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2015|16 Annual Report Fraunhofer IGB

62 MEDICINE AMBULUNG – BIOARTIFICIAL LUNG Annika Wenz, Kirstin Linke, Markus Schandar, Petra Kluger, Kirsten Borchers Bioartificial lung e reported last year on the development of a bioartificial lung assist device called “AmbuLung” as part of an EU-funded project. Within the scope of this project, Fraunhofer IGB de- veloped a biological coating for a miniaturized gas exchange module. The coating was designed to mimic the natural interface between blood vessels and blood. Blood vessel cells endothelial cells should create a confluent monolayer across the hollow fiber module of the device that will be in constant contact with the patient’s blood. The vision is that this cell layer will ensure the blood compatibility of the gas exchanger, which should translate to a module that is functional for several weeks. This is a major improvement over the currently used devices that can only be used for a couple of days and under intensive care due to their low hemocompatibility. Biofunctionalization of the gas exchange membrane The overall aim of the work at Fraunhofer IGB was to coat the e isting polymethylpentene PMP hollow fiber membranes with a hemocompatible and endothelial cell friendly surface and then to seed the membranes with endothelial cells. The aim of the second half of the project was to evaluate the blood compatibility of the coating, to upscale the deployment of endothelial cells and the cell seeding of the entire module. The hemocompatibility evaluation was performed at the University of Tübingen as a Chandler-loop-study of different heparin-containing coatings and it showed that the blood compatibility of the hollow fiber surface was e tensively im- proved by a layer-by-layer coating with albumin and heparin. Coating of PMP with heparin that was chemically coupled via benzophenone-functions did not result in a reduction of blood clotting nor of platelet activation as compared to uncoated PMP. The additional functionalization of the coat- ings with endothelial cell-specific R and I P T peptide se uences had no significant effect on the hemocompatibility of the surfaces. sing the lcian blue staining techni ue and fluorescence- labeled peptides, we could demonstrate that the hollow-fiber mats in the AmbuLung prototype could be completely func- tionalized with heparin, albumin and peptides (Fig. 1). Seeding the AmbuLung-prototype with endothelial cells We worked with bioreactors to create dynamic conditions for cell seeding and nutrient supply in the first part of the pro ect (see Fraunhofer IGB Annual Report 2014). The next project goal was the cell seeding of a multilayer membrane stack and the upscaling of the system in a full gas exchanger (Fig. 1). We successfully upscaled the membrane stack to 66 membranes completely seeded with endothelial cells (Fig. 3). After 14 days of dynamic culture, the cells were analyzed for cell morphol- ogy and the e pression of endothelial cell specific markers such as CD31. The analysis showed that the cells were stably seeded over the entire membrane stack surface and expressed specific endothelial markers ig 21 2×106 cells stack of 2 fiber mats 1 8×106 cells stack of 8 fiber mats 2 80×106 cells stack of 66 fiber mats 3 18×106