| 1. |
- Arkan, Sertan, et al.
(författare)
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DNAJB6 suppresses alpha-synuclein induced pathology in an animal model of Parkinson's disease
- 2021
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- Background: α-synuclein (α-syn) aggregation can lead to degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) as invariably observed in patients with Parkinson's Disease (PD). The co-chaperone DNAJB6 has previously been found to be expressed at higher levels in PD patients than in control subjects and was also found in Lewy bodies. Our previous experiments showed that knock out of DNAJB6 induced α-syn aggregation in cellular level. However, effects of overexpression of DNAJB6 against α-syn aggregation remains to be investigated. Methods: We used a α-syn CFP/YFP HEK293 FRET cell line to investigate the effects of overexpression of DNAJB6 in cellular level. α-syn aggregation was induced by transfection α-syn preformed fibrils (PPF), then was measured FRET analysis. We proceeded to investigate if DNAJB6b can impair α-syn aggregation and toxicity in an animal model and used adeno associated vira (AAV6) designed to overexpress of human wt α-syn, GFP-DNAJB6 or GFP in rats. These vectors were injected into the SNpc of the rats, unilaterally. Rats injected with vira to express α-syn along with GFP in the SNpc where compared to rats expressing α-syn and GFP-DNAJB6. We evaluated motor functions, dopaminergic cell death, and axonal degeneration in striatum. Results: We show that DNAJB6 prevent α-syn aggregation induced by α-syn PFF's, in a cell culture model. In addition, we observed α-syn overexpression caused dopaminergic cell death and that this was strongly reduced by co-expression of DNAJB6b. The lesion caused by α-syn overexpression resulted in behavior deficits, which increased over time as seen in stepping test, which was rescued by co-expression of DNAJB6b. Conclusion: We here demonstrate for the first time that DNAJB6 is a strong suppressor of α-syn aggregation in cells and in animals and that this results in a suppression of dopaminergic cell death and PD related motor deficits in an animal model of PD.
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| 2. |
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| 3. |
- Arvidsson, Andreas, et al.
(författare)
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Neuronal replacement from endogenous precursors in the adult brain after stroke.
- 2002
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 8:9, s. 963-970
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Tidskriftsartikel (refereegranskat)abstract
- In the adult brain, new neurons are continuously generated in the subventricular zone and dentate gyrus, but it is unknown whether these neurons can replace those lost following damage or disease. Here we show that stroke, caused by transient middle cerebral artery occlusion in adult rats, leads to a marked increase of cell proliferation in the subventricular zone. Stroke-generated new neurons, as well as neuroblasts probably already formed before the insult, migrate into the severely damaged area of the striatum, where they express markers of developing and mature, striatal medium-sized spiny neurons. Thus, stroke induces differentiation of new neurons into the phenotype of most of the neurons destroyed by the ischemic lesion. Here we show that the adult brain has the capacity for self-repair after insults causing extensive neuronal death. If the new neurons are functional and their formation can be stimulated, a novel therapeutic strategy might be developed for stroke in humans.
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| 4. |
- Baldo, Barbara, et al.
(författare)
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Quantification of Total and Mutant Huntingtin Protein Levels in Biospecimens Using a Novel alphaLISA Assay
- 2018
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Ingår i: eNeuro. - 2373-2822. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- The neurodegenerative Huntington's disease (HD) is caused by a polyglutamine (polyQ) amplification in the huntingtin protein (HTT). Currently there is no effective therapy available for HD; however, several efforts are directed to develop and optimize HTT-lowering methods to improve HD phenotypes. To validate these approaches, there is an immediate need for reliable, sensitive, and easily accessible methods to quantify HTT expression. Using the AlphaLISA platform, we developed two novel sensitive and robust assays for quantification of HTT in biological samples using commercially available antibodies. The first, a polyQ-independent assay, measures the total pool of HTT, while the second, a polyQ-dependent assay, preferentially detects the mutant form of HTT. Using purified HTT protein standards and brain homogenates from an HD mouse model, we determine a lower limit of quantification of 1 and 3 pm and optimal reproducibility with CV values lower than 7% for intra- and 20% for interassay. In addition, we used the assays to quantify HTT in neural stem cells generated from patient-derived induced pluripotent stem cells in vitro and in human brain tissue lysates. Finally, we could detect changes in HTT levels in a mouse model where mutant HTT was conditionally deleted in neural tissue, verifying the potential to monitor the outcome of HTT-lowering strategies. This analytical platform is ideal for high-throughput screens and thus has an added value for the HD community as a tool to optimize novel therapeutic approaches aimed at modulating HTT protein levels.
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| 5. |
- Barbu, Andrea R, et al.
(författare)
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Gene Therapy
- 2010. - 4th edition
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Ingår i: Textbook of Diabetes. - Thousand Oaks, CA : Wiley-Blackwell. - 9781405191814 ; 25, s. 604-604
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Barkholt, P., et al.
(författare)
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Long-term polarization of microglia upon α-synuclein overexpression in nonhuman primates
- 2012
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Ingår i: Neuroscience. - : Elsevier BV. - 1873-7544 .- 0306-4522. ; 208, s. 85-96
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that persistent a-synuclein overexpression in ventral midbrain of marmoset leads to a distinctive neurodegenerative process and motor defects. The neurodegeneration was confined to caudate putamen dopaminergic fibers in animals overexpressing wild-type (wt) alpha-synuclein. However, A53T alpha-synuclein overexpression induced neurodegeneration that resulted in nigral dopaminergic cell death. Here, we analyze the microglia population in the midbrain of these animals by stereological quantification of lba1 + cells. Our data here show that monkeys overexpressing A53T alpha-synuclein showed a long-term increase in microglia presenting macrophagic morphology. However, wt alpha-synuclein overexpression, despite the absence of dopaminergic cell death, resulted in a permanent robust increase of the microglia population characterized by a range of distinct morphological types that persisted after 1 year. These results confirm that the microglial response differs depending on the type of alpha-synuclein (wt/A53T) and/or whether alpha-synuclein expression results in cell death or not, suggesting that microglia may play different roles during disease progression. Furthermore, the microglial response is modulated by events related to alpha-synuclein expression in substantia nigra and persists in the long term. The data presented here is in agreement with that previously observed in a recombinant adeno-associated virus (rAAV) alpha-synuclein rat model, thereby validating both the findings and the model, and highlighting the translational potential of the rodent model to higher species closer to humans. (C) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.
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| 7. |
- Barraud, Perrine, et al.
(författare)
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Isolation and characterization of neural precursor cells from the Sox1-GFP reporter mouse.
- 2005
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 22:7, s. 1555-1569
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Tidskriftsartikel (refereegranskat)abstract
- We have made use of a reporter mouse line in which enhanced green fluorescence protein (GFP) is inserted into the Sox1 locus. We show that the GFP reporter is coexpressed with the Sox1 protein as well as with other known markers for neural stem and progenitor cells, and can be used to identify and isolate these cells by fluorescence-activated cell sorting (FACS) from the developing or adult brain and from neurosphere cultures. All neurosphere-forming cells with the capacity for multipotency and self-renewal reside in the Sox1–GFP-expressing population. Thus, the Sox1–GFP reporter system is highly useful for identification, isolation and characterization of neural stem and progenitor cells, as well as for the validation of alternative means for isolating neural stem and progenitor cells. Further, transplantation experiments show that Sox1–GFP cells isolated from the foetal brain give rise to neurons and glia in vivo, and that many of the neurons display phenotypic characteristics appropriate for the developing brain region from which the Sox1–GFP precursors were derived. On the other hand, Sox1–GFP cells isolated from the adult subventricular zone or expanded neurosphere cultures gave rise almost exclusively to glial cells following transplantation. Thus, not all Sox1–GFP cells possess the same capacity for neuronal differentiation in vivo.
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| 8. |
- Bergh, Sofia, et al.
(författare)
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Effects of mutant huntingtin in oxytocin neurons on non-motor features of Huntington's disease
- 2023
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Ingår i: Neuropathology and Applied Neurobiology. - : Wiley. - 0305-1846 .- 1365-2990. ; 49:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Early non-motor features including anxiety, depression and altered social cognition are present in Huntington's disease (HD). The underlying neurobiological mechanisms are not known. Oxytocin (OXT) is involved in the regulation of emotion, social cognition and metabolism, and our previous work showed that the OXT system is affected early in HD. The aim of the study was to investigate the potential causal relationship between the selective expression of mutant huntingtin (mHTT) in OXT neurons and the development of non-motor features and neuropathology. Methods: To express mHTT only in OXT neurons, we used a novel flex-switch adeno-associated viral vector design to selectively express either mHTT or wild-type HTT in the paraventricular nucleus of the hypothalamus using OXT-Cre-recombinase mice. We also performed a mirror experiment to selectively delete mHTT in OXT neurons using the BACHD mouse model. Mice underwent a battery of behavioural tests to assess psychiatric and social behaviours 3 months post-injection or at 2 months of age, respectively. Post-mortem analyses were performed to assess the effects on the OXT system. Results: Our results show that selective expression of mHTT in OXT neurons was associated with the formation of mHTT inclusions and a 26% reduction of OXT-immunopositive neurons as well as increased anxiety-like behaviours compared with uninjected mice. However, selective deletion of mHTT from OXT neurons alone was not sufficient to alter the metabolic and psychiatric phenotype of the BACHD mice at this early time point. Conclusions: Our results indicate that mHTT expression can exert cell-autonomous toxic effects on OXT neurons without affecting the non-motor phenotype at early time points in mice.
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| 9. |
- Berglin-Enquist, Ida, et al.
(författare)
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Murine models of acute neuronopathic Gaucher disease
- 2007
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 104:44, s. 17483-17488
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Tidskriftsartikel (refereegranskat)abstract
- Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by mutations in the glucosidase, beta, acid (GBA) gene that encodes the lysosomal enzyme glucosylceramidase (GCase). GCase deficiency leads to characteristic visceral pathology and, in some patients, lethal neurological manifestations. Here, we report the generation of mouse models with the severe neuronopathic form of GD. To circumvent the lethal skin phenotype observed in several of the previous GCase-deficient animals, we genetically engineered a mouse model with strong reduction in GCase activity in all tissues except the skin. These mice exhibit rapid motor dysfunction associated with severe neurodegeneration and apoptotic cell death within the brain, reminiscent of neuronopathic GD. In addition, we have created a second mouse model, in which GCase deficiency is restricted to neural and glial cell progenitors and progeny. These mice develop similar pathology as the first mouse model, but with a delayed onset and slower disease progression, which indicates that GCase deficiency within microglial cells that are of hematopoietic origin is not the primary determinant of the CNS pathology. These findings also demonstrate that normal microglial cells cannot rescue this neurodegenerative disease. These mouse models have significant implications for the development of therapy for patients with neuronopathic GD.
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| 10. |
- Berglind, Fredrik, et al.
(författare)
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Optogenetic inhibition of chemically induced hypersynchronized bursting in mice.
- 2014
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 65, s. 133-141
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Tidskriftsartikel (refereegranskat)abstract
- Synchronized activity is common during various physiological operations but can culminate in seizures and consequently in epilepsy in pathological hyperexcitable conditions in the brain. Many types of seizures are not possible to control and impose significant disability for patients with epilepsy. Such intractable epilepsy cases are often associated with degeneration of inhibitory interneurons in the cortical areas resulting in impaired inhibitory drive onto the principal neurons. Recently emerging optogenetic technique has been proposed as an alternative approach to control such seizures but whether it may be effective in situations where inhibitory processes in the brain are compromised has not been addressed. Here we used pharmacological and optogenetic techniques to block inhibitory neurotransmission and induce epileptiform activity in vitro and in vivo. We demonstrate that NpHR-based optogenetic hyperpolarization and thereby inactivation of a principal neuronal population in the hippocampus is effectively attenuating seizure activity caused by disconnected network inhibition both in vitro and in vivo. Our data suggest that epileptiform activity in the hippocampus caused by impaired inhibition may be controlled by optogenetic silencing of principal neurons and potentially can be developed as an alternative treatment for epilepsy.
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| 11. |
- Bezard, Erwan, et al.
(författare)
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Animal Models of Parkinson's Disease: Limits and Relevance to Neuroprotection Studies
- 2013
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Ingår i: Movement Disorders. - : Wiley. - 0885-3185. ; 28:1, s. 61-70
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Forskningsöversikt (refereegranskat)abstract
- Over the last two decades, significant strides has been made toward acquiring a better knowledge of both the etiology and pathogenesis of Parkinson's disease (PD). Experimental models are of paramount importance to obtain greater insights into the pathogenesis of the disease. Thus far, neurotoxin-based animal models have been the most popular tools employed to produce selective neuronal death in both in vitro and in vivo systems. These models have been commonly referred to as the pathogenic models. The current trend in modeling PD revolves around what can be called the disease gene-based models or etiologic models. The value of utilizing multiple models with a different mechanism of insult rests on the premise that dopamine-producing neurons die by stereotyped cascades that can be activated by a range of insults, from neurotoxins to downregulation and overexpression of disease-related genes. In this position article, we present the relevance of both pathogenic and etiologic models as well as the concept of clinically relevant designs that, we argue, should be utilized in the preclinical development phase of new neuroprotective therapies before embarking into clinical trials. (C) 2012 Movement Disorder Society
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| 12. |
- Björklund, Anders, et al.
(författare)
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Gene therapy for dopamine replacement in Parkinson's disease.
- 2009
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Ingår i: Science Translational Medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6242 .- 1946-6234. ; 1:2, s. 2-2
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Tidskriftsartikel (refereegranskat)abstract
- The introduction of L-dopa (L-3,4-dihydroxyphenylalanine) therapy 40 years ago was a revolution in the treatment of patients with Parkinson s disease (PD). With time, however, the shortcomings of oral L-dopa medication became apparent, in particular the appearance of troublesome side effects, expressed as involuntary movements (dyskinesias) that developed over time in many patients. A gene therapy approach, aimed at restoring dopamine synthesis in the affected brain by viral vector delivery of genes that encode the dopamine-synthesizing enzymes, may offer a solution to this problem. Now, a team of French and UK researchers reports promising results in a nonhuman primate model of PD, paving the way for clinical trials of this enzyme-replacement approach.
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| 13. |
- Björklund, Anders, et al.
(författare)
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Studies on neuroprotective and regenerative effects of GDNF in a partial lesion model of Parkinson's disease
- 1997
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 4:3-4, s. 186-200
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Forskningsöversikt (refereegranskat)abstract
- Intrastriatal 6-hydroxydopamine injections in rats induce partial lesions of the nigrostriatal dopamine (DA) system which are accompanied by a delayed and protracted degeneration of DA neurons within the substantia nigra. By careful selection of the dose and placement of the toxin it is possible to obtain reproducible and regionally defined partial lesions which are well correlated with stable functional deficits, not only in drug-induced behaviors but also in spontaneous motoric and sensorimotoric function, which are analogous to the symptoms seen in patients during early stages of Parkinson's disease. The intrastriatal partial lesion model has proved to be particularly useful for studies on the mechanisms of action of neurotrophic factors since it offers opportunities to investigate both protection of degenerating DA neurons during the acute phases after the lesion and stimulation of regeneration and functional recovery during the chronic phase of the postlesion period when a subset of the spared nigral DA neurons persist in an atrophic and dysfunctional state. In the in vivo experiments performed in this model glial cell line-derived neurotrophic factor (GDNF) has been shown to exert neurotrophic effects both at the level of the cell bodies in the substantia nigra and at the level of the axon terminals in the striatum. Intrastriatal administration of GDNF appears to be a particularly effective site for induction of axonal sprouting and regeneration accompanied by recovery of spontaneous sensorimotor behaviors in the chronically lesioned nigrostriatal dopamine system.
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| 14. |
- Björklund, Anders, et al.
(författare)
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Towards a neuroprotective gene therapy for Parkinson's disease: use of adenovirus, AAV and lentivirus vectors for gene transfer of GDNF to the nigrostriatal system in the rat Parkinson model
- 2000
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Ingår i: Brain Research. - 1872-6240. ; 886:1-2, s. 82-98
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Tidskriftsartikel (refereegranskat)abstract
- During the last few years, recombinant viral vectors derived from adenovirus (Ad), adeno-associated virus (AAV) or lentivirus (LV) have been developed into highly effective vehicles for gene transfer to the adult central nervous system. In recent experiments, in the rat model of Parkinson's disease, all three vector systems have been shown to be effective for long-term delivery of glial cell line-derived neurotrophic factor (GDNF) at biologically relevant levels in the nigrostriatal system. Injection of the GDNF encoding vectors into either striatum or substantia nigra thus makes it possible to obtain a regionally restricted over-expression of GDNF within the nigrostriatal system that is sufficient to block the toxin-induced degeneration of the nigral dopamine neurons. Injection of GDNF vectors in the striatum, in particular, is effective not only in rescuing the cell bodies in the substantia nigra, but also in preserving the nigrostriatal projection and a functional striatal dopamine innervation in the rat Parkinson model. Long-term experiments using AAV-GDNF and LV-GDNF vectors show, moreover, that sustained GDNF delivery over 3-6 months can promote regeneration and significant functional recovery in both 6-OHDA-lesioned rats and MPTP-lesioned monkeys. The impressive efficacy of the novel AAV and LV vectors in rodent and primate Parkinson models suggests that the time may now be ripe to explore these vector systems as tools for neuroprotective treatments in patients with Parkinson's disease.
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| 15. |
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| 16. |
- Björklund, Tomas, et al.
(författare)
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Gene therapy for dopamine replacement.
- 2010
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Ingår i: Progress in Brain Research. - 1875-7855. ; 184, s. 221-235
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Forskningsöversikt (refereegranskat)abstract
- Dopamine replacement for Parkinson's disease (PD) have seen three major iterations of improvements since the introduction of l-3,4-dihydroxyphenylalanine (l-DOPA) pharmacotherapy: dopamine receptor agonists, ex vivo gene transfer for cell transplantation and most recently in vivo gene therapy. In this chapter, we describe the principles behind viral vector-mediated enzyme replacement in PD. We focus on the enzymes involved in the dopamine synthesis and their internal regulation, the early experimental work on gene therapy using different viral vector types and selection of transgenes, and finally discuss the recently completed early phase clinical trials in PD patients.
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| 17. |
- Björklund, Tomas, et al.
(författare)
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Optimization of continuous in vivo DOPA production and studies on ectopic DA synthesis using rAAV5 vectors in Parkinsonian rats
- 2009
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Ingår i: Journal of Neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 111:2, s. 355-367
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Tidskriftsartikel (refereegranskat)abstract
- Viral vector-mediated gene transfer is emerging as a novel therapeutic approach with clinical utility in treatment of Parkinson's disease. Recombinant adeno-associated viral (rAAV) vector in particular has been utilized for continuous l-3,4 dihydroxyphenylalanine (DOPA) delivery by expressing the tyrosine hydroxylase (TH) and GTP cyclohydrolase 1 (GCH1) genes which are necessary and sufficient for efficient synthesis of DOPA from dietary tyrosine. The present study was designed to determine the optimal stoichiometric relationship between TH and GCH1 genes for ectopic DOPA production and the cellular machinery involved in its synthesis, storage, and metabolism. For this purpose, we injected a fixed amount of rAAV5-TH vector and increasing amounts of rAAV5-GCH1 into the striatum of rats with complete unilateral dopamine lesion. After 7 weeks the animals were killed for either biochemical or histological analysis. We show that increasing the availability of 5,6,7,8-tetrahydro-l-biopterin (BH4) in the same cellular compartment as the TH enzyme resulted in better efficiency in DOPA synthesis, most likely by hindering inactivation of the enzyme and increasing its stability. Importantly, the BH4 synthesis from ectopic GCH1 expression was saturable, yielding optimal TH enzyme functionality between GCH1 : TH ratios of 1 : 3 and 1 : 7.
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| 18. |
- Björklund, Tomas, et al.
(författare)
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Optimized adeno-associated viral vector-mediated striatal DOPA delivery restores sensorimotor function and prevents dyskinesias in a model of advanced Parkinson's disease.
- 2010
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 133:Pt 2, s. 496-511
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Tidskriftsartikel (refereegranskat)abstract
- Viral vector-mediated gene transfer utilizing adeno-associated viral vectors has recently entered clinical testing as a novel tool for delivery of therapeutic agents to the brain. Clinical trials in Parkinson's disease using adeno-associated viral vector-based gene therapy have shown the safety of the approach. Further efforts in this area will show if gene-based approaches can rival the therapeutic efficacy achieved with the best pharmacological therapy or other, already established, surgical interventions. One of the strategies under development for clinical application is continuous 3,4-dihydroxyphenylalanine delivery. This approach has been shown to be efficient in restoring motor function and reducing established dyskinesias in rats with a partial lesion of the nigrostriatal dopamine projection. Here we utilized high purity recombinant adeno-associated viral vectors serotype 5 coding for tyrosine hydroxylase and its co-factor synthesizing enzyme guanosine-5'-triphosphate cyclohydrolase-1, delivered at an optimal ratio of 5 : 1, to show that the enhanced 3,4-dihydroxyphenylalanine production obtained with this optimized delivery system results in robust recovery of function in spontaneous motor tests after complete dopamine denervation. We found that the therapeutic efficacy was substantial and could be maintained for at least 6 months. The tyrosine hydroxylase plus guanosine-5'-triphosphate cyclohydrolase-1 treated animals were resistant to developing dyskinesias upon peripheral l-3,4-dihydroxyphenylalanine drug challenge, which is consistent with the interpretation that continuous dopamine stimulation resulted in a normalization of the post-synaptic response. Interestingly, recovery of forelimb use in the stepping test observed here was maintained even after a second lesion depleting the serotonin input to the forebrain, suggesting that the therapeutic efficacy was not solely dependent on dopamine synthesis and release from striatal serotonergic terminals. Taken together these results show that vector-mediated continuous 3,4-dihydroxyphenylalanine delivery has the potential to provide significant symptomatic relief even in advanced stages of Parkinson's disease.
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| 19. |
- Björklund, Tomas, et al.
(författare)
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Scientific rationale for the development of gene therapy strategies for Parkinson's disease.
- 2009
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Ingår i: Biochimica et Biophysica Acta - Molecular Basis of Disease. - : Elsevier BV. - 0925-4439. ; 1792:7, s. 703-713
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Tidskriftsartikel (refereegranskat)abstract
- The ever-evolving understanding of the neuronal systems involved in Parkinson's disease together with the recent advances in recombinant viral vector technology has led to the development of several gene therapy applications that are now entering into clinical testing phase. To date, four fundamentally different approaches have been pursued utilizing recombinant adeno-associated virus and lentiviruses as vectors for delivery. These strategies aim either to restore the lost brain functions by substitution of enzymes critical for synthesis of neurotransmitters or neurotrophic factors as a means to boost the function of remaining neurons in the diseased brain. In this review we discuss the differences in mechanism of action and describe the scientific rationale behind the currently tested gene therapy approaches for Parkinson's disease in some detail and pinpoint their individual unique strengths and weaknesses.
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| 20. |
- Breysse, Nathalie, et al.
(författare)
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The functional impact of the intrastriatal dopamine neuron grafts in parkinsonian rats is reduced with advancing disease
- 2007
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 27:22, s. 5849-5856
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Tidskriftsartikel (refereegranskat)abstract
- Clinical trials involving intrastriatal transplants of human embryonic mesencephalic tissue have provided proof-of-principle that nigral dopamine (DA) neurons can survive and functionally integrate into the host neural circuitry. However, the degree of graft-induced symptomatic relief differs significantly between the patients. This variability has led to investigations aimed at identifying factors that could affect the clinical outcome. The extent and pattern of dopaminergic denervation in the brain may be one of the major determinants of the functional outcome after intrastriatal DA cell grafts. Here, we report that in animals subjected to an intrastriatal 6-hydroxydopamine lesion of the striatal dopaminergic afferent, the integrity of the host dopaminergic innervation outside the areas innervated by the graft is critical for optimal function of DA neurons placed in the striatum. Established graft-induced functional recovery, as assessed in the stepping and cylinder tests, was compromised in animals in which the dopaminergic lesion was extended to include also the medial and ventral striatum as well as the cortical and limbic DA projections. Poor clinical outcome after transplantation may, thus, at least in part, be caused by dopaminergic denervation in areas outside the graft-innervated territories, and similarly beneficial effects initially observed in patients may regress if the degeneration of the host extrastriatal DA projection systems proceeds with advancing disease. This would have two implications: first, patients with advanced disease involving the ventral striatum and/ or nonstriatal DA projections would be unlikely to respond well to intrastriatal DA grafts and, second, to retain the full benefit of the grafts, progression of the disease should be avoided by, for example, combining cell therapy with a neuroprotective approach.
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| 21. |
- Buck, Kerstin, et al.
(författare)
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Ser129 phosphorylation of endogenous α-synuclein induced by overexpression of polo-like kinases 2 and 3 in nigral dopamine neurons is not detrimental to their survival and function.
- 2015
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 78:Mar 25, s. 100-114
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorylation of the α-synuclein (α-syn) protein at Ser129 [P(S129)-α-] was found to be the most abundant form in intracellular inclusions in brains from Parkinson's disease (PD) patients. This finding suggests that P(S129)-α-syn plays a central role in the pathogenesis of PD. However, it is at present unclear whether P(S129)-α-syn is pathogenic driving the neurodegenerative process. Rodent studies using neither the phosphomimics of human α-syn nor co-expression of human wild-type α-syn and kinases phosphorylating α-syn at Ser129 gave consistent results. One major concern in interpreting these findings is that human α-syn was expressed above physiological levels inducing neurodegeneration in rat nigral neurons. In order to exclude this confounding factor, we took a different approach and increased the phosphorylation level of endogenous α-syn. For this purpose, we took advantage of recombinant adeno-associated viral (rAAV) vectors to deliver polo-like kinase 2 (PLK2) or PLK3 in the substantia nigra and investigated whether increased levels of P(S129)-α-syn compromised the function and survival of nigral dopaminergic neurons. Interestingly, we observed that hyperphosphorylated α-syn did not induce nigral dopaminergic cell death, as assessed at 1 and 4months. Furthermore, histological analysis did not show any accumulation of α-syn protein or formation of inclusions. Using in vivo microdialysis, we found that the only measurable functional alteration was the depolarisation-induced release of dopamine, while the in vivo synthesis rate of DOPA and dopamine baseline release remained unaltered. Taken together, our results suggest that phosphorylation of α-syn at Ser129 does not confer a toxic gain of function per se.
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| 22. |
- Carlsson, Thomas, et al.
(författare)
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Graft placement and uneven pattern of reinnervation in the striatum is important for development of graft-induced dyskinesia.
- 2006
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 21:3, s. 657-668
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Tidskriftsartikel (refereegranskat)abstract
- In two recent double-blind clinical trials of fetal ventral mesencephalic cell transplants into the striatum in patients with Parkinson's disease (PD), a significant proportion of the grafted patients developed dyskinetic side effects, which were not seen in the sham operated patients. Comparison between dyskinetic and non-dyskinetic grafted patients in one of the trials suggested that an uneven pattern of striatal reinnervation might be the leading cause of the dyskinesias. Here, we studied the importance of graft placement for the development of dyskinesias in parkinsonian rats. Abnormal involuntary movements resembling peak-dose dyskinesias seen in PD patients were induced by daily injections of L-DOPA for 6 weeks. The dyskinetic animals received about 130.000 fetal ventral mesencephalic cells as single grafts placement in the rostral or the caudal aspect of the head of striatum. The results show that grafts placed in the caudal, but not the rostral, part are effective in reducing the L-DOPA-induced limb and orolingual dyskinesia, predominantly seen as hyperkinesia. The same grafts, however, also induced a new type of dyskinetic behavior after activation with amphetamine, which were not seen in non-grafted lesion controls. The severity of these abnormal involuntary movements was significantly correlated with a higher graft-derived dopaminergic reinnervation in the caudal aspect of the head of striatum relative to the rostral part. The results indicate that graft-induced dyskinesias in PD patients may be linked to single, small graft deposits that provide an uneven, patchy reinnervation of the putamen.
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| 23. |
- Carlsson, Thomas, et al.
(författare)
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Impact of grafted serotonin and dopamine neurons on development of L-DOPA-induced dyskinesias in parkinsonian rats is determined by the extent of dopamine neuron degeneration.
- 2009
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 132, s. 319-335
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have shown that serotonin neurons play an important role in the induction and maintenance of l-DOPA-induced dyskinesia in animals with lesion of the nigrostriatal dopamine system. Patients with Parkinson's disease that receive transplants of foetal ventral mesencephalic tissue, the graft cell preparation is likely to contain, in addition to dopamine neurons, serotonin neurons that will vary in number depending on the landmarks used for dissection. Here, we have studied the impact of grafted serotonin neurons-alone or mixed with dopamine neurons-on the development of l-DOPA-induced dyskinesia in rats with a partial 6-hydroxydopamine lesion of the host nigrostriatal projection. In these rats, which showed only low-level dyskinesia at the time of transplantation, serotonin grafts induced a worsening in the severity of dyskinesia that developed during continued l-DOPA treatment, while the dopamine-rich graft had the opposite, dampening effect. The detrimental effect seen in animals with serotonin neuron grafts was dramatically increased when the residual dopamine innervation in the striatum was removed by a second 6-hydroxydopamine lesion. Interestingly, rats with grafts that contained a mixture of dopamine and serotonin neurons (in approximately 2:1) showed a marked reduction in l-DOPA-induced dyskinesia over time, and the appearance of severe dyskinesia induced by the removal of the residual dopamine innervation, seen in the animals with transplants of serotonin neurons alone, was blocked. FosB expression in the striatal projection neurons, which is associated with dyskinesias, was also normalized by the dopamine-rich grafts, but not by the serotonin neuron grafts. These data indicate that as long as a sufficient portion, some 10-20%, of the dopamine innervation still remains, the increased host serotonin innervation generated by the grafted serotonin neurons will have limited effect on the development or severity of l-DOPA-induced dyskinesias. At more advanced stages of the disease, when the dopamine innervation of the putamen is reduced below this critical threshold, grafted serotonin neurons are likely to aggravate l-DOPA-induced dyskinesia in those cases where the dopamine re-innervation derived from the grafted neurons is insufficient in magnitude or do not cover the critical dyskinesia-inducing sub-regions of the grafted putamen. We conclude that it is not the absolute number of serotonin neurons in the grafts, but the relative densities of dopamine and serotonin innervations in the grafted striatum that is the critical factor in determining the long-term effect of foetal tissue graft, beneficial or detrimental, on dyskinesia in grafted Parkinson's disease patients.
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| 24. |
- Carlsson, Thomas, et al.
(författare)
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Restoration of the striatal dopamine synthesis for Parkinson's disease: viral vector-mediated enzyme replacement strategy.
- 2007
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Ingår i: Current Gene Therapy. - : Bentham Science Publishers Ltd.. - 1566-5232. ; 7:2, s. 109-120
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Forskningsöversikt (refereegranskat)abstract
- arkinson's disease is the second most common neurodegenerative disease. It is charaterized by a progressive loss of dopamine (DA) producing neurons in the midbrain, which result in a decline of DA innervations present in the forebrain, in particular, the striatum. The disease leads to appearance of motor symptoms involving akinesia/bradykinesia, gait disturbances, postural imbalance and tremor. Oral administration of L-3,4-dihydroxyphenylalanine (L-DOPA), the precursor of DA, provides very good symptomatic relief, but this intermittent and pharmacological treatment is compromised by severe side effects, such as the appearance of abnormal involuntary movements. Viral vector-mediated direct gene transfer techniques are currently being explored in order to provide continuous and stable synthesis of DA in the brain. This review focuses on the basic idea of DA replacement, first describing the enzymatic machinery important for DA synthesis and secondly the various alternative strategies pursued in several laboratories. The DOPA delivery strategy, based on the co-transduction of tyrosine hydroxylase (TH), and GTP cyclohydrolase 1 (GCH1) genes, has been shown to be a powerful approach providing a robust behavioral recovery and reversal of side effects of the pulsatile administration of L-DOPA medication. The DA delivery strategy, on the other hand, aims at triple transduction of the TH, GCH1 and aromatic amino-acid decarboxylase (AADC) enzymes, and thereby provide a higher rate of conversion of DOPA to DA. Finally, transduction of AADC alone has been proposed as a means to improve the conversion of peripherally administered L-DOPA. As the basic scientific rationale behind these strategies are well understood and the results of the animal experiments are very encouraging, we are now entering into an exciting phase with increasing momentum toward the first clinical applications using this experimental therapy in patients suffering from PD.
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| 25. |
- Carlsson, Thomas, et al.
(författare)
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Reversal of dyskinesias in an animal model of Parkinson's disease by continuous L-DOPA delivery using rAAV vectors.
- 2005
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156. ; 128:3, s. 559-569
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Tidskriftsartikel (refereegranskat)abstract
- Dyskinesias are a major complication of long-term l-3,4-dihydroxyphenylalanine (L-DOPA) treatment in Parkinson's disease, and are believed to result from the intermittent and pulsatile supply of L-DOPA. Daily injections of L-DOPA can prime similar abnormal involuntary movements of the limb, orolingual and axial muscles in rats rendered parkinsonian by destruction of the nigrostriatal dopamine (DA) neurons. In this study we used 33 rats with severe nigrostriatal dopamine depletion and showed that in vivo gene transfer of the DA-synthetic enzymes tyrosine hydroxylase (TH) and GTP cyclohydrolase 1 (GCH1) using recombinant adeno-associated virus vectors can provide a constant source of DOPA production locally in the striatum, at a level that is effective in reducing L-DOPA-induced dyskinesias by >85%, and reverse lesion-induced motor impairments. Furthermore, the abnormal expression of DeltaFosB, prodynorphin and preproenkephalin mRNA within the striatal projection neurons normally seen in dyskinetic animals was completely reversed by TH-GCH1 gene transfer. These findings form a strong basis for replacing, or supplementing, conventional systemic L-DOPA therapy by continuous intrastriatal DOPA using in vivo gene transfer in the treatment of patients with advanced Parkinson's disease.
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