968 resultados para Laser Microdissection Microscopy
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Este trabalho teve como principal objetivo estudar e modificar as propriedades funcionais das proteínas de soja de forma a otimizar e diversificar a sua aplicação industrial. Para tal, foram propostas e estudadas quatro estratégias: i) extração do isolado de proteínas de soja (IPS) a partir de diferentes matérias-primas, ii) adição de galactomananas (GM) com graus de ramificação e massas moleculares diferentes, iii) hidrólise enzimática controlada das proteínas de soja, iv) processamento por alta pressão hidrostática. O estudo e a interpretação da influência destas estratégias sobre as propriedades funcionais das proteínas de soja, nomeadamente, na capacidade gelificante e emulsionante, foram realizados recorrendo fundamentalmente a ensaios reológicos dinâmicos a baixas deformação, espectroscopia de infravermelho, electroforeses, calorimetria diferencial de varrimento e ensaios de microscopia confocal de varrimento laser. O estudo da extração e caracterização dos isolados de proteínas de soja obtidos a partir de diferentes matérias-primas permitiu concluir que as caraterísticas físico-químicas dos isolados são dependentes da origem da matéria-prima de extração e da severidade dos tratamentos industriais prévios à extração do isolado. Contudo, as propriedades viscoelásticas dos géis obtidos por aquecimento controlado não foram significativamente distintas embora tenha sido possível relacionar o grau de agregação com a diminuição da temperatura de gelificação e com o aumento inicial dos módulos viscoelásticos. As alterações sofridas pelos isolados de origem comercial mostraram ser irreversíveis resultando em géis menos rígidos e com maior caráter viscoso. A adição de galactomanana alterou significativamente o mecanismo de gelificação induzido termicamente das proteínas de soja, bem como as propriedades viscoelásticas dos géis e a microestrutura dos géis, demonstrando-se a ocorrência de separação de fases, em virtude da incompatibilidade termodinâmica entre os biopolímeros, resultando em géis mais rígidos e no decréscimo da temperatura de gelificação. A extensão destas alterações foi dependente da massa molecular, grau de ramificação e da razão IPS/GM. O efeito da hidrólise enzimática por ação da bromelina, nas propriedades gelificantes e emulsionantes das proteínas de soja, mostrou ser dependente do grau de hidrólise (GH). Valores de GH inferiores a 15 % melhoraram as propriedades gelificantes das proteínas de soja. Por outro lado, o aumento do GH teve um efeito negativo nas propriedades emulsionantes, o qual foi atenuado por adição da goma de alfarroba, com efeito positivo na gelificação das proteínas de soja. A concentração crítica limite de compatibilidade entre os hidrolisados de proteína de soja e a goma de alfarroba aumentou com o decréscimo do GH e da massa molecular do polissacacrídeo. O efeito da AP sobre as propriedades físico-químicas e funcionais dos IPS foi influenciado pela origem do isolado e pelas condições de tratamento. O processamento até 100 MPa desencadeou um aumento da atividade emulsionante e considerável melhoria da capacidade gelificante. Contudo, valores de pressão superiores promoveram a desnaturação das proteínas constituintes dos isolados, resultando no decréscimo da temperatura de gelificação e numa re-associação das subunidades proteicas, diminuindo a elasticidade dos géis finais. Os resultados sugeriram que as alterações nas proteínas de soja promovidas durante o tratamento por AP constituem um fator limitante para o desdobramento e re-associação durante o aquecimento térmico, necessários para a formação e fortalecimento de gel formado. O processamento por AP influenciou a estrutura secundária e a microestrutura das amostras. A presença de GA teve um papel baroprotetor. Assim, com este trabalho demonstrou-se que com as estratégias seguidas para manipulação das propriedades funcionais de proteínas de soja, nomeadamente através da adição de um polissacarídeo com propriedades estruturais controladas, da adequada combinação da adição de um polissacarídeo neutro com a hidrólise controlada das proteínas ou com tratamento por alta pressão, é possível a criação de novas funcionalidades, com utilidade no desenvolvimento de novas formulações alimentares, permitindo expandir a aplicação destas proteínas vegetais.
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The purpose of this study was to develop a bone substitute material capable of preventing or treating osteomyelitis through a sustainable release of vancomycin and simultaneously inducing bone regeneration. Porous heparinized nanohydroxyapatite (nanoHA)/collagen granules were characterized using scanning electron microscopy, micro-computed tomography and attenuated total reflectance Fourier transform infrared spectroscopy. After vancomycin adsorption onto the granules, its releasing profile was studied by UV molecular absorption spectroscopy. The heparinized granules presented a more sustainable release over time, in comparison with nonheparinized nanoHA and nanoHA/collagen granules. Vancomycin was released for 360 h and proved to be bioactive until 216 h. Staphylococcus aureus adhesion was higher on granules containing collagen, guiding the bacteria to the material with antibiotic, improving their eradication. Moreover, cytotoxicity of the released vancomycin was assessed using osteoblast cultures, and after 14 days of culture in the presence of vancomycin, cells were able to remain viable, increasing their metabolic activity and colonizing the granules, as observed by scanning electron microscopy and confocal laser scanning microscopy. These findings suggest that heparinized nanoHA/collagen granules are a promising material to improve the treatment of osteomyelitis, as they are capable of releasing vancomycin, eliminating the bacteria, and presented morphological and chemical characteristics to induce bone regeneration.
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In the colon, the urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitors, PAI-1 and PAI-2, are implicated in the transition from mucosa to adenoma and tumour progression. However, expression in the mucosa adjacent, or distant, to an adenoma has not yet been investigated. Three biopsies from mucosae adjacent (20 cm, ipsilateral) and distant (contralateral) to an isolated tubular adenoma were analysed in 14 patients and 8 controls. Laser microdissection isolated stromal and epithelial crypt components, and quantitative RT-PCR analyses of uPA, uPAR, PAI-1 and PAI-2 mRNA levels were performed. Among controls, no significant differences in the markers were noted. With left colon isolated tubular adenoma, uPA, uPAR, and PAI-2 mRNA levels were significantly increased in the adjacent mucosal stroma compared to epithelial crypt levels (p < 0.05). In right colon adenoma, the mRNA levels of these 3 molecular markers were significantly increased only in the adjacent mucosal stromal samples (p < 0.05). Isolated tubular adenoma in the colon increases significantly the mRNA levels of 3 proteolysis-associated molecular markers in the stromal, but not in the epithelial, components of adjacent mucosa. These results suggest the presence of regional and dynamic interactions in apparently non-involved mucosae.
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Introduction : La chronicité de la rhinosinusite, sa résistance aux antibiotiques, et ses exacerbations aiguës laissent croire que les biofilms sont impliqués dans la rhinosinusite chronique. Objectifs : Nous avons évalué la capacité des bactéries Pseudomonas aeruginosa, staphylocoques à coagulase négative et Staphylococcus aureus à former des biofilms par un essai in vitro, et si cette capacité de formation a un lien avec l’évolution de la maladie. Nous avons évalué in vitro l’effet de la moxifloxacine, un antibiotique utilisé dans le traitement de la rhinosinusite chronique sur des biofilms matures de Staphylococcus aureus. Méthodes : Trent et une souches bactériennes ont été isolées de 19 patients atteints de rhinosinusite chronique et qui ont subit au moins une chirurgie endoscopique des sinus. L’évolution de la maladie a été notée comme "bonne" ou "mauvaise" selon l’évaluation du clinicien. La production de biofilm a été évaluée grâce à la coloration au crystal violet. Nous avons évalué la viabilité du biofilm après traitement avec la moxifloxacine. Ces résultats ont été confirmés en microscopie confocale à balayage laser et par la coloration au LIVE/DEAD BacLight. Résultat et Conclusion : Vingt deux des 31 souches ont produit un biofilm. La production d’un biofilm plus importante chez Pseudomonas aeruginosa et Staphylococcus aureus était associée à une mauvaise évolution. Ceci suggère un rôle du biofilm dans la pathogenèse de la rhinosinusite chronique. Le traitement avec la moxifloxacine, à une concentration de 1000X la concentration minimale inhibitrice réduit le nombre des bactéries viables de 2 à 2.5 log. Ces concentrations (100 µg/ml - 200 µg/ml) sont faciles à atteindre dans des solutions topiques. Les résultats de notre étude suggèrent que l’utilisation de concentrations supérieure à la concentration minimale inhibitrice sous forme topique peut ouvrir des voies de recherche sur de nouveaux traitements qui peuvent être bénéfiques pour les patients atteints de forme sévère de rhinosinusite chronique surtout après une chirurgie endoscopique des sinus.
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Les biofilms sont des communautés structurées de micro-organismes enrobées dans une matrice extracellulaire. Les biofilms sont impliqués dans la persistance de plusieurs maladies infectieuses et la matrice extracellulaire du biofilm protège les bactéries contre les cellules du système immunitaire de l'hôte, les antibiotiques et les désinfectants. Récemment notre laboratoire a démontré que le zinc inhibe la formation de biofilm chez Actinobacillus pleuropneumoniae, une bactérie pathogène du porc. Le but de cette étude est d'évaluer l'effet du zinc sur la croissance et la formation du biofilm chez différentes bactéries pathogènes du porc, telles que Bordetella bronchiseptica, Escherichia coli, Haemophilus parasuis, Salmonella, Staphylococcus aureus et Streptococcus suis. Les bactéries ont été cultivées dans des plaques de 96 puits sous condition optimale de formation de biofilm et les biofilms ont été colorés au cristal violet. La présence du biofilm a été confirmée par microscopie confocale à balayage laser à l’aide du marqueur fluorescent FilmTracerTM FM ® 1-43. À des concentrations micromolaires, le zinc inhibe faiblement la croissance bactérienne et bloque d'une manière dose-dépendante la formation de biofilm d’A. pleuropneumoniae, Salmonella Typhimurium et H. parasuis. De plus, la formation de biofilm de E. coli, S. aureus et S. suis a été faiblement inhibée par le zinc. Nos résultats indiquent que le zinc a un effet inhibiteur sur la formation de biofilm de la plupart des pathogènes bactériens d'origine porcine. Cependant, le mécanisme sous-jacent de l'activité anti-biofilm du zinc reste à être caractérisé.
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Nous démontrons qu'il est possible de former des bicouches fluides non phospholipides en milieu aqueux avec un mélange d'acide palmitique (PA), cholestérol (Chol) et sulfate de cholestérol (Schol) avec une proportion molaire de 30/28/42. Ces liposomes non phospholipidiques peuvent maintenir un gradient de pH (pHinterne 8 / pHexterne 6) sur une période 100 fois plus longue que les liposomes faits de 1-palmitoyl-2-oléoyl-sn-glycéro-3-phosphocholine (POPC) et de cholestérol (60/40 mol/mol). De plus, ces LUV non phospholipidiques protègent l'acide ascorbique d'un milieu oxydant (1 mM de fer (III)). Une fois piégé dans les liposomes, l'acide ascorbique présente une vitesse de dégradation similaire à celle obtenue en l'absence de fer(III). Ces performances illustrent la perméabilité exceptionnellement limitée de ces liposomes, ce qui implique qu'ils peuvent présenter des avantages comme nanocontenants pour certaines applications. D'autre part, des vésicules unilamellaires géantes (GUV pour Giant Unilamellar Vesicles) ont été formées à partir d'un mélange d'acide palmitique et de cholestérol (30/70 mol/mol). Ces GUV sont stables sur l'échelle de temps de semaines, elles ne s'agrègent pas et elles sont sensibles au pH. Afin d'établir la formation des GUV, l'imagerie par microscopie confocale à balayage laser a été utilisée. Deux sondes fluorescentes ont été utilisées: le rouge du Nile, une sonde hydrophobe qui s'insère dans le cœur hydrophobe des bicouches lipidiques, et la calcéine, une sonde hydrophile qui a été emprisonné dans le réservoir interne des GUV. Cette approche a permis l'observation des parois des GUV ainsi que de leur contenu. Ces résultats montrent la possibilité de former de nouveaux microcontenants à partir d'un mélange d'un amphiphile monoalkylé et de stérol.
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Introducción: el fotoenvejecimiento cutáneo es causado principalmente por la exposición crónica y acumulativa a los rayos ultravioleta. Las clasificaciones y escalas existentes evalúan el envejecimiento cutáneo de forma global y no existe un instrumento que valore exclusivamente el fotoenvejecimiento cutáneo. Objetivo: Construir y realizar la validación de contenido, de una escala para valoración clínica del fotoenvejecimiento cutáneo en la cara. Materiales y métodos: Estudio de validez de contenido, de una escala para valoración clínica del fotoenvejecimiento cutáneo en cara, construida a partir del marco conceptual, y evaluada por 15 expertos con especialidades médicas que manejan el fotoenvejecimiento. Los datos obtenidos se analizaron así: porcentaje de la pertinencia; la media; coeficiente de variación (CV) e índice de validez de contenido por ítem (CVIi) de cada ítem incluido en la escala. Resultados: Para el grupo de 15 expertos evaluadores, la pertinencia de los 6 ítems incluidos en los criterios clínicos, arrojo una media de 4,2/5 con CVIi entre 73,3% y 100% y con CV por debajo del 20%; el ítem de surcos tuvo un CV de 26,93%; la pertinencia de los 5 ítems incluidos en los antecedentes, arrojo una media de 3,9/5, un CVIi entre 73,3% y 80% y un CV entre 33,67% y 39,84%. Discusión y conclusiones: La validez de contenido de los criterios clínicos de la escala cumplió en un nivel alto con la pertinencia, lo que indica que miden adecuada y exclusivamente las dimensiones del grado clínico de fotoenvejecimiento cutáneo en cara evaluado por los expertos.
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The aim of this study was to evaluate the distribution of inhibin/activin alpha, beta(A) and beta(B) subunits and follistatin in immature oocytes and in matured oocytes before and after IVF. Denuded oocytes were submitted to a whole-mount immunofluorescence procedure. Specimens were imaged and fluorescent intensities quantified by scanning laser confocal microscopy. Immunoreactivity for inhibin alpha subunit (both alpha(C) and pro-alpha. regions), abundant in the ooplasm of immature oocytes, decreased after maturation (a 68% and 88% decrease, respectively; P < 0.001), but increased after IVF by 2- and 5.7-fold, respectively (P < 0.01). Intense staining for PA was detected in immature oocytes (predominantly in the outer ooplasm and zona pellucida) but after maturation and fertilization it was localized mainly in the zona pellucida, perivitelline space and oolemma. Immunoreactivity for RA in the ooplasm decreased by 58% after maturation (P < 0.001) but increased again by 75% after fertilization (P < 0.01). Immunoreactivity for beta(B) was localized mainly in the zona pellucida and did not change after maturation. However, immurloreactivity for beta(B) was not detected in the zona pellucida after fertilization, but remained unchanged in unfertilized oocytes. Immunoreactivity for follistatin was detected in the ooplasm and zona pellucida of immature oocytes but decreased progressively in the ooplasm after maturation (a 63% decrease; P < 0.001) and did not change after IVF. Examination of partially denuded cumulus-oocyte complexes confirmed abundant expression of alpha(C), pro-alpha, beta(A) and follistatin immunoreactivity in cumulus cells, whereas beta(B) subunit staining was weak or absent in cumulus cells, but intense in the zona pellucida. In conclusion, the present study shows that qualitative and quantitative changes in the distribution of inhibin/activin subunits and follistatin accompany oocyte maturation and fertilization. The possibility, indicated by these observations, that activin A and activin B may play distinct roles in bovine oocyte maturation and fertilization warrants further study.
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Changes in the theological properties during crystallisation and in the crystal size and morphology of blends containing rapeseed oil with varying percentages of palm stearin (POs) and palm olein (POf) have been studied. The crystals formed from all three blends were studied by confocal laser scanning microscopy, light microscopy and environmental scanning electron microscopy, which revealed the development of clusters of 3-5 individual elementary "spherulites" in the early stages of crystallisation. The saturated triacylglycerol content of the solid crystals separated at the onset of crystallisation was much greater than that in the total fat. Fat blends with a higher content of palm stearin had a more rapid nucleation rate when observed by light microscopy, and this caused an earlier change in the rheological properties of the fat during crystallisation. Using a low torque amplitude (0.005 Pa, which was within the linear viscoelastic region of all samples studied) and a frequency of 1 Hz, the viscoelastic properties of melted fat during cooling were studied. All samples, prior to crystallisation, showed weak viscoelastic liquid behaviour (G '', loss modulus >G', storage modulus). After crystallisation a more "solid like" behaviour was observed (G' similar to or greater than G ''). The blend having the highest concentration of POs was found to have the earliest onset of crystallisation (27% w/w POs; 12 mins, 22% w/w POs; 13.5 mins, 17% w/w POs, 15 mins, respectively). However, there were no significant differences in the time to the point when G' became greater than G' among the three blends. (c) 2006 Elsevier Ltd. All rights reserved.
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This study investigates the production of alginate microcapsules, which have been coated with the polysaccharide chitosan, and evaluates some of their properties with the intention of improving the gastrointestinal viability of a probiotic (Bifidobacterium breve) by encapsulation in this system. The microcapsules were dried by a variety of methods, and the most suitable was chosen. The work described in this Article is the first report detailing the effects of drying on the properties of these microcapsules and the viability of the bacteria within relative to wet microcapsules. The pH range over which chitosan and alginate form polyelectrolyte complexes was explored by spectrophotometry, and this extended into swelling studies on the microcapsules over a range of pHs associated with the gastrointestinal tract. It was shown that chitosan stabilizes the alginate microcapsules at pHs above 3, extending the stability of the capsules under these conditions. The effect of chitosan exposure time on the coating thickness was investigated for the first time by confocal laser scanning microscopy, and its penetration into the alginate matrix was shown to be particularly slow. Coating with chitosan was found to increase the survival of B. breve in simulated gastric fluid as well as prolong its release upon exposure to intestinal pH.
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This paper represents a study of the transient changes occurring in temperature, and moisture and oil contents during the so called “post-frying drainage”—which is the duration for which a product is held in the head space of the fryer after it is removed from the oil. Since most of the oil adhering to the product penetrates into the structure during this period, this paper examines the effects of applying vacuum during drainage (1.33 kPa) to maintain the product temperature consistently above the water saturation temperature corresponding to the prevailing pressure (11 °C), which potentially eliminates water condensation and prevents the occluded surface oil from penetrating into the product structure. Draining under vacuum significantly lowers the oil content of potato chips by 38% compared to atmospheric drainage. This phenomenon can be further confirmed by confocal laser scanning microscopy (CLSM) images, which show that the boundary between the core and the crust regions is clearly visible in the case of vacuum drainage, whereas in the case of atmospheric drainage, the oil is distributed throughout the structure. Unfortunately, the same approach did not reduce the oil content of French fries—the oil content of vacuum-drained product was found similar to the product obtained by draining under atmospheric pressure. This is because the reduction in oil content only occurs when there is net moisture evaporation from the product and the evaporation rate is sufficient to force out the oil from the product; this was clearly not the case with French fries. The CLSM images show that the oil distribution in the products drained under atmospheric pressure and vacuum was similar.
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A nitric oxide synthase (NOS)-like activity has been demonstrated in human red blood cells (RBCs), but doubts about its functional significance, isoform identity and disease relevance remain. Using flow cytometry in combination with the NO-imaging probe DAF-FM we find that all blood cells form NO intracellularly, with a rank order of monocytes > neutrophils > lymphocytes > RBCs > platelets. The observation of a NO-related fluorescence within RBCs was unexpected given the abundance of the NO-scavenger oxyhemoglobin. Constitutive normoxic NO formation was abolished by NOS inhibition and intracellular NO scavenging, confirmed by laser-scanning microscopy and unequivocally validated by detection of the DAF-FM reaction product with NO using HPLC and LC-MS/MS. Employing immunoprecipitation, ESI-MS/MS-based peptide sequencing and enzymatic assay we further demonstrate that human RBCs contain an endothelial NOS (eNOS) that converts L-3H-Arginine to L-3H-Citrulline in a Ca2+/Calmodulin-dependent fashion. Moreover, in patients with coronary artery disease, red cell eNOS expression and activity are both lower than in age-matched healthy individuals and correlate with the degree of endothelial dysfunction. Thus, human RBCs constitutively produce NO under normoxic conditions via an active eNOS isoform the activity of which is compromised in patients with coronary artery disease.
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The oral administration of probiotic bacteria has shown potential in clinical trials for the alleviation of specific disorders of the gastrointestinal tract. However, cells must be alive in order to exert these benefits. The low pH of the stomach can greatly reduce the number of viable microorganisms that reach the intestine, thereby reducing the efficacy of the administration. Herein, a model probiotic, Bifidobacterium breve, has been encapsulated into an alginate matrix before coating in multilayers of alternating alginate and chitosan. The intention of this formulation was to improve the survival of B. breve during exposure to low pH and to target the delivery of the cells to the intestine. The material properties were first characterized before in vitro testing. Biacore™ experiments allowed for the polymer interactions to be confirmed; additionally, the stability of these multilayers to buffers simulating the pH of the gastrointestinal tract was demonstrated. Texture analysis was used to monitor changes in the gel strength during preparation, showing a weakening of the matrices during coating as a result of calcium ion sequestration. The build-up of multilayers was confirmed by confocal laser-scanning microscopy, which also showed the increase in the thickness of coat over time. During exposure to in vitro gastric conditions, an increase in viability from <3 log(CFU) per mL, seen in free cells, up to a maximum of 8.84 ± 0.17 log(CFU) per mL was noted in a 3-layer coated matrix. Multilayer-coated alginate matrices also showed a targeting of delivery to the intestine, with a gradual release of their loads over 240 min.
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If acid-sensitive drugs or cells are administered orally, there is often a reduction in efficacy associated with gastric passage. Formulation into a polymer matrix is a potential method to improve their stability. The visualization of pH within these materials may help better understand the action of these polymer systems and allow comparison of different formulations. We herein describe the development of a novel confocal laser-scanning microscopy (CLSM) method for visualizing pH changes within polymer matrices and demonstrate its applicability to an enteric formulation based on chitosan-coated alginate gels. The system in question is first shown to protect an acid-sensitive bacterial strain to low pH, before being studied by our technique. Prior to this study, it has been claimed that protection by these materials is a result of buffering, but this has not been demonstrated. The visualization of pH within these matrices during exposure to a pH 2.0 simulated gastric solution showed an encroachment of acid from the periphery of the capsule, and a persistence of pHs above 2.0 within the matrix. This implies that the protective effect of the alginate-chitosan matrices is most likely due to a combination of buffering of acid as it enters the polymer matrix and the slowing of acid penetration.
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Due to their broad differentiation potential and their persistence into adulthood, human neural crest-derived stem cells (NCSCs) harbour great potential for autologous cellular therapies, which include the treatment of neurodegenerative diseases and replacement of complex tissues containing various cell types, as in the case of musculoskeletal injuries. The use of serum-free approaches often results in insufficient proliferation of stem cells and foetal calf serum implicates the use of xenogenic medium components. Thus, there is much need for alternative cultivation strategies. In this study we describe for the first time a novel, human blood plasma based semi-solid medium for cultivation of human NCSCs. We cultivated human neural crest-derived inferior turbinate stem cells (ITSCs) within a blood plasma matrix, where they revealed higher proliferation rates compared to a standard serum-free approach. Three-dimensionality of the matrix was investigated using helium ion microscopy. ITSCs grew within the matrix as revealed by laser scanning microscopy. Genetic stability and maintenance of stemness characteristics were assured in 3D cultivated ITSCs, as demonstrated by unchanged expression profile and the capability for self-renewal. ITSCs pre-cultivated in the 3D matrix differentiated efficiently into ectodermal and mesodermal cell types, particularly including osteogenic cell types. Furthermore, ITSCs cultivated as described here could be easily infected with lentiviruses directly in substrate for potential tracing or gene therapeutic approaches. Taken together, the use of human blood plasma as an additive for a completely defined medium points towards a personalisable and autologous cultivation of human neural crest-derived stem cells under clinical grade conditions.