Accuracy of motor axon regeneration across autograft, single-lumen, and multichannel poly(lactic-co-glycolic acid) nerve tubes.
OBJECTIVE
The accuracy of motor axon regeneration becomes an important issue in the development of a nerve tube for motor nerve repair. Dispersion of regeneration across the nerve tube may lead to misdirection and polyinnervation. In this study, we present a series of methods to investigate the accuracy of regeneration, which we used to compare regeneration across autografts and single-lumen poly(lactic-co-glycolic acid) (PLGA) nerve tubes. We also present the concept of the multichannel nerve tube that may limit dispersion by separately guiding groups of regenerating axons.


METHODS
The simultaneous tracing of the tibial and peroneal nerves with fast blue and diamidino yellow was performed 8 weeks after the repair of a 1-cm nerve gap in the rat sciatic nerve to determine the percentage of double-projecting motoneurons. Sequential tracing of the peroneal nerve with diamidino yellow 1 week before repair and fast blue 8 weeks after repair was performed to determine the percentage of correctly directed peroneal motoneurons.


RESULTS
In the cases in which there was successful regeneration across single-lumen nerve tubes, more motoneurons had double projections to both the tibial and peroneal nerve branches after single-lumen nerve tube repair (21.4%) than after autograft repair (5.9%). After multichannel nerve tube repair, this percentage was slightly reduced (16.9%), although not significantly. The direction of regeneration was nonspecific after all types of repair.


CONCLUSIONS
Retrograde tracing techniques provide new insights into the process of regeneration across nerve tubes. The methods and data presented in this study can be used as a basis for the development of a nerve tube for motor nerve repair.
de Ruiter
Godard C
GC
Cellular Neurobiology Laboratory and Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota 55905, USA.
Spinner
Robert J
RJ
Malessy
Martijn J A
MJ
Moore
Michael J
MJ
Sorenson
Eric J
EJ
Currier
Bradford L
BL
Yaszemski
Michael J
MJ
Windebank
Anthony J
AJ
D000818:Animals; D001369:Axons / Q000502:physiology* / Q000637:transplantation / Q000648:ultrastructure; D048091:Guided Tissue Regeneration / Q000379:methods / Q000592:standards; D019344:Lactic Acid / Q000008:administration & dosage*; D009046:Motor Neurons / Q000502:physiology* / Q000637:transplantation / Q000648:ultrastructure; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D011100:Polyglycolic Acid / Q000008:administration & dosage*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051381:Rats; D017207:Rats, Sprague-Dawley; D014182:Transplantation, Autologous / Q000379:methods / Q000592:standards
D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid