Antigen-specific CD8 T cells play a critical role in protecting the host from infection by intracellular pathogens including viruses, bacteria and parasites. During the course of an infection, antigen-specific CD8 T cells undergo proliferative expansion to increase in number, which is followed by contraction and generation of a stable pool of long-lived memory cells. Importantly, memory CD8 T cells provide enhanced resistance to re-infection by the same pathogen. Moreover, the number of memory CD8 T cells correlates strongly with the level of protection against re-infection. Therefore, vaccines designed to promote cellular immunity should logically focus on achieving sufficiently high number of these memory cells for protection. Most current vaccines have relied on inducing antibodies to protect the host by neutralizing pathogens or blocking pathogen entry into the cells. However, there is a recognized need to design vaccines that also stimulate a strong CD8 T cell component of the adaptive immune response in addition to antibodies. Importantly, inflammatory cytokines induced by infection or vaccination with adjuvant act directly or indirectly on CD8 T cells to modulate their expansion, contraction and acquisition of memory characteristics. Thus, an understanding of how inflammatory cytokines regulate CD8 T cell memory differentiation may help guide the strategies for rational vaccine design. My studies examine the roles of inflammatory cytokines in regulating CD8 T cell memory differentiation. Specifically, my studies investigate the timing of inflammatory cytokine exposure and the role of type I IFNs and IL-12 in regulating effector/memory CD8 T cell differentiation, and exploiting the cross-presentation pathway to rapidly generate protective CD8 T cell immunity. Specifically, my results indicate that (i) encounter with inflammatory cytokines during the rapid proliferative phase deflects CD8 T cell differentiation away from memory towards a sustained effector program, (ii) that direct signaling by either type I IFN or IL-12 to the responding CD8 T cells promotes maximal expansion, but neither of these cytokines is essential to regulate the effector/memory differentiation program, and (iii) cross-priming with both cell-associated antigen and antigen-coated, biodegradable microspheres, accelerates CD8 T cell memory development that can be exploited to rapidly generate protective CD8 T cell immunity.

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

O processo de micrencapsulação de proteínas em microesferas (MS) de PLGA [poli (ácido lactico-co-glicolico)] é fácil de fazer e é uma ferramenta útil para melhorar tanto uma formulação quanto para aumentar a atividade imunológica de vacinas de novas gerações. A MS-PLGA têm caráter adjuvante porque é um sistema particulado e, além disto, controla a liberação do antígeno. O escopo desta tese foi o de dar uma nova roupagem para um antígeno vacinal tradicional e muito bem estudado- o toxoide diftérico (Dtxd). Estudaram-se a produção de MS de tamanho desejado; os mecanismos que controlam danos nas proteínas durante o processo de micrencapsulação; a produção de microesferas com características de liberações em tempos distintos e ensaios biológicos. O tamanho de MS é um determinante fundamental para controlar a velocidade de liberação de um soluto. Para se produzir MS com tamanhos controlados usou-se um desenho fatorial experimental com três fatores distintos e três pontos centrais, para se determinar a influência das variáveis (concentração de poli álcool vinílico; velocidade de agitação e relação fase dispersa/fase contínua) na determinação do tamanho das MS. Foram obtidas MS esféricas e lisas de 4- 15 µm de diâmetro. Estes resultados abrem a possibilidade de se formular PLGA-MS com tamanhos planejados através de um mínimo de experimentos. O mecanismo de danos conformacionais nas proteínas nas várias fases do processo de produção de PLGA-MS é ainda uma questão em aberto. Usaram-se várias técnicas biofísicas (HPLC, espectroscopias no uv, fluorescência e CD) além de ELISA para se testar a interferência dos sais da série de Hofmeister sobre a solubilidade e estabilidade da proteína durante a emulsificação e do contacto com a interface água/cloreto de metileno (primeira etapa do processo de preparação de MS). Estudaram-se também a influência de oligômeros de PLGA e SDS sobre a estrutura da proteína no meio de liberação (etapa de liberação do soluto). A emulsificação de Dtxd na presença de Mg2+ induziu agregação protéica, com exposição de resíduos hidrofóbicos para o meio; variações no ângulo diédrico do S-S proteico e perda de identidade imunológica. Esta agregação foi quase abolida pelo caotrópico SCN- (toxicidade = 30 g/ homem adulto de 70 kg). A conformação \"nativa\" do Dtxd e sua atividade biológica foram protegidas pelo KSCN. Os oligômeros de PLGA e o SDS induziram uma conformação de Dtxd nova. A adição de KSCN na fase aquosa aumentou a eficiência de encapsulação de Dtxd pela PLGA-MS em 20 %. Esta foi a solução mais simples quando comparada com aquelas descritas na literatura. Produziram-se seis formulações diferentes (diferentes massas molares e carboximetilações do PLGA) com pelo menos três cinéticas de liberações distintas. Imunizaram-se camundongos com 5 µg de Dtxd encapsulado em MS-PLGA usando-se dois polímeros de 12 kDa (-COOH livre ou metilado) e um outro de 63 kDa (metilado). O padrão de resposta e a maturidade imunológicas foram medidos por titulações de IgG1 e IgG2a. Mantiveram-se os mesmos padrões de resposta humoral (desejável). Menores quantidades de antígenos foram necessárias para se obter os mesmos benefícios gerados pela vacina tradicional de Dtxd. Aumentaram-se a produção e a seletividade de anticorpos através de duas manipulações simples: a formulação e o tempo da aplicação da dose de reforço. Estes resultados colocam estas formulações na área de vacinas de sucesso uma vez que também foram obtidas memórias imunológicas. / The protein microencapsulation within microspheres (MS) of PLGA (Poly-lactide-co-glycolide) is easy to do and, it is a useful tool to enhance formulation and immunologic performances for new generation vaccines. MS-PLGA has adjuvant character because it is a particulate system and can control the antigen release. The question addressed in this thesis was to give this new dress for the traditional and well studied vaccine antigen - the diphtheria toxoid (Dtxd). The steps of MS control size production; mechanism to control protein damages; MS production with different polymers and biological assay were addressed here. MS size is a primary determinant of solute release velocity. A full factorial experimental design 23 with triplicate at the central point was used to determine the influence of variables (polyvinyl alcohol concentration, stirring velocity and the relationship between dispersed /continuous phase) on MS size. Uniformly spherical and smooth microspheres (4 - 15 µm of diameter) were obtained. These results open the possibility of formulating PLGA microspheres with custom sizes performing a minimum of experiments as required for specific applications. It stills an open question to detail the conformational mechanism of protein damages during the various steps of the PLGA microencapsulation process. Various techniques (HPLC gel filtration, ELISA, Fluorescence, UV and Circular dichroism spectroscopies) were tested on the interference of the Hofmeister ion series over protein solubility and stability during the emulsification and contact with the interface water/CH2Cl2 interface (First step on MS preparation). The interference of SDS and PLGA olygomers over protein structure in the liberation media was also studied (solute liberation step). The Dtxd emulsification in the presence of Mg2+ was followed by protein aggregation, with exposition of hydrophobic residues and changes on the dihedral S-S protein angle and loses on immunological identity. This aggregation is 95% avoided by the chaotropic and little toxic salt KSCN (30g/ adult human of 70 kg). All the \"native\" Dtxd conformation and biological properties were maintained by KSCN. MS with different liberation kinetics profile and different erosion characteristics were obtained by using six different polymers. The SDS and PLGA olygomers exerted a generation of new Dtxd molecular organization. The KSCN increased Dtxd encapsulation within PLGA-MS in more than 20 %. This was the simplest solution used to solve protein aggregation compared with others solutions used in the literature. The six different formulations produced (differing in molar mass and carboxymethylation) produced, at least, three different Dtxd liberation profiles. Mice were primed with 5 µg of Dtxd microencapsulated within MS prepared with 12 kDa (ended carboxymethylated or free PLGA) and with 63 kDa (methylated) PLGA. The response patterns and the immune maturity were measured by IgG1 and IgG2a titrations. The humoral pattern was maintained, but fewer antigens were needed to obtain the same traditional Dtxd vaccine benefits. The simple change on Dtxd-PLGA formulation and timing of the booster enhanced both, antibody production and selectivity. An immunological memory was also obtained, putting so, these formulations in the field of successful vaccine.

O processo de micrencapsulação de proteínas em microesferas (MS) de PLGA [poli (ácido lactico-co-glicolico)] é fácil de fazer e é uma ferramenta útil para melhorar tanto uma formulação quanto para aumentar a atividade imunológica de vacinas de novas gerações. A MS-PLGA têm caráter adjuvante porque é um sistema particulado e, além disto, controla a liberação do antígeno. O escopo desta tese foi o de dar uma nova roupagem para um antígeno vacinal tradicional e muito bem estudado- o toxoide diftérico (Dtxd). Estudaram-se a produção de MS de tamanho desejado; os mecanismos que controlam danos nas proteínas durante o processo de micrencapsulação; a produção de microesferas com características de liberações em tempos distintos e ensaios biológicos. O tamanho de MS é um determinante fundamental para controlar a velocidade de liberação de um soluto. Para se produzir MS com tamanhos controlados usou-se um desenho fatorial experimental com três fatores distintos e três pontos centrais, para se determinar a influência das variáveis (concentração de poli álcool vinílico; velocidade de agitação e relação fase dispersa/fase contínua) na determinação do tamanho das MS. Foram obtidas MS esféricas e lisas de 4- 15 µm de diâmetro. Estes resultados abrem a possibilidade de se formular PLGA-MS com tamanhos planejados através de um mínimo de experimentos. O mecanismo de danos conformacionais nas proteínas nas várias fases do processo de produção de PLGA-MS é ainda uma questão em aberto. Usaram-se várias técnicas biofísicas (HPLC, espectroscopias no uv, fluorescência e CD) além de ELISA para se testar a interferência dos sais da série de Hofmeister sobre a solubilidade e estabilidade da proteína durante a emulsificação e do contacto com a interface água/cloreto de metileno (primeira etapa do processo de preparação de MS). Estudaram-se também a influência de oligômeros de PLGA e SDS sobre a estrutura da proteína no meio de liberação (etapa de liberação do soluto). A emulsificação de Dtxd na presença de Mg2+ induziu agregação protéica, com exposição de resíduos hidrofóbicos para o meio; variações no ângulo diédrico do S-S proteico e perda de identidade imunológica. Esta agregação foi quase abolida pelo caotrópico SCN- (toxicidade = 30 g/ homem adulto de 70 kg). A conformação \"nativa\" do Dtxd e sua atividade biológica foram protegidas pelo KSCN. Os oligômeros de PLGA e o SDS induziram uma conformação de Dtxd nova. A adição de KSCN na fase aquosa aumentou a eficiência de encapsulação de Dtxd pela PLGA-MS em 20 %. Esta foi a solução mais simples quando comparada com aquelas descritas na literatura. Produziram-se seis formulações diferentes (diferentes massas molares e carboximetilações do PLGA) com pelo menos três cinéticas de liberações distintas. Imunizaram-se camundongos com 5 µg de Dtxd encapsulado em MS-PLGA usando-se dois polímeros de 12 kDa (-COOH livre ou metilado) e um outro de 63 kDa (metilado). O padrão de resposta e a maturidade imunológicas foram medidos por titulações de IgG1 e IgG2a. Mantiveram-se os mesmos padrões de resposta humoral (desejável). Menores quantidades de antígenos foram necessárias para se obter os mesmos benefícios gerados pela vacina tradicional de Dtxd. Aumentaram-se a produção e a seletividade de anticorpos através de duas manipulações simples: a formulação e o tempo da aplicação da dose de reforço. Estes resultados colocam estas formulações na área de vacinas de sucesso uma vez que também foram obtidas memórias imunológicas. / The protein microencapsulation within microspheres (MS) of PLGA (Poly-lactide-co-glycolide) is easy to do and, it is a useful tool to enhance formulation and immunologic performances for new generation vaccines. MS-PLGA has adjuvant character because it is a particulate system and can control the antigen release. The question addressed in this thesis was to give this new dress for the traditional and well studied vaccine antigen - the diphtheria toxoid (Dtxd). The steps of MS control size production; mechanism to control protein damages; MS production with different polymers and biological assay were addressed here. MS size is a primary determinant of solute release velocity. A full factorial experimental design 23 with triplicate at the central point was used to determine the influence of variables (polyvinyl alcohol concentration, stirring velocity and the relationship between dispersed /continuous phase) on MS size. Uniformly spherical and smooth microspheres (4 - 15 µm of diameter) were obtained. These results open the possibility of formulating PLGA microspheres with custom sizes performing a minimum of experiments as required for specific applications. It stills an open question to detail the conformational mechanism of protein damages during the various steps of the PLGA microencapsulation process. Various techniques (HPLC gel filtration, ELISA, Fluorescence, UV and Circular dichroism spectroscopies) were tested on the interference of the Hofmeister ion series over protein solubility and stability during the emulsification and contact with the interface water/CH2Cl2 interface (First step on MS preparation). The interference of SDS and PLGA olygomers over protein structure in the liberation media was also studied (solute liberation step). The Dtxd emulsification in the presence of Mg2+ was followed by protein aggregation, with exposition of hydrophobic residues and changes on the dihedral S-S protein angle and loses on immunological identity. This aggregation is 95% avoided by the chaotropic and little toxic salt KSCN (30g/ adult human of 70 kg). All the \"native\" Dtxd conformation and biological properties were maintained by KSCN. MS with different liberation kinetics profile and different erosion characteristics were obtained by using six different polymers. The SDS and PLGA olygomers exerted a generation of new Dtxd molecular organization. The KSCN increased Dtxd encapsulation within PLGA-MS in more than 20 %. This was the simplest solution used to solve protein aggregation compared with others solutions used in the literature. The six different formulations produced (differing in molar mass and carboxymethylation) produced, at least, three different Dtxd liberation profiles. Mice were primed with 5 µg of Dtxd microencapsulated within MS prepared with 12 kDa (ended carboxymethylated or free PLGA) and with 63 kDa (methylated) PLGA. The response patterns and the immune maturity were measured by IgG1 and IgG2a titrations. The humoral pattern was maintained, but fewer antigens were needed to obtain the same traditional Dtxd vaccine benefits. The simple change on Dtxd-PLGA formulation and timing of the booster enhanced both, antibody production and selectivity. An immunological memory was also obtained, putting so, these formulations in the field of successful vaccine.

ABSTRACT<p><p>This project aimed at developing a drug delivery system (DDS) able to enhance the stability and<p>residence time in vivo of antibodies (Abs). The system will deliver drug by the subcutaneous<p>route (SC), while ensuring accurate control of the drug release and the resulting plasmatic level. This technology platform will allow to reduce frequency of injection, potentially decrease side effects and maintain high concentration of Abs which will improve life of patient having chronic disease such as autoimmune and inflammatory disease. Biodegradable synthetic polymer-based formulations (polylactide-co-glycolide (PLGA)) were selected as carriers for encapsulated Abs. This was because they offer good protection for the Abs and allow sustained release of the Abs for a controlled period of time. After the evaluation of different encapsulation methods such as the water-oil-in-water (w/o/w) and the solid-in-oil-inwater<p>(s/o/w) processes, the encapsulation of the Ab in solid state (s/o/w) appeared to be more appropriate for producing Ab-loaded PLGA microspheres (MS). It allowed us to maintain the<p>Ab in a monomeric conformation and to avoid the formation of unsoluble aggregates mainly present at the water/oil interface. The first part of the project was the optimization of both the method for producing the Ab solid particles (spray-drying process) and the encapsulation of these Ab solid particles into the polymeric MS (s/o/w process) by design of experiment (DoE). These optimizations were carried out using a bovine polyclonal immunoglobulin G (IgG) as model molecule. In further optimization of the spray-drying process by (DoE), aqueous Ab solutions were spray-dried using a mini Spray-Dryer assembly with a 0.7 mm spray nozzle. In accordance with the particle size (d(0.5) ~5 μm), the stability (no loss of monomer measured by<p>size exclusion chromatography (SEC) and the yield of the spray-drying process (> 60 % w/w), the process parameters were set of follow: 3 mL/min as liquid feed flow rate, 130°C /75°C as inlet temperature (inlet T°) / outlet temperature (outlet T°), 800 L/h as atomization flow rate and<p>30 m3/h as drying air flow rate. For the s/o/w, the methylene chloride (MC) commonly used for<p>an encapsulation process was replaced by ethyl acetate (EtAc), which was considered as a more<p>suitable organic solvent in terms of both environmental and human safety. The effects of several processes and formulation factors were evaluated on IgG:PLGA MS properties such as: particle size distribution, drug loading, IgG stability, and encapsulation efficiency (EE%). Several formulations and processing parameters were also statistically identified as critical to get reproducible process (e.g. the PLGA concentration, the volume of the external phase, the emulsification rate, and the quantity of IgG microparticles). The optimized encapsulation<p>method of the IgG has shown a drug loading of up to 6 % (w/w) and an encapsulation efficiency<p>of up to 60 % (w/w) while preserving the integrity of the encapsulated antibody. The produced MS were characterized by a d(0.9) lower than 110 μm and showed burst effect lower than 50 %(w/w). In the second part of the project, the optimized spray-drying and s/o/w processes<p>developed with the IgG were applied to a humanized anti-tumor necrosis factor (TNF) alpha<p>MAb to confirm the preservation of the MAb activity during these processes. The selected s/o/w method allowed us to produce MAb-loaded PLGA MS with an appropriate release profile up to 6 weeks and MAb stability. In order to maintain the Abs’ activity, both during encapsulation and<p>dissolution, the addition of a stabilizer such as trehalose appeared to be crucial, as did the<p>selection of the PLGA. It was demonstrated that the use of a PLGA characterized by a 75:25<p>lactide:glycolide (e.g. Resomer ® RG755S) ratio decreased the formation of low molecular weight species during dissolution, which led to preserve Abs activity through its release from the<p>delivery system. Furthermore, the release profile was adjusted according to the type of polymer<p>and its concentration. E.g. 10 % w/v RG755S allowed Ab MS with a release time of 6 weeks to<p>be obtained. The optimization of both the formulation and the encapsulation process allowed<p>maximum 13 % w/w Ab-loaded MS to be produced. It was demonstrated that the Ab-loaded PLGA MS were stable when stored at 5°C for up to 12 weeks and that the selection of the appropriate type of PLGA was critical to assuring the stability of the system. The better stability observed when using a PLGA characterized by a 75:25 lactide:glycolide ratio was attributed to<p>its slower degradation rate. Finally, the sustained release of Ab from the developed MS and the preservation of its activity was confirmed in vivo in a pharmacokinetic (pK) study realized in<p>rats. In conclusion, the application of the concept of entrapment into a polymer matrix for<p>stabilization and sustained release of biological compounds was demonstrated through this work.<p><p><p><p>RÉSUMÉ<p><p>Ce projet a pour but de développer un système de délivrance de médicament capable d’augmenter la stabilité et le temps de résidence in vivo des anticorps. Ce système sera administré par voie sous-cutanée et permettra un control précis de la libération du produit et de son niveau plasmatique. Cette plateforme technologique nous permettra de réduire la fréquence d’injection, de réduire potentiellement les effets secondaires et de maintenir des concentrations élevées en anticorps tout en améliorant la vie des patients atteints de maladies chroniques autoimmunes ou inflammatoires. Les formulations à base de polymères synthétiques, biodégradables (PLGA) ont été sélectionnés comme véhicules pour encapsuler les anticorps. Ils offrent en effet une bonne protection pour les anticorps and permettent une libération contrôlée de ceux-ci pendant une période définie. Après l’évaluation de différents méthodes d’encapsulation tels que les procédés d’eau-dans-huile-dans-eau (w/o/w) et solide-dans-huile-dans-eau (s/o/w), l’encapsulation des anticorps sous forme solide apparaissait plus apporpriée pour produire des microsphères de polymère chargées en anticorps. Cette technique nous permettait de maintenir l’anticorps sous sa forme monomérique et d’éviter la formation d’agrégats insolubles qui apparaissaient principalement à l’interface eau/huile. La première partie du projet a été d’optimiser à la fois la méthode nous permettant d’obtenir les anticorps sous forme de particules solides (spray-drying) et la méthode d’encapsulation de ces particules d’anticorps dans les microsphères de polymères. Cela a été réalisé par des plans d’expérience en utilisant une IgG bovine polyclonale comme molécule modèle. Durant l’optimisation du procédé de spray-drying,<p>les solutions aqueuses d’anticorps ont été atomisées en utilisant le mini Spray-Dryer assemblé avec une buse de pulvérisation d’un diamètre de 0.7 mm. En accord avec la taille particulaire (d(0.5) ~5 μm), la stabilité (absence de perte en monomère mesurée par chromatographie d’exclusion de taille et le rendement d’atomisation (> 60 % w/w), les paramètres d’atomisation ont été fixés: 3 mL/min pour le débit de liquide, 130°C /75°C pour la température d’entrée / température de sortie, 800 L/h pour le débit d’air d’atomisation et 30 m3/h pour le débit d’air de séchage. Pour le s/o/w, le dichlorométhane communément utilisé dans les procédés d’encapsulation a été remplacé par l’acétate d’éthyle qui est considéré comme un meilleure solvant organique en terme d’environnement et de sécurité. Les effets de plusieurs paramètres de fabrication ou de formulation ont été évalués sur les propriétés des microsphères polymériques d’anticorps (distribution de taille particulaire, taux de charge en anticorps, stabilité de l’anticorps et efficacité d’encapsulation). Plusieurs paramètres de fabrication et de formulation ont été statistiquement identifiés comme critiques pour obtenir un procédé reproductible (par exemple. La concentration en PLGA, le volume de phase externe, la vitesse d’émulsification et la quantité d’anticorps). La méthode d’encapsulation ainsi optimisée permettait d’obtenir un taux<p>de charge jusqu’à 6% (w/w) avec une efficacité d’encapsulation jusqu’à 60 % (w/w) tout en<p>préservant l’intégrité de l’anticorps encapsulé. Les microsphères produites étaient caractérisées<p>par un d(0.9) inférieur à 110 μm et montraient une libération après 24 h inférieure à 50 % (w/w).<p>Dans le seconde partie du projet, les procédés d’atomisation et d’encapsulation développés avec<p>l’IgG ont été appliqués à un anticorps monoclonal anti-TNF alpha humanisé pour confirmer la<p>conservation de l’activité de l’anticorps pendant ces procédés. La méthode s/o/w sélectionnée<p>permettait de produire des microsphères de PLGA chargées en anticorps avec un profil de libération jusqu’à 6 semaines et un maintien de la stabilité de l’actif. Afin de maintenir l’activité de l’anticorps, à la fois pendant le procédé d’encapsulation et pendant la libération, l’ajout d’un stabilisant tel que le tréhalose est apparu crucial ainsi que le choix du type de PLGA. Il a été démontré que l’utilisation du PLGA caractérisé par un ratio lactide :glycolide de 75 :25 (par exemple, Resomer ® RG755S) diminuait la formation d’espèces de faible poids moléculaire<p>pendant la dissolution. Cela contribuait à préserver l’activité de l’anticorps durant la libération à partir des microsphères. De plus, le profil de libération était modulé en fonction du type de polymère et de sa concentration. Par exemple, l’utilisation d’une solution à 10 % w/v RG755S conduisait à la production de microsphères d’anticorps avec un temps de libération sur 6<p>semaines. L’optimisation de la formulation et du procédé d’encapsulation a permis de produire<p>des microsphères avec des taux de charge en anticorps de maximum 13 % w/w. Il a été démontré<p>que ces microsphères, stockées à 5°C, étaient stables jusqu’à 12 semaines et que la sélection du<p>type de PLGA était critique pour assurer la stabilité du système. La meilleure stabilité a été<p>obtenue en utilisant le PLGA caractérisé par un ratio lactide :glycolide de 75 :25. Cela a été<p>attribué à sa plus faible vitesse de dégradation. Enfin, la libération contrôlée de l’anticorps à<p>partir de ces microsphères et la conservation de son activité ont été confirmées in vivo lors d’une<p>étude pharmacocinétique réalisée chez le rat. En conclusion, ce travail a permis de démontrer<p>l’application du concept d’ « emprisonnement » des composés biologiques dans des matrices<p>polymériques afin de les stabiliser et contrôler leur libération. / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

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Since current prosthetic heart valve replacements are costly, cause medical complications, and lack the ability to regenerate, tissue-engineered heart valves are an attractive alternative. These could provide an unlimited supply of immunological-tolerated biological substitutes, which respond to patients' physiological condition and grow with them. Since collagen is a major extra cellular matrix component of the heart valve, it is ideal material for constructing scaffolds. Collagen sources have been shown to influence the manufacturing of collagen scaffolds, and two commercial sources of collagen were obtained from Sigma Aldrich and Devro PLC for comparison. Consistencies between the collagens were shown in the primary and secondary structures of the collagen, while inconsistencies were shown at the tertiary level, when a higher level of natural crosslinking in the Sigma collagen and longer polymer chains in the Devro collagen were observed. These variations were reduced and the consistency increased by introducing crosslinking via dehydrothermal treatment (DHT). Collagen scaffolds produced via freeze-drying (FD) and critical point-drying with cross-linking via DHT or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide /N-hydroxysuccinimide (EDC/NHS) were investigated. All the scaffolds were compatible with mesenchymal stem cells (MSCs) according to the proliferation of the cells and their ability to produce ECM, without differentiating between osteogenic, chondrogenic or endothelial lineages. The FD EDC/NHS scaffold demonstrated the most suitable physical property of all. This result illustrates that FD EDC/NHS crosslinking is the most suitable scaffold investigated as a start for heart valve tissue engineering. To prepare a scaffold with a controlled local, spatial and temporal delivery of growth factor, a composite scaffold comprising poly (lactic-co-glycolic acid) (PLGA) microspheres was developed. This composite scaffold demonstrated the same compatibility to the MSCs as untreated scaffold. However, the PLGA microspheres showed an increase in the deterioration rate of Young's modulus because of the detachment of the microspheres from the scaffold via cellular degradation.