bdnf and parkinson’s disease
DESCRIPTION
BDNF and Parkinson’s Disease. March 26 th , 2010. What is Parkinson’s Disease?. Progressive loss of dopaminergic neurons in the substantia nigra Reduction in SN and striatal DA Increase in glial cells in the SN Neuromelanin (DA pigment) loss Lewy bodies. Diagnosis. - PowerPoint PPT PresentationTRANSCRIPT
BDNF and Parkinson’s Disease
March 26th, 2010
What is Parkinson’s Disease?
Progressive loss of dopaminergic neurons in the substantia nigra
Reduction in SN and striatal DA
Increase in glial cells in the SN
Neuromelanin (DA pigment) loss
Lewy bodies
Diagnosis
Clinical features: Bradykinesia, resting tremors, muscle rigidity, loss of postural reflexes, flexed posture, and the freezing phenomenon
– Parkinsonism diagnosis with 2 symptoms Parkinsonisms:
– Primary: Parkinson’s disease (PD) – most common asymmetrical onset of motor symptoms rest tremor Substantial clinical response to levodopa therapy
– Secondary: drug-induced or postencephalitic parkinsonism– Parkinson-plus syndromes - w/ other neurological features, i.e.
progressive supranuclear palsy and multiple system atrophy– heredodegenerative disorders – parkinsonism features in a heritable
degenerative disorder (juvenile Huntington or Wilson disease)
Fahn and Sulzer, 2004
Neurotrophin Hypothesis in Neurodegenerative (ND) disorders
Neurotrophins promote: development, heath, survival of neurons– BDNF: synaptic plasticity, neuronal survival and
differentiation Studies suggest BDNF disruption in:
– Huntington’s– Alzheimer’s– Multiple Sclerosis– Parkinson’s
BREIF Overview of Parkinson’s & BDNF Research…
Postmortem studies of PD patients: reduced levels of BDNF in the SCN- substantia nigra pars compacta (Mogi et al., 1999; Parain et al., 1999; Howells et al., 2000; Chauhan et al. 2001)
BDNF promotes survival & differentiation mesencephalic DA neurons in culture (Hyman et al., 1999; Feng et al., 1999)
BDNF protects from toxic insults (Murer et al., 2001)
BDNF+/- mice have decreased striatal DA and impaired behavioral responses (Dluzen et al., 2001, 2002)
trkB partial deletion – decreased TH, formation of α-synuclein deposits (von Bohlen Und Halbach et al., 2005)
BDNF
Normal BDNF Expression
DA neurons normally co-express BDNF in:– Substantia Nigra– Ventral Tegmental Area– Frontal cortex
DA neuron depletion Decrease in BDNF (trophic support)?
Exogenous BDNF Replacement
Goal: increase BDNF to preserve DA neurons and improve disease symptoms
Problems:– Large molecular size (~28 kDa)– trkB wide distribution – no targeted effects – Carrier molecules: stem cells, viral vectors, biomaterials– Unknown treatment length for protection, BDNF delivery
rate, BDNF pharmokinetics– BDNF overexpression in animal models seizures
Experimental therapeutic strategies for restoring BDNF in ND diseases
Zuccato and Cattaneo, 2009
Brain-Derived Neurotrophic Factor Is Required for the Establishment of Proper Number of Dopaminergic Neurons in the
Substantia Nigra Pars Compacta
Baquet et al., 2005. Journal of Neuroscience. 25(26): 6251-6259.
Aim of Study
Investigate the link between reduced BDNF in the substantia nigra and deterioration of dopamergic neurons in PD patients.
Create a conditional knock-out, as BDNF-/- mice die.
Cre-Lox recombination
Wnt-1 promoter
(BDNFneo) LacZR26R Cre
Resulting Mice
Wnt-BDNFKO BDNFneo/lox+
Heterozygous for BDNF
Wildtype BDNF
BDNF-/- BDNF+/- BDNF+/+
Wnt-1:R26R
Figure 1: BDNF Expression Characterization
What is TH?
Kreek, et al. 2002
Figure 2: Expression of Cre in midbrain BDNF-expressing neurons
Figure 3: Reduced BDNF protein leads to motor deficits and reduced striatal TH in Wnt-BDNFKO
KO HT WT
KO HT WT
Figure 4: Wnt-BDNFKO Mice have reduced TH expression in the SNC, but not the VTA
Anterior
Posterior
KO HT WT
Figure 5: No change in NeuN, CB, CR
NeuN CB CR
Conclusions
Selective BDNF deletion from the midbrain & hindbrain show:– reduced TH (differentiated DA neurons)– reduction in striatal DA– display early PD phenotype
More evidence for a link between BDNF and PD?
Protective Effects of Neurotrophic Factor-Secreting Cells in a 6-OHDA
Rat Model of Parkinson Disease
Sadan et al., 2009. Stem Cells and Development. 18(8):1179-90.
Aim of study
Induce MSC to differentiate into neurotrophic factor secreting astrocytes– Safe & efficient protocol– Increase NTF secretion
Study effects NTF (BDNF and GDNF) in:– behavior– dopamine levels/neurons in striatum– in vivo tracking of transplanted cells
Definition of a Stem Cell
1. make identical copies of themselves for long periods of time (long-term self-renewal)
2. give rise to mature cell types that have characteristic morphologies (shapes) and specialized functions
8-cell stage
Why use stem cells for ND therapy?
1. Replacement of degenerated cells
2. Improve the environment of diseased neural tissue – i.e. release neuroprotective factors Factors already secreted by stem cells Specific gene introduction to stem cells for
secretion
3. Stem cells to induce/enhance neurogenesis to mimic native stem cell populations
Obstacles in stem cell therapy
Immune (graft) rejection Transplantation procedure Risk of tumor development Ethical issues Matched donor Fate assessment after therapy
Types of Stem Cells
Embryonic Stem Cells (ESC) – totipotent– Ethical issues– Tumorigenic– Non-autologous source
Adult stem cells – many types, multipotent– Different properties
induced Pluripotent stem cells– Autologous source– Unlimited differentiation– Tumorigenic– Lentivirus vectors for induction – dangerous mutations
Safer method = piggyBac
Hematopoietic stem cell
Bone marrow stem cells
Neural
Neuron
Gl ia
Opposition to idea of MSC transdifferentiation to neuronal cells
Observations of extending neurites mistaken for cell-cell contacts
‘neural’ makers could have different roles in MSC
Yet, recent reports suggest a subpopulation of MSC originate from the neural crest– likely that at least of subset of the MSCs may
have a neural predisposition.
MSC advantages
Differentiate to DA neurons, astrocytes, oligodendrocytes
Paracrine effect– Secrete soluble trophic factors (BDNF, VEGF, GDNF)
Cytokine secretion to inhibit lymphocyte proliferation Migratory behavior Neurogenesis – seen in stroke model and transplant
to dentate gyrus of hippocampus, attributed to NTF secretion
Genetic manipulations to overexpress genes or program cells
SPN L-glutamate
N2hEGRhbFGF
MSC induction to NF-SC
Human Mesenchymal
Stem Cells
dbcAMP IBMX
PDGFHRG1-β1hbFGF
Neurotrophic factor secreting
cells
Passaged 12-18 days
Media replaced 72 hrs later
Figure 1: Confirmation of neurotrophic factor secretion.
In vitro model of Parkinson’s
Serum-free
media (control)
Culture supernatant
(control)Serum-free media
Culture supernatant
(contains NTF)
MSC
Serum-free media
NTF-SC
32-160 μM 6-OHDA
+ 1h
6-OHDA
6-hydroxydopamine – selectively neurotoxic for DA neurons
drug redistributes DA from synaptic vesicles Oxidized DA = DA-quinone reacts w/ DA
uptake transporter
Figure 2: NTF-SC/MSC protect neuroblastoma cells against 6-OHDA toxicity
• MSC and NTF-SC groups were
statistically significant @ 32,
48, and 72μM 6-OHDA.
• No statistical difference b/t MSC
& NTF-SC
• @ 160μM, NTF-SC were statistically different from others
Figure 3: Behavioral tests after stem cell transplant in 6-OHDA treated rats
Control Treated
PBS
MSC
NTF-SC
Cellular transplantation inhibited 6-OHDA-induced dopamine depletion
0
10
20
30
40
50
60
70
80
90
100
Control MSC NTF-SC% D
op
amin
e in
les
ion
ed c
om
par
ed t
o c
on
tro
l si
de
*
Conclusions and Future Directions
NTF-SC could – increase production/ secretion of BDNF & GDNF– Attenuate 6-OHDA-induced behavior– Increase striatal dopamine
Autotransplantation of rat-derived MSC and induced NTF-SC
Transplantation later and at a site further from the lesion
Treatment for PD
Baquet et al., 2005 S Fig 1
Baquet et al., 2005 S Fig 2
Baquet et al., 2005 S Fig 2
Sudan et al, 2009 S Fig 1
S Fig 2
S Fig 3
Gene’s associated with early onset PD
α-synuclein UCHL1 (ubiquitin carboxy-terminal hydrolase L1)
Parkin – ubiquitin E3 ligase that prepares proteins for degradation
DJ1: a parkin associated protein involved with oxidative stress
PINK1: Phosphatase and tensin homolog–INduced Kinase; putative serine threonine kinase
possible pathogenic mechanisms?
PD Etiology
10% of cases: genes– α-synuclein– Parkin– DJ-1
90% of cases – unknown– Age– Environment (toxic exposure, drug use)