Indiana University-Purdue University Indianapolis (IUPUI) / The non-hematopoietic, stationary stromal cells located inside and surrounding skin-draining lymph nodes play a key role in regulating immune responses. We studied distinct populations of lymph node stromal cells from both human subjects and animal models in order to describe their phenotype and function. In the mouse model, we studied two distinct populations: an endothelial cell population expressing Ly51 and MHC-II, and an epithelial cell population expressing the epithelial adhesion molecule EpCAM. Analysis of intra-nodal and extra-nodal lymph node (CD45-) stromal cells through flow cytometry and qPCR provides a general phenotypic profile of the distinct populations. My research focused on the EpCAM+ epithelial cell population located in the fat pad surrounding the skin draining lymph nodes. The EpCAM+ population has been characterized by surface marker phenotype, anatomic location, and gene expression profile. This population demonstrates the ability to inhibit the activation and proliferation of both CD4 and CD8 T cells. This population may play a role in suppressing overactive inflammation and auto-reactive T cells that escaped thymic deletion. The other major arm of my project consisted of identifying a novel endothelial cell population in human lymph nodes. Freshly resected lymph nodes were processed into single cell suspensions and selected for non-hematopoietic CD45- stromal cells. The unique endothelial population expressing CD34 HLA-DR was then characterized and analyzed for anatomic position, surface marker expression, and gene profiles. Overall, these studies emphasize the importance of stationary lymph node stromal cells to our functioning immune systems, and may have clinical relevance to autoimmune diseases, inflammation, and bone marrow transplantation.

La technologie des cellules souches et les sciences de biomatériaux ont obtenu des grands progrès au cours des dernières décennies et sont devenues plus populaires dans le monde. Les chercheurs cherchent à étudier et à évaluer les différentes sources de cellules et de biomatériaux qui, en combinaison, peuvent fournir une plateforme d’ingénierie tissulaire produite à grande échelle et à bas prix, pour être utilisée aux tests de médicaments, aux thérapies cellulaires et transplantations, dans le but de fournir un soutien thérapeutique aux blessures et à la régénération des tissus endommagés. En général, les trois constituants les plus importants de l’ingénierie tissulaire sont : le choix du type cellulaire, la source du biomatérial (charpente), la création et le maintien d’un lieu favorable à la formation des tissus. Lorsque ces trois constituants sont gérés avec succès, le microenvironnement cellulaire in vitro est plus similaire à ce que la cellule est exposée in vivo, en permettant que la croissance et la différenciation cellulaire survient de façon plus fiable et efficace. Le placenta bovin décellularisé a démontré avoir une riche matrice extracellulaire, des vaisseaux bien développés, étant un biomatérial à haute disponibilité et à bas prix. Mais, on ne sait pas si les charpentes placentaires ont le potentiel d’être repeuplés avec des cellules souches mésenchymateuses (MSC) dérivées du tissu adipeux, et ce processus s’appelle recelularisation. Encore, on ne sait pas si les charpentes placentaires ont la capacité d’offrir, après recelularisation, un ambient approprié pour différencier ces cellules en différentes lignées. Ainsi, afin de fournir des informations sur la capacité du complexe MSC – charpente placentaire à être utilisé avec succès dans l’ingénierie tissulaire, les objectifs de cette thèse ont été : étudier le potentiel des charpentes placentaires bovins en offrir un soutien à la recelularisation par des cellules dérivées du tissu adipeux bovin, et aussi bien qu’évaluer la capacité de différenciation cellulaire en lignées ostéogéniques et chondrogéniques. Le premier article de cette thèse c’est une revue de la littérature qui aborde la nature des cellules souches mésenchymateuses, leurs applications en médicine régénérative, l’importance de la technologie des cellules souches dans l’industrie de l’élevage et l’utilisation de l’espèce bovine en médicine translationnelle. Le deuxième article aborde l’évaluation de la recelularisation et la différenciation cellulaire. Les placentas bovins ont été décellularisés par perfusion de SDS du vaisseau ombilical et les lignées cellulaires établies après la digestion enzymatique du tissu adipeux de six vaches et la sélection par adhésion rapide à la plaque de culture. Ensuite, les cellules ont été cultivées avec les charpentes dans un système d’agitation 2D pendant 21 jours en milieu de différenciation ou de maintenance. Lorsqu’elles sont cultivées sur la plaque de culture, les cellules isolées ont présenté morphologie similaire au fibroblaste, l’expression de CD90, CD73 et CD105, tandis qu’elles n’ont pas exprimé les marqueurs CD34 et CD45. Par ailleurs, les cellules ont été capables de se différencier en lignées chondrogéniques et ostéogeniques, en fournant des preuves de leur nature mésenchymateuse. Ensuite, quand elles ont été cultivées avec les charpentes, les cellules y ont adhéré par des projections cellulaires, établies une communication cellule-charpente et se sont proliférées, fait mis en évidence par l’analyse histologique et microscopie électronique à balayage (MEB). Après, le potentiel des cellules à se différencier en lignées ostéogéniques a été exploré, lorsqu’elles ont été cultivées avec charpente. Au cours d’une période de culture de 21 jours en milieu ostéogénique, les cellules ont proliféré et se sont différenciées de façon dépendante du temps, c’est-à-dire, à chaque semaine, la plus grande abudance de cellules a été observée, fait en évidence par la coloration des noyaux cellulaires et l’augmentation de l’intensité de la coloration pour COLLAGEN 1 (COL1), qui a aussi été exprimée par réaction quantitative en chaîne de la polymérase en temps réel (qRT-PCR). Le standard a été observé par l’analyse histologique, les accumulations généralisées de calcium a aussi été plus abondantes dans les charpentes au cours de la troisième semaine de culture, demontré par la coloration de Von Kossa. L’analyse MEB a montré que les cellules ont sécrété des structures globulaires lorsqu’elles ont été cultivées sur conditions d’induction ostéogénique, cohérentes avec la sécrétion observée par l’analyse histologique. Sur la différenciation chondrogénique, les colorants Safranine et Vert Solide ont démontré succès à la différenciation, grâce à la coloration des protéoglycanes, des cellules similaires aux chondrocytes et aux collagène type II. L’analyse MEB a montré que les cellules ont changé leur morphologie de fibroblastes en globulaires quand elles ont été cultivées avec milieu d’induction chondrogène pendant 21 jours. De plus, les complexes de cellules-charpentes ont exprimé un marqueur de la lignée cartilagineuse, COLLAGEN 2 (COL2), qui est cohérent avec les observations histologiques et MEB. Face aux résultats obtenus, cette étude a démontré que les charpentes placentaires cultivés avec des cellules dérivées du tissu adipeux ont le potentiel d’être utilisés dans l’ingénierie de tissus osseux et cartilagineux. / A tecnologia de células-tronco e as ciências de biomateriais obtiveram um grande avanço nas últimas décadas e se tornaram mais populares em todo o mundo. Pesquisadores buscam investigar e avaliar diferentes fontes de células e de biomateriais que, em combinação, possam fornecer uma plataforma de engenharia tecidual de baixo custo e produzida em larga escala, para serem utilizadas em testes de drogas, terapias celulares e transplantes, com objetivo de fornecer suporte terapêutico à lesões e regeneração de tecidos danificados. Em geral, os três componentes mais importantes da engenharia de tecidos são: a escolha do tipo de célula, a fonte do biomaterial (scaffold), criação e manutenção de um ambiente propício à formação tecidual. Quando esses três componentes são gerenciados com sucesso, o microambiente celular in vitro é mais semelhante ao que a célula está exposta in vivo, permitindo que o crescimento e diferenciação celular ocorra de maneira mais fidedigna e eficiente. A placenta bovina descelularizada demonstrou ter uma rica matriz extracelular, vasos bem desenvolvidos, sendo um biomaterial com alta disponibilidade e baixo custo. No entanto, não há informação sobre o potencial dos scaffolds placentários em serem repovoados com células-tronco mesenquimais (MSC) derivadas do tecido adiposo, processo chamado recelularização. Ainda, também não há informação sobre a capacidade dos scaffolds placentários, de após recelularização, oferecer um ambiente adequado para diferenciação dessas células em diferentes linhagens. Assim, a fim de fornecer informações sobre a capacidade do complexo MSC - scaffold placentário em ser usado com sucesso na engenharia tecidual, os objetivos desta tese foram: estudar o potencial dos scaffolds placentários bovinos em oferecer suporte para recelularização por células-tronco derivadas do tecido adiposo bovino, bem como avaliar a capacidade de diferenciação celular em linhagens osteogênica e condrogênica. O primeiro artigo desta tese trata-se de uma revisão de literatura, que discute a natureza das células-tronco mesenquimais, suas aplicações na medicina regenerativa, a importância da tecnologia com células- tronco na indústria pecuária e o uso da espécie bovina na medicina translacional. O segundo artigo consiste na avaliação da recelularização e da diferenciação celular. As placentas bovinas foram decelularizadas por perfusão de SDS do vaso umbilical e as linhas celulares estabelecidas após digestão enzimática do tecido adiposo de seis vacas e seleção por adesão rápida à placa de cultivo. Em seguida, as células foram cultivadas com os scaffolds em um sistema de agitação 2D por 21 dias em meio de diferenciação ou manutenção. Quando cultivadas na placa de cultivo, as células isoladas exibiram morfologia semelhante ao fibroblasto, expressão de CD90, CD73 e CD105, enquanto não expressaram os marcadores CD34 e CD45. Além disso, as células foram capazes de se diferenciar em linhagens condrogênicas e osteogênicas, fornecendo evidências de sua natureza mesenquimal. Posteriormente, quando cultivadas com os scaffolds, as células aderiram-se aos mesmos por projeções celulares, estabeleceram comunicação célula-scaffold e se proliferaram, fato evidenciado por análise histológica e microscopia eletrônica de varredura (SEM). Em seguida, o potencial das células em se diferenciarem em linhagem osteogênica quando cultivadas com scaffold foi avaliado. Durante um período de cultivo de 21 dias no meio osteogênico, as células se proliferaram e diferenciaram de maneira dependente do tempo, ou seja, a cada semana pode ser observado maior abundância de células, evidenciada pela coloração dos núcleos celulares e aumento da intensidade da coloração para COLAGENO 1 (COL1), que também foi expresso por reação quantitativa em cadeia da polimerase em tempo real (qRT-PCR). O mesmo padrão foi observado pela análise histológica; acúmulos generalizados de cálcio também foram mais abundantes nos scaffolds na terceira semana de cultivo, evidenciado pela coloração de Von Kossa. A análise SEM revelou que as células secretaram estruturas globulares quando cultivadas sob condições de indução osteogênica, condizente com a secreção observada pela análise histológica. Em relação à diferenciação condrogênica, os corantes Safranina e Fast Green revelaram sucesso na diferenciação, através da coloração de proteoglicanos, células semelhantes aos condrócitos e colágeno tipo II. A análise SEM mostrou que as células mudaram sua morfologia de fibroblastos para globulares quando cultivadas com meio de indução condrogênica por 21 dias. Além disso, os complexos células-scaffold expressaram um marcador de linhagem cartilaginosa, COLAGENO 2 (COL2), condizente com as observações histológicas e SEM. Considerando os resultados, este estudo demonstrou que os scaffolds placentários bovinos cultivados com células-tronco derivadas de tecido adiposo bovino possuem potencial para serem utilizados na engenharia de tecidos ósseos e cartilaginosos. / Stem cell technologies and biomaterial sciences have advanced and grown more popular all over the world. The researchers aim to investigate and evaluate different sources of cells and biomaterials that, in combination, could provide a low cost, highly scalable tissue engineering platform that could be used in drug tests, cell therapies and cell transplantation. The three most important components of tissue engineering systems in general are cell source, biomaterial source (scaffolding system), and the creation and maintenance of an environment that is conducive to tissue formation. When these three components are successfully managed, the tissue engineering treatment achieves a faithful imitation of the in vivo environment, allowing for the differentiation of cells into the desirable cell types. Decellularized bovine placenta has been demonstrated to be rich in extracellular matrix (ECM) and to have well-developed vasculature, representing a highly available, low cost, practically scalable biomaterial. However, it is not known if placental scaffolds have the potential to support recellularization with adipose-derived cells and their subsequent differentiation into different lineages. Thus, in order to provide information on the ability of the mesenchymal stem cell (MSC) - placental scaffold complex to be used in tissue engineering approaches, the objectives of this thesis were: to study the potential of bovine placental scaffolds to support adipose-derived cell recellularization and their differentiation into osteogenic and chondrogenic lineages. The first article of this thesis is a literature review that discusses the nature of mesenchymal stem cells, their applications in regenerative medicine, the importance of stem cell technologies to the livestock industry and the use of bovine species for translational medicine. The second article consists of an evaluation of scaffold recellularization and the differentiation of cells on the scaffolds. The bovine placentae were decellularized by umbilical vessel sodium dodecyl sulfate (SDS) perfusion and cell lines were established after the enzymatic digestion of adipose tissue from six cows and cell selection by rapid adherence to the culture plate. Then, cells were seeded onto the scaffolds and cultured in a 2D rocker system for 21 days in either differentiation or maintenance medium. The isolated cells, when cultured in the plastic dish, exhibited fibroblast-like morphology, CD90, CD73 and CD105 expression, and lacked CD34 and CD45 expression. Moreover, the cells were able to undergo differentiation into chondrogenic and osteogenic lineages, providing evidence of their mesenchymal nature. 8 Subsequently, the cells adhered to the scaffolds by cell projections, established cell-scaffold communication, and proliferated while maintaining cell-cell communication, which was evidenced by histological and scanning electron microscopy (SEM) assays. Throughout a 21- day culture period in the osteogenic medium, the cells exhibited proliferation and differentiation in a time-dependent manner, which can be observed by the greater abundance of cells in later periods, evidenced by cell nuclei staining (4′,6-diamidino-2- phenylindole - DAPI) and increased intensity of staining for COLLAGEN 1 (COL1) in the immunohistochemical assay, and by its expression as measured by real time polymerase chain reaction (qRT-PCR). This same pattern was observed by histological analysis. Widespread calcium accumulations were also more abundant on the scaffolds as time progressed, as evidenced by Von Kossa staining. The SEM analysis revealed that cells secreted globular/round structures when seeded under osteogenic induction conditions, in accordance with histological findings. Regarding chondrogenic differentiation, Safranin O and Fast Green staining revealed successful differentiation through staining of proteoglycans, chondrocyte-like cells and type II collagen on the scaffold. The SEM analysis showed that the cells changed morphology from fibroblast-like to globular when cultured with chondrogenic induction medium for 21 days. Additionally, cell-scaffold complexes expressed a cartilage marker, COLLAGEN 2 (COL2), which is conducive to the histological and SEM observations. Considering the results as a whole, this study demonstrated that placental scaffolds seeded with adipose-derived cells have the potential to be used in bone and cartilage tissue- engineering applications

Indiana University-Purdue University Indianapolis (IUPUI) / The potential of hematopoietic stem cells (HSC) to home and to anchor within the bone marrow (BM) microenvironment controls the ability of transplanted HSCs to establish normal hematopoiesis. Activated Leukocyte Cell Adhesion Molecule (ALCAM; also identified as CD166), which participates in homophilic interactions, is expressed on a group of osteoblasts in the hematopoietic niche capable of sustaining functional HSC in vitro. Since we could also detect ALCAM expression on HSC, we suspect that ALCAM may play a role in anchoring primitive hematopoietic cells to ALCAM expressing components of the hematopoietic niche via dimerization. We investigated the role of ALCAM on the homing abilities of hematopoietic stem and progenitor cells (HSPC) by calculating recovery frequency of Sca-1+ALCAM+ cells in an in vivo murine bone marrow transplantation model. Our data supports the notion that ALCAM promotes improved homing potential of hematopoietic Sca-1+ cells. Recovery of BM-homed Sca-1+ cells from the endosteal region was 1.8-fold higher than that of total donor cells. However, a 3.0-fold higher number of Sca-1+ALCAM+ cells homed to the endosteal region compared to total donor cells. Similarly, homed Sca-1+ALCAM+ cells were recovered from the vascular region at 2.1-fold greater frequency than total homed donor cells from that region, compared to only a 1.3-fold increase in the recovery frequency of Sca-1+ cells. In vitro quantitation of clonogenic BM-homed hematopoietic progenitors corroborate the results from the homing assay. The frequency of in vitro clonogenic progenitors was significantly higher among endosteal-homed Sca-1+ALCAM+ cells compared to other fractions of donor cells. Collectively, these data demonstrate that engrafting HSC expressing ALCAM home more efficiently to the BM and within the BM microenvironment, these cells preferentially seed the endosteal niche.

Indiana University-Purdue University Indianapolis (IUPUI). / Tumor necrosis factor-induced protein 6 (TSG-6) has been shown to mitigate inflammation. Its presence in the secretome of adipose stem / stromal cells (ASC) and its role in activities of ASC have been overlooked. This thesis described for the first time the release of TSG-6 from ASC, and its modulation by endothelial cells. It also revealed that protection of endothelial barrier function was a novel mechanism underlying the anti-inflammatory activity of both ASC and TSG-6. Moreover, TSG-6 was found to inhibit mitogen-activated lymphocyte proliferation, extending the understanding of its pleiotropic effects on major cell populations involved in inflammation. Next, enzyme-linked immunosorbent assays (ELISA) were established to quantify secretion of TSG-6 from human and murine ASC. To study the importance of TSG-6 to specific activities of ASC, TSG-6 was knocked down in human ASC by siRNA. Murine ASC from TSG-6-/- mice were isolated and the down-regulation of TSG-6 was verified by ELISA. The subsequent attempt to determine the efficacy of ASC in ameliorating ischemic limb necrosis and the role of TSG-6, however, was hampered by the highly variable ischemic tissue necrosis in the BALB/c mouse strain. Afterwards in a mouse model of cigarette smoking (CS), in which inflammation also plays an important role, it was observed, for the first time, that 3-day CS exposure caused an acute functional exhaustion and cell cycle arrest of hematopoietic progenitor cells; and that 7-week CS exposure led to marked depletion of phenotypic bone marrow stem and progenitor cells (HSPC). Moreover, a dynamic crosstalk between human ASC and murine host inflammatory signals was described, and specifically TSG-6 was identified as a necessary and sufficient mediator accounting for the activity of the ASC secretome to ameliorate CS-induced myelotoxicity. These results implicate TSG-6 as a key mediator for activities of ASC in mitigation of inflammation and protection of HSPC from the myelotoxicity of cigarette smoke. They also prompt the notion that ASC and TSG-6 might potentially play therapeutic roles in other scenarios involving myelotoxicity.

Eine bevorzugte Zellquelle für den Einsatz im Tissue Engineering sind mesenchymale Stammzellen (MSZ). Diese besitzen, neben einer hohen Proliferationsrate, die Fähigkeit, sich in verschiedene Zellen des mesodermen Ursprungs und in die entsprechenden Gewebetypen zu entwickeln. Um ein funktionales Gewebe zu erhalten ist es Ziel, sich bereits in vitro den in vivo Bedingungen anzunähern. Hierbei spielen neben der dreidimensionalen Struktur der Scaffolds auch die biochemische Mikroumgebung der Zellen in Form der unlöslichen extrazellulären Matrix (EZM) und den löslichen Mediatorproteinen wie Wachstums- und Differenzierungsfaktoren, sowie die physikalische Stimulation der Zellen eine wichtige Rolle. Während sich gegenwärtige Untersuchungen im TE vorwiegend mit den alleinigen Einflussfaktoren beschäftigen, verfolgt die vorliegende Arbeit das Ziel, die Auswirkungen kombinierter Stimuli durch Verwendung einer artifiziellen EZM, bestehend aus definierten Komponenten der nativen EZM, und physikalischer Stimuli durch elektrische Felder zu untersuchen. Letzteres erfolgte mit einem innerhalb der Arbeitsgruppe neu entwickelten System, dass die Stimulation von Zellen mit ausschließlich elektrischen Feldern, ohne störende Nebeneinflüsse, erlaubt.:1 Einleitung und Zielstellung 2 Theoretische Grundlagen 2.1 Der Knochen 2.1.1 Allgemeine Biologie und Physiologie des Knochengewebes 2.1.2 Knochenersatzmaterialien 2.2 Tissue Engineering von Knochengewebe 2.2.1 Trägermaterialien für das TE von Knochen 2.2.2 Zellen für das TE von Knochen 2.2.3 Artifizielle extrazelluläre Matrizes für das TE von Knochen 2.3 Einfluss elektrischer Felder auf Knochenumbauprozesse 2.3.1 Methoden zur Applikation von elektrischen Feldern 2.3.2 In vitro Untersuchungen zum Einfluss elektrischer Felder 2.3.3 Methode der Transformator-ähnlichen Einkopplung (TC) 3 Materialien 3.1 Technische Hilfsmittel und Geräte 3.2 Verbrauchsmaterialien 3.3 Chemikalien, Reagenzien und Kits 3.4 Antikörper 3.5 Oligonukleotide 3.6 Puffer-, Medien- und Lösungszusammensetzungen 3.7 Zellen 4 Methoden 4.1 Polycaprolacton-Co-Lactid (PCL)-Scaffolds 4.1.1 Präparation und Hydrophilisierung der PCL-Scaffolds 4.1.2 Beschichtung der PCL-Scaffolds 4.1.3 Charakterisierung der Beschichtung auf den PCL-Scaffolds 4.2 Zellkulturtechniken 4.2.1 Auftauen und Subkultivierung 4.2.2 Einfrieren 4.2.3 Induktion der osteogenen Differenzierung 4.2.4 Induktion der adipogenen Differenzierung 4.2.5 Induktion der chondrogenen Differenzierung 4.2.6 Besiedlung und Kultivierung der Zell-Matrix-Konstrukte 4.2.7 Elektrische Stimulation der Zell-Matrix-Konstrukte 4.2.8 Blockierung definierter Signaltransduktionswege 4.3 Mikroskopische Analytik der Zellen 4.3.1 Darstellung der Zellverteilung mittels Rasterelektronenmikroskopie (REM) 4.3.2 Qualitative Bestimmung von Fetttröpfchen mittels Oil-Red-O Färbung 4.3.3 Qualitative Bestimmung der Mineralisierung mittels vonKossa- Färbung 4.4 Durchflusszytometrie 4.5 Biochemische Analytik der Zellen 4.5.1 Bestimmung der Zellzahl mittels Lactatdehydrogenase (LDH)- Aktivität 4.5.2 Bestimmung der alkalische Phosphatase (ALP)-Aktivität 4.5.3 Quantitative Bestimmung des Kalziumgehaltes 4.6 Molekularbiologische Analytik / Genexpressionsanalyse 4.6.1 RNA Extraktion 4.6.2 cDNA-Synthese / Reverse Transkriptase PCR (RT-PCR) 4.6.3 Amplifikation von cDNA mittels quantitativer Real-Time PCR (qPCR) 4.7 Statistische Auswertung 5 Weiterentwicklung der Kammer zur TC-Einkopplung 5.1 Grundlegende theoretische Betrachtungen zur TC-Einkopplung 5.1.1 Ersatzschaltbild der TC-Einkopplung 5.1.2 Abschätzung des Eisenkernquerschnitts 5.1.3 Einfluss der Primärwindungszahl 5.2 Neudimensionierung und Aufbau der Stimulationseinrichtung 5.3 Verlauf der elektrischen Größen 5.3.1 Simulation 5.3.2 Messung 5.3.3 Abschätzung des magnetischen Feldes in der Kammer 5.4 Zusammenfassung 6 Zellexperimentelle Ergebnisse 6.1 Charakterisierung der humanen MSZ nach in vitro Kultivierung 6.1.1 Morphologie 6.1.2 Phänotypische Charakterisierung mittels Durchflusszytometrie 6.1.3 Multipotentes Differenzierungspotential 6.2 Zellverhalten auf den unbeschichteten PCL-Scaffolds 6.2.1 Ermittlung eines geeigneten Besiedlungsregimes 6.2.2 Zellverteilung und Proliferation der MSZ 6.2.3 Osteogene Differenzierung der MSZ 6.3 Einfluss der aEZM auf das Zellverhalten von MSZ 6.3.1 Quantitative Bestimmung der aEZM-Komponenten 6.3.2 Einfluss der aEZM auf die Adhärenz und Proliferation von MSZ 6.3.3 Einfluss der aEZM auf die osteogene Differenzierung von MSZ 6.4 Einfluss elektrischer Felder auf das Zellverhalten von MSZ 6.4.1 Einfluss der elektrischen Felder auf die Proliferation und osteogene Differenzierung von MSZ 6.4.2 Einfluss elektrischer Felder in Kombination mit Koll/sHya enthaltenden aEZM auf die Proliferation und osteogene Differenzierung von MSZ 6.4.3 Untersuchungen zu möglichen Signaltransduktionswegen 7 Diskussion der Ergebnisse 7.1 Charakterisierung der humanen MSZ nach in vitro Kultivierung 7.2 Zellverhalten auf den unbeschichteten PCL-Scaffolds 7.3 Einfluss der aEZM auf das Zellverhalten von MSZ 7.4 Einfluss elektrischer Felder auf das Zellverhalten von MSZ 8 Zusammenfassung und Ausblick Literaturverzeichnis Danksagung Eigene Publikationen und Mitautorschaften A Zusatzinformationen für die quantitative RT-PCR A.1 Versuchsdesign der Genexpressionsanalysen A.2 Qualitätskontrolle der isolierten RNA