Allograft pretreatment for the repair of sciatic nerve defects: green tea polyphenols versus radiation

Abstract

Pretreatment of nerve allografts by exposure to irradiation or green tea polyphenols can eliminate neuroimmunogenicity, inhibit early immunological rejection, encourage nerve regeneration and functional recovery, improve tissue preservation, and minimize postoperative infection. In the present study, we investigate which intervention achieves better results. We produced a 1.0 cm sciatic nerve defect in rats, and divided the rats into four treatment groups: autograft, fresh nerve allograft, green tea polyphenol-pretreated (1 mg/mL, 4°C) nerve allograft, and irradiation-pretreated nerve allograft (26.39 Gy/min for 12 hours; total 19 kGy). The animals were observed, and sciatic nerve electrophysiology, histology, and transmission electron microscopy were carried out at 6 and 12 weeks after grafting. The circumference and structure of the transplanted nerve in rats that received autografts or green tea polyphenol-pretreated nerve allografts were similar to those of the host sciatic nerve. Compared with the groups that received fresh or irradiation-pretreated nerve allografts, motor nerve conduction velocity in the autograft and fresh nerve allograft groups was greater, more neurites grew into the allografts, Schwann cell proliferation was evident, and a large number of new blood vessels was observed; in addition, massive myelinated nerve fibers formed, and abundant microfilaments and microtubules were present in the axoplasm. Our findings indicate that nerve allografts pretreated by green tea polyphenols are equivalent to transplanting autologous nerves in the repair of sciatic nerve defects, and promote nerve regeneration. Pretreatment using green tea polyphenols is better than pretreatment with irradiation.

Green Tea, A Medicinal Food with Promising Neurological Benefits

“…Irradiation is typically done before allogenic nerve transplantation to reduce neuro-immunogenicity, inhibit of early rejection and improve the tissue preservation and minimize the postoperative infections. The study proposed that using green tea polyphenols is better than pretreatment with irradiation [ 42 ].…”

“…This disease affects more than 10 million people worldwide [ 62 ]. This neurodegenerative disease has different obvious clinical symptoms, including; rigidity, bradykinesia (slowness of movement), difficulty in walking, and tremor [ 42 ]. Cell death in the brain's basal ganglia dopamine pathway and presence of Lewy bodies leads to lower the level of dopamine [ 28 ].…”