Dr Barrett graduated in 1995 with a BSc in Biochemistry from the Imperial College of Science, Technology and Medicine, London. It was at this time that he developed an interest in CNS repair and regeneration. Studying in the laboratory of Dr Robert Hallewell at Imperial, Dr Barrett was involved in the generation of transgenic mice, containing single point-mutations (G93R and D101N) of the human superoxide dismutase gene (hSOD-1), for the study of familial amyotrophic lateral sclerosis (FALS). He then completed a PhD in Gene Therapy vector development, and it’s application in CNS and PNS neurons, in the laboratory of Dr Len Seymour at the CRC Institute for Cancer Studies. Here, his research was focused on the delivery of anti-apoptotic (Bcl2, Bclxl) and neurotrophic factors (FGF-2, NGF, BDNF) with both viral (Ad, AAV, Lentivirus and HSV) and non-viral (polylysine; Dash et al, 1999, polyethylenimine, polyglutamic acid; Dekie et al 2000 and cationic lipid) vectors. Dr Barrett showed it was possible to target the expression of transgenes using targeting ligands, such as basic FGF, in retinal ganglion cell neurons in vivo (Berry et al, 2001) and the b-subunit, of Cholera toxin, in neuronal like cells in vitro (Barrett et al, 2004). In 2001, following the completion of his PhD, Dr Barrett moved as a post-doctoral fellow to the Division of Medicine at the University of Birmingham, UK, where he continued his work on Gene Therapy in CNS/PNS neurons, in the Molecular Neuroscience group of Professor Ann Logan. It was here that Dr Barrett developed non-viral vectors based upon mRNA encoding neurotrophic factors, for the rapid and sustained transfection of sensory neurons (Read et al, 2005 Farrow et al, 2006). In addition, an interest in myelin-associated growth inhibition of uninjured sensory neurons (Berry et al, 2003, Sandvig et al, 2004), and the associated changes in the expression profile of certain key signaling molecules, compared to neurons subject to a pre-conditioning PNS lesion, led to the application of siRNA technology to suppress neuron signaling pathways. siRNA mediated knockdown of proteins such as the p75, nogo receptor (NgR) and RhoA, lead to statistically significant neurite outgrowth on myelin inhibitory substrates (Ahmed et al, 2005, 2006). This work is ongoing, with the application of viral vectors expressing unique shRNA sequences in the injured spinal cord and visual system, for the successful modulation of the inhibitory growth response in CNS neurons. In 2004, Dr Barrett moved to the Neural Plasticity Research Group at Massachusetts General Hospital. The research he conducts in the laboratory of Professor Clifford Woolf is focused on the transcriptional control of PNS regeneration and the study of the potential application of these transcription factors for the successful repair of the injured CNS.
Nerve injury causes a dramatic change in the transcriptional programming of injured neurons. My research is focused on sciatic nerve pre-conditioning lesion in adult rats to effect such a molecular change. Using transcription factor over-expressors, chromatin immunoprecipitation (ChIP), ChIP on chip microarrays and knockout mice we hope to learn what are the master regulators in the repair and regeneration of insulted CNS neurons.
Farrow et al., Cytoplasmic expression systems triggered by mRNA yield increased gene expression in post-mitotic neurons. Nucleic Acids Res. 2006 Jul 11;34(11):e80.
Lin CR et al., Prostaglandin E2 receptor EP4 contributes to inflammatory pain hypersensitivity. J Pharmacol Exp Ther. 2006 319:1096-103.
Ahmed et al., Schwann cell-derived factor-induced modulation of the NgR/p75NTR/EGFR axis disinhibits axon growth through CNS myelin in vivo and in vitro. Brain. 2006 Jun;129(Pt 6):1517-33.
Read et al., A versatile reducible polycation-based system for efficient delivery of a broad range of nucleic acids.Nucleic Acids Res. 2005 May 24;33(9):e86.
Ahmed et al., Disinhibition of neurotrophin-induced dorsal root ganglion cell neurite outgrowth on CNS myelin by siRNA-mediated knockdown of NgR, p75NTR and Rho-A. Mol Cell Neurosci. 2005 Mar;28(3):509-23.
Barrett et al., CTb targeted non-viral cDNA delivery enhances transgene expression in neurons. J Gene Med. 2004 Apr;6(4):429-38.