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Cells Jun 2020Parkinson's Disease (PD) is a neurodegenerative disorder affecting the motor system. It is primarily due to substantial loss of midbrain dopamine (mDA) neurons in the... (Review)
Review
Parkinson's Disease (PD) is a neurodegenerative disorder affecting the motor system. It is primarily due to substantial loss of midbrain dopamine (mDA) neurons in the substantia nigra pars compacta and to decreased innervation to the striatum. Although existing drug therapy available can relieve the symptoms in early-stage PD patients, it cannot reverse the pathogenic progression of PD. Thus, regenerating functional mDA neurons in PD patients may be a cure to the disease. The proof-of-principle clinical trials showed that human fetal graft-derived mDA neurons could restore the release of dopamine neurotransmitters, could reinnervate the striatum, and could alleviate clinical symptoms in PD patients. The invention of human-induced pluripotent stem cells (hiPSCs), autologous source of neural progenitors with less ethical consideration, and risk of graft rejection can now be generated in vitro. This advancement also prompts extensive research to decipher important developmental signaling in differentiation, which is key to successful in vitro production of functional mDA neurons and the enabler of mass manufacturing of the cells required for clinical applications. In this review, we summarize the biology and signaling involved in the development of mDA neurons and the current progress and methodology in driving efficient mDA neuron differentiation from pluripotent stem cells.
Topics: Animals; Cell Differentiation; Cell- and Tissue-Based Therapy; Dopaminergic Neurons; Humans; Induced Pluripotent Stem Cells; Levodopa; Mesencephalon; Models, Neurological; Nerve Regeneration; Neurogenesis; Parkinson Disease; Translational Research, Biomedical
PubMed: 32570916
DOI: 10.3390/cells9061489 -
Cell Oct 2016Understanding human embryonic ventral midbrain is of major interest for Parkinson's disease. However, the cell types, their gene expression dynamics, and their... (Comparative Study)
Comparative Study
Understanding human embryonic ventral midbrain is of major interest for Parkinson's disease. However, the cell types, their gene expression dynamics, and their relationship to commonly used rodent models remain to be defined. We performed single-cell RNA sequencing to examine ventral midbrain development in human and mouse. We found 25 molecularly defined human cell types, including five subtypes of radial glia-like cells and four progenitors. In the mouse, two mature fetal dopaminergic neuron subtypes diversified into five adult classes during postnatal development. Cell types and gene expression were generally conserved across species, but with clear differences in cell proliferation, developmental timing, and dopaminergic neuron development. Additionally, we developed a method to quantitatively assess the fidelity of dopaminergic neurons derived from human pluripotent stem cells, at a single-cell level. Thus, our study provides insight into the molecular programs controlling human midbrain development and provides a foundation for the development of cell replacement therapies.
Topics: Animals; Cell Line; Cellular Reprogramming Techniques; Dopaminergic Neurons; Humans; Machine Learning; Mesencephalon; Mice; Neural Stem Cells; Neurogenesis; Neuroglia; Pluripotent Stem Cells; Sequence Analysis, RNA; Single-Cell Analysis
PubMed: 27716510
DOI: 10.1016/j.cell.2016.09.027 -
Cells Jan 2019Parkinson's Disease (PD) is an intractable disease resulting in localized neurodegeneration of dopaminergic neurons of the substantia nigra pars compacta. Many current... (Review)
Review
Parkinson's Disease (PD) is an intractable disease resulting in localized neurodegeneration of dopaminergic neurons of the substantia nigra pars compacta. Many current therapies of PD can only address the symptoms and not the underlying neurodegeneration of PD. To better understand the pathophysiological condition, researchers continue to seek models that mirror PD's phenotypic manifestations as closely as possible. Recent advances in the field of cellular reprogramming and personalized medicine now allow for previously unattainable cell therapies and patient-specific modeling of PD using induced pluripotent stem cells (iPSCs). iPSCs can be selectively differentiated into a dopaminergic neuron fate naturally susceptible to neurodegeneration. In iPSC models, unlike other artificially-induced models, endogenous cellular machinery and transcriptional feedback are preserved, a fundamental step in accurately modeling this genetically complex disease. In addition to accurately modeling PD, iPSC lines can also be established with specific genetic risk factors to assess genetic sub-populations' differing response to treatment. iPS cell lines can then be genetically corrected and subsequently transplanted back into the patient in hopes of re-establishing function. Current techniques focus on iPSCs because they are patient-specific, thereby reducing the risk of immune rejection. The year 2018 marked history as the year that the first human trial for PD iPSC transplantation began in Japan. This form of cell therapy has shown promising results in other model organisms and is currently one of our best options in slowing or even halting the progression of PD. Here, we examine the genetic contributions that have reshaped our understanding of PD, as well as the advantages and applications of iPSCs for modeling disease and personalized therapies.
Topics: Animals; Dopaminergic Neurons; Genetic Therapy; Humans; Induced Pluripotent Stem Cells; Models, Biological; Parkinson Disease; Precision Medicine
PubMed: 30621042
DOI: 10.3390/cells8010026 -
Methods in Molecular Biology (Clifton,... 2018None of the current genetic Parkinson's disease (PD) models in mouse recapitulates all features of PD. Additionally, only a few of these models develop mild dopamine...
None of the current genetic Parkinson's disease (PD) models in mouse recapitulates all features of PD. Additionally, only a few of these models develop mild dopamine (DA) neurodegeneration. And the most parsimonious explanation for the lack of DA neurodegeneration in genetic PD models is a compensatory mechanism that results from adaptive changes during development, making it hard to observe the degenerative phenotype over the life span of mice. Here, we characterize DA neuron-specific autophagy-deficient mice and provide in vivo evidence for Lewy body formation. Atg7-deficient mice demonstrate typical Lewy pathology, including endogenous synuclein and neuronal loss, which resembles PD. Furthermore DA levels are affected by dopaminergic neuronal loss. The age-related motor dysfunction and pathology in DA neurons suggest that impairment of autophagy is a potential mechanism underlying the pathology of PD.
Topics: Animals; Autophagy; Autophagy-Related Protein 7; Behavior, Animal; Biomarkers; Disease Models, Animal; Dopaminergic Neurons; Mice; Mitochondria; Parkinson Disease; Phenotype
PubMed: 29804260
DOI: 10.1007/7651_2018_156 -
Regenerative Medicine Nov 2019Current cell therapy product limitations include the need for in-depth product understanding to ensure product potency, safety and purity. New technologies require... (Review)
Review
Current cell therapy product limitations include the need for in-depth product understanding to ensure product potency, safety and purity. New technologies require development and validation to address issues of production scale-up to meet clinical need; assays are required for process control, validation and release. Prior to clinical realization, an understanding of production processes is required to implement process changes that are essential for process control. Identification of key parameters forms the basis of process tolerances, allowing for validated, adaptive manufacturing processes. This enables greater process control and yield while withstanding regulatory scrutiny. This report summaries key milestones in specifically for ventral midbrain dopaminergic neuroprogenitor differentiation and key translational considerations and recommendations to enable successful, robust and reproducible current cell therapy product-manufacturing.
Topics: Carcinogenesis; Cell Differentiation; Dopaminergic Neurons; Humans; Mesencephalon; Parkinson Disease; Translational Research, Biomedical
PubMed: 31718456
DOI: 10.2217/rme-2019-0076 -
Journal of Neurochemistry May 2022
Topics: Dopamine; Dopaminergic Neurons; Mesencephalon
PubMed: 35129216
DOI: 10.1111/jnc.15580 -
Journal of Molecular Cell Biology Feb 2014Neurons synthesizing the neurotransmitter dopamine exert crucial functions in the mammalian brain. The biggest and most important population of dopamine-synthesizing... (Review)
Review
Neurons synthesizing the neurotransmitter dopamine exert crucial functions in the mammalian brain. The biggest and most important population of dopamine-synthesizing neurons is located in the mammalian ventral midbrain (VM), and controls and modulates the execution of motor, cognitive, affective, motivational, and rewarding behaviours. Degeneration of these neurons leads to motor deficits that are characteristic of Parkinson's disease, while their dysfunction is involved in the pathogenesis of psychiatric disorders including schizophrenia and addiction. Because the aetiology and therapeutic prospects for these diseases include neurodevelopmental aspects, substantial scientific interest has been focused on deciphering the mechanistic pathways that control the generation and survival of these neurons during embryonic development. Researches during the last decade revealed the pivotal role of the secreted Wnt1 ligand and its signalling cascade in the generation of the dopamine-synthesizing neurons in the mammalian VM. Here, we summarize the initial and more recent findings that have unravelled several Wnt1-controlled genetic networks required for the proliferation and commitment of VM progenitors to the dopaminergic cell fate during midgestational embryonic stages, and for the correct differentiation of these progenitors into postmitotic dopamine-synthesizing neurons at late midgestational embryonic and foetal stages.
Topics: Animals; Dopaminergic Neurons; Gene Regulatory Networks; Mesencephalon; Mice; Models, Biological; Wnt Signaling Pathway; Wnt1 Protein
PubMed: 24326514
DOI: 10.1093/jmcb/mjt046 -
Journal of Molecular Cell Biology Feb 2014Loss of midbrain dopaminergic (mDA) neurons underlies the motor symptoms of Parkinson's disease. Towards cell replacement, studies have focused on mechanisms underlying... (Review)
Review
Loss of midbrain dopaminergic (mDA) neurons underlies the motor symptoms of Parkinson's disease. Towards cell replacement, studies have focused on mechanisms underlying embryonic mDA production, as a rational basis for deriving mDA neurons from stem cells. We will review studies of β-catenin, an obligate component of the Wnt cascade that is critical to mDA specification and neurogenesis. mDA neurons have a unique origin--the midbrain floor plate (FP). Unlike the hindbrain and spinal cord FP, the midbrain FP is highly neurogenic and Wnt/β-catenin signaling is critical to this difference in neurogenic potential. In β-catenin loss-of-function experiments, the midbrain FP resembles the hindbrain FP, and key mDA progenitor genes such as Otx2, Lmx1a, Msx1, and Ngn2 are downregulated whereas Shh is maintained. Accordingly, the neurogenic capacity of the midbrain FP is diminished, resulting in fewer mDA neurons. Conversely, in β-catenin gain-of-function experiments, the hindbrain FP expresses key mDA progenitor genes, and is highly neurogenic. Interestingly, when excessive β-catenin is supplied to the midbrain FP, less mDA neurons are produced suggesting that the dosage of Wnt/β-catenin signaling is critical. These studies of β-catenin have facilitated new protocols to derive mDA neurons from stem cells.
Topics: Animals; Cell Differentiation; Dopaminergic Neurons; Mesencephalon; Mice; Neurogenesis; Spinal Cord; Wnt Signaling Pathway; beta Catenin
PubMed: 24287202
DOI: 10.1093/jmcb/mjt043 -
Journal of Visualized Experiments : JoVE Nov 2021Dopamine neuron loss is involved in the pathology of Parkinson's Disease (PD), a highly prevalent neurodegenerative disorder affecting over 10 million people worldwide....
Dopamine neuron loss is involved in the pathology of Parkinson's Disease (PD), a highly prevalent neurodegenerative disorder affecting over 10 million people worldwide. Since many details about PD etiology remain unknown, studies investigating genetic and environmental contributors to PD are needed to discover methods of prevention, management, and treatment. Proper characterization of dopaminergic neuronal loss may be relevant not only to PD research, but to other increasingly prevalent neurodegenerative disorders. There are established genetic and chemical models of dopaminergic neurodegeneration in the Caenorhabditis elegans model system, with easy visualization of neurobiology supported by the nematodes' transparency and invariant neuronal architecture. In particular, hermaphroditic C. elegans' dopaminergic neuron morphological changes can be visualized using strains with fluorescent reporters driven by cell-specific promotors such as the dat-1 dopamine transporter gene, which is expressed exclusively in their eight dopaminergic neurons. With the capabilities of this model system and the appropriate technology, many laboratories have studied dopaminergic neurodegeneration. However, there is little consistency in the way the data is analyzed and much of the present literature uses binary scoring analyses that capture the presence of degeneration but not the full details of the progression of neuron loss. Here, we introduce a universal scoring system to assess morphological changes and degeneration in C. elegans' cephalic neuron dendrites. This seven-point scale allows for analysis across a full range of dendrite morphology, ranging from healthy neurons to complete dendrite loss, and considering morphological details including kinks, branching, blebs, and breaks. With this scoring system, researchers can quantify subtle age-related changes as well as more dramatic chemical-induced changes. Finally, we provide a practice set of images with commentary that can be used to train, calibrate, and assess the scoring consistency of researchers new to this method. This should improve within- and between- laboratory consistency, increasing rigor and reproducibility.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Disease Models, Animal; Dopaminergic Neurons; Humans; Reproducibility of Results
PubMed: 34866619
DOI: 10.3791/62894 -
Journal of Molecular Cell Biology Feb 2014Wnts are a highly conserved family of lipid-modified glycoproteins that work as morphogens to activate several signaling pathways, leading to remodeling of the... (Review)
Review
Wnts are a highly conserved family of lipid-modified glycoproteins that work as morphogens to activate several signaling pathways, leading to remodeling of the cytoskeleton and the regulation of gene transcription. Wnt signaling regulates multiple cellular functions and cell systems, including the development and maintenance of midbrain dopaminergic (mDA) neurons. These neurons are of considerable interest for regenerative medicine because their degeneration results in Parkinson's disease (PD). This review focuses on new advances in understanding key functions of Wnts in mDA neuron development and using novel tools to regulate Wnt signaling in regenerative medicine for PD. Particularly, recent reports indicate that appropriate levels of Wnt signaling are essential to improve the quantity and quality of stem cell- or reprogrammed cell-derived mDA neurons to be used in drug discovery and cell replacement therapy for PD.
Topics: Cell Differentiation; Dopaminergic Neurons; Drug Discovery; Humans; Mesencephalon; Models, Biological; Nerve Degeneration; Parkinson Disease; Regenerative Medicine; Stem Cell Transplantation; Wnt Signaling Pathway
PubMed: 24431302
DOI: 10.1093/jmcb/mju001