since then, has been widely studied because they can be obtained non-invasively and due to their osteogenic potential. Stem cells from the orbicularis oris muscle (OOMDSC) are also obtained non-invasively and do not cause additional pain to individuals, because the fragments of this tissue are routinely discarded during lip reconstruction surgeries. In the present work we investigated, in vitro and in vivo, the osteoblastic differentiation potential of OOMDSC and compared with SHED; furthermore, we associated these cells with HA/&beta;-TCP scaffolds and investigate its contribution in the bone formation in vivo. The immunophenotype of each OOMDSC and SHED sample was verified to attest their mesenchymal stem cell identity. Then, cell cultures were submitted to osteoblastic differentiation in vitro. In 9 and 14 days of differentiation, OOMDSC exhibited lower alkaline phosphatase activity (p <0.0001) and lower mineralized extracellular matrix staining compared to SHED (p <0.001), whereas at 21 days, these differences were no longer observed. When associated with scaffolds and implanted into bilateral critical-sized calvarial defects in Wistar rats, both OOMDSC and SHED were able to induce bone formation after 50 days of surgery, as evidenced by morphological analysis and micro-CT. However, bone cells found at sites of bone formation were not of human origin. The evaluation of new bone formation in vivo induced by SHED as well as its distribution in the graft was performed at 07, 15 and 30 days after surgery. During these periods there was no evidence of new bone formation, however, SHED were located in the connective tissue that formed and filled the graft. Furthermore, our results suggest that these cells are related to changes in the microarchitecture of the scaffold and also to the modulation of the number of osteoclasts observed in these samples. In summary, our results suggest that OOMDSC are as capable to differentiate into osteoblasts as SHED in vitro, but this differentiation is slower. In vivo experiments indicate that SHED has a greater ability to induce bone formation when compared with OOMDSC, and that in our model, the human stem cells do not differentiate into osteoblasts in vivo. Nonetheless, the addition of SC to the scaffolds promotes bone formation, as well as variations in microarchitecture and modulation of osteoclasts. The fact that the bone islands are not of human origin indicates that the stem cells may be secreting osteogenesis-inducing factors, stimulating the host\'s cells to regenerate the defects.

A cicatrização de feridas crônicas e de defeitos complexos representam desafios para a cirurgia plástica reconstrutiva. Novos tratamentos emergiram com a utilização de células tronco mesenquimais, com especial interesse para as derivadas de tecido adiposo (CTMs-TA), por possuir algumas vantagens em relação às derivadas da medula óssea. Algumas doenças poderiam se beneficiar com o uso das CTMs-TA, em particular, as feridas de pacientes portadores de anemia falciforme que ainda representam um desafio terapêutico. Neste estudo, investigou-se a existência de possíveis áreas doadoras preferenciais de CTMs-TA no tecido adiposo (TA) por meio da comparação de aspectos qualitativos e quantitativos das CTMs-TA derivadas de cinco diferentes áreas corporais. Posteriormente, analisou-se a influência do sobrenadante dessas células, rico em citocinas e fatores de crescimento, sobre a migração de fibroblastos de indivíduos normais e de portadores de anemia falciforme in vitro. Não foram observadas diferenças qualitativas entre as CTMs-TA das cinco áreas analisadas. A região do dorso apresentou número maior de CTMs, com diferença significativa em relação à região das coxas. A adição de sobrenadante produzido por CTMs-TA demonstrou aumento da velocidade de migração dos fibroblastos de forma similar para os normais e os falciformes. O microambiente desfavorável presente nas feridas falciformes parece exercer importante influência sobre esses fibroblastos, pois uma vez corrigido o microambiente com os meios de cultivo apropriados, as células apresentaram taxa de duplicação e velocidade de migração semelhante à dos fibroblastos normais in vitro. / The healing of chronic wounds and complex defects represents challenges for reconstructive plastic surgery. New treatments have emerged with the use of multipotent mesenchymal cells, with special interest for the adipose-derived stem cells (ADSCs) as it has some advantages over the bone marrow-derived. Some diseases could benefit from the use of ADSCs, in particular, the wounds of patients with sickle cell anemia that still represent a therapeutic challenge. In this study, we investigated the existence of possible preferential donor areas of ADSCs in adipose tissue by comparing qualitative and quantitative aspects of ADSCs derived from five different body areas. Later, we analyzed the influence of the supernatant of these cells, rich in cytokines and growth factors, on the migration of fibroblasts from healthy individuals and from patients with sickle cell anemia in vitro. No qualitative differences were observed among the ADSCs of the five areas analyzed. The dorsum presented a higher number of ADSCs, with a significant difference in relation to the thigh. Addition of supernatant produced by ADSCs has been shown to increase the rate of migration of fibroblasts in a similar way to healthy and sickle cells. The unfavorable microenvironment present in sickle wounds seems to exert a significant influence on these fibroblasts because once the microenvironment was corrected with the appropriate culture media, the cells had a doubling rate and migration rate similar to normal fibroblasts in vitro.

O osteossarcoma é um tumor ósseo maligno, de maior ocorrência em cães, possui rápido crescimento e alto potencial metastático. Assim, o cão é um modelo útil para o estudo da doença em humanos, tendo em vista as semelhanças clínicas e histopatológicas que ocorrem em ambas às espécies. Atualmente, os estudos a respeito de células-tronco são promissores considerando seu alto potencial terapêutico. Entretanto, ainda prevalecem muitas dúvidas referentes ao tratamento de tumores utilizando a terapia celular. Este tema é pouco conhecido e estudado, por isso, o objetivo deste trabalho foi avaliar a interação entre células-tronco obtidas da polpa dentária canina com as células derivadas osteossarcoma canino. Foram realizados cocultivos celulares das células derivadas de polpa dentária canina, osteossarcoma canino e derivadas de osso normal canino. Analisou-se os aspectos morfológicos das células cocultivadas e controle, assim como a atividade proliferativa, a morte celular, o potencial elétrico mitocondrial e a expressão gênica. A partir dos resultados obtidos, concluiu-se que a interação entre a célula-tronco da polpa dentária canina imatura e as células de osteosarcoma canino não apresentam alterações morfológicas. Entretanto, as células-tronco derivadas da polpa dentária canina e de osso fetal canino sadio parecem servir de suporte para o crescimento tumoral. Além disso, a cocultura celular, em todos os grupos testados, promove alterações na expressão gênica e proteica. / Osteosarcoma is a malignant bone tumor most frequent in dogs. It has fast growth and high metastatic potential. Thus, the dog is an useful model for the study of human disease, due to the clinical and histological similarities found in both species. Currently, studies about stem cells are promising considering its high therapeutic potential. However, many doubts still exist regarding the treatment of tumors using cell therapy. This theme is little known and studied. Therefore, the aim of this study was to evaluate the interaction between stem cells obtained from canine immature dental pulpstem cells with osteosarcoma cells derived from dogs. Cellular coculture were performed using cells derived from canine dental pulp, canine osteosarcoma and canine normal bone. The morphological aspects of cocultured cells and control were analyzed, as well as proliferative activity, cell death, the mitochondrial membrane electric potential and gene expression. In summary, it was concluded that the interaction between stem cells from canine immature dental pulp and canine osteosarcoma cells did not show morphological changes. However, stem cells derived from canine dental pulp and healthy canine fetal bone serve to support tumor growth. Furthermore, the cell coculture in all groups tested, causes changes in gene and protein expression.

A cicatrização de feridas crônicas e de defeitos complexos representam desafios para a cirurgia plástica reconstrutiva. Novos tratamentos emergiram com a utilização de células tronco mesenquimais, com especial interesse para as derivadas de tecido adiposo (CTMs-TA), por possuir algumas vantagens em relação às derivadas da medula óssea. Algumas doenças poderiam se beneficiar com o uso das CTMs-TA, em particular, as feridas de pacientes portadores de anemia falciforme que ainda representam um desafio terapêutico. Neste estudo, investigou-se a existência de possíveis áreas doadoras preferenciais de CTMs-TA no tecido adiposo (TA) por meio da comparação de aspectos qualitativos e quantitativos das CTMs-TA derivadas de cinco diferentes áreas corporais. Posteriormente, analisou-se a influência do sobrenadante dessas células, rico em citocinas e fatores de crescimento, sobre a migração de fibroblastos de indivíduos normais e de portadores de anemia falciforme in vitro. Não foram observadas diferenças qualitativas entre as CTMs-TA das cinco áreas analisadas. A região do dorso apresentou número maior de CTMs, com diferença significativa em relação à região das coxas. A adição de sobrenadante produzido por CTMs-TA demonstrou aumento da velocidade de migração dos fibroblastos de forma similar para os normais e os falciformes. O microambiente desfavorável presente nas feridas falciformes parece exercer importante influência sobre esses fibroblastos, pois uma vez corrigido o microambiente com os meios de cultivo apropriados, as células apresentaram taxa de duplicação e velocidade de migração semelhante à dos fibroblastos normais in vitro. / The healing of chronic wounds and complex defects represents challenges for reconstructive plastic surgery. New treatments have emerged with the use of multipotent mesenchymal cells, with special interest for the adipose-derived stem cells (ADSCs) as it has some advantages over the bone marrow-derived. Some diseases could benefit from the use of ADSCs, in particular, the wounds of patients with sickle cell anemia that still represent a therapeutic challenge. In this study, we investigated the existence of possible preferential donor areas of ADSCs in adipose tissue by comparing qualitative and quantitative aspects of ADSCs derived from five different body areas. Later, we analyzed the influence of the supernatant of these cells, rich in cytokines and growth factors, on the migration of fibroblasts from healthy individuals and from patients with sickle cell anemia in vitro. No qualitative differences were observed among the ADSCs of the five areas analyzed. The dorsum presented a higher number of ADSCs, with a significant difference in relation to the thigh. Addition of supernatant produced by ADSCs has been shown to increase the rate of migration of fibroblasts in a similar way to healthy and sickle cells. The unfavorable microenvironment present in sickle wounds seems to exert a significant influence on these fibroblasts because once the microenvironment was corrected with the appropriate culture media, the cells had a doubling rate and migration rate similar to normal fibroblasts in vitro.

Baicalin, which is a flavonoid, was previously shown to exert neuroprotective effects against ischemic injury and oxidative insults. In this study, baicalin was found to induce neuronal differentiation on both C17.2 NSC and primary mouse NSC originated from hippocampuses of E14.5 mouse embryos. The baicalin-mediated differentiation of C17.2 NSC was noted in dose- and time-dependent manners. Baicalin-treated NSC displayed long processes of neurites. The gene expression of neuronal markers, NF-L, TUBB3 and MAP2 was also significantly increased after treated with 20 to 50 muM baicalin on C17.2 NSC. Treating C17.2 NSC with baicalin significantly increased the number of TUBB3 positive cells by 300%. A significant increase in the gene expression of TUBB3 was also observed on primary NSC upon baicalin treatment at 5 to 10 muM. The number of TUBB3 positive cells was increased by 100% after treating with 10 muM baicalin. C17.2 NSC treated with baicalin also increased the gene expression of GABAergic and serotonergic neuronal subtype specific enzymes GAD1 and TPH1. / Nature provides a vast pool of natural compounds with neuroprotection and neurotrophism. A few of these compounds can induce the differentiation of neural stem cells (NSC). There are ample opportunities to discover more natural compounds with differentiation inducing effect on NSC. One of the objectives of this project is to look for novel natural compounds showing neurogenic effect on NSC. This project has established a platform for screening medicinal materials and natural compounds with neural differentiation promoting effect on C17.2 mouse neural stem cell line. Screening results identified total Sanqi saponins, total Renshen saponins, Huangqin extracts and baicalin as potent candidates for inducing this differentiation of NSC. / This project also aims at characterizing the mechanisms involved in the neuronal differentiation effect of baicalin on NSC. Annotation from microarray analysis indicated that baicalin treatment on C17.2 NSC is related to development of tissue and nervous system. qPCR study attested the increased gene expression of nerve growth factor-beta, neurotrophin-3, pro-neural transcriptional factors Ngn1, Ngn2 and NeuroD2. Western blotting showed that baicalin activated ERK1/2 MAP kinase but not JNK and p38 MAP kinases. / This project demonstrated the neurogenic potential of natural resources on NSC. A novel neuronal induction effect of baicalin on NSC was also demonstrated with its mechanisms characterized. This project also revealed that baicalin can be used for promoting functional recovery of post-ischemia animals. / This study showed for the first time that baicalin exerts neuronal differentiation inducing effect on NSC. Another objective of this project is to study whether baicalin can promote functional recovery of animals with ischemia brain injury. Mice having undergone transient occlusion of the bilateral common carotid arteries with blood-reperfusion to induce global cerebral ischemia were treated with baicalin and/or EGFP-NSC. Ischemia animals received implantation of EGFP-NSC into the caudate putamen and/or intravenous injection of baicalin on alternate days for two-week on day seven post-ischemia displayed significant improvement of the cognitive function in terms of the incident of error and escape time in the water T-maze task compared to the control arm of ischemia mice. Data of the study suggested that the therapeutic effect of baicalin would be comparable to that of neural stem cell transplant in improving the cognitive function in a mouse ischemic stroke model. / Li, Ming. / Adviser: P. C. Shaw. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 199-232). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Scientific research is propelled by two objectives: Understanding and recognizing the essential biology of life, and deciphering this to uncover possible therapeutics in order to improve quality of life as well as relieve pain from disease. The aim of the work described in this thesis was to dissect the fundamental requirements of induced pluripotent stem cells both in pluripotency and differentiation with a particular focus on atrial specificity. Drug targeting of atrial-specific ion channels has been difficult because of lack of availability of appropriate cardiac cells, and preclinical testing studies have been carried out in non-cardiac cell lines, heterogeneous cardiac populations or animal models that have been unable to accurately represent human cardiomyocyte physiology. Therefore, we sought out to develop a preparation of cardiomyocytes showing an atrial phenotype with adult characteristics from human induced-pluripotent stem cells. A culture programme involving the use of Gremlin 2 allowed differentiation of cardiomyocytes with an atrial phenotype from human induced-pluripotent stem cells. When these differentiated cultures were dissociated into single myocytes a substantial fraction of cells showed a rod-shaped morphology with a single central nucleus that was broadly similar to that observed in cells isolated from atrial chambers of the heart. Immunolabelling of these myocytes for cardiac proteins (including RyR2 receptors, actinin-2, F-actin) showed striations with a sarcomere spacing of slightly less than 2um. The isolated rod-shaped cells were electrically quiescent unless stimulated to fire action potentials with an amplitude of 100 mV from a resting potential of approximately -70 mV. Proteins expressed included those for IK₁, IK_ur channels. Ca²⁺ Transients recorded from spontaneously beating cultures showed increases in amplitude in response to stimulation of adrenoceptors (both alpha and beta). With the aim of identifying key signaling mechanisms in directing cell fate, our new protocol allowed differentiation of human myocytes with an atrial phenotype and adult characteristics that show functional adrenoceptor signaling pathways and are suitable for investigation of drug effects.

Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter involved in the embryonic neural development and adult neurogenesis. But the effects of 5-HT on stem cells are not fully known. In this study, the effects and underlying signal pathways of 5- HT on proliferation and neural differentiation of mouse embryonic stem (ES) cells, neural progenitor (NP) cell line C 17.2 and embryonic neural stem (NS) cells were explored. Molecular analysis, immunostaining and western blotting revealed that NP/NB cells expressed the rate-limiting enzyme tryptophan hydroxylase (TPH) and produced endogenous 5-HT. While mouse ES cells showed no expression of TPH. Quantitative PCR demonstrated that ES cells and NPINS cells expressed majority of 5-HT receptor sUbtypes. In serum free propagation culture, WST1, BrdU incorporation and neural colony forming cell assay demonstrated that 5-HT enhanced proliferation of ES cells and NPINS cells in a dose-dependent manner. Tryptophan hydroxylase (TPH) inhibitor para-chlorophenylalanine (PCPA) which can inhibit biosynthesis of endogenous 5-HT decreased viability of mouse NP/NS cells. Mouse ES cells derived embryoid bodies (EB) and NS/NP cells were subjected to neural induction in serum-free medium with and without 5-HT or PCPA. On day 8 of EB cultures, immunofluorescence staining displayed a less percentage of SSEA-1+ cells derived from cultures supplemented with 5-HT. Nestin positivity are comparable. Quantitative PCR analysis suggested that supplement of 5-HT in EB culture inhibit neural differentiation of ES cells and induce mesodermal commitment. On day 21 of ES cells neural induction, compared to cultures without 5-HT treatment, a significantly less number of ß-tubulin III+ neurons, GEAP+ astrocytes and GaIC+ oligodendrocytes were noted in 5-HT -supplemented cultures. For NS/NP cells, the inhibitory effects of 5-HT on neuronal and oligodendrocytic commitment were also observed. And the application of PCPA exerted a promoting effect on neural differentiation of NS cells. Manipulating 5-HT level can affect the expression level of key genes which involved in 5-HT metabolism. ES and NS/NP cells treated with 5-HT showed decreased production of endogenous reactive oxygen species (ROS). 5-HT demonstrated a significant anti-apoptotic effect on NP cells and this antiapoptotic effect may be mediated by up-regulated expression of anti-apoptotic gene Bel- 2. Whole genome cDNA microarray analysis and quantitative RT-PCR revealed that notch signal pathway was involved in mediating the biological effects of 5-HT. Western blotting further confirmed that 5-HT treatment up-regulated the protein level of NICD and notch downstream effectors Hes-l and Hes-5. Finally, the therapeutic effects of ES cell-derived neural cells were testified in a mouse model of global ischemia. Two weeks post-transplantation, BrdU labeled ES cell-derived neural cells survived and migrated throughout brain parenchyma. A majority of transplanted cells remained nestin positive. The cognitive functions of cell transplanted groups showed significant recovery compared with untransplanted arms, but no significant difference was observed between transplanted groups treated with and without 5-HT. Taken together, data of this study indicated 5-HT play an important role in neural development and ES cell-derived neural cells might be applicable in the treatment of stroke. / Li, Jin. / "November 2011." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 195-241). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstracts in English. / ACKNOWLEDGEMENTS --- p.i / LIST OF PUBLICATIONS --- p.ii / ABSTRACT --- p.iii / ABSTRACT [in Chinese] --- p.v / TABLE OF CONTENT --- p.vi / LISTS OF FLOWCHARTS --- p.xii / LISTS OF FIGURES --- p.xiii / LIST OF TABLES --- p.xvi / LIST OF EQUIPMENTS --- p.xvii / LIST OF ABBREVATIONS --- p.xvii / Chapter Chapter1 --- Introduction --- p.1 / Chapter 1.1 --- Central nervous system disorder --- p.1 / Chapter 1.1.1 --- Stroke --- p.1 / Chapter 1.1.2 --- Spinal cord injuries --- p.4 / Chapter 1.1.3 --- Parkinson's disease --- p.6 / Chapter 1.1.4 --- Amyotrophic Lateral Sclerosis --- p.8 / Chapter 1.2 --- Stem cell therapy --- p.10 / Chapter 1.2.1 --- General considerations in stem cell therapy --- p.11 / Chapter 1.2.2 --- Stem cell therapy for stroke --- p.11 / Chapter 1.2.3 --- Stem cell therapy for spinal cord injury --- p.15 / Chapter 1.2.4 --- Stem cell therapy for Parkinson's disease --- p.16 / Chapter 1.2.5 --- Stem cell therapy for ALS --- p.18 / Chapter 1.3 --- Stem cells --- p.20 / Chapter 1.3.1 --- Embryonic stem cells --- p.21 / Chapter 1.3.1.1 --- Derivation and characterization --- p.21 / Chapter 1.3.1.2 --- Biology of ES cells --- p.21 / Chapter 1.3.1.2.1 --- Pluripotency of ES cells --- p.21 / Chapter 1.3.1.2.2 --- Differentiation of ES cells to multiple lineages --- p.24 / Chapter 1.3.1.2.2.1 --- Ectodermal differentiation --- p.25 / Chapter 1.3.1.2.2.2 --- Mesodermal differentiation --- p.27 / Chapter 1.3.1.2.2.3 --- Endodermal differentiation --- p.28 / Chapter 1.3.2 --- Neural stem cells --- p.30 / Chapter 1.3.2.1 --- Derivation and characterization --- p.30 / Chapter 1.3.2.2 --- Biology of NS cells --- p.32 / Chapter 1.3.3 --- Induced pluripotent stem cells --- p.34 / Chapter 1.3.4 --- Mesenchymal stem cells --- p.35 / Chapter 1.4 --- Serotonin (5-HT) --- p.36 / Chapter 1.4.1 --- Distribution --- p.37 / Chapter 1.4.2 --- Metabolism --- p.37 / Chapter 1.4.3 --- Biological effects of 5-HT --- p.38 / Chapter 1.4.4 --- Serotonin receptor subtypes and receptor signal transduction pathways --- p.40 / Chapter Chapter2 --- Aim --- p.43 / Chapter 2.1 --- Hypothesis and study objectives --- p.43 / Chapter Chapter3 --- Materials and Methods --- p.49 / Chapter 3.1 --- Chemicals and Reagents --- p.49 / Chapter 3.1.1 --- Cell culture --- p.49 / Chapter 3.1.2 --- Serotonin, serotonin receptor subtypes specific agonists/antagonists and drugs that regulate serotonin metabolism --- p.51 / Chapter 3.1.3 --- Cell proliferation assay --- p.52 / Chapter 3.1.4 --- Cell apoptosis assay --- p.52 / Chapter 3.1.5 --- Immunohistochemistry and staining --- p.52 / Chapter 3.1.6 --- Western blotting --- p.55 / Chapter 3.1.7 --- Molecular biology --- p.56 / Chapter 3.1.8 --- Whole genome cDNA micro array --- p.58 / Chapter 3.1.9 --- MAO activity assay --- p.58 / Chapter 3.1.10 --- Endogenous ROS production assay --- p.58 / Chapter 3.2 --- Consumable --- p.58 / Chapter 3.3 --- Cells --- p.60 / Chapter 3.3.1 --- Feeder cell --- p.60 / Chapter 3.3.1.1 --- Mouse embryonic fibroblasts --- p.60 / Chapter 3.3.2 --- ES cells --- p.61 / Chapter 3.3.2.1 --- ES cell D3 --- p.61 / Chapter 3.3.2.2 --- ES cell-E14TG2a --- p.61 / Chapter 3.3.3 --- NS cells --- p.61 / Chapter 3.3.3.1 --- Neural progenitor cells line C172 --- p.61 / Chapter 3.3.3.2 --- Mouse embryonic neural stem cells --- p.61 / Chapter 3.4 --- In-house prepared solutions --- p.62 / Chapter 3.4.1 --- Stock solution ofInsulin, Transferrin, Selentine (ITS) Supplement --- p.63 / Chapter 3.4.2 --- Gelatin solution 01% --- p.62 / Chapter 3.4.3 --- Paraformaldehyde solution 4% (PFA) --- p.62 / Chapter 3.4.4 --- Tritox X-lOO solution 03% --- p.63 / Chapter 3.4.5 --- Popidium iodide solution 1 ug/ml (PI) --- p.63 / Chapter 3.4.6 --- Poly-L-ornithine solution --- p.63 / Chapter 3.4.7 --- Laminin solution --- p.64 / Chapter 3.4.7 --- MEF Maintenance medium --- p.64 / Chapter 3.4.9 --- Cryopreservation Media for MEF and C172 (2X) --- p.64 / Chapter 3.4.10 --- Cryopreservation Media for mouse ES cell (2X) --- p.65 / Chapter 3.4.11 --- Cryopreservation Media for mouse NS cell (2X) --- p.65 / Chapter 3.4.12 --- Serum based maintenance medium for C172 --- p.65 / Chapter 3.4.13 --- Serum free maintenance medium for C172 --- p.66 / Chapter 3.4.14 --- Serum-based propagation medium for ES cells --- p.66 / Chapter 3.4.15 --- Serum-free propagation medium forES cells --- p.67 / Chapter 3.4.16 --- Serum-free induction medium for ES cells --- p.67 / Chapter 3.4.16.1 --- Serum-free induction medium I --- p.67 / Chapter 3.4.16.2 --- Serum-free induction medium II --- p.68 / Chapter 3.4.16.3 --- Serum-free induction medium III --- p.68 / Chapter 3.4.17 --- Tris-HCl (1 M), pH 74 --- p.68 / Chapter 3.4.18 --- Tris-HCl (1 M), pH 87 --- p.69 / Chapter 3.4.19 --- Tris-HCI (1 M), pH 69 --- p.69 / Chapter 3.4.20 --- APS 10% (wt/vol) --- p.69 / Chapter 3.4.21 --- Protease inhibitor (10X) --- p.70 / Chapter 3.4.22 --- RIPA --- p.70 / Chapter 3.4.23 --- Resolving buffer (8X) --- p.70 / Chapter 3.4.24 --- Stacking buffer (4X) --- p.71 / Chapter 3.4.25 --- Protein running buffer (lOX) --- p.71 / Chapter 3.4.26 --- Transfer buffer (10X) --- p.72 / Chapter 3.4.27 --- Transfer buffer (IX) --- p.72 / Chapter 3.4.28 --- Blocking buffer (lOX) --- p.72 / Chapter 3.4.29 --- TBS (10X) --- p.73 / Chapter 3.4.30 --- TBS-T (IX) --- p.73 / Chapter 3.4.31 --- Stacking gel --- p.73 / Chapter 3.4.32 --- Resolving gel --- p.74 / Chapter 3.5 --- Methods --- p.75 / Chapter 3.5.1 --- Cell culture --- p.75 / Chapter 3.5.1.1 --- Preparation of acid washed cover slips --- p.75 / Chapter 3.5.1.2 --- Preparation of gelatinized culture wares --- p.75 / Chapter 3.5.1.3 --- Poly-L-omithine and laminin coating --- p.76 / Chapter 3.5.1.4 --- Thawing cryopreserved cells --- p.76 / Chapter 3.5.1.5 --- Passage of culture --- p.77 / Chapter 3.5.1.5 --- 6 Cell count --- p.78 / Chapter 3.5.1.7 --- Cytospin --- p.78 / Chapter 3.5.1.8 --- Trypan blue dye exclusion test --- p.78 / Chapter 3.5.1.9 --- Cryopreservation --- p.79 / Chapter 3.5.1.10 --- Derivation and culture of mouse embryonic fibroblasts (MEF) --- p.79 / Chapter 3.5.1.11 --- Propagation of ES cells in serum-based/free medium --- p.81 / Chapter 3.5.1.12 --- Neural differentiation ofES cells --- p.83 / Chapter 3.5.1.13 --- Propagation ofNP cell C172 in serum-based or serum-free medium --- p.84 / Chapter 3.5.1.14 --- Neural differentiation ofC172 --- p.85 / Chapter 3.5.1.15 --- Derivation and propagation of embryonic NS cells --- p.85 / Chapter 3.5.1.13 --- Neural differentiation of embryonic NS cells --- p.86 / Chapter 3.5.1.17 --- BrdU labeling of the ES cells derived products --- p.87 / Chapter 3.5.2 --- Cell proliferation assay --- p.87 / Chapter 3.5.2.1 --- Cell morphology --- p.87 / Chapter 3.5.2.2 --- WST-1 assay --- p.88 / Chapter 3.5.2.3 --- BrdU incorporation assay --- p.88 / Chapter 3.5.2.4 --- NCFC assay --- p.89 / Chapter 3.5.3 --- Conventional and quantitative RT-PCR --- p.89 / Chapter 3.5.3.1 --- RNA extraction --- p.89 / Chapter 3.5.3.2 --- RNA quantitation --- p.90 / Chapter 3.5.3.3 --- Reverse Transcription ofthe First Strand complementary DNA --- p.90 / Chapter 3.5.3.4 --- Polymerase chain reaction --- p.91 / Chapter 3.5.3.5 --- RNA Integrity Check --- p.91 / Chapter 3.5.3.6 --- Electrophoresis and visualization of gene products --- p.91 / Chapter 3.5.3.7 --- Real-time quantitative PCR --- p.92 / Chapter 3.5.4 --- Microarray --- p.94 / Chapter 3.5.5 --- Immunofluoresent staining --- p.94 / Chapter 3.5.6 --- Western blot --- p.95 / Chapter 3.5.6.1 --- Harvesting samples --- p.95 / Chapter 3.5.6.2 --- Protein extraction --- p.96 / Chapter 3.5.6.3 --- Protein quantification --- p.96 / Chapter 3.5.6.4 --- SDS-PAGE --- p.97 / Chapter 3.5.6.5 --- Wet transfer of protein to PVDF membrane --- p.97 / Chapter 3.5.6.6 --- Blocking the membrane --- p.97 / Chapter 3.5.6.7 --- Immunoblotting --- p.97 / Chapter 3.5.6.8 --- Signal detection --- p.98 / Chapter 3.5.7 --- Cell apoptosis assay --- p.98 / Chapter 3.5.7.1 --- ANNEXINV-FITC apoptosis detection --- p.98 / Chapter 3.5.7.2 --- TUNEL --- p.99 / Chapter 3.5.8 --- Endogenous ROS assay --- p.100 / Chapter 3.5.9 --- In vivo studies --- p.101 / Chapter 3.5.9.1 --- Induction of cerebral ischemia in mice --- p.101 / Chapter 3.5.9.2 --- Transplantation --- p.101 / Chapter 3.5.9.3 --- Assessment of learning ability and memory --- p.102 / Chapter 3.5.10 --- Histological analysis --- p.103 / Chapter 3.5.10.1 --- Animal sacrifice for brain harvest --- p.103 / Chapter 3.5.10.2 --- Cryosectioning --- p.103 / Chapter 3.5.10.3 --- Haematoxylin and eosin staining --- p.104 / Chapter 3.6 --- Data analysis --- p.104 / Chapter Chapter4 --- Results --- p.113 / Chapter 4.1 --- Expression profile of 5-HT receptors and metablism of endogenous 5-HT --- p.113 / Chapter 4.1.1 --- Expression profiles of 5-HT receptors in stem cells --- p.113 / Chapter 4.1.2 --- Biosynthesis of endogenous 5-HT --- p.115 / Chapter 4.2 --- Effects of 5-HT on proliferation of mouse ES cells and NS cells --- p.115 / Chapter 4.2.1 --- Effects of 5-HT on proliferation ofES cells --- p.115 / Chapter 4.2.2 --- Effects of 5-HT on proliferation ofNP and NS cells --- p.117 / Chapter 4.3 --- Effects of 5-HT on differentiation of mouse ES cells and NS cells --- p.119 / Chapter 4.3.1 --- Neural differentiation ofES cells --- p.119 / Chapter 4.3.2 --- Effects of 5-HT on differentiation ofES cells --- p.119 / Chapter 4.3.3 --- Neural differentiation ofNP and NS cells --- p.120 / Chapter 4.3.4 --- Effects of 5-HT on differentiation ofNP and NS cells --- p.121 / Chapter 4.4 --- 5-HT metabolism in mouse ES cells and NS cells --- p.122 / Chapter 4.4.1 --- Expression of key 5-HT metablic genes in stem cells --- p.122 / Chapter 4.4.2 --- Detection ofROS generation in mouse NS cells --- p.123 / Chapter 4.4.3 --- Effects of 5-HT on expression level of MAO-A, MAO-B and SERT --- p.123 / Chapter 4.5 --- Anti-apoptotic effect of 5-HT on NP and NS cells in neural induction --- p.127 / Chapter 4.6 --- Potential signaling pathways mediated by 5-HT --- p.130 / Chapter 4.7 --- Therapeutic effects of 5-HT treated mouse ES cell-derived cells in a stoke model --- p.130 / Chapter 4.7.1 --- Induction of global ischemia by transient BCCAO --- p.130 / Chapter 4.7.1.1 --- HE staining of post ischemic brain --- p.131 / Chapter 4.7.1.2 --- TUNEL analysis of cell apoptosis at post ischemia day 3 --- p.132 / Chapter 4.7.2 --- Cell labelling --- p.132 / Chapter 4.7.3 --- Cognition monitoring post transplantation --- p.133 / Chapter 4.7.4 --- Survival, migration and differentiation of transplanted neural cells --- p.135 / Chapter Chapter5 --- Discussion --- p.180 / Chapter Chapter6 --- Conclusions --- p.192 / References --- p.195