Techn. Universiẗat, Diss., 2005--München.

Blutplättchen werden von Megakaryozyten im Knochenmark in einem Prozess produziert, an dem Aktin beteiligt ist. Aktin-Depolymerisierungsfaktor (ADF) und Cofilin sind Aktin-bindende Proteine, die als entscheidende Regulatoren im Aktinumsatz agieren, indem sie das Schneiden und Depolymerisieren von Filamenten unterstützen. Die Bedeutung von ADF/Cofilin und des Aktinumsatzes in der Bildung von Blutplättchen ist gegenwärtig nicht bekannt. In der vorliegenden Arbeit wurden Mäuse untersucht, die eine konstitutive ADF-Defizienz und/oder die eine konditionale n-Cofilin Defizienz (Cre/loxP) aufweisen. Um Cofilin nur in Megakaryozyten und Blutplättchen auszuschalten, wurden Cofilinfl/fl Mäuse mit PF4-Cre Mäusen verpaart. ADF- oder n-Cofilin-defiziente Mäuse hatten keinen oder nur einen geringen Phänotyp in Blutplättchen. Eine Defizienz von ADF und n-Cofilin führte hingegen zu einem beinahe kompletten Verlust der Blutplättchen, was mit Defekten in der Bildung von Plättchenzonen in Knochenmark-Megakaryozyten einherging. Weitere Untersuchungen an in vitro und ex vivo kultivierten Megakaryozyten zeigten eine Reduzierung der Bildung von Proplättchen und das Fehlen der typischen Verdickungen der Proplättchen. Diese Daten zeigen redundante aber essentielle Funktionen von ADF und n-Cofilin im terminalen Schritt der Plättchenbildung in vitro und in vivo, und belegen erstmals eine wichtige Rolle des Aktinumsatzes in diesem Prozess. Im zweiten Teil dieser Dissertation wurden die Mechanismen untersucht, die für die zelluläre Regulierung des Hauptkollagenrezeptors auf Blutplättchen, Glykoprotein VI (GPVI), verantwortlich sind. Nach einer Gefäßwandverletzung wird subendotheliales Kollagen freigelegt, wodurch GPVI die Aktivierung von Blutplättchen vermittelt, und damit zur Blutstillung (Hämostase), aber auch zum Verschluss eines verletzten Gefäßes beitragen kann, was letztendlich zu einem Myokardinfarkt oder einem Schlaganfall führen kann. Deshalb ist GPVI ein attraktives Zielprotein für eine anti-thrombotische Therapie, insbesondere weil frühere Studien gezeigt haben, dass anti-GPVI Antikörper eine irreversible Herunterregulierung des Rezeptors auf zirkulierenden Blutplättchen mittels Internalisierung und Abspaltung induzieren. Es wird vermutet, dass Metalloproteinasen der ADAM (a disintegrin and metalloproteinase domain) - Familie das Abspalten vermitteln, jedoch fehlt in vivo der Beweis dafür. Um die Mechanismen des Abspaltungsprozesses des GPVI Rezeptors in vivo besser verstehen zu können, wurden zwei Mauslinien, GPVI- und konditionale ADAM10-defiziente Mäuse, generiert und zusätzlich sogenannte „low TACE (TNFalpha converting enzyme)“ Mäuse analysiert. Es konnte gezeigt werden, dass GPVI in vitro von ADAM10 oder TACE in Abhängigkeit der Signalwege, die zum Abspalten des Rezeptors führen, geschnitten werden kann. Darüberhinaus wurde GPVI in vivo nach Antikörperverabreichung in ADAM10-defizienten Mäusen und „low TACE“ Mäusen herunterreguliert, was vermuten lässt, dass entweder beide Metalloproteinasen an diesem Prozess beteiligt sind oder noch eine zusätzliche Metalloproteinase für die GPVI Regulation in vivo verantwortlich ist. / Platelets are produced by bone marrow megakaryocytes in a process involving actin dynamics. Actin-depolymerizing factor (ADF) and cofilin are actin-binding proteins that act as key regulators in actin turnover by promoting filament severing and depolymerization. The overall significance of ADF/cofilin function and actin turnover in platelet formation is presently unclear. In the first part of this thesis, platelet formation and function were studied in mice constitutively lacking ADF and/or mice with a conditional deficiency (Cre/loxP) in n-cofilin. To delete cofilin exclusively in megakaryocytes and platelets, cofilinfl/fl mice were crossed with PF4 (platelet factor 4)-Cre mice. While a single-deficiency in ADF or n-cofilin resulted in no or only a minor platelet formation defect, respectively, a double-deficiency in ADF and n-cofilin led to an almost complete loss of platelets. Bone marrow megakaryocytes of ADF/n-cofilin-deficient mice showed defective platelet zone formation. Interestingly, in vitro and ex vivo megakaryocyte differentiation revealed reduced proplatelet formation and absence of platelet-forming swellings. These data establish that ADF and n-cofilin have redundant but essential roles in the terminal step of platelet formation in vitro and in vivo. In the second part of the thesis, mechanisms underlying cellular regulation of the major platelet collagen receptor, glycoprotein VI (GPVI), were studied. GPVI mediates platelet activation on exposed subendothelial collagens at sites of vascular injury, and thereby contributes to normal hemostasis but also to occlusion of diseased vessels in the setting of myocardial infarction or stroke. Thus, GPVI is an attractive target for anti-thrombotic therapy, particularly because previous studies have shown that anti-GPVI antibodies induce irreversible down-regulation of the receptor in circulating platelets by internalization and ectodomain shedding. Metalloproteinases of the ADAM (a disintegrin and metalloproteinase domain) family are suspected to mediate this ectodomain shedding, but in vivo evidence for this is lacking. To study the mechanism of GPVI regulation in vivo, two mouse lines, Gp6 knock-out and Adam10fl/fl, PF4-Cre mice, were generated and in addition low TACE (TNFalpha converting enzyme) mice were analyzed. It was shown that GPVI can be cleaved in vitro by ADAM10 or TACE depending on the shedding-inducing signaling pathway. Moreover, GPVI was down-regulated in vivo upon antibody injection in ADAM10-deficient and low TACE mice suggesting that either both or an additional metalloproteinase is involved in GPVI regulation in vivo.

Techn. Universiẗat, Diss., 2003--Berlin.

Bone fractures and pathologic conditions like chronic wounds significantly reduce the quality of life for the patients, which is especially dramatic in an elderly population with considerable multi-morbidity and lead to substantial socio-economic costs. To improve the wound healing capacity of these patients, new strategies for the design of novel multi-functional biomaterials are required: they should be able to decrease extensive pathologic tissue degradation and specifically control angiogenesis in damaged vascularized tissues like bone and skin. Glycosaminoglycans (GAGs) like hyaluronan (HA) and chondroitin sulfate (CS) as important extracellular matrix (ECM) components are involved in several biological processes such as matrix remodeling and growth factor signaling, either by directly influencing the cellular response or by interacting with mediator proteins. This could be useful in functionalizing biomaterials, but native sulfated GAGs (sGAGs) show a high batch-to-batch variability and are limited in their availability. Chemically modified HA and CS derivatives with much more defined characteristics regarding their carbohydrate backbone, sulfate group distribution and sulfation degree are favorable to study the structure-function relationship of GAGs in their interaction with mediator proteins and/or cells and this might be used to precisely modulate activity profiles to stimulate wound healing. By combining collagen type I as the main structural protein of the bone and skin ECM with these GAG derivatives, 2.5-dimensional (2.5D) and 3D artificial ECM (aECM) coatings and hydrogels were developed. These biomaterials as well as the respective GAG derivatives alone were compared to native GAGs and used to analyze how the sulfation degree, pattern and carbohydrate backbone of GAGs influence: i) the activity of tissue inhibitor of metalloproteinase-3 (TIMP-3) and vascular endothelial growth factor-A (VEGF-A) as main regulators of ECM remodeling and angiogenesis, ii) the composition and characteristics of the developed 2.5D and 3D aECMs, iii) the enzymatic degradation of collagen-based aECMs and HA/collagen-based hydrogels, iv) the proliferation and functional morphology of endothelial cells. Surface plasmon resonance (SPR) and enzyme linked immunosorbent assay (ELISA) binding studies revealed that sulfated HA (sHA) derivatives interact with TIMP-3 and VEGF-A in a sulfation-dependent manner. sHA showed an enhanced interplay with these proteins compared to native GAGs like heparin (HEP) or CS, suggesting a further impact of the carbohydrate backbone and sulfation pattern. sGAGs alone were weak modulators of the matrix metalloproteinase-1 and -2 (MMP-1 and -2) activity and did not interfere with the inhibitory potential of TIMP-3 against these proteinases during enzyme kinetic analyses. However, the formation of TIMP 3/GAG complexes reduced the binding of TIMP-3 to cluster II and IV of its endocytic receptor low-density lipoprotein receptor-related protein-1 (LRP-1, mediates the up-take and degradation of TIMP-3 from the extracellular environment) in a sulfation- and GAG type-dependent manner. It is of note that the determined complex stabilities of TIMP-3 with cluster II and IV were almost identical indicating for the first time that both clusters contribute to the TIMP-3 binding. Competitive SPR experiments demonstrated that GAG polysaccharides interfere stronger with the TIMP 3/LRP-1 interplay than GAG oligosaccharides. The importance of the position of sulfation is highlighted by the finding that a sHA tetrasaccharide exclusively sulfated at the C6 position of the N-acetylglucosamine residues significantly blocked the receptor binding, while CS and HEP hexasaccharides had no detectable effects. Thus, sHA derivatives as part of biomaterials could be used to sequester and accumulate TIMP 3 in aECMs in a defined manner where sHA-bound TIMP-3 could decrease the matrix breakdown by potentially restoring the MMP/TIMP balance. GAG binding might extend the beneficial presence of TIMP-3 into wounds characterized by excessive pathologic tissue degradation (e.g. chronic wounds, osteoarthritis). Mediator protein interaction studies with sHA coated surfaces showed the simultaneous binding of TIMP-3 and VEGF-A, even though the sHA/VEGF-A interplay was preferred. Moreover, kinetic analysis revealed almost comparable affinities of both proteins for VEGF receptor-2 (VEGFR-2), explaining their competition that mainly regulates the activation of endothelial cells. Additional SPR measurements demonstrated that the binding of sGAGs to TIMP-3 or VEGF-A decreases the binding of the respective mediator protein to VEGFR-2. Likewise, a sulfation-dependent reduction of the binding signal was observed after pre-incubation of a mixture of TIMP-3 and VEGF-A with sGAG poly- and oligosaccharides. The biological consequences of GAGs interfering with VEGF-A/VEGFR-2 and TIMP-3/VEGFR 2 were assessed in vitro using porcine aortic endothelial cells stably transfected with VEGFR 2 (PAE/KDR cells). The presence of sHA both decreased VEGF-A activity and the activity of TIMP-3 to inhibit the VEGF-A-induced VEGFR-2 phosphorylation. The same decreased activities could be observed for the migration of endothelial cells. However, if sHA, TIMP-3 and VEGF-A were present simultaneously, sHA partially restored the TIMP-3-mediated blocking of VEGF-A activity. These findings provide novel insights into the regulatory potential of sHA during endothelial cell activation as an important aspect of angiogenesis, which could be translated into the design of biomaterials to treat abnormal angiogenesis. These sHA-containing materials might control the angiogenic response by modulating the activity of TIMP 3 and VEGF-A. The in vitro fibrillogenesis of collagen type I in the presence of sHA derivatives led to 2.5D collagen-based aECM coatings with stable collagen contents and GAG contents that resemble the organic part of the bone ECM. A burst release of GAGs was observed during the first hour of incubation in buffer with the GAG content remaining almost constant afterwards, implying that the number of GAG-binding sites of collagen restricts the amounts of associated GAGs. Moreover, two differently sulfated HA derivatives could for the first time be incorporated into one multi-GAG aECM as verified via agarose gel electrophoresis and fluorescence measurements. This illustrates the multiple options to modify the aECM composition and thereby potentially their functionality. Atomic force microscopy showed that the presence of sHA derivatives during fibrillogenesis significantly reduced the resulting fibril diameter in a concentration- and sulfation-dependent manner, indicating an interference of the GAGs with the self-assembly of collagen monomers. In line with enzyme kinetic results, none of the GAGs as part of aECMs altered the enzymatic collagen degradation via a bacterial collagenase. Thus aECMs were proven to be biodegradable independent from their composition, which is favorable concerning a potential biomedical usage of the aECMs e.g. as implant coatings. HA/collagen-based hydrogels containing fibrillar collagen embedded into a network of crosslinked HA and sGAGs were developed as 3D aECMs. Scanning electron microscopy demonstrated a porous structure of the gels after lyophilization, which could favor the cultivation of cells. The presence of collagen markedly enhanced the stability of the gels against the enzymatic degradation via hyaluronidase, something beneficial to clinical use as this is often limited by the generally fast breakdown of HA. Binding and release experiments with lysozyme, as positively charged model protein for e.g. pro-inflammatory cytokines, and VEGF A revealed that the sulfation of GAGs increased the protein binding capacity for pure GAG coatings and retarded the protein release from hydrogels compared to hydrogels without sGAGs. Moreover, the additional acrylation of sHA was shown to strongly reduce the interaction with both proteins when the primary hydroxyl groups were targets of acrylation. This stresses the influence of the substitution pattern on the protein binding properties of the GAG derivatives. However, hydrogel characteristics like the elastic modulus remained unaffected. The different interaction profiles of lysozyme and VEGF-A with GAGs demonstrated a protein-specific preference of different monosaccharide compositions, suggesting that the mediator protein binding could be simultaneously adjusted for several proteins by combining different GAG derivatives. This might allow the scavenging of pro-inflammatory cytokines and at the same time a binding and release of wound healing stimulating growth factors. Since there is a growing demand for biomaterials to regenerate injured vascularized tissues like bone and skin, endothelial cells were used to examine the direct effects of solute GAGs and hydrogels containing these GAGs in vitro. In both cases, sHA strongly enhanced the proliferation of PAE/KDR cells. A VEGFR-2-mediated effect of GAGs on endothelial cells as underlying mechanism is unlikely since GAGs alone did not bind to VEGFR-2 and had no influence on VEGFR-2 phosphorylation. Other factors like GAG-induced alterations of cell-matrix interactions and cell signaling could be responsible. In accordance with SPR results, a decreased endothelial cell proliferation stimulating activity of VEGF-A was observed in the presence of solute GAGs or after binding to hydrogels compared to the respective treatment without VEGF-A. However, tube formation could be observed in the presence of solute VEGF A and GAGs and within hydrogels with sGAGs that released sufficient VEGF-A amounts over time. Overall the presence of GAGs and VEGF-A strongly promoted the endothelial cell proliferation compared to the treatment with GAGs or VEGF-A alone. Thus, HA/collagen-based hydrogels functionalized with sHA derivatives offer a promising option for the design of “intelligent” biomaterials that direct and regulate the cellular behavior instead of simply acting as inert filling material. They could be used for the controlled delivery and/or scavenging of multiple mediator proteins, thus enhancing the local availability or reducing the activity of these GAG-interacting mediator proteins, or by directly influencing the cellular response. This might be applied to a range of pathological conditions by tuning the biomaterial compositions to patient-specific needs. However, extensive in vivo validation is required to show whether these in vitro findings could be used to control the biological activity of for instance TIMP-3 and VEGF-A, especially under the pathological conditions of extended matrix degradation and dysregulated angiogenesis.

Bone fractures and pathologic conditions like chronic wounds significantly reduce the quality of life for the patients, which is especially dramatic in an elderly population with considerable multi-morbidity and lead to substantial socio-economic costs. To improve the wound healing capacity of these patients, new strategies for the design of novel multi-functional biomaterials are required: they should be able to decrease extensive pathologic tissue degradation and specifically control angiogenesis in damaged vascularized tissues like bone and skin. Glycosaminoglycans (GAGs) like hyaluronan (HA) and chondroitin sulfate (CS) as important extracellular matrix (ECM) components are involved in several biological processes such as matrix remodeling and growth factor signaling, either by directly influencing the cellular response or by interacting with mediator proteins. This could be useful in functionalizing biomaterials, but native sulfated GAGs (sGAGs) show a high batch-to-batch variability and are limited in their availability. Chemically modified HA and CS derivatives with much more defined characteristics regarding their carbohydrate backbone, sulfate group distribution and sulfation degree are favorable to study the structure-function relationship of GAGs in their interaction with mediator proteins and/or cells and this might be used to precisely modulate activity profiles to stimulate wound healing. By combining collagen type I as the main structural protein of the bone and skin ECM with these GAG derivatives, 2.5-dimensional (2.5D) and 3D artificial ECM (aECM) coatings and hydrogels were developed. These biomaterials as well as the respective GAG derivatives alone were compared to native GAGs and used to analyze how the sulfation degree, pattern and carbohydrate backbone of GAGs influence: i) the activity of tissue inhibitor of metalloproteinase-3 (TIMP-3) and vascular endothelial growth factor-A (VEGF-A) as main regulators of ECM remodeling and angiogenesis, ii) the composition and characteristics of the developed 2.5D and 3D aECMs, iii) the enzymatic degradation of collagen-based aECMs and HA/collagen-based hydrogels, iv) the proliferation and functional morphology of endothelial cells. Surface plasmon resonance (SPR) and enzyme linked immunosorbent assay (ELISA) binding studies revealed that sulfated HA (sHA) derivatives interact with TIMP-3 and VEGF-A in a sulfation-dependent manner. sHA showed an enhanced interplay with these proteins compared to native GAGs like heparin (HEP) or CS, suggesting a further impact of the carbohydrate backbone and sulfation pattern. sGAGs alone were weak modulators of the matrix metalloproteinase-1 and -2 (MMP-1 and -2) activity and did not interfere with the inhibitory potential of TIMP-3 against these proteinases during enzyme kinetic analyses. However, the formation of TIMP 3/GAG complexes reduced the binding of TIMP-3 to cluster II and IV of its endocytic receptor low-density lipoprotein receptor-related protein-1 (LRP-1, mediates the up-take and degradation of TIMP-3 from the extracellular environment) in a sulfation- and GAG type-dependent manner. It is of note that the determined complex stabilities of TIMP-3 with cluster II and IV were almost identical indicating for the first time that both clusters contribute to the TIMP-3 binding. Competitive SPR experiments demonstrated that GAG polysaccharides interfere stronger with the TIMP 3/LRP-1 interplay than GAG oligosaccharides. The importance of the position of sulfation is highlighted by the finding that a sHA tetrasaccharide exclusively sulfated at the C6 position of the N-acetylglucosamine residues significantly blocked the receptor binding, while CS and HEP hexasaccharides had no detectable effects. Thus, sHA derivatives as part of biomaterials could be used to sequester and accumulate TIMP 3 in aECMs in a defined manner where sHA-bound TIMP-3 could decrease the matrix breakdown by potentially restoring the MMP/TIMP balance. GAG binding might extend the beneficial presence of TIMP-3 into wounds characterized by excessive pathologic tissue degradation (e.g. chronic wounds, osteoarthritis). Mediator protein interaction studies with sHA coated surfaces showed the simultaneous binding of TIMP-3 and VEGF-A, even though the sHA/VEGF-A interplay was preferred. Moreover, kinetic analysis revealed almost comparable affinities of both proteins for VEGF receptor-2 (VEGFR-2), explaining their competition that mainly regulates the activation of endothelial cells. Additional SPR measurements demonstrated that the binding of sGAGs to TIMP-3 or VEGF-A decreases the binding of the respective mediator protein to VEGFR-2. Likewise, a sulfation-dependent reduction of the binding signal was observed after pre-incubation of a mixture of TIMP-3 and VEGF-A with sGAG poly- and oligosaccharides. The biological consequences of GAGs interfering with VEGF-A/VEGFR-2 and TIMP-3/VEGFR 2 were assessed in vitro using porcine aortic endothelial cells stably transfected with VEGFR 2 (PAE/KDR cells). The presence of sHA both decreased VEGF-A activity and the activity of TIMP-3 to inhibit the VEGF-A-induced VEGFR-2 phosphorylation. The same decreased activities could be observed for the migration of endothelial cells. However, if sHA, TIMP-3 and VEGF-A were present simultaneously, sHA partially restored the TIMP-3-mediated blocking of VEGF-A activity. These findings provide novel insights into the regulatory potential of sHA during endothelial cell activation as an important aspect of angiogenesis, which could be translated into the design of biomaterials to treat abnormal angiogenesis. These sHA-containing materials might control the angiogenic response by modulating the activity of TIMP 3 and VEGF-A. The in vitro fibrillogenesis of collagen type I in the presence of sHA derivatives led to 2.5D collagen-based aECM coatings with stable collagen contents and GAG contents that resemble the organic part of the bone ECM. A burst release of GAGs was observed during the first hour of incubation in buffer with the GAG content remaining almost constant afterwards, implying that the number of GAG-binding sites of collagen restricts the amounts of associated GAGs. Moreover, two differently sulfated HA derivatives could for the first time be incorporated into one multi-GAG aECM as verified via agarose gel electrophoresis and fluorescence measurements. This illustrates the multiple options to modify the aECM composition and thereby potentially their functionality. Atomic force microscopy showed that the presence of sHA derivatives during fibrillogenesis significantly reduced the resulting fibril diameter in a concentration- and sulfation-dependent manner, indicating an interference of the GAGs with the self-assembly of collagen monomers. In line with enzyme kinetic results, none of the GAGs as part of aECMs altered the enzymatic collagen degradation via a bacterial collagenase. Thus aECMs were proven to be biodegradable independent from their composition, which is favorable concerning a potential biomedical usage of the aECMs e.g. as implant coatings. HA/collagen-based hydrogels containing fibrillar collagen embedded into a network of crosslinked HA and sGAGs were developed as 3D aECMs. Scanning electron microscopy demonstrated a porous structure of the gels after lyophilization, which could favor the cultivation of cells. The presence of collagen markedly enhanced the stability of the gels against the enzymatic degradation via hyaluronidase, something beneficial to clinical use as this is often limited by the generally fast breakdown of HA. Binding and release experiments with lysozyme, as positively charged model protein for e.g. pro-inflammatory cytokines, and VEGF A revealed that the sulfation of GAGs increased the protein binding capacity for pure GAG coatings and retarded the protein release from hydrogels compared to hydrogels without sGAGs. Moreover, the additional acrylation of sHA was shown to strongly reduce the interaction with both proteins when the primary hydroxyl groups were targets of acrylation. This stresses the influence of the substitution pattern on the protein binding properties of the GAG derivatives. However, hydrogel characteristics like the elastic modulus remained unaffected. The different interaction profiles of lysozyme and VEGF-A with GAGs demonstrated a protein-specific preference of different monosaccharide compositions, suggesting that the mediator protein binding could be simultaneously adjusted for several proteins by combining different GAG derivatives. This might allow the scavenging of pro-inflammatory cytokines and at the same time a binding and release of wound healing stimulating growth factors. Since there is a growing demand for biomaterials to regenerate injured vascularized tissues like bone and skin, endothelial cells were used to examine the direct effects of solute GAGs and hydrogels containing these GAGs in vitro. In both cases, sHA strongly enhanced the proliferation of PAE/KDR cells. A VEGFR-2-mediated effect of GAGs on endothelial cells as underlying mechanism is unlikely since GAGs alone did not bind to VEGFR-2 and had no influence on VEGFR-2 phosphorylation. Other factors like GAG-induced alterations of cell-matrix interactions and cell signaling could be responsible. In accordance with SPR results, a decreased endothelial cell proliferation stimulating activity of VEGF-A was observed in the presence of solute GAGs or after binding to hydrogels compared to the respective treatment without VEGF-A. However, tube formation could be observed in the presence of solute VEGF A and GAGs and within hydrogels with sGAGs that released sufficient VEGF-A amounts over time. Overall the presence of GAGs and VEGF-A strongly promoted the endothelial cell proliferation compared to the treatment with GAGs or VEGF-A alone. Thus, HA/collagen-based hydrogels functionalized with sHA derivatives offer a promising option for the design of “intelligent” biomaterials that direct and regulate the cellular behavior instead of simply acting as inert filling material. They could be used for the controlled delivery and/or scavenging of multiple mediator proteins, thus enhancing the local availability or reducing the activity of these GAG-interacting mediator proteins, or by directly influencing the cellular response. This might be applied to a range of pathological conditions by tuning the biomaterial compositions to patient-specific needs. However, extensive in vivo validation is required to show whether these in vitro findings could be used to control the biological activity of for instance TIMP-3 and VEGF-A, especially under the pathological conditions of extended matrix degradation and dysregulated angiogenesis.

Die invasiven und metastatischen Eigenschaften vieler Tumore werden mit einer Veränderung im physiologischen Gleichgewicht der Matrix Metalloproteinasen (MMP) und ihrer spezifischen und unspezifischen Inhibitoren in Zusammenhang gebracht. Das Ziel dieser Dissertation war es, die Wirkung von Batimastat, einem synthetischen Inhibitor der MMP, auf hormonabhängige und hormonunabhängige Prostatakarzinomzellinien sowie auf das Tumorwachstum im orthotopen Tumormodell des Dunning Tumor (R3327) zu untersuchen. Methoden: Im Zellkulturversuch wurde die Wirkung verschiedener Konzentrationen von Batimastat untersucht und die Proliferation mit dem MTT Test gemessen. Die Induktion des orthotopen Tumors erfolgte durch Inokulation von MATLyLu Zellen in die Rattenprostata (Dunning Tumor der Copenhagen Ratte). 10 Tiere wurden nach Tumorinduktion täglich mit 30 mg/kg Batimastat durch intraperitoneale Gabe behandelt, 10 weitere Ratten erhielten nur das Vehikel. Zehn Kontrolltiere blieben unbehandelt. Der Effekt auf des lokale Tumorwachstum wurden durch Bestimmung des Tumorgewichtes nach 20 Tagen definiert. Results:Batimastat zeigte eine dosisabhänige Hemmung des Wachstums der Prostatakarzinomzellinien in vitro. Bei 4000 ng/ml kam es zu einer eindeutigen Hemmung des Zellwachstums. Im Tierversuch fand sich nach 20 Tagen in der Kontrollgruppe ein mittleres Tumorgewicht von 18.9 ± 5,4 g, in der Vehikelgruppe von 22.3 ± 4,3 g und in der mit Batimastat behandelten Gruppe von 11.1 ± 2,6 g. Im Vergleich zur Kontroll- und Vehikelgruppe, zeigte sich in der Batimastatgruppe ein signifikant geringeres Tumorgewicht. Zusammenfassung: Batimastat kann das Tumorwachstum in einem Standardtiermodell des Prostatakarzinoms vermindern. Der Dunning Tumor der Copenhagen Ratte ist ein zuverlässiges Tiermodell zur weiteren Untersuchung von synthetischen Inhibitoren der MMP. / Background: Increased concentrations of metalloproteinases are associated with the invasive and metastatic behavior of several human malignant tumors. Normally, enzymatic activity is tightly regulated by nonspecific mechanisms and specific inhibitors. The aim of this dissertation was to determine the potential of a synthetic metallproteinase inhibitor, batimastat, to show its in vitro effect on hormonedependent and hormoneindependent prostate cancer cell lines and its in vivo effect on tumor growth in orthotopic cancer (R3327 Dunning tumor) in rats. Methods: In vitro, a dose response curve of batimastat was generated over 5 days using the MTT assay. Prostate cancer was injected in vivo in male Copenhagen rats by inoculating R3327 Dunning tumor cells (MATLyLu) into the ventral prostatic lobe of 30 rats. Each of 10 rats received batimastat (30 mg / kg / body weight) or vehicle once a day by i.p. application beginning the day of cell inoculation. Ten rats remained untreated. The effect on local tumor growth was evaluated by measuring tumor weights 20 days after tumor cell inoculation. Results: Significant inhibiton of tumor cell proliferation in vitro occurred at 4000 ng / ml batimastat. After orthotopic cell inoculation, tumors grew to mean weights of 18.9 ± 5,4 g in the control group without treatment, to 22.3 ± 4,3 g in the vehicle group, an to 11.1 ± 2,6 g in the treated group. In comparison to the control group and to the vehicle group, tumor weights increased significantly less under treatment with batimastat. Conclusions: Batimastat is able to reduce tumor growth in the standard prostate cancer model. Using this model, activity against cancer progression of future inhibitory agents can be reliably assessed.