Experimental study of chemically extracted acellular nerve allograft / 中华骨科杂志

ABSTRACT

Objective To research the immunologic reaction and the potential of chemically extracted acellular nerve allograft(CEANA) to repair peripheral nerve defects in primates. Methods Adult SD rats were used as nerve donors and adult male Wistar rats used as nerve recipient hosts. 25 mm long nerve segments were excised from SD rats' sciatic nerves. The nerve segments were decellularized via an improved chemical decelluarization treatment as follows 1) nerve segments were rinsed with cold sterile Ringer's solution; 2)stabilized by pinning the ends to a thin plastic support, and submerged in 4% Triton-100 solution 12 h; 3)soaked into 72 mM sodium deoxycholate for 12 h; 4)washed in distilled water for 6 h. The procedures were repeated once again. Median nerve segments were obtained from macaques and decellularized according to above procedures. The CEANA from SD rats were implanted into Wistar rats subcutanously. The control group was implantation of fresh nerve allografts from SD rats. The immunogenicity of acellular nerve allograft was tested by immunohistochemical examination of the intensity of CD3+, CD4+ and CD8+ cells that infiltrated the allografts. Median nerve defects for 5 cm were created in three macaques. CEANA were interposed across the gap. The CEANA were anastomosed microsurgically to the epineurium of proximal and distal stumps. Results The number of CD3, CD4 and CD8 positive lymphocytes infiltration in CEANA was far lower than that in the control group of fresh nerve allografts at 2 weeks and 4 weeks after implantation. There was no significant evidence of inflammatory in the CEANA grafted group. In the experiment of nerve regeneration of macaques, electromyographic activity was recorded across the allografts. The conduction velocity of regenerated nerve was (40.5?6.8) m/s. Regenerated axons sprouted from the proximal portion reached the distal portion of the grafts, and Schwann cells were also present in the central portion of the CEANA. Motor end-plates were observed in reinnervated muscles. Conclusion The immunogenicity that would have initiated cell-mediated immunological rejection of CEANA are removed. The implantation of CEANA could repair the defect of median nerve 5 cm long in the arm 5 months postoperatively. The CEANA as a type of substitute of nerve autografts has the potential to repair peripheral nerve defects in primates.