Biocompatibility of Chronically Implanted Transverse Intrafascicular Multichannel Electrode (TIME) in the Rat Sciatic Nerve

The transverse intrafascicular multichannel electrode (TIME) is intended to be transversally implanted in the peripheral nerve and to selectively interface subsets of axons in different fascicles within the same nerve. Two versions of TIME (TIME-2 and TIME-3) were designed and tested for biocompatibility and safety in the sciatic nerve of the rat. TIME-2 was implanted in two groups: the first group had only an acute implant and the second group had chronic implantation for two months; a third group was also chronically implanted with the TIME-3 version, designed to avoid the mechanical traction produced by muscles motion. We evaluated the functional and morphological effects of either TIME-2 or TIME-3 implanted in the rat sciatic nerve for two months. The results of the study indicate that implantation of the TIME-2 and TIME-3 devices in the nerve did not cause significant axonal loss or demyelination, as evidenced by the functional and histological results. The results of this study indicate that the TIME-2 and TIME-3 designs are biocompatible and safe after chronic implantation in a small peripheral nerve, such as the rat sciatic nerve.