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[Nerve transplantation and accompanying peripheral vessels for repair of long nerve defect].

OBJECTIVE
To observe the revascularization process of transplanted nerve after transplantation of long nerve and accompanying peripheral vessels, to investigate its relationship with nerve regeneration.


METHODS
The median nerve defect models of the left forelimb (3 cm in length) were made in 60 New Zealand rabbits (aged 6-8 months, weighing 2.0-2.5 kg, and male or female), which were randomly divided into 2 groups (n=30). In situ anastomosis of the median nerves was performed in the control group; in situ anastomosis of the median nerves was made in parallel to the surrounding elbow veins, the transplanted epineurium and the adventitia were sutured with nerve anastomosis line in the experimental group. After operation, the gross observation, electrophysiological testing, and histopathology observation was performed at 1, 2, 4, 8, and 12 weeks, and transmission electron microscope at 12 weeks to observe the revascularization of nerve grafts, nerve fiber regeneration, and functional recovery.


RESULTS
In the experimental group, revascularization was observed at 1 week after operation, and the degree of revascularization was significantly higher than that in the control group at 2, 4, 8, and 12 weeks. At 8 and 12 weeks, the nerve fiber regeneration speed, quality, and quantity in the experimental group were better than those in the control group. At 2, 4, 8, and 12 weeks, the nerve conduction velocities were (10.32 +/- 0.94), (13.14 +/- 1.22), (22.68 +/- 1.16), and (24.09 +/- 1.27) m/s respectively in the experimental group, and were (9.18 +/- 1.07), (11.12 +/- 1.03), (19.81 +/- 1.37), and (20.67 +/- 1.19) m/s in the control group, showing significant difference at 12 weeks after operation (t = 3.167, P = 0.001). At 12 weeks in the experimental group, the myelin sheath had similar size, less sheath plate delamination, normal Schwann cells and rich organelles, in which normal microfilaments, microtubules and axonal mitochondria were observed; axonal mitochondria had clear crest film and no swelling and vacuolization, and the neurofibrils basically became normal. The myelinated nerve fibers area, myelin thickness, and axon diameter were (5.93 +/- 0.94) mm2, (0.72 +/- 0.12) microm, and (3.12 +/- 0.12) microm respectively in the experimental group, and were (5.28 +/- 0.72) mm2, (0.65 +/- 0.09) microm, and (2.98 +/- 0.16) microm respectively in the control group, all showing significant differences (t = 3.736, P = 0.002; t = 3.271, P = 0.002; t = 4.533, P = 0.001).


CONCLUSION
The transplanted nerves in parallel to large blood vessels can promote angiogenesis of the transplanted nerve, and accelerate the regeneration and functional recovery of the nerves.