Gene Therapy For Parkinson's Disease Research Articles

Some Novel Therapies in Parkinson's Disease: A Promising Path Forward or Not Yet? A Systematic Review of the Literature.

In light of the unsuccessful traditional therapies for Parkinson's disease (PD) overmany years, there is an unmet need for the development of novel therapies to alleviate the symptoms of PD retardation or halt the progression of the disease itself. This systematic review aims to critically update some of the most promising novel treatments including gene therapy, cell-based therapies, targeted drug delivery, and neuroprotective agents, focusing on their challenges, limitations and future directions in PD research. Gene therapy in PD is encouraging, with AAV-based approaches targeting neurotrophic factors, dopamine production, and neuronal circuits in animal and clinical trials. A promising approach to targeted drug delivery for PD involves the use of nanotechnology to create drug delivery vehicles that can traverse the blood-brain barrier and deliver medications specifically to the regions of the brain affected by PD. Neuroprotective agents are compounds that have the ability to protect neurons from degeneration and death, and they hold great promise for the evolution of disease-modifying treatments for PD. Magnetic field therapy is a promising non-invasive method that promotes neural plasticity in PD. The establishment of standardized protocols for animal and human studies, safety, ethical considerations, and cost-effectiveness are the major challenges for the future research of novel PD therapies. The development of novel therapies for PD represents a promising path toward to effective personalized disease-modifying treatments for PD.

Treatment of Parkinson's disease with biologics that penetrate the blood-brain barrier via receptor-mediated transport.

Parkinson's disease (PD) is characterized by neurodegeneration of nigral-striatal neurons in parallel with the formation of intra-neuronal α-synuclein aggregates, and these processes are exacerbated by neuro-inflammation. All 3 components of PD pathology are potentially treatable with biologics. Neurotrophins, such as glial derived neurotrophic factor or erythropoietin, can promote neural repair. Therapeutic antibodies can lead to disaggregation of α-synuclein neuronal inclusions. Decoy receptors can block the activity of pro-inflammatory cytokines in brain. However, these biologic drugs do not cross the blood-brain barrier (BBB). Biologics can be made transportable through the BBB following the re-engineering of the biologic as an IgG fusion protein, where the IgG domain targets an endogenous receptor-mediated transcytosis (RMT) system within the BBB, such as the insulin receptor or transferrin receptor. The receptor-specific antibody domain of the fusion protein acts as a molecular Trojan horse to ferry the biologic into brain via the BBB RMT pathway. This review describes the re-engineering of all 3 classes of biologics (neurotrophins, decoy receptor, therapeutic antibodies) for BBB delivery and treatment of PD. Targeting the RMT pathway at the BBB also enables non-viral gene therapy of PD using lipid nanoparticles (LNP) encapsulated with plasmid DNA encoding therapeutic genes. The surface of the lipid nanoparticle is conjugated with a receptor-specific IgG that triggers RMT of the LNP across the BBB in vivo.

Parkinson's disease gene therapy: a comparative effectiveness review of completed clinical trials in terms of their possible implementation in treatment

Background: Parkinsons disease (PD) is a neurodegenerative disease in which dopaminergic neurons are damaged, and Lewy bodies accumulate in the brain, leading to both motor and non-motor symptoms. Currently, no treatment is available to slow down or reverse disease progression. The need to find new solutions has prompted research interest in gene therapy. Aim of the study: The purpose of this review is to analyze a selection of completed clinical trials on gene therapy in PD and their possible implementation in treatment. Material and Methods: Clinical trials were selected from the ClinicalTrials.gov database using the following search criteria: Parkinsons disease, gene therapy, and completed status. Trials that were ongoing, terminated, preclinical, or with different research subjects were excluded. PubMed and Google Scholar databases were also searched for neuropathology, symptoms, and treatment recommendations for PD. The results of reviewed clinical trials have been checked in terms of the efficacy and safety of the investigated therapies in the treatment of PD. Results: We analyzed 7 completed clinical trials, namely VY-AADC01 (NCT01973543), AAV-GAD (NCT00195143), ProSavin (NCT00627588), AAV2-GDNF (NCT01621581), CERE-120 (NCT00252850), VY-AADC01 (NCT03065192), and CERE-120 (NCT00985517) with a total of 152 patients. Five of the studies had published results and four of these five had satisfactory results. VY-AADC01, AAV-GAD, and CERE-120 were found to be safe and potentially effective in the treatment of PD, while ProSavin demonstrated insufficient effectiveness. Conclusions: There is limited available data regarding completed clinical trials for PD gene therapy, with a small number of patients, making it difficult to give a final statement on the possibility of using gene therapy to treat PD. However, the clinical trials reviewed herein show promising results with the potential to revolutionize the treatment of PD.

Synthesis of Double Interfering Biodegradable Nano-MgO Micelle Composites and Their Effect on Parkinson's Disease.

Although gene therapy targeting the α-synuclein gene (SNCA) has achieved outstanding results in the treatment of Parkinson's disease (PD), the lack of a suitable gene delivery system and inadequate therapeutic effects remains a tremendous obstacle for RNAi therapy. Here, a degradable nano-MgO micelle composite (MgO(pDNA)-INS-Plu-mRNA-NGF) with double interference (mediated by RNAi and α-synuclein (α-syn)-targeted mRNA) was constructed. Binding mRNA treatment significantly increased the inhibitory effect compared to the reduction of α-syn expression by RNAi alone. Moreover, the cell experiments demonstrated that the viability of the PD cell model can be significantly improved by nano-MgO micelle composite treatment. More importantly, the composite has the ability to penetrate the blood brain barrier and deliver genes and mRNA to neurons through endocytosis mediated by the nerve growth factor and its receptors, thus significantly downregulating the expression of α-syn in the PD mice model without causing damage to other major organs. Overall, this work provides a novel insight into the design of biomaterials for gene therapy for PD.

Potential therapeutic role of fibroblast growth factor 21 in neurodegeneration: Evidence for ameliorating parkinsonism via silent information regulator 2 homolog 1 and implication for gene therapy

Parkinson's disease (PD) is one of the common complex neurodegenerative diseases and characterized by abnormal metabolic brain networks. Fibroblast growth factor 21 (FGF21), an endocrine hormone that belongs to the fibroblast growth factor superfamily, plays an extensive role in the regulation of metabolism. However, our understandings of the specific function and mechanisms of FGF21 on PD are still quite limited. Here we aimed to elucidate the actions and the underlying mechanisms of FGF21 on dopaminergic neurodegeneration using cellular and animal models of parkinsonism. To investigate the effects of FGF21 on dopaminergic neurodegeneration in vivo and in vitro, 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine models of PD were utilized, and animals were treated with recombinant FGF21 protein or FGF21 gene delivered via an adeno-associated virus. In the present study, systemic and continuous intracerebroventricular recombinant FGF21 protein administration to mice both prevented behavioral deficits, protected dopaminergic neurons against degeneration, and ameliorated α-synuclein pathology in PD models; and in vivo gene delivery of FGF21 improved PD-like symptoms and pathologies suggesting a potential implication of FGF21 in gene therapy for PD. In vitro evidence confirmed FGF21 mediated neuroprotective benefits against PD pathologies. Further, our data suggested that enhanced autophagy was involved in the FGF21 neuroprotection in PD models, and silent information regulator 2 homolog 1 may play a crucial role in molecular mechanisms underlying anti-PD activities of FGF21.

Actively targeted gold nanoparticle composites improve behavior and cognitive impairment in Parkinson's disease mice

Parkinson's disease (PD) is characterized by motor and non-motor symptoms, primarily affecting dopaminergic neurons (DAergic neurons) in substantia nigra (SN). However, it is still very challenging to identify new drugs that not only inhibit motor dysfunction but also improve non-motor dysfunction. It has been identified as a potential PD treatment that the inhibition of α-syn aggregation could decrease the death of DAergic neurons in SN. In this study, we synthesized gold nanoparticle composites (NPs) that were loaded with plasmid DNA (pDNA) to inhibit α-syn expression. In vivo, our results showed that NPs improved tyrosine hydroxylase (TH) levels and decreased aggregation of α-syn in the SN. Additionally, NPs attenuated motor dysfunction and exploration ability declined. Moreover, NPs reversed the inhibition of long-term potentiation (LTP) and improved non-motor dysfunction in PD mice. These results indicated that NPs had significantly neuroprotective effects not only in motor, but also in non-motor dysfunction to PD mice, providing a new strategy for gene therapy in PD.

Gene Therapy for Parkinson Disease

Gene Therapy for Parkinson Disease

Parkinson's disease gene therapy: Will focused ultrasound and nanovectors be the next frontier?

Parkinson's disease gene therapy: Will focused ultrasound and nanovectors be the next frontier?

Parkinson disease gene therapy rewires brain circuits to improve motor function.

Parkinson disease gene therapy rewires brain circuits to improve motor function.

Gene Therapy for Parkinson's Disease, AnUpdate.

The current mainstay treatment of Parkinson’s disease (PD) consists of dopamine replacement therapy which, in addition to causing several side effects, does not delay disease progression. The field of gene therapy offers a potential means to improve current therapy. The present review gives an update of the present status of gene therapy for PD. Both non-disease and disease modifying transgenes have been tested for PD gene therapy in animal and human studies. Non-disease modifying treatments targeting dopamine or GABA synthesis have been successful and promising at improving PD symptomatology in randomized clinical studies, but substantial testing remains before these can be implemented in the standard clinical treatment repertoire. As for disease modifying targets that theoretically offer the possibility of slowing the progression of disease, several neurotrophic factors show encouraging results in preclinical models (e.g., neurturin, GDNF, BDNF, CDNF, VEGF-A). However, so far, clinical trials have only tested neurturin, and, unfortunately, no trial has been able to meet its primary endpoint. Future clinical trials with neurotrophic factors clearly deserve to be conducted, considering the still enticing goal of actually slowing the disease process of PD. As alternative types of gene therapy, opto- and chemogenetics might also find future use in PD treatment and novel genome-editing technology could also potentially be applied as individualized gene therapy for genetic types of PD.

Novel Focused Ultrasound Gene Therapy Approach Noninvasively Restores Dopaminergic Neuron Function in a Rat Parkinson's Disease Model.

Therapies capable of decelerating, or perhaps even halting, neurodegeneration in Parkinson's disease (PD) remain elusive. Clinical trials of PD gene therapy testing the delivery of neurotrophic factors, such as the glial cell-line derived neurotrophic factor (GDNF), have been largely ineffective due to poor vector distribution throughout the diseased regions in the brain. In addition, current delivery strategies involve invasive procedures that obviate the inclusion of early stage patients who are most likely to benefit from GDNF-based gene therapy. Here, we introduce a two-pronged treatment strategy, composed of MR image-guided focused ultrasound (FUS) and brain-penetrating nanoparticles (BPN), that provides widespread but targeted GDNF transgene expression in the brain following systemic administration. MR image-guided FUS allows circulating gene vectors to partition into the brain tissue by noninvasive and transient opening of the blood-brain barrier (BBB) within the areas where FUS is applied. Once beyond the BBB, BPN provide widespread and uniform GDNF expression throughout the targeted brain tissue. After only a single treatment, our strategy led to therapeutically relevant levels of GDNF protein content in the FUS-targeted regions in the striatum of the 6-OHDA-induced rat model of PD, which lasted at least up to 10 weeks. Importantly, our strategy restored both dopamine levels and dopaminergic neuron density and reversed behavioral indicators of PD-associated motor dysfunction with no evidence of local or systemic toxicity. Our combinatorial approach overcomes limitations of current delivery strategies, thereby potentially providing a novel means to treat PD.

Persistent Expression of Dopamine-Synthesizing Enzymes 15 Years After Gene Transfer in a Primate Model of Parkinson's Disease.

Restoring dopamine production in the putamen through gene therapy is a straightforward strategy for ameliorating motor symptoms for Parkinson's disease (PD). In a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity-based primate model of PD, we previously showed the safety and efficacy of adeno-associated viral (AAV) vector-mediated gene delivery to the putamen of three dopamine-synthesizing enzymes (tyrosine hydroxylase [TH], aromatic l-amino acid decarboxylase [AADC], and guanosine triphosphate cyclohydrolase I [GCH]) up to 10 months postprocedure. Although three of four monkeys in this study have previously undergone postmortem analysis, one monkey was kept alive for 15 years after gene therapy to evaluate long-term effects. Here, we report that this monkey showed behavioral recovery in the right-side limb that remained unchanged for 15 years, at which time euthanasia was carried out owing to onset of senility. Immunohistochemistry of the postmortem brain from this monkey revealed persistent expression of TH, AADC, and GCH genes in the lesioned putamen. Transduced neurons were broadly distributed, with the estimated transduction region occupying 91% of the left postcommissural putamen. No signs of cytotoxicity or Lewy body pathology were observed in the AAV vector-injected putamen. This study provides evidence of long-term safety and efficacy of the triple-transduction method as a gene therapy for PD.

Polylysine-modified polyethylenimine (PEI-PLL) mediated VEGF gene delivery protects dopaminergic neurons in cell culture and in rat models of Parkinson's Disease (PD).

In this report, we exploited the potential of PEI-PLL to deliver VEGF gene for the potential therapeutic treatment of PD by using both cell culture and animal models of PD. To the best of our knowledge, this is the first report describing the use of novel polymeric gene carriers for the delivery of VEGF gene to DA neurons with improved transfection efficiency. Finally, the study will lead to a significant advancement in the field of non-viral PD gene therapy treatment.

Treatment of Parkinson's disease in rats by Nrf2 transfection using MRI-guided focused ultrasound delivery of nanomicrobubbles

Parkinson's disease (PD) is a very common neurological disorder. However, effective therapy is lacking. Although the blood-brain-barrier (BBB) protects the brain, it prevents the delivery of about 90% of drugs and nucleotides into the brain, thereby hindering the development of gene therapy for PD. Magnetic resonance imaging (MRI)-guided focused ultrasound delivery of microbubbles enhances the delivery of gene therapy vectors across the BBB and improves transfection efficiency. In the present study, we delivered nuclear factor E2-related factor 2 (Nrf2, NFE2L2) contained in nanomicrobubbles into the substantia nigra of PD rats by MRI-guided focused ultrasound, and we examined the effect of Nrf2 over-expression in this animal model of PD. The rat model of PD was established by injecting 6-OHDA in the right substantia nigra stereotactically. Plasmids (pDC315 or pDC315/Nrf2) were loaded onto nanomicrobubbles, and then injected through the tail vein with the assistance of MRI-guided focused ultrasound. MRI-guided focused ultrasound delivery of nanomicrobubbles increased gene transfection efficiency. Furthermore, Nrf2 gene transfection reduced reactive oxygen species levels, thereby protecting neurons in the target region.

Gene therapy targeting mitochondrial pathway in Parkinson's disease.

Parkinson's disease (PD) presents a relative selective localization of pathology to substantia nigra and well-defined motor symptoms caused by dopaminergic degeneration that makes it an ideal target for gene therapy. Parallel progress in viral vector systems enables the delivery of therapeutic genes directly into brain with reasonable safety along with sustained transgene expression. To date, gene therapy for PD that has reached clinical trial evaluation is mainly based on symptomatic approach that involves enzyme replacement strategy and restorative approach that depends on the addition of neurotrophic factors. Mitochondrial dysregulation, such as reduced complex I activity, increased mitochondria-derived reactive oxygen species (ROS) production, ROS-mediated mitochondrial DNA damage, bioenergetic failure, and perturbation of mitochondrial dynamics and mitophagy, has long been implicated in the pathogenesis of PD. Many of mutated genes linked to familial forms of PD affect these mitochondrial features. In this review, we discuss the recent progress that has been made in preclinical development of gene therapy targeting the mitochondrial pathway as disease modifying approach for PD. This review focuses on the potential therapeutic efficacy of candidate genes, including Parkin, PINK1, alpha synuclein, PGC-1 alpha, and anti-apoptotic molecules.

715. Impact of Aging on Recombinant Adeno-Associated and Lentiviral Vector Transduction Efficiency in the Rat Nigrostriatal and Striatonigral Systems

Clinical trials currently examine the efficacy of viral vector-mediated gene delivery for treating age-related neurodegenerative diseases such as Parkinson's disease (PD). While viral vector strategies have been successful in preclinical studies, to date, human clinical trials have been unsuccessful. This may be partially due to the fact that preclinical studies fail to account for advanced age as an important covariate despite aging being the primary risk factor for PD. Previously, we found that gene transfer using recombinant adeno-associated virus pseudotype 2/5 (rAAV2/5) results in decreased transduction efficiency in the aged (20 month) rat midbrain as compared to young adult (3 month) rat at 12 days post-injection (Polinski et al., 2014, PMID: 25457558). Specifically, injection of rAAV2/5 expressing green fluorescent protein (rAAV2/5 GFP) to the substantia nigra (SN) of aged rats resulted in: 1) ~60% fewer cells expressing detectable GFP, 2) ~50% less striatal GFP protein, and 3) 4-fold lower GFP mRNA expression than identical injections into the young adult rat SN. These results were generalizable over rat strain, duration of expression, and location sampled in the nigrostriatal system. In the present series of experiments, we investigated whether the phenomenon of deficient transduction in the aged brain is generalizable to other vector constructs. Further, since the striatum is the structure most often targeted in PD gene therapy clinical trials, we examined the impact of aging on transduction efficiency in striatum. Aged (20 month) and young adult (3 month) male Fischer 344 rats were stereotaxically injected into the SN or striatum with rAAV2/5, rAAV2/2, rAAV2/9, or lentivirus (LV) expressing GFP. Four weeks after injection in the SN, three of the four vector constructs (rAAV2/5, rAAV2/2, and LV) were less efficient in transduction of the aged nigrostriatal system as assessed through levels of GFP protein in the striatum. In contrast, rAAV2/9 was equally as efficient in aged as compared to young adult rats. These results implicate vector capsid-related steps of transduction in the deficiencies observed in the aged brain as this is the only difference between the rAAV pseudotypes used. Results examining whether similar deficiencies are observed following intrastriatal injection of the four vector constructs are pending. Outcome measures will include stereological quantification of NeuN+ or GFP+ cells in the striatum and measurement of GFP protein levels in striatonigral terminals. Aging-related deficits in transduction have the potential to negatively impact current and future gene therapy trials. Our results will identify which vector constructs are better suited for transduction of the aged nigrostriatal and striatonigral systems to optimize future gene therapy clinical trials for age-related neurodegenerative diseases.

Expression of GDNF Throughout Rat Brain After Intranasal Delivery of hGDNF Plasmid Nanoparticles

Glial cell line‐derived neurotrophic factor (GDNF) gene therapy is a promising approach for CNS disorders such as Parkinson's disease (PD). We are examining intranasal administration of PEG‐CK30 DNA nanoparticles (NPs) encoding hGDNF, developed by Copernicus Therapeutics, Inc. We have shown that intranasal NPs incorporating hGDNF DNA (pGDNF), or a hGDNF‐eGFP fusion plasmid (pUGG), transfect brain cells in vivo, and that intranasal pGDNF NPs protect substantia nigra (SN) dopamine neurons in a rat model of PD.Here, we examined transfection in rat brain 7 days after intranasal delivery of these NPs. ELISA showed increased GDNF levels throughout the brain of rats given pGDNF relative to saline controls. Immunohistochemistry (IHC) revealed that the number of eGFP positive cells was significantly higher in rats given intranasal pUGG NPs compared to background fluorescence in controls, with the highest numbers in midbrain. Double label IHC showed that most eGFP positive cells were immediately adjacent to capillary endothelial cells staining for RECA‐1, and they were often contiguous to GFAP positive astrocytic endfeet enwrapping capillaries. When eGFP cells were observed adjacent to dopamine neurons in SN, or NeuN labeled cells in any region, these neurons were also found close to a capillary. This pattern suggests that pericytes are transfected after intranasal administration of DNA NPs, consistent with distribution by perivascular transport. These results confirm delivery and transfection of cells in rat brain after intranasal administration of Copernicus' DNA NPs and support use of intranasal hGDNF NPs as a non‐invasive gene therapy for PD.

Modeling Parkinson's disease in the common marmoset (Callithrix jacchus): overview of models, methods, and animal care.

The common marmoset (Callithrix jacchus) is a small-bodied, popular New World monkey and is used widely in reproductive biology, neuroscience, and drug development, due to its comparative ease of handling, high reproductive efficiency, and its unique behavioral characters. In this review, we discuss the marmoset models in Parkinson's disease (PD), which is a neurological movement disorder primarily resulting from a degeneration of dopaminergic neurons with clinical features of tremor, rigidity, postural instability, and akinesia. The most common PD models involve the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 6-hydroxydopamine to study the pathogenesis and to evaluate novel therapies. Following the systemic or local administration of these neurotoxins, the marmosets with very severe Parkinson's symptoms are recommended to be placed in an intensive care unit with artificial feeding to increase survival rate. All procedures with MPTP should be conducted in a special room with enclosed cages under negative-pressure by trained researchers with personal protection. Behavioral tests are conducted to provide an external measure of the brain pathology. Along with several biomarkers, including α-synuclein and DJ-1, non-invasive neuroimaging techniques such as positron emission tomography and magnetic resonance imaging are used to evaluate the functional changes associated with PD. With the recent growing interest in potential and novel therapies such as stem cell and gene therapy for PD in Korea, the marmoset can be considered as a suitable non-human primate model in PD research to bridge the gap between rodent studies and clinical applications.

Roles of Rheb(S16H) in substantia nigra pars compacta dopaminergic neurons in vivo.

Although there are ongoing intensive research efforts, no effective pharmacological therapies for Parkinson's disease (PD) have been developed thus far. However, with the development of efficient gene delivery systems, gene therapy for PD has become a focus of research and increasing evidence suggests that continuous production of neurotrophic factors play a significant role in the functional restoration of the nigrostriatal dopaminergic (DA) system. Our recent study reported that the transduction of DA neurons with ras homolog enriched in brain, which has an S16H mutation [Rheb(S16H)], protected the nigrostriatal DA projection in a neurotoxin model of PD in vivo. In addition, Rheb(S16H) expression significantly increased the levels of glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor, which contributed to the neuroprotective effects of Rheb(S16H) in DA neurons in the adult brain, indicating that the activation of the signaling pathways involved in cell survival by a specific gene delivery, such as Rheb(S16H) to adult neurons, may be a useful strategy to protect neural systems in the adult brain. In the present study, a brief overview of our recent studies is provided, which demonstrates the neuroprotective mechanisms of Rheb(S16H) on the nigrostriatal DA projection in the adult brain.

Fiber-modified adenovirus for central nervous system Parkinson's disease gene therapy.

Gene-based therapies for neurological diseases continue to develop briskly. As disease mechanisms are elucidated, flexible gene delivery platforms incorporating transcriptional regulatory elements, therapeutic genes and targeted delivery are required for the safety and efficacy of these approaches. Adenovirus serotype 5 (Ad5)-based vectors can carry large genetic payloads to provide this flexibility, but do not transduce neuronal cells efficiently. To address this, we have developed a tropism-modified Ad5 vector with neuron-selective targeting properties for evaluation in models of Parkinson disease therapy. A panel of tropism-modified Ad5 vectors was screened for enhanced gene delivery in a neuroblastoma cell line model system. We used these observations to design and construct an unbiased Ad vector platform, consisting of an unmodified Ad5 and a tropism-modified Ad5 vector containing the fiber knob domain from canine Ad serotype 2 (Ad5-CGW-CK2). Delivery to the substantia nigra or striatum showed that this vector produced a neuronally-restricted pattern of gene expression. Many of the transduced neurons were from regions with afferent projections to the injection site, implicating that the vector binds the presynaptic terminal resulting in presynaptic transduction. We show that Ad5-CGW-CK2 can selectively transduce neurons in the brain and hypothesize that this modular platform is potentially adaptable to clinical use.