Silicon wires for nerve gap management: Role of surface properties in nerve regeneration

Abstract

Up to 15% of combat trauma cases are accompanied by neuroinjuries with nerve gap formation that need to be bridged using various techniques and materials. Both with this prevalence of limb loss, especially traumatic amputations, tends to grow. Loosed limbs must be prosthetized by modern functional mind-controlled prosthesis based on nerve- or brain-computer interfaces. This study aimed at morphological evaluation of interaction between nerve fibers and silicon wires with different surface properties using peripheral nerve injury and grafting model. Experiment was performed on 50 male Wistar rats, weighing 180-250 g. Rats from experimental groups underwent sciatic nerve injury Sunderland 5 degree with a 10 mm gap formation that was subsequently filled with conduit consisting of decellularized aorta, carboxymethylcellulose gel and a set of longitudinally oriented ptype silicon wires 2-20 µm in diameter. We used silicon wires with native oxide in group Ia, with hydrogen-cleaned surface in group Ib and thermally grown oxide in group Ic. The gap in control groups was filled with decellularized aorta with gel alone (group II) or by autoneurograft (group III). 6 weeks postoperatively the conduit site was harvested and light microscopy performed. Implantation of conduit with native oxide on silicon wires surface resulted in more complete and equal neurotization of the conduit site with close adherence between the newly-formed nerve fibers and silicon wires, in comparison with groups where wires with other surface properties have been used. P-type silicon wires with native oxide are seems to be more suitable than other types of wires for further electrode preparation as a part of regenerative implants.