Spelling suggestions: "subject:"phosphatidylcholine""
11 |
SERUM ANTI-PHOSPHORYLCHOLINE AND ANTI-CARDIOLIPIN CONCENTRATIONS FOLLOWING PERIODONTAL SCALING AND ROOT PLANINGChaston, Reve W 01 January 2006 (has links)
Atherosclerosis is an insidious disease with serious morbidity and mortality including ischemic heart disease, stroke, and myocardial infarction. This condition is progressive and can start early in life eventually leading to large plaques and arterial occlusion. Two key components of this process are the immune system and lipids; in particular, LDL which accumulates within the arterial walls and macrophages which recognize and engulf oxidized-LDL (oxLDL) to form foam cells. Knowing that certain antibodies directed against bacterial antigens such as phosphorylcholine (PC) and cardiolipin (CL) show opsonizing cross-reactivity with oxLDL it can be proposed that there is a link between immune responses to periodontal bacteria and atherosclerosis. The aim of this investigation was to determine whether periodontal bacteria are capable of inducing serum antibodies potentially involved in cardiovascular diseases; specifically, IgG anti-PC, IgG anti-CL, and IgM anti-CL. To test this, 17 subjects with chronic periodontitis received scaling and root planing in conjunction with blood sample analysis to determine if periodontal instrumentation resulted in changes in these serum antibodies. If plaque bacteria are responsible for an immune response then serum levels of these antibodies should decrease following periodontal therapy. We found that serum levels of IgG anti-PC, IgG anti-CL, and IgM anti-CL decreased following periodontal scaling and root planing but the change was significant only for IgG anti-PC (P 0.045). Serum levels of IgM anti-CL approached significance (P 0.054). The results support the hypothesis that the immune response to periodontal bacterial microflora contributes to serum concentrations of antiphospholipid antibodies.
|
12 |
Le 17B-Estradiol combiné à un biopolymère à base de chitosan accroît la biocompatibilité des cellules progénitrices dérivées de la moelle osseuseTardif, Kim 07 1900 (has links)
Les cellules dérivées de la moelle osseuse, principalement les cellules endothéliales progénitrices, sont réduites chez les patients souffrant de maladies cardiovasculaires. Leur mobilisation et leur incorporation aux sites de lésion vasculaire sont des évènements prépondérants dans l’accélération des processus de réendothélialisation. Dans un modèle murin, le 17β-estradiol favorise les processus de guérison vasculaire par la mobilisation et le recrutement des cellules endothéliales progénitrices dérivées de la moelle osseuse. Il existe présentement plusieurs stratégies afin d’augmenter la mobilisation des cellules progénitrices ainsi que leur incorporation à la paroi vasculaire. Cependant, peu d’études privilégient la livraison locale d’un nombre élevé de cellules progénitrices fonctionnelles par un véhicule biodégradable et leur maintien au site de lésion afin de favoriser la réendothélialisation ciblée. Un polymère d’intérêt pour cette application s’avère être le chitosan. Ce biopolymère non toxique et biodégradable est couramment utilisé dans l’ingénierie tissulaire et, depuis peu, est utilisé dans la guérison vasculaire. Le chitosan complexé à la phosphorylcholine voit sa solubilité s’accroître dans les solutions aqueuses ainsi que sa biocompatibilité cellulaire en condition physiologique.
Le projet de ce mémoire visait donc : 1) à étudier in vitro, la capacité d’un polymère de chitosan complexé à la phosphorylcholine à influencer l’adhésion, la survie, la différenciation et la fonctionnalité cellulaire dans un modèle murin de culture mixte de cellules dérivées de la moelle osseuse et 2) de déterminer l’impact de la présence du 17β-estradiol sur ces mêmes comportements cellulaires.
Nos travaux démontrent que la matrice de chitosan-phosphorylcholine s’avère compatible avec notre modèle de culture cellulaire. En effet, ce polymère est capable de promouvoir l’organisation et le développement des cellules dérivées de la moelle osseuse de façon comparable à la matrice normalement utilisée dans la croissance in vitro des cellules endothéliales progénitrices, la fibronectine. De plus, ce polymère n’a nullement compromis l’activité migratoire des cellules, laissant supposer qu’il pourrait éventuellement être un véhicule approprié pour effectuer une livraison cellulaire à un site de lésion.
Il s’avère que le 17β-estradiol, lorsqu’ajouté au milieu de culture ou complexé au polymère de chitosan phosphorylcholine, est capable de moduler le comportement cellulaire, et ce, de façon différente. Le 17β-estradiol complexé au polymère de chitosan-phosphorylcholine démontre, par rapport à sa forme soluble, une plus grande aptitude à accroître le nombre de cellules hématopoïétiques ainsi que des cellules endothéliales progénitrices dérivées de la moelle osseuse in vitro. De plus, le 17β-estradiol complexé au polymère de chitosan-phosphorylcholine permet une amplification marquée des cellules endothéliales progénitrices et leur offre un support adéquat afin de favoriser la guérison vasculaire.
L’ensemble de nos travaux suggère que le polymère de chitosan complexé à la phosphorylcholine en présence ou non de 17β-estradiol est une matrice compatible avec les cellules progénitrices dérivées de la moelle osseuse in vitro. Le 17β-estradiol complexé au polymère est toutefois plus efficace que sa forme soluble à promouvoir l’amplification du nombre de cellules progénitrices. Ce polymère représente un outil thérapeutique attrayant et une matrice de livraison d’agent bioactif prometteuse pour le recrutement cellulaire dans l’accélération de la guérison vasculaire. / Bone marrow derived cells, including endothelial progenitor cells, are reduced in numbers in patient with cardiovascular disease or risk factors. Mobilization and incorporation of these cells at the vascular lesion site are important events in the reendothelialization process. 17β-estradiol was shown in a mouse model of injury, to favour this healing process through mechanisms which involve the mobilization and incorporation of endothelial progenitor cells derived from the bone marrow. At the moment, there are many strategies to increase endothelial progenitor cells mobilization as well as recruitment into the vascular wall. However, few studies favour local delivery of a large number of functional progenitor cells on a biodegradable scaffold and to maintain them at the lesion site in order to promote reendothelialization. An interesting biopolymer for this application is chitosan. This non toxic and biodegradable biopolymer is commonly used in tissue engineering and was recently used in vascular healing. Phosphorylcholine modified chitosan can increase the water solubility and cell biocompatibility of the biopolymer in physiological condition.
This master project was thus designed to :1) evaluate, in vitro, the capacity of phosphorylcholine modified chitosan to influence cell adhesion, survival, differentiation and functionality in a mouse model of bone marrow mixed culture and 2) determine the impact of 17β-estradiol on these cell behaviours.
Our results suggest an adequate biocompatibility of phosphorylcholine modified chitosan with our cell culture system. Indeed, this polymer was able to promote cell organization and development of bone marrow derived cells in the same way that fibronectin, the most commonly matrix used in the progenitor cells in vitro culture. Moreover, cell migratory activity was not compromised by the chitosan polymer.
It appears that 17β-estradiol, when added to cell culture media or attached on phosphorylcholine modified chitosan is able to modulate differently cell behaviour. Our data suggest that 17β-estradiol coupled to the chitosan polymer was superior to increase the number of haematopoietic and endothelial progenitor cells derived from bone marrow in vitro compared to the soluble form. 17β-estradiol coupled to the polymer of phosphorylcholine modified chitosan allowed an increased amplification of progenitor cell number and provided adequate scaffold to favour vascular healing.
We propose that phosphorylcholine modified chitosan in presence or not of 17β-estradiol is a compatible matrix with bone marrow derived progenitor cells in vitro. 17β-estradiol enhances the amplification of progenitor cell in vitro when associated to the polymer compared to its soluble form. This biopolymer may be an attractive matrix and a promising vehicle in a drug delivery therapeutic system for progenitor cells recruitment and to promote vascular healing.
|
13 |
Phosphorylcholine based amphiphilic polymers for the solubilization of integral membrane proteinsDiab, Charbel January 2008 (has links)
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal
|
14 |
Estudo físico-químico de nanopartículas de DNA com derivado de quitosana contendo grupos fosforilcolinaPicola, Isadora Pfeifer Dalla [UNESP] 09 October 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:55Z (GMT). No. of bitstreams: 0
Previous issue date: 2009-10-09Bitstream added on 2014-06-13T18:08:50Z : No. of bitstreams: 1
picola_ipd_me_sjrp.pdf: 3509245 bytes, checksum: 8de529c6653b0006e089cc79f4b6700d (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Na presente dissertação, foram preparadas quitosanas com diferentes massas molares, 16 kDa, 18 kDa e 29 kDa, e com diferentes graus de substituição de fosforilcolina (PC). As quitosanas de baixa massa molecular foram obtidas pela degradação de quitosana desacetilada. Essas quitosanas foram purificadas com membranas de diálise de tamanho de exclusão apropriadas e caracterizadas por meio de titulação potenciométrica, H-RMN e Cromatografia de permeação em gel (GPC). O estudo físico-químico da interação das quitosanas com DNA foi realizado utilizando-se as técnicas de fluorescência, eletroforese, microscopia óptica, microscopia eletrônica de transmissão e espalhamento de luz dinâmico. As propriedades avaliadas foram a eficiência de interação, a estabilidade dos complexos, potencial zeta e tamanho de poliplexos. Os experimentos foram conduzidos variando-se a força iônica, pH do meio, massa molar de policátion e razão de cargas para quitosanas com diferentes conteúdos de grupos PC. Além das quitosanas preparadas durante o projeto, também se utilizou quitosanas de diferentes massas molares, de 5 e 150 kDa, para estudo dos poliplexos em diferentes forças iônicas. Os resultados mostraram que a eficiência de interação entre quitosana e DNA é reduzida com a presença do grupo PC. Nos estudos de DLS, verificou-se que, em baixos valores de pH, o método de coacervação permite a obtenção de nanopartículas de 150 a 300 nm. A força de interação, o tamanho e a estabilidade das nanopartículas dependem do pH do meio, da força iônica da solução, da massa molar e do conteúdo de fosforilcolina. Em pHs mais elevados, os poliplexos são mais estáveis quanto maior a massa molar ou quando há a presença de grupo fosforilcolina. O trabalho permitiu ampliar os estudos sobre os efeitos da força iônica, do pH, da massa molar e conteúdos de PC e como, tais parâmetros... / In this work chitosans with different molecular weights and their derivatives containing different amounts of phosphorylcholine (PC) were prepared. The low molecular weights chitosans were obtained by degradation of deacetylated chitosan. These chitosans were purified by dialysis membranes of appropriate sizes of exclusion and characterized by potentiometric titration, H-NMR and gel permeation chromatography (GPC) techniques. The physico-chemical study of the interaction between chitosan and DNA was performed using the ethidium bromide fluorescence assay, gel electrophoresis, optical microscopy, transmission electron microscopy and dynamic light scattering techniques. The experiments were carried out at varying experimental conditions as ionic strength, pH, and charge ratio with chitosans of different molecular weights and phosphorylcholine contents. The results showed that the efficiency of the interaction between chitosan and DNA was reduced with the incorporation of PC on the chitosan chain. The results showed that at low pH values the sizes of the nanoparticles obtained by the coacervation method varied from 150 to 300 nm. The strength of the interaction and the size of the nanoparticles were shown to be dependent of pH, ionic strength, chitosan molecular weight and of the phosphorylcholine contents. The study at high pH values showed that more stable nanoparticles were formed with chitosans having the higher molecular weights. The attaching of phosphorylcholine groups to the chitosan main chain allows obtaining more stable particles at high pH values. In this work we provide new insights on the effects of molecular weight, pH, ionic strength and PC contents on both the chitosan-DNA interaction and the stability of formed nanoparticles
|
15 |
Synthesis, Characterisation and Properties of Biomimetic Biodegradable PolymersNederberg, Fredrik January 2005 (has links)
<p>The acceptance of blood contacting implants creating favorable conditions <i>in vivo</i> is decisively determined by their interaction with proteins that mediate inter cellular interactions with synthetic substrates. Adsorbed proteins can activate blood cascade systems like coagulation and complement that may result in serious blood clots, and/or immunological reactions. Poly (ethylene glycol) (PEG), heparin, and phosphoryl choline (PC) functional poly (methacrylates) are previously used polymers with known non-adhesive properties in blood contacting events.</p><p>This thesis contributes to this extensive research by introducing a novel type of biomaterial that equips biodegradable polymers with biomimetic functionalities. The phospholipid mimetic material is synthesized by combining biodegradable polymers with various functional polar end-groups consisting of zwitterionic phosphoryl choline (PC), anionic succinates, and cationic quaternary ammonium. The polymer backbone provides mechanical stability and biodegradability whilst the various head groups provide a variety of functions. The careful evaluation of the synthesis has allowed reaction conditions to be optimized leading to complete conversion at each step and subsequently high yields. Initially, poly (e-caprolactone) (PCL) was used since it provided a suitable synthetic starting point. However, the synthesis has also included poly (trimethylene carbonate) (PTMC) to provide a material that allows spontaneous surface enrichment of the polar PC group. This was achieved with an added hydrophilic environment. </p><p>Through the synthesis of multi PC functional PTMC, additional bulk organisation by the formation of zwitterionomers (PC ionomer) was achieved. Low modulus elasticity and water uptake were some of the properties of the formed material. As a result it was shown that the PC ionomer could be used for protein/drug loading and subsequent release. Furthermore, the material possessed non-adhesive properties in different biological environments.</p><p>Importantly, the result suggests that a versatile synthetic platform has been established that may provide a smorgasbord of different functional polymers, or combinations of such. This is indeed important since it was shown that the polymer in many ways dictates how the material may take advantage of an added functionality. </p><p>Such materials should be interesting for a variety of biomedical applications including the production of soft hemocompatible tissue.</p>
|
16 |
Synthesis, Characterisation and Properties of Biomimetic Biodegradable PolymersNederberg, Fredrik January 2005 (has links)
The acceptance of blood contacting implants creating favorable conditions in vivo is decisively determined by their interaction with proteins that mediate inter cellular interactions with synthetic substrates. Adsorbed proteins can activate blood cascade systems like coagulation and complement that may result in serious blood clots, and/or immunological reactions. Poly (ethylene glycol) (PEG), heparin, and phosphoryl choline (PC) functional poly (methacrylates) are previously used polymers with known non-adhesive properties in blood contacting events. This thesis contributes to this extensive research by introducing a novel type of biomaterial that equips biodegradable polymers with biomimetic functionalities. The phospholipid mimetic material is synthesized by combining biodegradable polymers with various functional polar end-groups consisting of zwitterionic phosphoryl choline (PC), anionic succinates, and cationic quaternary ammonium. The polymer backbone provides mechanical stability and biodegradability whilst the various head groups provide a variety of functions. The careful evaluation of the synthesis has allowed reaction conditions to be optimized leading to complete conversion at each step and subsequently high yields. Initially, poly (e-caprolactone) (PCL) was used since it provided a suitable synthetic starting point. However, the synthesis has also included poly (trimethylene carbonate) (PTMC) to provide a material that allows spontaneous surface enrichment of the polar PC group. This was achieved with an added hydrophilic environment. Through the synthesis of multi PC functional PTMC, additional bulk organisation by the formation of zwitterionomers (PC ionomer) was achieved. Low modulus elasticity and water uptake were some of the properties of the formed material. As a result it was shown that the PC ionomer could be used for protein/drug loading and subsequent release. Furthermore, the material possessed non-adhesive properties in different biological environments. Importantly, the result suggests that a versatile synthetic platform has been established that may provide a smorgasbord of different functional polymers, or combinations of such. This is indeed important since it was shown that the polymer in many ways dictates how the material may take advantage of an added functionality. Such materials should be interesting for a variety of biomedical applications including the production of soft hemocompatible tissue.
|
17 |
Estudo físico-químico de nanopartículas de DNA com derivado de quitosana contendo grupos fosforilcolina /Picola, Isadora Pfeifer Dalla. January 2009 (has links)
Orientador: Marcio José Tiera / Banca: Marcelo Henrique Gehlen / Banca: Rose Mary Zumstein Georgetto Naal / Resumo: Na presente dissertação, foram preparadas quitosanas com diferentes massas molares, 16 kDa, 18 kDa e 29 kDa, e com diferentes graus de substituição de fosforilcolina (PC). As quitosanas de baixa massa molecular foram obtidas pela degradação de quitosana desacetilada. Essas quitosanas foram purificadas com membranas de diálise de tamanho de exclusão apropriadas e caracterizadas por meio de titulação potenciométrica, H-RMN e Cromatografia de permeação em gel (GPC). O estudo físico-químico da interação das quitosanas com DNA foi realizado utilizando-se as técnicas de fluorescência, eletroforese, microscopia óptica, microscopia eletrônica de transmissão e espalhamento de luz dinâmico. As propriedades avaliadas foram a eficiência de interação, a estabilidade dos complexos, potencial zeta e tamanho de poliplexos. Os experimentos foram conduzidos variando-se a força iônica, pH do meio, massa molar de policátion e razão de cargas para quitosanas com diferentes conteúdos de grupos PC. Além das quitosanas preparadas durante o projeto, também se utilizou quitosanas de diferentes massas molares, de 5 e 150 kDa, para estudo dos poliplexos em diferentes forças iônicas. Os resultados mostraram que a eficiência de interação entre quitosana e DNA é reduzida com a presença do grupo PC. Nos estudos de DLS, verificou-se que, em baixos valores de pH, o método de coacervação permite a obtenção de nanopartículas de 150 a 300 nm. A força de interação, o tamanho e a estabilidade das nanopartículas dependem do pH do meio, da força iônica da solução, da massa molar e do conteúdo de fosforilcolina. Em pHs mais elevados, os poliplexos são mais estáveis quanto maior a massa molar ou quando há a presença de grupo fosforilcolina. O trabalho permitiu ampliar os estudos sobre os efeitos da força iônica, do pH, da massa molar e conteúdos de PC e como, tais parâmetros... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work chitosans with different molecular weights and their derivatives containing different amounts of phosphorylcholine (PC) were prepared. The low molecular weights chitosans were obtained by degradation of deacetylated chitosan. These chitosans were purified by dialysis membranes of appropriate sizes of exclusion and characterized by potentiometric titration, H-NMR and gel permeation chromatography (GPC) techniques. The physico-chemical study of the interaction between chitosan and DNA was performed using the ethidium bromide fluorescence assay, gel electrophoresis, optical microscopy, transmission electron microscopy and dynamic light scattering techniques. The experiments were carried out at varying experimental conditions as ionic strength, pH, and charge ratio with chitosans of different molecular weights and phosphorylcholine contents. The results showed that the efficiency of the interaction between chitosan and DNA was reduced with the incorporation of PC on the chitosan chain. The results showed that at low pH values the sizes of the nanoparticles obtained by the coacervation method varied from 150 to 300 nm. The strength of the interaction and the size of the nanoparticles were shown to be dependent of pH, ionic strength, chitosan molecular weight and of the phosphorylcholine contents. The study at high pH values showed that more stable nanoparticles were formed with chitosans having the higher molecular weights. The attaching of phosphorylcholine groups to the chitosan main chain allows obtaining more stable particles at high pH values. In this work we provide new insights on the effects of molecular weight, pH, ionic strength and PC contents on both the chitosan-DNA interaction and the stability of formed nanoparticles / Mestre
|
18 |
Novel surface-tethered estrogen polymeric platforms in cardiovascular regenerative medicineQi, Baowen 07 1900 (has links)
L’estradiol (E2) est une hormone femelle qui joue un rôle essentiel, à la fois dans la régulation et dans la détermination de certaines conditions physiologiques in vivo, telle que la différenciation et la prolifération cellulaire. Lorsque l’E2 est donné en supplément, par exemple dans le cas de thérapie hormonale, deux effets sont observés, un effet génomique et un effet non-génomique, de par son interaction avec les récepteurs à œstrogène du noyau ou de la membrane cellulaire, respectivement. L’effet non-génomique est plus difficile à étudier biologiquement parce que l’effet se produit sur une échelle de temps extrêmement courte et à cause de la nature hydrophobe de l’E2 qui réduit sa biodisponibilité et donc son accessibilité aux cellules cibles. C’est pourquoi il est nécessaire de développer des systèmes d’administration de l’E2 qui permettent de n’étudier que l’effet non-génomique de l’œstrogène. Une des stratégies employée consiste à greffer l’E2 à des macromolécules hydrophiles, comme de l’albumine de sérum bovin (BSA) ou des dendrimères de type poly(amido)amine, permettant de maintenir l’interaction de l’E2 avec les récepteurs d’œstrogène de la membrane cellulaire et d’éviter la pénétration de l’E2 dans le noyau des cellules. Toutefois, ces systèmes macromolécules-E2 sont critiquables car ils sont peu stables et l’E2 peut se retrouver sous forme libre, ce qui affecte sa localisation cellulaire. L’objectif de cette thèse est donc de développer de nouvelles plateformes fonctionnalisées avec de l’E2 en utilisant les approches de synthèses ascendantes et descendantes. Le but de ces plateformes est de permettre d’étudier le mécanisme de l’effet non-génomique de l’E2, ainsi que d’explorer des applications potentielles dans le domaine biomédical.
L’approche ascendante est basée sur un ligand d’E2 activé, l’acide 17,α-éthinylestradiol-benzoïque, attaché de façon covalente à un polymère de chitosan avec des substitutions de phosphorylcholine (CH-PC-E2). L’estradiol est sous forme de pro-drogue attachée au polymère qui s’auto-assembler pour former un film. L’effet biologique de la composition chimique du film de chitosan-phosphorylcholine a été étudié sur des cellules endothéliales. Les films de compositions chimiques différentes ont préalablement été caractérisés de façon physicochimique. La topographie de la surface, la charge de surface, ainsi que la rhéologie des différents films contenant 15, 25, ou 40% molaires de phosphorylcholine, ont été étudiés par microscopie à force atomique (AFM), potentiel zêta, résonance plasmonique de surface et par microbalance à cristal de quartz avec dissipation (QCM-D). Les résultats de QCM-D ont montré que plus la part molaire en phosphorylcholine est grande moins il y a de fibrinogène qui s’adsorbe sur le film de CH-PC. Des cellules humaines de veine ombilicale (HUVECs) cultivées sur des films de CH-PC25 et de CH-PC40 forment des amas cellulaire appelés sphéroïdes au bout de 4 jours, alors que ce n’est pas le cas lorsque ces cellules sont cultivées sur des films de CH-PC15. L’attachement de l’estradiol au polymère a été caractérisé par plusieurs techniques, telles que la résonance magnétique nucléaire de proton (1H NMR), la spectroscopie infrarouge avec transformée de Fourier à réfraction totale atténuée (FTIR-ATR) et la spectroscopie UV-visible. La nature hydrogel des films (sa capacité à retenir l’eau) ainsi que l’interaction des films avec des récepteurs à E2, ont été étudiés par la QCM-D. Des études d’imagerie cellulaires utilisant du diacétate de diaminofluoresceine-FM ont révélé que les films hydrogels de CH-PC-E2 stimulent la production d’oxyde nitrique par les cellules endothéliales, qui joue un rôle protecteur pour le système cardiovasculaire. L’ensemble de ces études met en valeur les rôles différents et les applications potentielles qu’ont les films de type CH-PC-E2 et CH-PC dans le cadre de la médecine cardiovasculaire régénérative. L’approche descendante est basée sur l’attachement de façon covalente d’E2 sur des ilots d’or de 2 μm disposés en rangées et espacés par 12 μm sur un substrat en verre. Les ilots ont été préparés par photolithographie. La surface du verre a quant à elle été modifiée à l’aide d’un tripeptide cyclique, le cRGD, favorisant l’adhésion cellulaire. L’attachement d’E2 sur les surfaces d’or a été suivi et confirmé par les techniques de SPR et de QCM-D. Des études d’ELISA ont montré une augmentation significative du niveau de phosphorylation de la kinase ERK (marqueur important de l’effet non-génomique) après 1 heure d’exposition des cellules endothéliales aux motifs alternant l’E2 et le cRGD. Par contre lorsque des cellules cancéreuses sont déposées sur les surfaces présentant des motifs d’E2, ces cellules ne croissent pas, ce qui suggère que l’E2 n’exerce pas d’effet génomique. Les résultats de l’approche descendante montrent le potentiel des surfaces présentant des motifs d’E2 pour l’étude des effets non-génomiques de l’E2 dans un modèle in vitro. / Estradiol (E2) is an essential female hormone in the regulation and determination of various physiological conditions in vivo, such as cell proliferation and differentiation. When supplementing exogenous E2 as a clinical strategy for hormone therapy, it generates genomic and non-genomic effect simultaneously via binding to the estrogen receptors in the cell nucleus or membrane site. Compared to the genomic effect, it is quite difficult to monitor the E2-induced non-genomic biological behavior because this effect occurs in extremely transient time scale and the bioavailability and accessibility of E2 to target cells is very low due to the hydrophobic nature of E2. As a result, it is indispensable to develop E2 delivery systems to specifically understand estrogenic non-genomic nature. One of strategies is to graft E2 to the hydrophilic macromolecules, e.g. bovine serum albumin (BSA) or poly(amido)amine dendrimer, to maintain E2 interacting with membrane estrogen receptors instead of penetrating into the cell nucleus. However, the instability of those E2-macromolecules systems, either containing free E2 leaching or discrepancies of cellular localizations, led to controversies. Herein, the objective of present thesis is to develop novel E2-functionlized platforms by the principle of bottom-up and top-down approaches for understanding the mechanism of estrogenic non-genomic effect, and further, to explore their potential applications in the biomedicine.
As a bottom-up approach, an activated E2 ligand, 17α-ethinylestradiol-benzoic acid was covalently conjugated onto a phosphorylcholine substituted chitosan polymer (CH-PC-E2) as a prodrug strategy for the fabrication of self-assembled films. Through a series of combined physicochemical and cellular investigations, the relationship between various chemical compositions of chitosan-phosphorylcholine (CH-PC) films and cellular responses was also evaluated. Based on atomic force microscopy (AFM) examination, zeta-potential measurements, surface plasmon resonance (SPR), and quartz crystal microbalance with dissipation (QCM-D) measurements, surface topography, charge, and rheology of CH-PC films with 15, 25, and 40 mol% PC contents were characterized. Moreover, QCM-D measurements indicated that the amount of fibrinogen adsorbed on CH-PC films decreased significantly with increasing PC content. Finally, it was also showed that human umbilical vein endothelial cells (HUVECs) form spheroids on CH-PC25 and CH-PC40 films, but not on CH-PC15 films cultured over 4 days. In addition, the CH-PC-E2 polymer conjugates were prepared and characterized by several techniques, such as 1H nuclear magnetic resonance (1H NMR), Fourier transformed infrared-attenuated total refraction (FTIR-ATR) and UV/Vis spectra measurements. The hydrogel nature of CH-PC-E2 film as well as its interactions to estrogen receptors was further extensively investigated by QCM-D study. In the cellular study, CH-PC-E2 hydrogel films can significantly stimulate the production of nitric oxide, a protective molecule in the cardiovascular system, in the endothelial cells by a diaminofluorescein-FM diacetate imaging study. The studies above demonstrated the different roles and potential applications of CH-PC-E2 and CH-PC surfaces in the cardiovascular regenerative medicine. As a top-down approach, micropatterned substrates were used for E2 functionalization, which were prepared by photolithography via aligning ~ 2 μm in diameter gold arrays onto a glass substrate. After that, a cell adhesive peptide, cyclic RGD was introduced to the glass surface in order to induce the attachment of cells. Meanwhile, estradiol was covalently immobilized on the gold surface and the process was monitored and validated by combining SPR and QCM-D studies. In the micropatterned substrate-coupled cell ELISA study, a phosphorylation level of extracellular signal-regulated kinase (ERK), which is an important non-genomic marker, was significantly elevated by this E2-functionalized micropatterned surface after 1 hour incubation. Furthermore, E2-functionalized micropatterned substrate didn’t proliferate cancer cells indicating the absence of genomic effect stimulation. Based on these results, our E2-functionalized micropatterned substrates can function as an in vitro model for the elucidation of estrogenic non-genomic behaviors.
|
Page generated in 0.1078 seconds