INJECTABLE CRYOGELS FOR NEURAL TISSUE ENGINEERING APPLICATIONS A. Béduer 1 *, T. Braschler 1 *, O. Peric 1 , G. Fantner 1 , S. Mosser 1 , P. Fraering 1 , S. Bencherif 2 , D.J . Mooney 2 and P. Renaud 1 1 EPFL, Station 17, 1015 Lausanne, Switzerland 2 Mooneylab, 60 Oxford St, Harvard University, 02138 Cambridge MA, USA ABSTRACT We show novel millimeter-sized injectable neural scaffolds based on cryogels exhibiting intercon- nected macropores, for neural tissue engineering applications. The polymer-scaffolds are designed to be compressible, allow cell adherence and it injection through a syringe needle while preserving neural cells viability and neurite integrity. The system is a potential answer to a major dilemma encountered in neural tissue engineering for the central nervous system: cellular scaffolds must be pre-organized and potential- ly large, but at the same time they should be delivered in a minimally invasive fashion to avoid further tissue damage. KEYWORDS: Neurons, cryogels, tissue engineering, alginate INTRODUCTION In the field of tissue engineering, experimental strategies employing cell transplantation have notably held great promise for repairing the injured central nervous system. Cell transplant alone is not sufficient to regenerate a functional neuronal network in a lesion cavity: cell survival after graft is very low and transplanted cells appear to build chaotic constructs only around the lesion area [1]. Scaffolds made from various polymers and hydrogels have been proposed in order to support and protect the transplanted cells, guide graft growth and facilitate its integration with the host tissue. However, the transplantation of such scaffolds remains challenging. One proposed solution to this problem consists in minimally invasive delivery of in-situ gelling formulations or scaffold suspensions [2] through narrow-bore needles. Howev- er, without the guidance of a large-scale organized scaffold, the cells typically build disorganized struc- tures rather than repairing the native tissue architecture as desired. The scaffolds developed here are both: organized at a large size scale, and nevertheless injectable thanks to their compressibility. To the best of our knowledge, the injectable neuronal cryogels reported here are the first to combine macroscop- ic scaffold size and injectability through a narrow-bore conduit for neuronal tissue engineering applica- tions. EXPERIMENTAL Cryogel synthesis Cryogels were synthesized based on established carbodiimide chemistry [3]. Briefly, alginate is dissolved in deionized (DI) water to the desired concentration, and crosslinking initiated by adding adipic acid dihydrazide (AAD) and an excess of the carbodiimide EDC (1-Ethyl-3-(3- dimethylaminopropyl)carbodiimide). The reaction mixture is placed at -20°C in a mold. This results in ice crystal formation prior to completion of gel crosslinking. After 24h, the cryogels are thawed, washed and autoclaved in PBS. Cryogel coating Autoclave-sterilized cryogels were coated prior to cell culture. A poly-L-ornithine (PLO, 1mg/mL diluted in sterile deionized water) droplet was then deposited on top of each cryogel and left for 1 hour at 37°C. The PLO droplet was then removed, and the cryogel samples rinsed with DI water. The cryogels were again partially dehydrated, and laminin (1µg/mL in sterile DI water) was added (1x cryogel sample volume) and left for four hours at 37°C. 978-0-9798064-7-6/µTAS 2014/$20©14CBMS-0001 1134 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences October 26-30, 2014, San Antonio, Texas, USA