Delineation of Vascular Disruption and Investigation of a Bioengineered ZFP-VEGF Gene Therapy Following Traumatic Spinal Cord Injury

Background: Traumatic spinal cord injury (SCI) results in vascular disruption which appears to contribute to the pathobiology of SCI. Vascular endothelial growth factor (VEGF) is known for vascular development and repair, and more recently for its neuroprotective properties. Given this, I investigated the temporal-spatial changes to the spinal vasculature, as well as examined the role of VEGF as a therapeutic approach for SCI. Hypothesis: It is hypothesized that clip-compression injury will result in significant vascular changes, and that ZFP-VEGF gene therapy will enhance molecular and functional recovery following spinal cord injury. Methods: Briefly, female Wistar rats received a two-level laminectomy and a 35g clip-compression injury at T6-T7 for 1 minute. Control animals received a laminectomy only. AdV-ZFP-VEGF or AdV-eGFP was administered 24 hour post-injury by intraspinal injection. For molecular and vascular analysis, tissues were extracted at various time points between 1 hour and 14 days post-SCI. For behavioural experiments animals were studied for 8 consecutive weeks. Results: I have shown that vasculature undergoes structural and functional changes, which occur as early as 1 hour following SCI. Although endogenous improvement is observed, SCI results in permanent vascular damage. Animals receiving AdV-ZFP-VEGF treatment had increased levels of VEGF mRNA and protein. AdV-ZFP-VEGF resulted in neuroprotection, as observed by increased NF200 protein and NeuN counts, and decreased TUNEL staining. Animals treated with AdV-ZFP-VEGF also showed an increased number of newly formed vessels (angiogenesis), as well as an increase in total number of vessels. Moreover, animals treated with AdV-ZFP-VEGF showed significant increases in hindlimb weight support and reduction neuropathic pain. Conclusions: I have characterized the dramatic temporal-spatial changes which occur in the spinal vasculature following SCI. Additionally, I have demonstrated that AdV-ZFP-VEGF administration results in beneficial molecular and functional outcomes. Overall, the results of this study indicate that AdV-ZFP-VEGF administration can be delivered in a clinically relevant time-window following SCI (24 hours) and provide significant molecular and neurobehavioural benefits, by acting through angiogenic and neuroprotective mechanisms.Ph