Juan Colazo
Last active: 11/28/2019

Diffusion tensor tractography to visualize axonal outgrowth and regeneration in a 4-cm reverse autograft sciatic nerve rabbit injury model.

Farinas AF, Pollins AC, Stephanides M, O'Neill D, Al-Kassis S, Esteve IVM, Colazo JM, Keller PR, Rankin T, Wormer BA, Kaoutzanis C, Dortch RD, Thayer WP
Neurol Res. 2019 41 (3): 257-264

PMID: 30582740 · PMCID: PMC6435384 · DOI:10.1080/01616412.2018.1554284

BACKGROUND - Diffusion tensor tractography (DTT) has recently been shown to accurately detect nerve injury and regeneration. This study assesses whether 7-tesla (7T) DTT imaging is a viable modality to observe axonal outgrowth in a 4 cm rabbit sciatic nerve injury model fixed by a reverse autograft (RA) surgical technique.

METHODS - Transection injury of unilateral sciatic nerve (4 cm long) was performed in 25 rabbits and repaired using a RA surgical technique. Analysis of the nerve autograft was performed at 3, 6, and 11 weeks postoperatively and compared to normal contralateral sciatic nerve, used as control group. High-resolution DTT from ex vivo sciatic nerves were obtained using 3D diffusion-weighted spin-echo acquisitions at 7-T. Total axons and motor and sensory axons were counted at defined lengths along the graft.

RESULTS - At 11 weeks, histologically, the total axon count of the RA group was equivalent to the contralateral uninjured nerve control group. Similarly, by qualitative DTT visualization, the 11-week RA group showed increased fiber tracts compared to the 3 and 6 weeks counterparts. Upon immunohistochemical evaluation, 11-week motor axon counts did not significantly differ between RA and control; but significantly decreased sensory axon counts remained. Nerves explanted at 3 weeks and 6 weeks showed decreased motor and sensory axon counts.

DISCUSSION - 7-T DTT is an effective imaging modality that may be used qualitatively to visualize axonal outgrowth and regeneration. This has implications for the development of technology that non-invasively monitors peripheral nerve regeneration in a variety of clinical settings.

MeSH Terms (9)

Animals Axons Diffusion Tensor Imaging Imaging, Three-Dimensional Nerve Regeneration Peripheral Nerve Injuries Rabbits Sciatic Nerve Transplantation, Autologous

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