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GDNF gene delivery in an animal model of Parkinson's disease. Long-term effects on intact, injured and transplanted dopamine neurons using lentiviral gene transfer

Georgievska, Biljana LU (2004)
Abstract (Swedish)
Popular Abstract in Swedish

Parkinsons sjukdom är en av de vanligaste neurodegenerativa sjukdomarna och orsakas av en selektiv förlust av dopaminerga neuron i mellanhjärnans substantia nigra (SN). Detta leder till en minskad mängd dopamin (DA) i hjärnans motoriska centrum, striatum, vilket orsakar de karakteristiska symptomen bradykinesi, muskelrigiditet och tremor. Förlusten av DA neuron i SN sker successivt över flera år och de första symptomen uppträder när ungefär 50% av neuronen har dött. Den huvudsakliga behandlingen idag är baserad på att kompensera dopaminbristen i striatum genom tillförsel av L-DOPA, som i hjärnan omvandlas till DA. Denna behandling motverkar symptomen, men förhindrar inte den fortsatta... (More)
Popular Abstract in Swedish

Parkinsons sjukdom är en av de vanligaste neurodegenerativa sjukdomarna och orsakas av en selektiv förlust av dopaminerga neuron i mellanhjärnans substantia nigra (SN). Detta leder till en minskad mängd dopamin (DA) i hjärnans motoriska centrum, striatum, vilket orsakar de karakteristiska symptomen bradykinesi, muskelrigiditet och tremor. Förlusten av DA neuron i SN sker successivt över flera år och de första symptomen uppträder när ungefär 50% av neuronen har dött. Den huvudsakliga behandlingen idag är baserad på att kompensera dopaminbristen i striatum genom tillförsel av L-DOPA, som i hjärnan omvandlas till DA. Denna behandling motverkar symptomen, men förhindrar inte den fortsatta degenerationen av DA neuron i SN. Det progressiva förloppet i Parkinsons sjukdom ger oss möjligheter att förhindra den pågående degenerativa processen och skydda de kvarvarande cellerna. Den neurotrofa faktorn GDNF är särskilt intressant med tanke på dess effektivitet, vilken har demonstrerats i flera djurmodeller av Parkinsons sjukdom. Med tanke på det kroniska och progressiva förloppet vid Parkinsons sjukdom, är det troligt att GDNF behöver administreras kontinuerligt, över månader eller år, för att åstadkomma överlevnad och förbättrad funktion långsiktigt. Detta kan uppnås med hjälp av genterapi, vilket innebär transfer av genen för GDNF till hjärnan med hjälp av virala genbärare, så kallade vektorer. I denna avhandling har jag använt virala vektorer baserade på lentivirus för att studera de långvariga effekterna av kontinuerligt GDNF uttryck på normala, skadade eller transplanterade DA neuron. Resultaten visar att GDNF gentransfer till det nigrostriatala DA systemet effektivt kan motverka förlusten av DA neuron i djur med experimentellt inducerad parkinsonism, men att det långvariga uttrycket av GDNF kan ha funktionellt negativa effekter i dessa djur. GDNF kan också orsaka en kraftig nedreglering av tyrosinhydroxylas (TH), det hastighetsbestämmande enzymet i DA syntesen, i de skyddade DA neuronen. Den GDNF-inducerade nedregleringen av TH enzymet uppkommer även i det intakta DA systemet, men verkar inte orsaka några negativa effekter på den normala DA transmissionen. Kontinuerligt uttryck av GDNF kan kortsiktigt öka överlevnaden av fetala DA neuron efter transplantation till det denerverade striatum, men den funktionella effekten av transplantaten är försämrad i de GDNF- behandlade djuren. Baserat på dessa observationer, har jag i mitt avhandlingsarbete även försökt att utveckla ett lentiviralt vektorsystem som möjliggör en reglering av GDNF utrycket. Den kliniska appliceringen av GDNF genterapi med hjälp av virala vektorer kan endast genomföras när metoden har bevisats vara ofarlig. Fler experimentella studier behöver genomföras i djurmodeller av Parkinsons sjukdom för att fastslå den biologiskt relevanta dosen av GDNF som behöver uttryckas för att uppnå en positiv effekt, samt utvecklandet av vektor konstrukt som tillåter en effektiv reglering av genuttrycket, med möjlighet att stänga av uttrycket helt vid uppkomst av negativa effekter av GDNF behandlingen. (Less)
Abstract
Parkinson's disease is characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra, leading to a loss of dopamine in the target structure striatum and development of motor symptoms, such as bradykinesia, rigidity and tremor. New experimental treatment strategies for Parkinson's disease are aimed at either preventing the degeneration of the dopaminergic neurons, or at restoring dopamine in the striatum by fetal dopaminergic transplants. In this thesis work, we have evaluated the long-term effects of glial cell line-derived neurotrophic factor (GDNF) on intact, injured and transplanted dopaminergic neurons following GDNF gene delivery using a viral vector system based on lentiviruses. The results show that the... (More)
Parkinson's disease is characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra, leading to a loss of dopamine in the target structure striatum and development of motor symptoms, such as bradykinesia, rigidity and tremor. New experimental treatment strategies for Parkinson's disease are aimed at either preventing the degeneration of the dopaminergic neurons, or at restoring dopamine in the striatum by fetal dopaminergic transplants. In this thesis work, we have evaluated the long-term effects of glial cell line-derived neurotrophic factor (GDNF) on intact, injured and transplanted dopaminergic neurons following GDNF gene delivery using a viral vector system based on lentiviruses. The results show that the lentiviral vectors provide an efficient transfer of the GDNF gene into the nigrostriatal dopamine system, resulting in a stable and long-lasting expression of the GDNF protein at high levels. The neuroprotective effects of lentiviral-mediated delivery of GDNF were evaluated in a rat model of Parkinson's disease and demonstrated that continuous overexpression of GDNF in the striatum provided an efficient protection of the nigral dopamine neurons, however, improvements in motor function were not observed. Instead, GDNF induced an aberrant sprouting of nigrostriatal fibers in areas outside of the striatum, and the phenotypic expression of tyrosine hydroxylase was reduced in the preserved dopaminergic terminals. We further evaluated the GDNF-induced downregulation of tyrosine hydroxylase in the intact nigrostriatal dopamine system and showed that this effect was both time- and dose-dependent, and did not seem to have a detrimental effect on normal dopamine neurotransmission. The lentiviral vector was also used to study the long-term effects of GDNF on the survival and function of transplanted fetal dopamine neurons. GDNF initially increased the survival of the grafted dopamine neurons, however, the protected cells failed to survive long-term and the presence of GDNF around the grafts appeared to be detrimental to the transplant-induced recovery in these animals. Based on the observation that long-term and continuous GDNF delivery may have compromising effects on the functional outcome in either a neuroprotective or restorative paradigm, we developed a regulatable lentiviral vector system for controlled expression of GDNF in the rat brain. Efficient induction of GDNF gene expression was obtained following injection of the regulated lentiviral vector into the striatum, however, a significant basal expression was also observed, demonstrating the need to further improve the vector system for tight regulation in vivo. The findings of this thesis will have implications for the development of a GDNF gene therapy approach in Parkinson's disease. (Less)
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author
opponent
  • Prof Isacson, Ole
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Neurologi, Neurology, neuropsykologi, neurofysiologi, neurophysiology, transplantation, tyrosine hydroxylase, tetracycline, striatum, substantia nigra, sprouting, regulation, neuroprotection, lentivirus, gene therapy, GDNF, behavior, dopamine, neuropsychology
pages
176 pages
publisher
Biljana Georgievska, Div. Neurobiology, BMC A11, 221 84 Lund, Sweden,
defense location
Segerfalksalen, Wallenberg Neuroscience Center
defense date
2004-05-07 09:15
ISBN
91-628-6038-0
language
English
LU publication?
yes
id
45b6fe84-30f4-4b96-8cb9-e411e37378da (old id 466864)
date added to LUP
2007-09-07 13:23:05
date last changed
2016-09-19 08:45:12
@phdthesis{45b6fe84-30f4-4b96-8cb9-e411e37378da,
  abstract     = {Parkinson's disease is characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra, leading to a loss of dopamine in the target structure striatum and development of motor symptoms, such as bradykinesia, rigidity and tremor. New experimental treatment strategies for Parkinson's disease are aimed at either preventing the degeneration of the dopaminergic neurons, or at restoring dopamine in the striatum by fetal dopaminergic transplants. In this thesis work, we have evaluated the long-term effects of glial cell line-derived neurotrophic factor (GDNF) on intact, injured and transplanted dopaminergic neurons following GDNF gene delivery using a viral vector system based on lentiviruses. The results show that the lentiviral vectors provide an efficient transfer of the GDNF gene into the nigrostriatal dopamine system, resulting in a stable and long-lasting expression of the GDNF protein at high levels. The neuroprotective effects of lentiviral-mediated delivery of GDNF were evaluated in a rat model of Parkinson's disease and demonstrated that continuous overexpression of GDNF in the striatum provided an efficient protection of the nigral dopamine neurons, however, improvements in motor function were not observed. Instead, GDNF induced an aberrant sprouting of nigrostriatal fibers in areas outside of the striatum, and the phenotypic expression of tyrosine hydroxylase was reduced in the preserved dopaminergic terminals. We further evaluated the GDNF-induced downregulation of tyrosine hydroxylase in the intact nigrostriatal dopamine system and showed that this effect was both time- and dose-dependent, and did not seem to have a detrimental effect on normal dopamine neurotransmission. The lentiviral vector was also used to study the long-term effects of GDNF on the survival and function of transplanted fetal dopamine neurons. GDNF initially increased the survival of the grafted dopamine neurons, however, the protected cells failed to survive long-term and the presence of GDNF around the grafts appeared to be detrimental to the transplant-induced recovery in these animals. Based on the observation that long-term and continuous GDNF delivery may have compromising effects on the functional outcome in either a neuroprotective or restorative paradigm, we developed a regulatable lentiviral vector system for controlled expression of GDNF in the rat brain. Efficient induction of GDNF gene expression was obtained following injection of the regulated lentiviral vector into the striatum, however, a significant basal expression was also observed, demonstrating the need to further improve the vector system for tight regulation in vivo. The findings of this thesis will have implications for the development of a GDNF gene therapy approach in Parkinson's disease.},
  author       = {Georgievska, Biljana},
  isbn         = {91-628-6038-0},
  keyword      = {Neurologi,Neurology,neuropsykologi,neurofysiologi,neurophysiology,transplantation,tyrosine hydroxylase,tetracycline,striatum,substantia nigra,sprouting,regulation,neuroprotection,lentivirus,gene therapy,GDNF,behavior,dopamine,neuropsychology},
  language     = {eng},
  pages        = {176},
  publisher    = {Biljana Georgievska, Div. Neurobiology, BMC A11, 221 84 Lund, Sweden,},
  school       = {Lund University},
  title        = {GDNF gene delivery in an animal model of Parkinson's disease. Long-term effects on intact, injured and transplanted dopamine neurons using lentiviral gene transfer},
  year         = {2004},
}