Regeneration of injured CNS tracts poses a significant clinical challenge due to the multifactorial nature of the degenerative processes that ensues and technically complex delivery of therapeutic molecules. To circumvent these problems, highly disabled Herpes Simplex 1 (HSV1) based vectors were used to deliver NT3, BDNF and CNTF to the injured rat CNS. The ability of these vectors to promote the regeneration of corticospinal (CST), rubrospinal (RST) and optic nerve tracts was evaluated. Transgene expressing constructs were based on the backbone HSVl.pR19CMV that carries a combination of essential and non-essential gene deletions. These render it replication incompetent in vivo whilst allowing it to maintain transgene expression in the long term via expression cassettes that employ HSV1 latency associated transcript promoters. Via retrograde transport, a single spinal cord inoculation results in widespread, stable transgene expression in neurons throughout the CNS, from spinal cord to hypothalamus. In spinal cord regeneration experiments, NT3-expressing vector alone failed to promote regeneration in the chronically injured CST. In combination with transplanted embryonic day-14 spinal cord segments however, it led to enhanced CST sprouting and axon elongation up to 600ujn within the lesion site. In the chronically injured RST, BDNF and CNTF-expressing vectors produced no significant regeneration. In the optic nerve crush model however, both robust transduction and substantial axonal regeneration resulted from inoculation of retinal ganglion cell (RGC) targets. A combination of CNTF, BDNF, bFGF and Neurturin-expressing vectors induced regeneration of injured RGC axons in optic nerve, up to 1000 pjn distal to the crush site. Further vector development led to less-disabled vectors that supported strong transgene expression and targeted spinal cord, RGCs and even CST neurons, with high efficiency. By counteracting the host's immune response, minimally disabled ILlO-expressing vectors supported long-term expression of transgenes in DRG neurons following footpad inoculation. HSV1-based vectors are therefore powerful and versatile gene therapy tools for CNS regeneration.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:497816 |
| Date | January 2008 |
| Creators | Groutsi, Filitsa |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1443959/ |
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