No description available.

Mesenchymale Stammzellen können sich durch den Einfluss verschiedener Transkriptionsfaktor zu Osteoblasten, Adipozyten, Chondrozyten oder Myoblasten differenzieren. Während sie sich unter Runx2-Einfluss entlang der osteoblastären Linie differenzieren, entwickeln sie sich bei vorliegendem PPARγ entlang des adipogenen Differenzierungswegs. Das Gleichgewicht zwischen beiden Faktoren und ihr Zusammenspiel stellen einen wichtigen Bereich in der Osteoporoseforschung dar. In dieser Dissertation wurde durch Runx2-Suppression bzw. Runx2-Überexpression die Rolle dieses Faktors in pHOB und SCP1-Zellen erfasst und die Interaktion zwischen Runx2 und PPARγ untersucht. Der Runx2-Knockdown’ erfolgte mittels RNA-Interferenz, die Runx2-Überexpression durch ein Runx2 exprimierendes Plasmid. In RT-PCRs wurden mRNA-Messungen durchgeführt. Die Proteinbestimmung erfolgte im ‚Westernblot’. Der funktionelle Einfluss der Runx2-Überexpression auf die PPARγ-Transkription wurde durch Kotransfektion des an Luziferase gekoppelten PPARg-Promotorgens erfasst. Die funktionelle Aktivität des PPARg-Proteins wurde durch die Transfektion des an Luziferase gekoppelten PPRE-Gens gemessen. Promotoraktivität und Funktionalität der Proteine wurden in Luziferase-Reportergenassays erfasst. Unter basalen Kulturbedingungen differenzierten sich pHOB osteogen. Durch zweimalige siRunx2-Transfektion gelang auf mRNA-Ebene eine suffiziente Runx2-Suppression über 29 Tage auf durchschnittlich 10,1%. Neben einer Steigerung der PPARγ-mRNA nach sieben Tagen konnte darunter auch eine Suppression der osteogenen Differenzierungsmarker OC und AP beobachtet werden. Ein ‚Rescue’ der supprimierten Runx2-Genexpression konnte durch osteogene Stimulation nicht erreicht werden. In den Runx2-/PPARγ-Interaktionsversuchen wurden SCP1-Zellen adipogen stimuliert, um die PPARγ2-mRNA und PPARγ-Promotoraktivität zu erhöhen. Darunter konnte ebenfalls eine gesteigerte Funktionalität des PPARγ-Proteins beobachtet werden. Durch Runx2-Überexpression wurde in SCP1-Zellen die PPARγ-Promotoraktivität und somit der Beginn der mRNA-Synthese gehemmt. Die PPARγ2-mRNA hingegen blieb unbeeinflusst. Die zentrale Rolle des Runx2 in der osteogenen Differenzierung scheint durch den Einfluss auf die osteogenen Marker OC und AP in pHOB bestätigt zu werden. Auch der Einfluss auf die adipogene Differenzierung erfolgt über Runx2. Im Rahmen dieser Dissertation konnte erstmalig die Hemmung des PPARγ-Promotors durch Runx2 beschrieben werden. Hierdurch werden die PPARγ-Transkription und somit voraussichtlich die Interaktion zwischen Adipogenese und Osteogenese beeinflusst.

Mesenchymale Stammzellen bieten eine interessante Option in der regenerativen Medizin, da sie praktisch unlimitiert verfügbar sind. Um das Verhalten von humanen MSC zu studieren, werden Untersuchungen momentan an immundefizienten Mäusen durchgeführt, deren Verwendung kostenintensiv und aufwendig ist. Fra-gestellung war, ob durch Immunisolation (Alginat, Dialyseschlauch, Diffusionskammer) die Knorpel erhaltenden -, bzw. bildenden Eigenschaften von MSC-Konstrukten ebenso gut in immunkompetenten Mäusen untersucht werden können. Gleichzeitig sollte geprüft werden, ob die mit einer Immunabschirmung einhergehende Reduktion der Zellversorgung und damit die Annäherung an die Gelenksituation ihre Mineralisierung vermindern kann und ob Mauszellen für eine Veränderung der vordifferenzierten Knorpelpellets verantwortlich sind. Hierzu wurden hBMSC chondrogen differenziert. Die Zellpellets wurden mit Alginat, dem Dialyseschlauch oder der Diffusionskammer verkapselt und parallel zu unver-kapselten Kontrollpellets subkutan in immundefiziente SCID-Mäuse sowie in immunkompetente BDF1-Mäuse implantiert. Die Explantate wurden mit Alzianblau-, Alizarinrot-, Kollagen Typ II-Färbungen, sowie einer ALU in-situ Hybridisierung mar-kiert und mittels Histologiescore doppelt blind bewertet (MannWhitneyU). Überra-schenderweise zeigten die unverkapselten Kontrollen in den BDF1-Mäusen weder Zeichen von Inflammation noch von Destruktion und 4/5 der Pellets waren auf Kol-lagen Typ-II und Alzianblau positiv. Gleichzeitig war der Grad der Mineralisierung in den BDF1-Mäusen gegenüber SCID-Mäusen reduziert (p = 0,03). Durch Alginat wurde die Mineralisierung in den BDF1 Mäusen (0/8) völlig verhindert, während in den SCID-Mäusen noch 7/8 der Pellets Kalzifizierung zeigten (p = 0,001). Die Verkapselung mit Alginat verglichen mit der Kontrolle führte in beiden Mausstämmen zu höheren Scores für Kollagen Typ II (SCID: p = 0,013, BDF1: p = 0,042) und zeigte gleichzeitig eine Reduktion der Mineralisierung (SCID: p = 0,018, BDF1: p = 0,031). In SCID-Mäusen war außerdem der Alzianblau-Wert gegenüber den Kontrollen erhöht (p = 0,003). Die Diffusionskammer erwies sich als ungeeignet, da die Pellets ihre knorpeligen Eigenschaften verloren. Durch die Verwendung des Dialyseschlauches konnte lediglich in der SCID-Maus eine Erhöhung der Kollagen Typ II (p = 0,03) und eine Reduktion der Kalzifizierung (p = 0,004) erreicht werden. Sowohl im Alginatbead in der BDF1-Maus (1/3 Spendern), als auch im Dialyseschlauch mit Kollagenmembran (2/3 Spendern) konnte eine erfolgreiche in vivo Chondrogenese durchgeführt werden. Zur Untersuchung der in vivo Stabilität knorpeliger MSC-basierter Konstrukte stellt die BDF1-Maus eine attraktive, kostengünstige Alternative mit einer gegenüber der SCID-Maus verringerten Mineralisierungsrate dar. Die in vitro gebildete knorpelige Extrazellulärmatrix erzeugt dabei bereits eine Immunisolation, welche die Transplantatdestruktion verhindert. Ob ein intaktes lymphozytäres System die Knorpelstabilität gegenüber defizienten Immunsystemen begünstigt, muss durch die Untersuchung weiterer Ansätze belegt werden. Im Gegensatz zur Diffusionskammer bietet Alginat das richtige Maß an Versorgungsreduktion, um die Stabilisierung des Knorpelphänotyps der Konstrukte zu ermöglichen.

No description available.

BACKGROUND Adult bone marrow derived MSCs had been explored to treat myocardial infarction (MI) and heart failure, for which various beneficial paracrine effects had been suggested. Since MSCs in vitro express anti-inflammatory cytokines, we tested the hypothesis that changes in the pro-/anti-inflammatory cytokine ratio in the infarct microenvironment may provide such a paracrine mechanism to improve early cardiac function following acute coronary occlusion. / Methods Rats (n=88) underwent acute left coronary artery ligations and were randomized into groups M and C and then injected with culture media or MSCs, respectively. These rats underwent blinded echocardiography to evaluate left ventricular ejection fractions (LVEF). Real Time PCR was used to compare cytokine gene expression for IL-1beta, IL-6, IL-8 (pro-inflammatory) and IL-10 (anti-inflammatory) at various times. Extra-cellular matrix (ECM) deposition and inflammatory cell infiltration were also analyzed. / Results As early as 12 hours, the ratio of pro-/anti-inflammatory cytokine gene expression in group C was significantly lower than group M. Similar results were found at 24 hours, 1 and 2 weeks, respectively. LVEF improved significantly in group C (M=62% vs C=68% at 12 hours* , M=66% vs C=75% at 24 hours*, M=57% vs C=75% at 1 week *, and M=52% vs C=70% at 2 weeks*, *p<0.01). The ratio of MMP-2/TIMP1 levels was lower in the Group C at all time frames, reaching significance at 12 and 24 hours and 2 weeks. In group C, histopathological analysis revealed significantly less ECM deposition (M=1.95% vs C=0.75% at 24 hours*, M=19.30% vs C=9.36% at 1 week*, M=24.46% vs C=7.57% at 2 weeks*, *p<0.01). This was associated with significantly decreased inflammatory cell infiltration after 24 hours. / Conclusions The current data suggests that MSCs therapy decreases the pro-/anti-inflammatory cytokine ratio in the infarct microenvironment. This is associated with improved cardiac function, reduced ECM deposition, and decreased inflammatory cell infiltration. This paracrine mechanism of MSCs therapy may explain the early functional improvement after MI before cell transdifferentiation or other mechanisms takes place.

Baigiamajame darbe įvertintas skirtingų titano implantų paviršiaus modifikavimo strategijų poveikis pirminių dantenų fibroblastų savybėms – adhezijai, proliferacijai ir diferenciacijai. Tyrimuose naudoti titano mėginiai, kurių paviršiaus šiurkštumas pakeistas fizikiniais metodais – smėliasrove ir lazeriu. Iš gingivektomijos metu paimto ţmogaus dantenų subepitelinio audinio buvo išskirtos ir charakterizuotos dantenų fibroblastų ląstelės. Tiriant šių ląstelių adheziją ant modifikuotų titano mėginių paviršių nustatyta, kad ankstyvuoju laikotarpiu dantenų fibloblastų adhezija buvo panaši ant visų tirtų įvairiai modifikuotų titano mėginių paviršių, tačiau vėliau efektyviausias ląstelių prikibimui paviršius buvo lazeriu suformuotos grotelės. Siekiant pagerinti modifikuotų titano paviršių adhezines savybes, jie papildomai buvo padengti tarpląstelinio uţpildo baltymais – kolagenu ir lamininu, įvertintas tokio padengimo poveikis ląstelių prikibimui ir augimui. Analizuojant mechanizmus, reguliuojančius ląstelių adhezijos ant modifikuotų paviršių procesus, buvo tirta FAK ir Akt kinazių raiška ir aktyvinimas. Vertinant karkasų paviršiaus topografijos poveikį ląstelių diferenciacijai, buvo palygintas osteogeninės diferenciacijos laipsnis ląstelėse augintose ant įvairiai modifikuotų titano mėginių paviršių. Darbą sudaro 6 dalys: įvadas, literatūros apţvalga, medţiagos ir metodai, rezultatai ir jų aptarimas, išvados, literatūros sąrašas. Darbo apimtis – p. teksto be priedų, 24 pav., 2 lent... [toliau žr. visą tekstą] / The influence of different modification strategies of titanium implant surfaces on gingival fibroblasts properties - adhesion, proliferation, and differentiation was studies in this final master thesis. Different titanium surface roughness modifications using physical methods such as sand-blasting as well as laser irradiation were developed. Gingival fibroblasts derived from human gingival subepithelial tissues obtained during gingivectomy were isolated and characterized. The data suggested that the initial adhesion between tested cells and various modified titanium surfaces was similar, but the most efficient surface for subsequent cell attachment was laser-ablated holey arranged in grid-like structures. Additionally, in order to improve the modified titanium surface adhesion properties, these surfaces were coated by extracellular matrix proteins - collagen and laminin. The coating influence on the cell growth and adhesion was evaluated. To analyze the mechanisms regulating cell adhesion processes on the modified surfaces, FAK and Akt kinase expression as well as activation were studied. In order to evaluate the effect of surface topography on cell differentiation, the level of osteogenic differentiation was compared. Structure: introduction, literature review, materials and methods, results and discussion, conclusions, references.

The objective of the present study was to synthesize porous, biodegradable poly (D, l- lactide-co-glycolide) PLGA-B-HA (Bovine hydroxyapatite) composite and evaluate the effect of ceramic content on bone marrow cell differentiation in vitro. A macroporous biodegradable PLGA-B-HA composite with the pore size varying from 0.1 to 1000?? and a highly interconnected structure was fabricated using the freeze-drying/lyophilization technique. A pilot study was done to determine the effects of B-HA on to the osteoblast function. The main study was done to determine the effect of the increase in B-HA concentration on to the mesenchymal stem cell differentiation. Morphological characteristics of the composites were analyzed using FTIR and SEM/EDX analysis. The composites were seeded with neonatal rat calvarial osteoblasts (NRCO). The polymer: ceramic ratio in this study was 35%:65%. For comparison parallel experiments involving pure HA-200 discs were performed. SEM results indicated a higher proliferation and mineralization on PLGA-B-HA composites than pure HA discs. In addition, we evaluated the in vitro characteristics of PLGA-B-HA composites with varying ratios, i.e., 1:1, 1:2 and 1:3, seeded with rat marrow cells. FTIR indicated an increase in the area under the ceramic peak as ceramic concentration was increased. In addition, the average roughness values increased in the order of 1:3 andgt; 1:2 andgt; 1:1. Both compressive strength and modulus of 1:1 were significantly higher than 1:2 and 1:3 PLGA-B-HA composites. No significant difference in compressive modulli and strengths could be observed for 1:2 and 1:3 PLGA-B-HA composites. Cellular activity was determined by measuring AP activity, total protein analysis and osteocalcin concentration. Evaluation of alkaline phosphatase activity showed bone cells attached to 1:3 (PLGA-B-HA) expressed significantly higher alkaline phosphatase as compared to 1:1 and 1:2 PLGA-B-HA composites. In addition, cells seeded on to 1:3 composites secreted significantly higher osteocalcin and at a relatively short time period as compared to the other samples. Corrosion studies (ICP) and pH values indicate minimal difference in the concentration of Ca and P and pH in tissue culture media for all the samples at the end of all time periods. Hence we conclude that an increase in the ceramic concentration stimulated mesenchymal stem cell differentiation thereby promoting osteogenesis.

Introduction: Currently, there are no specific pharmacological treatments for sepsis-induced acute respiratory distress syndrome (ARDS). And mesenchymal stem cells (MSCs) have shown reparative potential in both sepsis and ARDS. Objectives: To determine the role of MSC administration in the modulation of pulmonary host-responses to sepsis via differential regulation of regulatory microRNAs (miRNAs/miRs). Methods: MicroRNA and mRNA profiling was performed to identify differential expression. Quantitative real time polymerase chain reaction (qRT-PCR), trans-endothelial electrical resistance (TEER) measurements, and luciferase activity assay were used. Results: MicroRNA expression was examined in Human Pulmonary Microvascular Endothelial Cells (HPMECs). One miRNA – miR-193b-5p, targets occludin, a tight junction protein associated with endothelial leakage. A specific regulatory relationship between miR-193b-5p and occludin was identified. The loss in endothelial integrity was rescued when miR-193b-5p inhibitor was transfected. Conclusion: miR-193b-5p is a suppressor of occludin. Studying transcriptional changes allows identification of therapeutically relevant mediators for ARDS/ALI treatment.

Introduction: Currently, there are no specific pharmacological treatments for sepsis-induced acute respiratory distress syndrome (ARDS). And mesenchymal stem cells (MSCs) have shown reparative potential in both sepsis and ARDS. Objectives: To determine the role of MSC administration in the modulation of pulmonary host-responses to sepsis via differential regulation of regulatory microRNAs (miRNAs/miRs). Methods: MicroRNA and mRNA profiling was performed to identify differential expression. Quantitative real time polymerase chain reaction (qRT-PCR), trans-endothelial electrical resistance (TEER) measurements, and luciferase activity assay were used. Results: MicroRNA expression was examined in Human Pulmonary Microvascular Endothelial Cells (HPMECs). One miRNA – miR-193b-5p, targets occludin, a tight junction protein associated with endothelial leakage. A specific regulatory relationship between miR-193b-5p and occludin was identified. The loss in endothelial integrity was rescued when miR-193b-5p inhibitor was transfected. Conclusion: miR-193b-5p is a suppressor of occludin. Studying transcriptional changes allows identification of therapeutically relevant mediators for ARDS/ALI treatment.

The regenerative potential of adult stem cell populations within the human body bears great promises for their use in regenerative medicine. The bone marrow (BM) harbours two different types of adult stem cells, haematopoietic stem and progneitor cells (HSPCs) and multipotent mesenchymal stromal cells (MSCs), which are tightly regulated in their distinct anatomically defined niches by multiple cues such as cytokines, cell-cell contacts, the extracellular matrix (ECM) and the physical microenvironment. The ex vivo expansion of these cells for applications in regenerative therapies is of great interest and several biomaterial approaches attempt to mimic the natural BM niche and its components to control stem cell maintenance and differentiation. However, as of now the complexity of such stem cell niches is hard to recapitulate. Towards this goal, this work was focussing on the ECM environment of BM stem cells and was set out to engineer improved in vitro culture systems. MSC themselves are one of the most important cell types within the BM that secrete and construct ECM-networks and thereby shape the microenvironment of the residing cells. The potential of primary human BM-MSC to secrete ECM in vitro has been exploited to generate niche-like ECM surrogates in a robust and versatile format. Application of decellularisation regimes allowed the fabrication of complex matrices which demonstrated suprastructural, compositional and physicochemical properties compareable to those of the native BM-ECM environment. Reliable stability and reproduciblity was achieved by a dedicated procedure of maleic anhydride co-polymer-mediated covalent binding of fibronectin and subsequent anchorage of cell-secreted ECM molecules. As a result of the high reproducibility, a complete proteomic register of ECM molecules was obtained in combination with determining the complex fibrillar and soft gel-like characteristics of MSC-derived matrices. Based on the established BM niche-like substrate, the impact of extracellular matrices on MSC and HSPC ex vivo behavior has been explored. Both cell types demonstrated strong adhesion to ECM substrates and depicted a changed cellular morphology upon contact with native ECM structures compared to standard culture substrates or simple ECM protein coatings, indicating an intense interplay between the cell and the microenvironment. MSC that re-grew into their own matrices have shown advantageous proliferation and cytokine secretion levels as well as enhanced differentiation intensity (upon differentiation induction) compared to MSC that were cultured on less complex substrates. Similarly, HSPC were also instructed for enhanced expansion on MSC-derived matrices without exhaustion of stem cell-marker expressing progenitor cells. The efficiency of these matrices was related to their ability to mimic the native composite suprastructure, ligand nano-topography, molecular composition and physical properties of natural BM ECM environments. The data obtained within this thesis set the ground for a more rational design of artificial stem cell niches with defined and distinct properties, offering exciting options for the in-depth analysis and understanding of stem cell regulation by exogenous cues.