A conformação de dispositivos médicos implantáveis a partir de uma blenda exige o desenvolvimento de um produto com propriedades próximas do comportamento ideal, combinando propriedades térmicas e mecânicas e boa resposta tecidual. O Poli (ácido láctico-co-glicólico) (PLGA) e o Poli (isopreno) (IR) foram escolhidos como componentes da blenda com finalidade de promover boa biocompatibilidade e características mecânicas especificas. As blendas foram obtidas por dissolução dos polímeros em solvente orgânico, seguida de secagem. Para determinar a influência do teor de IR sobre as propriedades da blenda, foram realizados ensaios de espectroscopia na região de infravermelho por transformada de Fourier (FTIR), calorimetria diferencial de varredura (DSC), análise dinâmico-mecânica (DMA), microscopia óptica por luz polarizada (POM), análise de dureza, ensaio de tração e análise de viabilidade celular. A presença de IR na blenda provocou alteração na estrutura molecular semi-cristalina do PLGA, bem como influenciou o comportamento mecânico analisado a partir da curva tensão-deformação do material. A blenda se mostrou biocompativel em ambiente celular e em ensaios preliminares em animais, apresentando potencial para aplicação como biomaterial. / The conformation of an implantable medical device from a polymeric blend requires the development of a product with properties as close as possible of ideal behavior with the combination between thermal and mechanical properties and good tissue response. The poly (lactic-co-glycolic acid) (PLGA) and the poly (isoprene) (IR) were chosen as the blend components to promote good biocompatibility and specific mechanical characteristics. The blends were obtained by dissolution of polymers in organic solvent, followed by drying. In order to determine the IR content influence over the blend properties, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light optical microscopy (POM), hardness analysis, tensile test and cell viability test were carried out. The IR presence caused changes in semi-crystalline molecular structure of PLGA, as well as actuated over the mechanical response analyzed on material’s stress-strain curve. The blend showed itself biocompatible at cellular environment and at preliminary animal tests, presenting potential for application as biomaterial.

Made available in DSpace on 2014-06-12T15:52:44Z (GMT). No. of bitstreams: 2 arquivo5042_1.pdf: 2545498 bytes, checksum: 4d1086c8bbc4dc337fe99bcb799334ab (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2003 / O ácido úsnico [2,6-Diacetil-7,9-dihidroxi-8,9b-dimetil-1,3[2H,9bH]-dibenzo-furadiona] (UA), composto natural obtido de diversas espécies de liquens, apresenta diferentes atividades biológicas e fisiológicas que podem apresentar grande relevância na farmacologia e clínica. Devido sua relevante ação antimitótica e antiproliferativa, existe potencial interesse de seu uso na terapia do câncer. Não obstante, o sucesso de sua aplicação clínica é limitado a sua dotada ação tóxica e pouca solubilidade em água e solventes orgânicos de alta polaridade. Nanopartículas são carreadores poliméricos que podem modificar o perfil de distribuição do fármaco no organismo. Estes vetores medicamentosos proporcionam a liberação do fármaco no sítio de ação desejada, potencializando a ação terapêutica e minimizando os efeitos colaterais. O principal objetivo deste estudo consiste em obter e caracterizar físicoquimicamente nanocápsulas de copolímero de ácido lático e glicólico (PLGA) contendo ácido úsnico e investigar a atividade citotóxica e antitumoral do ácido úsnico em comparação com a forma não encapsulada. Nanocápsulas contendo ácido úsnico (UA-NC) foram preparadas pelo método de deposição interfacial do polímero. Análises físico-químicas foram realizadas imediatamente após a preparação das nanocápsulas. Subseqüentemente, elas foram submetidas a ambos os testes de estabilidade acelerada e a longo termo. A morfologia e tamanho das partículas de UA-NC foram estudados utilizando a microscopia eletrônica de varredura (MEV). O teor de ácido úsnico nas nanocápsulas foi obtido através de ensaios cromatográficos e a taxa de encapsulação foi determinada após ultrafiltração e centrifugação. O perfil de liberação in vitro do ácido úsnico a partir das UA-NC foi determinado utilizando o método de diálise direta. O estudo da atividade citotóxica foi realizado pelo método de cultura de tecidos com células da linha contínua NCI-H 292. A viabilidade celular, foi determinada pelo Azul de Tripan e a ação citotóxica do UA e UA-NC foi avaliada pelo método colorimétrico de MTT (3-[4,5-dimetiltiazol-2-il]-2,5-difeniltetrazólio). Alterações morfológicas nas células NCI H292 tratadas com UA e UA-NC foram analisadas por microscopia óptica utilizando a técnica de Giemsa. A atividade antitumoral foi realizada em camundongos albinos Suíços (mus-musculus), frente ao tumor experimental sarcoma-180. Decorridos 24 h de implantação do tumor, foram administrados, intraperitonealmente, injeções de UA, UA-NC e placebo em dose equivalente a 15 mg/ 10 g de peso do animal. Após uma semana de tratamento, foram realizadas coletas de sangue para análises hematológicas e os animais foram sacrificados. Tumores foram removidos, mensurados e pesados e os órgãos (fígado, rins e baço) foram dissecados e submetidos a estudos histopatológicos. A inibição tumoral foi determinada a partir do peso médio da massa tumoral dos grupos de animais tratados em relação ao grupo controle (não tratado). O ácido úsnico apresentou limitada solubilidade em óleo de girassol, podendo ser encapsulado numa concentração máxima de 1 mg/ml. A formulação manteve um aspecto inicial macroscópico leitoso com reflexo azul opalescente durante 120 dias quando mantida a temperatura de 4° C ± 1°C. As formulações liofilizadas de UA-NC permaneceram estáveis por um período superior a 36 meses mantendo um aspecto inicial similar. A análise por microscopia de varredura demonstrou partículas bem dispersas, esféricas e homogêneas, com diâmetro médio de 367 ± 81 nm. UA-NC em suspensão após preparação apresentaram um conteúdo de ácido úsnico de 101,7 ± 1,7 % e uma taxa de encapsulação de 99,4 ± 0,16%. O perfil cinético de liberação revelou que as UA-NC podem ser utilizadas como sistema de liberação controlada. As concentrações requeridas para inibir 50% do crescimento celular, IC50, foram de aproximadamente 10 e 11,5 mg/ml para o ácido úsnico livre e encapsulado, respectivamente. Citoplasma irregular, com intensas áreas de vacuolização contendo material basófilo foram evidenciados nas células quando submetidas a tratamento com ácido úsnico (5μg/ml). Esta cultura quando tratada com ácido úsnico encapsulado demonstrou uma monocamada quase semelhante ao controle. A encapsulação do UA em nanocápsulas de PLGA promoveu uma inibição tumoral de 68% quando comparado ao tratamento com o ácido úsnico livre. Análises histopatológicas dos tumores tratados revelaram intensas áreas de necroses. Ações tóxicas representadas ao nível de hepatócitos foram evidenciadas no tratamento com UA livre. Estas lesões foram significativamente reduzidas quando os animais foram tratados com ácido úsnico nanoencapsulado. Nenhuma alteração histopatológica foi evidenciada nos rins e baço dos animais tratados. Em conclusão, a encapsulação do ácido úsnico em nanocápsulas de PLGA pode ser uma alternativa promissora a ser explorada para a terapia do câncer

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-08-24T17:06:37Z No. of bitstreams: 2 Dissertação - Layanny Kelly Silveira Praxedes - 2016.pdf: 3738908 bytes, checksum: 6340f77aec0ca6687fb5d273509f20b4 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-25T11:35:13Z (GMT) No. of bitstreams: 2 Dissertação - Layanny Kelly Silveira Praxedes - 2016.pdf: 3738908 bytes, checksum: 6340f77aec0ca6687fb5d273509f20b4 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-25T11:35:13Z (GMT). No. of bitstreams: 2 Dissertação - Layanny Kelly Silveira Praxedes - 2016.pdf: 3738908 bytes, checksum: 6340f77aec0ca6687fb5d273509f20b4 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-04-08 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The capacity of the tumor has not present as immunogenic to the immune system is one of its escape mechanisms. The aim of this study was to evaluate the use of nanoparticles formed from poly Lactic-co-glycolic acid (PLGA) associated with aluminum hydroxide may potentiate the effect of these on the resolution of the tumor. Balb/c mice inoculated with Sarcoma 180 tumor cells were distributed into nine groups for the implementation of the various immunotherapeutic treatments involving the use of aluminum hydroxide, PLGA nanoparticles, and activated macrophages. The evaluation of the treatment was performed by analysis of the tumor, considering the weight reduction of the dissected tumor, morphological and histological analysis, and analysis of pro-inflammatory and immunosuppressive cytokines in the serum of mice. The group of mice treated with PLGA nanoparticle associated with aluminum hydroxide caused a significant regression of the tumor (p = 0.039) compared with untreated mice. The treatment involving macrophages and PLGA nanoparticles showed significant tumor regression compared to the group treated only with macrophages (p = 0.021). The groups that had significant tumor regression have high levels of IFN--4 and IL-10, differing from the profile found in the other groups. In the other treatments tested there was a reduction of the tumor mass, but without significant statistical results, and without changes in the levels of cytokines measured in the serum of animals. Therefore, it is believed that PLGA nanoparticle by their ability to release hydroxide in target cells controlled manner, can enhance the action of the adjuvant aluminum hydroxide. Further studies are needed to elucidate the mechanisms involved in this phenomenon, which support the other investigations / A capacidade do tumor de não se apresentar como imunogênico ao sistema imune constitui um dos seus mecanismos de escape. O objetivo do presente trabalho foi avaliar se o uso de nanopartículas formadas a partir de co-polímeros de ácido láctico-co-glicólico (PLGA), associada ao hidróxido de alumínio poderia potencializar o efeito destes na resolução do tumor. Camundongos Balb/c inoculados com células tumorais de Sarcoma 180 e distribuídos em nove grupos para a realização dos diferentes tratamentos imunoterápicos, envolvendo a utilização de hidróxido de alumínio, nanopartículas de PLGA e macrófagos ativados. A avaliação dos tratamentos foi realizada pela análise do tumor, considerando a redução do peso do tumor dissecado, análise morfológica e histopatológica e análise de citocinas pró-inflamatórias e imunossupressoras no soro dos camundongos. O grupo de camundongos tratados com nanopartículas de PLGA associadas ao hidróxido de alumínio promoveu uma regressão significativa do tamanho da massa tumoral (p = 0,039) comparado com camundongos não tratados. O tratamento envolvendo macrófagos e nanopartículas de PLGA apresentou uma regressão tumoral significativa comparada com o grupo tratado apenas com macrófagos (p = 0,021). Os grupos que tiveram regressão tumoral significativa apresentaram níveis elevados das citocinas IFN-, IL-4 e IL-10, diferenciando-se do perfil encontrado nos demais grupos. Nos outros tratamentos testados houve a redução da massa tumoral, porém sem resultados estatísticos significativos e sem grandes alterações nos níveis de citocinas dosados no soro dos animais. Logo, acredita-se que a nanopartícula de PLGA, por meio de sua capacidade de transporte e liberação do hidróxido nas células alvo de forma controlada, possa potencializar a ação do adjuvante hidróxido de alumínio. Outros estudos são necessários para a elucidação dos mecanismos envolvidos nesse fenômeno.

<p>While drug-loaded biodegradable polymer microparticles have found many therapeutic applications, bulk manufacturing methods produce heterogeneous populations of particles. A more highly controlled manufacturing method may provide the ability improve the microparticle characteristics such as the drug release profile. Microfluidic droplet-makers manipulate liquids on the scale of tens of microns and can produce highly regular and controlled emulsions. However, microfluidic droplet manufacturing is not typically designed for clinical translation and the chemicals used are often not biocompatible.</p><p>I developed a two-chip PDMS-based microfluidic device that can manufacture PLGA microparticle loaded with hydrophilic or hydrophobic drugs. I characterized protein-loaded microparticles made using this device and compared them with bulk-generated microparticles. The microfluidics-generated microparticles had similar release curves and encapsulation efficiencies as bulk-generated microparticles but a much narrower size distribution. I generated peanut protein-loaded microparticles with this device and tested them in a mouse model of peanut allergy, improving the particles as the project evolved to have a higher loading level and lower burst release. The microparticles improved the safety and efficacy of an immunotherapy protocol. I also encapsulated hydrophilic and hydrophobic chemotherapeutic drugs for a brain cancer model.</p> / Dissertation

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22037号 / 医博第4522号 / 新制||医||1038(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 髙橋 良輔, 教授 湊谷 謙司, 教授 井上 治久 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

The work of the Cal Poly Tissue Engineering Lab is primarily focused on the fabrication, characterization, and improvement of “Blood Vessel Mimics” (BVMs), tissue engineered constructs used to evaluate cellular response to vascular medical devices. Currently, cells are grown onto fibrous, porous tubes made using an in-house electrospinning process from PLGA, a biocompatible co-polymer. The adhesion and proliferation of cells in a BVM is reliant on the micro-scale structure of the PLGA scaffold, and as such it is of great importance for the electrospinning process to consistently produce scaffolds of similar morphologies. Additionally, it has been shown that cell proliferation increases with scaffolds of smaller fibers and pores than the current electrospinning protocol can produce. Finally, the Tissue Engineering Lab has interest in testing devices in more tortuous BVM bioreactor designs, however the use of relatively rigid PLGA scaffolds has severely limited the ability to construct more complicated vessel geometries. The overall goal of this thesis was to improve fabrication and characterization of electrospun polymer scaffolds for BVM use. The specific aims of this thesis were to: 1) Improve scaffold characterization by comparing two techniques for fiber diameter measurement and implementing a technique for pore area measurement. 2) Reduce scaffold fiber diameter and pore area by investigating humidity and solvent composition electrospinning parameters. 3) Reduce process variability by developing a more specific electrospinning protocol. 4) Improve scaffold consistency and use by understanding and reducing PLGA scaffold shrinkage. 5) Identify and evaluate more flexible polymers as potential alternatives for electrospun BVM scaffolds. In order to accomplish these aims, first, several BVM and outside literature images were taken and evaluated with current and prospective fiber diameter techniques, and with 2 prospective pore area techniques to characterize accuracy and consistency of each method. It was found that the prospective fiber diameter measurement technique was not superior to the current method. The techniques developed for pore area measurement were found to produce results that differed significantly from each other and from the published value for a given image. Next, changes to environmental and solution composition parameters were made with the hopes of reducing fiber diameter and pore area of electrospun PLGA scaffolds. Changes in relative humidity did not appear to significantly affect scaffold fiber diameter while changes to solvent composition, specifically the use of acetone, resulted in fibers significantly smaller than those regularly achieved in the BVM lab. Next, several sources of variability in the electrospinning protocol were identified and subsequently altered to improve consistency and usability. Specifically, this included redefining the precision with which PLGA mass was measured, repositioning electrical equipment to reduce the effect of stray electrostatic forces on the polymer solution jet, attempting to control the temperature and humidity inside the electrospinning enclosure, and improving the ease with which scaffolds are removed from their mandrels through alternative mandrel surface treatments. In addition to overall process variability, the issue of scaffold shrinkage during BVM use was investigated and two possible treatments, exposure to either ethanol or elevated temperatures, were proposed based on previous electrospinning literature results. Each was tested for their effectiveness in mitigating shrinkage through exposure to BVM setup-mimicking conditions. It was found that both treatments reduced scaffold shrinkage compared to control samples when exposed to BVM setup-mimicking conditions. Finally, 3 flexible polymers were selected and electrospun to compare against typical PLGA results and to conduct a kink radius test as a metric for measuring flexibility as it pertains to the proposed BVM lab application. It was concluded that two types of thermoplastic polyurethane (tPU) were not acceptable electrospinning materials for use in the BVM lab. Additionally, while polycaprolactone (PCL) could be successfully electrospun it could not undergo the amount bending required for more tortuous BVM bioreactor designs without kinking. Overall, the work in this thesis provided insight into multiple scaffold characterization techniques, reduced overall electrospinning variability in the fabrication and use of PLGA scaffolds, and defined processing parameters that have been shown to yield scaffolds with smaller morphological features than all prior Tissue Engineering Lab work. By creating better, more effective scaffolds, researchers in the Tissue Engineering Lab can more accurately mimic the structure and properties of native blood vessels; this, in turn, will result in BVM cell responses that more closely resemble that of native tissue. Creating consistent and appropriate BVMs will then lead to impactful contributions to the existing body of tissue engineering research and to better preclinical device testing.

Charles University, Faculty of Pharmacy in Hradci Králové Department of: Pharmaceutical technology Consultants: Jana Kubačková, Ondřej Holas Student: Jáchym Vencl Title of Thesis: Optimization of polymeric nanoparticles separation and purification protocol Poly(lactic-co-glycolic) acid (PLGA) is one of the most successful polymeric molecule invented for biomedical use. PLGA's biggest advantage lies in its biodegradability and nontoxicityChyba! Záložka není definována.. It has been approved by EMA for human use. Because of increasing number of protein or nucleic acid based drugs the need for sophisticated drug delivery systems grows. PLGA nanoparticles (NPs) present exactly such drug delivery system capable of encapsulating large variety of compoundsChyba! Záložka není definována.. Within this study we have researched optimization of separation and purification of drug loaded NPs. They were prepared by nanoprecipitation of PLGAChyba! Záložka není definována.. Separation and purification of NPs was done using multiple cycles of centrifugation. We evaluated purification of particles prepared from five different PLGA polymers. Different centrifugation times were applied to find the most effective way. Water and two types of stabilizers each one in two concentrations have been used as purification...

Die Wundheilung stellt einen physiologischen Vorgang zur Regeneration zerstörten Gewebes dar. Der reibungslose Ablauf der Heilung wird durch ein komplexes Zusammenspiel von Zellen und extrazellulären Komponenten gewährleistet. Durch vielfältige Faktoren kann dieser fein abgestimmte Prozess zum Erliegen kommen, so dass eine chronische Wundheilungsstörung resultiert. Trotz zahlreicher Behandlungsmöglichkeiten chronischer Wunden bleibt jedoch die erfolgreiche Heilung oftmals aus. Die Anwendung von biodegradierbaren Materialen (Biomaterialien) in der Wundheilung wurde in den vergangenen Jahren intensiv erforscht und teilweise erfolgreich am Patienten eingesetzt. An dem Ziel, ein Biomaterial herzustellen, welches alle funktionellen und strukturellen Fähigkeiten gesunder menschlicher Haut mit sich bringt, wird jedoch nach wie vor gearbeitet. In verschiedenen Studien konnte die gute Verträglichkeit und Biodegradierbarkeit des Biopolymers PLGA, bestehend aus Lactat und Glycolsäure, bereits gezeigt werden. In der vorliegenden Dissertation wurden dreidimensionale (3D)-Gerüste (Scaffolds) aus PLGA hinsichtlich ihrer Wechselwirkungen mit humanen dermalen Fibroblasten (Fb) untersucht. Dermale Fb leisten einen entscheidenden Beitrag zur erfolgreichen Wundheilung, da sie unter der Einwirkung diverser Wachstumsfaktoren zur Migration ins Wundgebiet sowie zur Neusynthese und Reorganisation extrazellulärer Matrix (ECM) befähigt sind. In den Untersuchungen wurden grundlegende Kenntnisse zum Verhalten der Zellen bezüglich Proliferation sowie Synthese nativer ECM in den PLGA-Scaffolds gewonnen und das Migrationsverhalten der Fb in das Biomaterial untersucht. Dabei zeigte sich, dass dermale Fb in den PLGA-Scaffolds nicht nur proliferieren sondern auch einen ausgeprägten Matrixstoffwechsel aufweisen. Sie sind in der Lage, Kollagen und Hyaluronsäure, wichtige Bestandteile der ECM, abzulagern. Zudem konnte mit Hilfe der Arbeit der Einfluss von Wachstumsfaktoren sowohl auf relevante ECM-Komponenten im 3D-Kultursystem als auch auf das Migrationsverhalten der Fb in das Biomaterial verdeutlicht werden. Aus den Ergebnissen geht hervor, dass 3D-PLGA-Scaffolds geeignete Substrate zur Kultivierung dermaler Fb darstellen. Die zukünftig geplante Weiterentwicklung und Funktionalisierung dieses Biopolymers für den Einsatz in der Wundheilung scheint somit viel versprechend.

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