• Zachary K Zabarsky, Gabriella M Dean, Tianyi David Luo, Alejandro Marquez-Lara, Alexander H Jinnah, Mark Van Dyke, and Thomas L Smith.
• Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC.
• Spine. 2021 Aug 15; 46 (16): 105510621055-1062.

Study DesignLaboratory study using a rat T9 contusion model of spinal cord injury (SCI).ObjectiveThe purpose of this study was to evaluate which method of delivery of soluble keratin biomaterials would best support functional restoration through the macrophage polarization paradigm.Summary Of Background DataSCI is a devastating neurologic event with complex pathophysiological mechanisms that currently has no cure. After injury, macrophages and resident microglia are key regulators of inflammation and tissue repair exhibiting phenotypic and functional plasticity. Keratin biomaterials have been demonstrated to influence macrophage polarization and promote the M2 anti-inflammatory phenotype that attenuates inflammatory responses.MethodsAnesthetized female Lewis rats were subjected to moderate T9 contusion SCI and randomly divided into: no therapy (control group), an intrathecally injected keratin group, and a keratin-soaked sponge group (n = 11 in all groups). Functional recovery assessments were obtained at 3- and 6-weeks post-injury (WPI) using gait analysis performed with the DigiGait Imaging System treadmill and at 1, 3, 7, 14, 21, 28, 35, and 42 days post-injury by the Basso, Beattie, Bresnahan (BBB) locomotor rating scale. Histology and immunohistochemistry of serial spinal cord sections were performed to assess injury severity and treatment efficacy.ResultsCompared to control rats, applying keratin materials after injury improved functional recovery in certain gait parameters and overall trended toward significance in BBB scores; however, no significant differences were observed with tissue analysis between groups at 6 WPI.ConclusionResults suggest that keratin biomaterials support some locomotor functional recovery and may alter the acute inflammatory response by inducing macrophage polarization following SCI. This therapy warrants further investigation into treatment of SCI.Level of Evidence: N/A.Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.

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