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TISSUE ENGINEERING IN ZERO GRAVITY.  A. Cogoli.  Space Biology, ETH Zurich, Switzerland.

The purpose of this communication is to present a project recently selected by ESA within the application and commercialisation programme of the International Space Station. Team members from academic institutions are A. Bader, Hannover; S. Ambesi, Udine; P. Bruckner, Mьnster; R. Pцrtner, Hamburg; A. Cogoli and I. Walther, Zurich; W. Mьller is the industrial partner from Sulzer Medica, Winterthur. The objectives of the project are: to develop procedures of in vitro organogenesis of pancreatic islets, thyroid tissue, liver, vessels and cartilage; to study the mechanism of organogenesis in low-g; to define the requirements of a modular space bioreactor for medically relevant organ-like structures; to set up procedures for the production of implants for medical applications. It is believed that low-g may contribute in two aspects to progress in this field. First as a useful and non invasive tool to study important and still obscure biological events like signal transduction, gene expression, and cell proliferation. Second, low-g may favor the mass production of cells by obtaining higher cell densities per unit culture volume as well as a smooth cell-cell aggregation and three-dimension organogenesis in the absence of sedimentation and shear forces. The strategy adopted consists of a step by step approach: 1^st All mammalian biological systems (single cells and tissues) will be optimized according to the team members’ specific expertise. 2^nd The biological studies will be accompanied by ground-based simulations at 1 g, at simulated micro-gravity in clinostats (mainly in the random positioning machine) and at hypergravity in centrifuges. 3^rd Design of a modular bioreactor consisting of a central „servicing unit“ and of modules specific for each biological system. 4^th Optimization of the bioreactor to space laboratory requirements according to one selected system. 5^th Semi-automation of the bioreactor.

6^th Further expansion of the bioreactor to other systems. 7^th Flight opportunities for hardware and biological tests: Biopack, Modular Cultivation System, Biolab, BMTC Spacehab, International Space Station, sounding rockets. Preliminary tests in the random positioning machine will be followed by flights in space in 2001-2003.