Development of a bioreactor for evaluating novel nerve conduits

We describe an experimental closed bioreactor device for studying novel tissue engineered peripheral nerve conduits in vitro. The system integrates a closed loop system consisting of one, two, or three experimental nerve conduits connected in series or parallel, with the ability to study novel scaffolds within guidance conduits. The system was established using aligned synthetic microfiber scaffolds of viscose rayon and electrospun polystyrene. Schwann cells were seeded directly into conduits varying from 10 to 80 mm in length and allowed to adhere under 0 flow for 1 h, before being cultured for 4 days under static or continuous flow conditions. In situ viability measurements showed the distribution of live Schwann cells within each conduit and enabled quantification thereafter. Under static culture viable cells only existed in short conduit scaffolds (10 mm) or at the ends of longer conduits (20-80 mm) with a variation in viable cell distribution. Surface modification of scaffold fibers with type-1 collagen or acrylic acid increased cell number by 17% and 30%, respectively. However, a continuous medium flow of 0.8 mL/h was found to increase total cell number by 2.5-fold verses static culture. Importantly, under these conditions parallel viability measurements revealed a ninefold increase compared to static culture. Fluorescence microscopy of scaffolds showed cellular adhesion and alignment on the longitudinal axis. We suggest that such a system will enable a rigorous and controlled approach for evaluating novel conduits for peripheral nerve repair, in particular using hydrolysable materials for the parallel organization of nerve support cells, prior to in vivo study.