Peripheral nerve regeneration through allografts compared with autografts in FK5

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J Neurosurg. 2006 Oct;105(4):602-9.

Peripheral nerve regeneration through allografts compared with

autografts in FK506-treated monkeys.

Auba C, Hontanilla B, Arcocha J, Gorria O.

Department of Plastic and Reconstructive Surgery, Clinica

Universitaria, Universidad de Navarra, Pamplona, Spain.

OBJECT: The clinical use of nerve allografts combined with

immunosuppressant therapy has become a genuine possibility that

could supersede the classic use of autografts. However,

contradictory data have been reported on whether immunosuppressant

therapy should be temporarily administered. The purpose of this

study was to compare the nerve regeneration obtained using ulnar

nerve allografts in nonhuman primates temporarily treated with FK506

(tacrolimus) with that obtained using nerve autografts.

METHODS: Four-centimeter nerve autografts or allografts were placed

in the distal ulnar motor nerve of eight monkeys. The FK506 was

temporarily administered to the animals of the allograft group for 2

months. At periods of 3, 5, and 8 months postsurgery, quantitative

electrophysiological recordings were obtained to estimate muscle

response. A quantitative analysis of ulnar motor neurons in the

spinal cord was performed and axons were counted stereologically. No

statistically significant differences were found in the neuronal and

axonal counts between autograft and allograft groups at 8 months.

The electrophysiological studies showed no differences relative to

the amplitude, but the autograft group presented with a greater

nerve conduction velocity (NCV). However, no statistically

significant differences were found between the number of neurons and

distal axonal counts in the two groups.

CONCLUSIONS: Nerve regeneration through cold-preserved allografts in

a primate model temporarily treated with FK506 was similar to that

obtained using nerve autografts, in terms of neuronal and axonal

counts. Nevertheless, temporary immunosuppression produced lower NCV

when allografts were used, with less maturation of the myelinated

fibers, which indicated that a partial rejection had taken place.