Age-related pathological impairments in directly reprogrammed dopaminergic neurons derived from patients with idiopathic Parkinson's disease.

We have developed an efficient approach to generate functional induced dopaminergic (DA) neurons from adult human dermal fibroblasts. When performing DA neuronal conversion of patient fibroblasts with idiopathic Parkinson's disease (PD), we could specifically detect disease-relevant pathology in these cells. We show that the patient-derived neurons maintain age-related properties of the donor and exhibit lower basal chaperone-mediated autophagy compared with healthy donors. Furthermore, stress-induced autophagy resulted in an age-dependent accumulation of macroautophagic structures. Finally, we show that these impairments in patient-derived DA neurons leads to an accumulation of phosphorylated alpha-synuclein, the classical hallmark of PD pathology. This pathological phenotype is absent in neurons generated from induced pluripotent stem cells from the same patients. Taken together, our results show that direct neural reprogramming can be used for obtaining patient-derived DA neurons, which uniquely function as a cellular model to study age-related pathology relevant to idiopathic PD.

Huntington's disease: diagnosis and management.

Huntington's disease (HD) is an inherited neurodegenerative disease characterised by neuropsychiatric symptoms, a movement disorder (most commonly choreiform) and progressive cognitive impairment. The diagnosis is usually confirmed through identification of an increased CAG repeat length in the huntingtin gene in a patient with clinical features of the condition. Though diagnosis is usually straightforward, unusual presentations can occur, and it can be difficult to know when someone has transitioned from being an asymptomatic carrier into the disease state. This has become increasingly important recently, with several putative disease-modifying therapies entering trials. A growing number of conditions can mimic HD, including rare genetic causes, which must be considered in the event of a negative HD genetic test. Patients are best managed in specialist multidisciplinary clinics, including when considering genetic testing. Current treatments are symptomatic, and largely directed at the chorea and neurobehavioural problems, although supporting trial evidence for these is often limited.

Recent developments in the treatment of Parkinson's Disease.

Parkinson's disease (PD) is a common neurodegenerative disease typified by a movement disorder consisting of bradykinesia, rest tremor, rigidity, and postural instability. Treatment options for PD are limited, with most of the current approaches based on restoration of dopaminergic tone in the striatum. However, these do not alter disease course and do not treat the non-dopamine-dependent features of PD such as freezing of gait, cognitive impairment, and other non-motor features of the disorder, which often have the greatest impact on quality of life. As understanding of PD pathogenesis grows, novel therapeutic avenues are emerging. These include treatments that aim to control the symptoms of PD without the problematic side effects seen with currently available treatments and those that are aimed towards slowing pathology, reducing neuronal loss, and attenuating disease course. In this latter regard, there has been much interest in drug repurposing (the use of established drugs for a new indication), with many drugs being reported to affect PD-relevant intracellular processes. This approach offers an expedited route to the clinic, given that pharmacokinetic and safety data are potentially already available. In terms of better symptomatic therapies that are also regenerative, gene therapies and cell-based treatments are beginning to enter clinical trials, and developments in other neurosurgical strategies such as more nuanced deep brain stimulation approaches mean that the landscape of PD treatment is likely to evolve considerably over the coming years. In this review, we provide an overview of the novel therapeutic approaches that are close to, or are already in, clinical trials.

Impact of GBA1 variants on long-term clinical progression and mortality in incident Parkinson's disease.

INTRODUCTION: Variants in the GBA1 gene have been identified as a common risk factor for Parkinson's disease (PD). In addition to pathogenic mutations (those associated with Gaucher disease), a number of 'non-pathogenic' variants also occur at increased frequency in PD. Previous studies have reported that pathogenic variants adversely affect the clinical course of PD. The role of 'non-pathogenic' GBA1 variants on PD course is less clear. In this study, we report the effect of GBA1 variants in incident PD patients with long-term follow-up. METHODS: The study population consisted of patients in the Cambridgeshire Incidence of Parkinson's disease from General Practice to Neurologist and Parkinsonism: Incidence, Cognition and Non-motor heterogeneity in Cambridgeshire cohorts. Patients were grouped into non-carriers, carriers of 'non-pathogenic' GBA1 variants and carriers of pathogenic GBA1 mutations. Survival analyses for time to development of dementia, postural instability and death were carried out. Cox regression analysis controlling for potential confounders were used to determine the impact of GBA1 variants on these outcome measures. RESULTS: GBA1 variants were identified in 14.4% of patients. Pathogenic and 'non-pathogenic' GBA1 variants were associated with the accelerated development of dementia and a more aggressive motor course. Pathogenic GBA1 variants were associated with earlier mortality in comparison with non-carriers, independent of the development of dementia. DISCUSSION: GBA1 variants, including those not associated with Gaucher disease, are common in PD and result in a more aggressive disease course.

Dual modulation of neuron-specific microRNAs and the REST complex promotes functional maturation of human adult induced neurons.

Direct neuronal reprogramming can be achieved using different approaches: by expressing neuronal transcription factors or microRNAs; and by knocking down neuronal repressive elements. However, there still exists a high variability in terms of the quality and maturity of the induced neurons obtained, depending on the reprogramming strategy employed. Here, we evaluate different long-term culture conditions and study the effect of expressing the neuronal-specific microRNAs, miR124 and miR9/9*, while reprogramming with forced expression of the transcription factors Ascl1, Brn2, and knockdown of the neuronal repressor REST. We show that the addition of microRNAs supports neuronal maturation in terms of gene and protein expression, as well as in terms of electrophysiological properties.

Emerging Treatment Approaches for Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease, manifesting as a characteristic movement disorder with a number of additional non-motor features. The pathological hallmark of PD is the presence of intra-neuronal aggregates of α-synuclein (Lewy bodies). The movement disorder of PD occurs largely due to loss of dopaminergic neurons of the substantia nigra, resulting in striatal dopamine depletion. There are currently no proven disease modifying treatments for PD, with management options consisting mainly of dopaminergic drugs, and in a limited number of patients, deep brain stimulation. Long-term use of established dopaminergic therapies for PD results in significant adverse effects, and there is therefore a requirement to develop better means of restoring striatal dopamine, as well as treatments that are able to slow progression of the disease. A number of exciting treatments have yielded promising results in pre-clinical and early clinical trials, and it now seems likely that the landscape for the management of PD will change dramatically in the short to medium term future. Here, we discuss the promising regenerative cell-based and gene therapies, designed to treat the dopaminergic aspects of PD whilst limiting adverse effects, as well as novel approaches to reducing α-synuclein pathology.

Regenerative Therapies for Parkinson's Disease: An Update.

Parkinson's disease is the second most common neurodegenerative disorder. It is characterised by a typical movement disorder that occurs in part because of the selective degeneration of the dopaminergic neurons of the substantia nigra pars compacta. Current treatment for the motor disorder of Parkinson's disease consists of dopaminergic medications, but these come with significant adverse effects, themselves an important part of the clinical course of Parkinson's disease, particularly in advanced stages. Therefore, treatment is needed that can restore dopaminergic tone in the striatum in a physiological and targeted manner to avert these side effects. A number of potential regenerative treatments have been developed with a view to achieving this. Following decades of optimisation and development of stem-cell-based treatments and viral gene delivery, clinical trials are on the horizon. For these treatments to be widely useful, they must be clinically effective, cost efficient and safe, and a number of practical aspects regarding storage and delivery of treatment must be optimised. Many barriers have been overcome, and the field of regenerative medicine for Parkinson's disease is now increasingly focussed on how these treatments will be delivered, demonstrating the significant progress that has been made and the optimism surrounding these approaches.

Neural grafting for Parkinson's disease: challenges and prospects.

Parkinson's disease (PD) is a neurodegenerative condition which causes a characteristic movement disorder secondary to loss of dopaminergic neurons in the substanitia nigra. The motor disorder responds well to dopamine-replacement therapies, though these result in significant adverse effects due to non-physiological release of dopamine in the striatum, and off-target effects. Cell-based regenerative treatments offer a potential means for targeted replacement of dopamine, in a physiological manner. Dopaminergic neurons for cell-based therapies can be obtained from several sources. Fetal ventral mesencephalon tissue contains dopaminergic neuron progenitors, and has been transplanted into the striatum of PD patients with good results in a number of cases. However, the ethical implications and logistical challenges of using fetal tissue mean that fetal ventral mesencephalon is unlikely to be used in a widespread clinical setting. Induced pluripotent stem cells can be used to generate dopaminergic neurons for transplantation, providing a source of autologous tissue for grafting. This approach means that challenges associated with allografts, such as the potential for immune rejection, can be circumvented. However, the associated cost and difficulty in producing a standardized product from different cell lines means that, at present, this approach is not commercially viable as a cell-based therapy. Dopaminergic neurons derived from embryonic stem cells offer the most promising basis for a cell-based therapy for Parkinson's disease, with trials due to commence in the next few years. Though there are ethical considerations to take into account when using embryonic tissue, the possibility of producing a standardized, optimized cell product means that this approach can be both effective, and commercially viable.

Internal carotid artery dissection.

Internal carotid artery dissection is an important cause of ischaemic stroke in those aged under 50 years. Awareness of the clinical features is crucial as they may offer the opportunity to intervene to reduce strokes occurring or recurring.

Cell therapies for Parkinson's disease: how far have we come?

Over the past three decades, significant progress has been made in the development of potential regenerative cell-based therapies for neurodegenerative disease, with most success being seen in Parkinson's disease. Cell-based therapies face many challenges including ethical considerations, potential for immune-mediated rejection with allogeneic and xenogeneic tissue, pathological spread of protein-related disease into the grafted tissue as well as the risk of graft overgrowth and tumorigenesis in stem cell-derived transplants. Preclinical trials have looked at many tissue types of which the most successful to date have been those using fetal ventral mesencephalon grafts, which led to clinical trials, which have shown that in some cases they can work very well. With important proof-of-concept derived from these studies, there is now much interest in how dopaminergic neurons derived from stem cell sources could be used to develop cell-based therapies suitable for clinical use, with clinical trials poised to enter the clinic in the next couple of years.