Herpes simplex virus vector-mediated expression of Bcl-2 prevents 6-hydroxydopamine-induced degeneration of neurons in the substantia nigra in vivo

Abstract

ABSTRACT6-Hydroxydopamine (6-OHDA) is widely used to selectively lesion dopaminergic neurons of the substantia nigra (SN) in the creation of animal models of Parkinson's disease. In vitro, the death of PC-12 cells caused by exposure to 6-OHDA occurs with characteristics consistent with an apoptotic mechanism of cell death. To test the hypothesis that apoptotic pathways are involved in the death of dopaminergic neurons of the SN caused by 6-OHDA, we created a replication-defective genomic herpes simplex virusbased vector containing the coding sequence for the antiapoptotic peptide Bcl-2 under the transcriptional control of the simian cytomegalovirus immediate early promoter. Transfection of primary cortical neurons in culture with the Bcl-2-producing vector protected those cells from naturally occurring cell death over 3 weeks. Injection of the Bcl-2-expressing vector into SN of rats 1 week before injection of 6-OHDA into the ipsilateral striatum increased the survival of neurons in the SN, detected either by retrograde labeling of those cells with f luorogold or by tyrosine hydroxylase immunocytochemistry, by 50%. These results, demonstrating that death of nigral neurons induced by 6-OHDA lesioning may be blocked by the expression of Bcl-2, are consistent with the notion that cell death in this model system is at least in part apoptotic in nature and suggest that a Bcl-2-expressing vector may have therapeutic potential in the treatment of Parkinson's disease.

Neuroprotective effects of bcl‐2 overexpression in hippocampal cultures: interactions with pathways of oxidative damage

“…These protective Bcl-2 effects agree with prior reports showing neuroprotection by Bcl-2 against excitotoxins, hypoglycemia and adriamycin in primary cultures derived from a number of brain regions (Jia et al 1996;Lawrence et al 1996;McLaughlin et al 2000;Tamatani et al 2000) and against in vivo models of excitotoxicity, hypoxia-ischemia, ROS generators, or mechanical trauma (Linnik et al 1995;Lawrence et al 1996Lawrence et al , 1997Antonawich et al 1999;Yamada et al 1999;Phillips et al 2000;Shimazaki et al 2000).…”

“…In at least some reports, Bcl-2 does not prevent the cell death induced by the pro-oxidant 6-OHDA (Oh et al 1995(Oh et al , 1998, in a dopaminergic cell line; Yamada et al 1999, in the substantia nigra for example of protection against 6-OHDA).…”

Antinociceptive effect of a genomic herpes simplex virus-based vector expressing human proenkephalin in rat dorsal root ganglion

“…[15][16][17] Because HSV genes involved in viral replication are expressed in a rigid temporal cascade, deletion of essential immediate-early (IE) genes from the HSV genome allows the creation of a vector that is incapable of replicating in normal tissue in vivo, but nonetheless is capable of the efficient establishment of a quiescent state that is similar to natural viral latency but without the potential for reactivation. 18,19 We have previously demonstrated that genomic HSV-based vectors can be employed to express biologically active nerve growth factor 20 and the anti-apoptotic peptide Bcl-2 21 in vitro and in vivo.…”

Gene therapy in the CNS

“…Promising results have been obtained with both factors, particularly after viral vector delivery to the striatum or substantia nigra, 19,[166][167][168] but also after grafting of genetically modified cells. [169][170][171][172][173] Other factors with protective or regenerative effects include antiapoptotic Gene Therapy genes, such as bcl2, 174 and enzymes that produce antioxidant molecules, such as superoxide dismutase. In the case of PD, long-term expression of the transferred gene may be required over the subsequent lifetime to protect against the progressive nature of degeneration.…”