Abstract 12: Small heat shock protein gene therapy to protect damaged spinal cord from secondary injury.

Abstract

Objective: To test the hypothesis that overexpression of small heat shock protein (Hsp27) after spinal cord lesion protects neural cells from secondary injury. Design: Gene therapy study on animal models. Setting: Academic research center. Animals: Rats. Interventions: Not applicable. Main Outcome Measures: Clone human Hsp27 complementary deoxyribonucleic acid into a neural tropic recombinant herpes simples and adeno-associated virus hybrid vector; prepare amplicons carrying Hsp27 and green fluorescent protein (GFP) genes; induce rat spinal cord injury by weight-drop apparatus (10g, 25mm); microinject the injured and uninjured spinal cords with Hsp27 amplicons with GFP amplicons and saline as a control; observe the spinal cord target gene expressions, histology reaction, and neuron survival; and perform immunohistochemistry studies as well as apoptosis assay. Results: Hours after injection, obvious target gene expression was observed. The expression peaked at 48 hours and was quite constant, lasting >8 weeks. The expression area was mainly around the site of injection. No obvious local inflammatory reaction induced any amplicons. Protective signs of neural tissue were observed in the Hsp27 group. 2 weeks after the contusion, about 30% more neurons survived around the lesion area in the Hsp27 therapy group than in the controls. Many Hsp27 labeled axon-like processes were found around the lesion site. There were fewer cells with apoptosis markers around the injury area in the Hsp27 group. The differences showed statistical significance. Conclusion: Hsp27 gene therapy may limit secondary injury in the rat spinal lesion model. Further studies on the underlying mechanisms and functional outcomes are suggested.