FIGURE 1.

Design criteria for nerve guidance implants: For the development of effective synthetic nerve grafts biomaterial and biofabrication strategies should be applied in the service of established design criteria. The implant needs to comply with living tissue but possess enough strength and stability to withstand forces resulting from joint and muscle movement (top right). In order to avoid a surgical removal, the implant should degrade biologically and its degradation products must not harm the regenerating nerve nor other surrounding tissues (bottom right). The conduit wall should be permeable enough to allow for entry of nutrients and efflux of metabolic waste. At the same time the conduit wall creates a compartment that retains biochemical cues and soluble growth factors at the site of regeneration (top left). In order to bridge larger nerve gap injuries the implant should actively promote axon growth in a setting where regeneration would be otherwise ineffective or take too long. This can be achieved both by intrinsic properties of bioactive polymers, as well as their functionalization through biochemical or physical cues (bottom left).