1. Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, Kentucky, USA.
2. Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, Kentucky, USA.
3. Department of Neurological Surgery, University of Louisville, School of Medicine, Louisville, Kentucky, USA.
4. Department of Microbiology and Immunology, University of Louisville, School of Medicine, Louisville, Kentucky, USA.