Effects of a novel nerve conduit combined with a large-area irradiation of low-level laser phototherapy on neural regeneration of the transected sciatic nerve in rats

• Main Authors: Yi-Yu Lee, 李憶妤
• Other Authors: Bai-Shuan Liu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/40861802403899017355

碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 100 === This paper proposes a novel biodegradable nerve conduit comprising 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linked gelatin, annexed with β-tricalcium phosphate (TCP) ceramic particles (EDC-Gelatin-TCP, EGT). In this study the EGT-implant site in rats was irradiated using a large-area 660 nm aluminum-gallium-indium phosphide (AlGaInP) diode laser (50 mW) to investigate the feasibility of laser stimulation in the regeneration of a 15-mm transected sciatic nerve. The proposed EGT conduit has a cylindrical shape, ivory-like color, and a rough, compact outer surface. A water uptake test indicates that the unique properties of EGT noticeably increase the stability of the artificial nerve graft in water; and the hydrated conduit does not collapse or stenose. The cross-linked structure of the EGT conduit resists enzymatic hydrolysis, which led to improved structural properties in studies on in vitro degradation. Results show that the adherence of TCP ceramic particles to the EDC-cross-linked gelatin matrix provided a framework with mechanical strength sufficient to serve as a nerve conduit. The animals were divided into three groups: a sham-irradiated group (EGT/Sham); an experimental group undergoing low-level laser (LLL) therapy (EGT/Laser); a control group undergoing autologous nerve grafts (autografts). LLL therapy was applied for 30 min immediately following surgery, focusing on the area of nerve damage. The surgical site was then treated transcutaneously for 5 min daily for 9 consecutive days. Twelve weeks after implantation, walking track analysis showed a significantly higher sciatic functional index (SFI) (P < 0.05) and improved toe spreading development in the EGT/Laser and autograft groups than in the EGT/Sham group. In electrophysiological measurement, both the mean peak amplitude and the area under the compound muscle action potential (CMAP) curves in the EGT/Laser and autograft groups showed significantly improved functional recovery than the EGT/Sham group (P < 0.05). Compared with the EGT/Sham group, the EGT/Laser and autograft groups displayed a reduction in muscular atrophy. Histomorphometric assessments revealed that the EGT/Laser group had undergone more rapid nerve regeneration than the EGT/Sham group. The laser-treated group also presented greater neural tissue area as well as larger axon diameter and thicker myelin sheath than the tube group without the laser treatment, indicating improved nerve regeneration. Thus, motor function, electrophysiologic reaction, muscular reinnervation, and histomorphometric assessments demonstrate that LLL therapy can accelerate the repair of a transected peripheral nerve in rats after being bridged with EGT conduit.