Ex-vivo-Expansion perikardialer Patchstrukturen : zur Frage des Einflusses von zyklischem Stress und laminaren Strömungsbedingungen auf das Ex-vivo-Remodelling perikardialer Patchstrukturen
- Ex-vivo-expansion of pericardial patch structures : Concerning the influence of cyclic stress and laminar flow conditions on the ex-vivo-remodelling of pericardial patch structures
Hesse, Björn; Schmitz-Rode, Thomas (Thesis advisor)
Aachen : Publikationsserver der RWTH Aachen University (2009, 2010)
Dissertation / PhD Thesis
Aachen, Techn. Hochsch., Diss., 2009
BACKGROUND: Pericardium is widely used as a patch structure in paediatric cardiovascular heart surgery. However, the major problem still is the restricted availability and level of quality of autologous pericardium. Based on those limiting factors, a new concept has already been tested in a pilot study combining the mesh graft technique of burn surgery with the principles of tissue engineering to expand pericardial tissue ex vivo. The aims of this dissertation were to verify the preliminary result and improve the culture conditions and systems to optimize the synthesis of pericardial neo-tissue. In addition, the characteristics of native and pre-isolated pericardial cells concerning active migration and proliferation in fibrin gel scaffolds should be investigated. METHODS: Perforated porcine pericardial patches filled up with a fibrin-cell-carrier were cultivated in custom-designed bioreactor systems up to 20 days, one group under cyclic stress conditions observing the influences of different frequencies (f equal to or less than 10/min) on tissue-engineered samples and the other under laminar shear stress conditions using cell-seeded and cell-free fibrin gel scaffolds to compare levels of cell migration and proliferation. Extracellular matrix- (ECM) composition was analysed in all samples using routine histological and immunohistochemical techniques. RESULTS: Under stimuli of cyclic stress the neo-tissue synthesis has shown cell necrosis and scaffold dissections while under laminar flow conditions a positive development of ECM-deposition and matrix-remodelling could be observed. Moreover, active migration of pericardial cells into fibrin gel matrices from native tissue could be shown for the first time. The high number of migrated pericardial cells caused an extensive remodelling of fibrin gel matrix by typical ECM-proteins like type I and type III collagen as same as elastin. But in 20 days of cultivation the fibrin gel scaffold has not been entirely replaced by neo-tissue in any perforated patch. CONCLUSIONS: Native pericardial cells represent a promising resource to generate patch structures for pediatric cardiovascular heart surgery. In addition, this concept of ex vivo expansion can be realized without any cell culture. Nevertheless, further investigations have to verify the present results. Optimized culture parameters may increase the mechanical and functional characteristics of expanded pericardial tissue to the point of total replacement of scaffold while prospective animal studies will clarify the possible clinical benefit.