title: Lentiviral HSV-Tk.007-mediated suicide gene therapy is not toxic for normal brain cells.
abstract: BACKGROUND
  Gene therapeutic strategies with suicide genes are currently investigated in clinical trials for brain tumors. Previously, we have shown that lentiviral vectors delivering the suicide gene HSV-Tk to experimental brain tumors promote a highly significant treatment effect and thus are promising vectors for clinical translation.
  
  
  METHODS
  In the present study, we tested lentiviral vectors delivering the suicide gene HSV-Tk.007, a highly active mutant of HSV-Tk, to rat brains as a preclinical toxicity study. We injected 10(6) vesicular stomatitis virus glycoprotein (VSV-G) pseudotyped functional lentiviral particles harboring the suicide gene HSV-Tk.007 into the brain of healthy, immunocompetent rats. During prodrug treatment with ganciclovir (GCV), we measured weight and assessed the behavior of the rats in an open field test. After 14 days of GCV treatment, we analyzed HSV-Tk.007 expression in different brain cell populations, as well as inflammatory responses and apoptosis.
  
  
  RESULTS
  During prodrug treatment with GCV, behavior experiments did not reveal differences between the treated rats and the control groups. Analysis of HSV-Tk expression in different brain cell populations showed that transduced normal brain cells survived GCV treatment. There were no statistically significant differences in the number of transduced cells between treatment and control groups. Furthermore, inflammatory responses and apoptosis of brain cells were not observed.
  
  
  CONCLUSIONS
  We show that HSV-Tk.007-mediated suicide gene therapy is not toxic to normal brain cells. This observation is of high relevance for the translation of lentivirus-mediated suicide gene therapies into the clinic for the treatment of brain tumor patients. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Biomedicine, University of Bergen, Bergen, Norway.|KG Jebsen Brain Tumour Research Center, University of Bergen, Bergen, Norway.|Department of Pathology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Jubayer A
authors.initials: JA
authors.lastname: Hossain
authors.affiliation: Department of Biomedicine, University of Bergen, Bergen, Norway.|KG Jebsen Brain Tumour Research Center, University of Bergen, Bergen, Norway.
authors.forename: Lars Rømo
authors.initials: LR
authors.lastname: Ystaas
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.|Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
authors.forename: Jelena
authors.initials: J
authors.lastname: Mrdalj
authors.affiliation: Department of Biomedicine, University of Bergen, Bergen, Norway.|KG Jebsen Brain Tumour Research Center, University of Bergen, Bergen, Norway.
authors.forename: Kristjan
authors.initials: K
authors.lastname: Välk
authors.affiliation: Research Department Cell and Gene Therapy, Department of Stem Cell Transplantation, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Riecken
authors.affiliation: Research Department Cell and Gene Therapy, Department of Stem Cell Transplantation, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Fehse
authors.affiliation: Department of Biomedicine, University of Bergen, Bergen, Norway.|KG Jebsen Brain Tumour Research Center, University of Bergen, Bergen, Norway.|Norlux Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg.
authors.forename: Rolf
authors.initials: R
authors.lastname: Bjerkvig
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.|Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
authors.forename: Janne
authors.initials: J
authors.lastname: Grønli
authors.affiliation: Department of Biomedicine, University of Bergen, Bergen, Norway. hrvoje.miletic@uib.no.|KG Jebsen Brain Tumour Research Center, University of Bergen, Bergen, Norway. hrvoje.miletic@uib.no.|Department of Pathology, Haukeland University Hospital, Bergen, Norway. hrvoje.miletic@uib.no.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Miletic
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D045744:Cell Line, Tumor; D015774:Ganciclovir / Q000494:pharmacology; D041722:Genes, Transgenic, Suicide / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D018613:Microscopy, Confocal; D009043:Motor Activity / Q000187:drug effects / Q000235:genetics; D009154:Mutation; D051381:Rats; D018139:Simplexvirus / Q000201:enzymology* / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: D000998:Antiviral Agents; D013937:Thymidine Kinase; D015774:Ganciclovir
keywords: HSV-Tk; VSV-G; glioma; lentiviral vectors; suicide gene therapy; toxicity