Induction of functional dopamine neurons from human astrocytes in vitro and mouse astrocytes in a Parkinson's disease model
TL;DR: This work uses three transcription factors, NEUROD1, ASCL1 and LMX1A, and the microRNA miR218 to reprogram human and mouse astrocytes in vitro and in vivo into induced dopamine neurons (iDANs), which may enable clinical therapies for Parkinson's disease by delivery of genes rather than cells.
Abstract: Cell replacement therapies for neurodegenerative disease have focused on transplantation of the cell types affected by the pathological process. Here we describe an alternative strategy for Parkinson's disease in which dopamine neurons are generated by direct conversion of astrocytes. Using three transcription factors, NEUROD1, ASCL1 and LMX1A, and the microRNA miR218, collectively designated NeAL218, we reprogram human astrocytes in vitro, and mouse astrocytes in vivo, into induced dopamine neurons (iDANs). Reprogramming efficiency in vitro is improved by small molecules that promote chromatin remodeling and activate the TGFβ, Shh and Wnt signaling pathways. The reprogramming efficiency of human astrocytes reaches up to 16%, resulting in iDANs with appropriate midbrain markers and excitability. In a mouse model of Parkinson's disease, NeAL218 alone reprograms adult striatal astrocytes into iDANs that are excitable and correct some aspects of motor behavior in vivo, including gait impairments. With further optimization, this approach may enable clinical therapies for Parkinson's disease by delivery of genes rather than cells.
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TL;DR: An efficient one-step conversion of isolated mouse and human astrocytes to functional neurons by depleting the RNA-binding protein PTB is reported, identifying a potentially powerful and clinically feasible approach to treating neurodegeneration by replacing lost neurons.
Abstract: Parkinson's disease is characterized by loss of dopamine neurons in the substantia nigra1 Similar to other major neurodegenerative disorders, there are no disease-modifying treatments for Parkinson's disease While most treatment strategies aim to prevent neuronal loss or protect vulnerable neuronal circuits, a potential alternative is to replace lost neurons to reconstruct disrupted circuits2 Here we report an efficient one-step conversion of isolated mouse and human astrocytes to functional neurons by depleting the RNA-binding protein PTB (also known as PTBP1) Applying this approach to the mouse brain, we demonstrate progressive conversion of astrocytes to new neurons that innervate into and repopulate endogenous neural circuits Astrocytes from different brain regions are converted to different neuronal subtypes Using a chemically induced model of Parkinson's disease in mouse, we show conversion of midbrain astrocytes to dopaminergic neurons, which provide axons to reconstruct the nigrostriatal circuit Notably, re-innervation of striatum is accompanied by restoration of dopamine levels and rescue of motor deficits A similar reversal of disease phenotype is also accomplished by converting astrocytes to neurons using antisense oligonucleotides to transiently suppress PTB These findings identify a potentially powerful and clinically feasible approach to treating neurodegeneration by replacing lost neurons
266 citations
TL;DR: Glia-to-neuron conversion by CasRx-mediated Ptbp1 knockdown represents a promising in vivo genetic approach for treating a variety of disorders due to neuronal loss.
252 citations
TL;DR: Recent studies highlighting the complex contribution of astrocytes in the process of various neurodegenerative diseases are discussed, which may provide us with new prospects for the development of an excellent therapeutic target for neurodegnerative diseases.
Abstract: Astrocytes, the largest and most numerous glial cells in the central nervous system (CNS), play a variety of important roles in regulating homeostasis, increasing synaptic plasticity and providing neuroprotection, thus helping to maintain normal brain function At the same time, astrocytes can participate in the inflammatory response and play a key role in the progression of neurodegenerative diseases Reactive astrocytes are strongly induced by numerous pathological conditions in the CNS Astrocyte reactivity is initially characterized by hypertrophy of soma and processes, triggered by different molecules Recent studies have demonstrated that neuroinflammation and ischemia can elicit two different types of reactive astrocytes, termed A1s and A2s However, in the case of astrocyte reactivity in different neurodegenerative diseases, the recently published research issues remain a high level of conflict and controversy So far, we still know very little about whether and how the function or reactivity of astrocytes changes in the progression of different neurodegenerative diseases In this review, we aimed to briefly discuss recent studies highlighting the complex contribution of astrocytes in the process of various neurodegenerative diseases, which may provide us with new prospects for the development of an excellent therapeutic target for neurodegenerative diseases
229 citations
TL;DR: New approaches using stem-cell-derived cell products and direct cell reprogramming have opened up the possibility of reconstructing neural circuits and achieving better repair, especially with respect to chronic neurodegenerative disorders.
Abstract: The ability to repair or promote regeneration within the adult human brain has been envisioned for decades. Until recently, such efforts mainly involved delivery of growth factors and cell transplants designed to rescue or replace a specific population of neurons, and the results have largely been disappointing. New approaches using stem-cell-derived cell products and direct cell reprogramming have opened up the possibility of reconstructing neural circuits and achieving better repair. In this Review we briefly summarize the history of neural repair and then discuss these new therapeutic approaches, especially with respect to chronic neurodegenerative disorders.
152 citations
TL;DR: The mutations of main seven genes linked to Parkinson disease are summarized, the potential mechanisms for the loss of dopaminergic neurons are discussed, the development direction for treatment of PD is expected, and the findings from scientists are conducive to understand the pathological mechanisms.
Abstract: It has been 200 years since Parkinson disease (PD) was described by Dr. Parkinson in 1817. The disease is the second most common neurodegenerative disease characterized by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Although the pathogenesis of PD is still unknown, the research findings from scientists are conducive to understand the pathological mechanisms. It is well accepted that both genetic and environmental factors contribute to the onset of PD. In this review, we summarize the mutations of main seven genes (α-synuclein, LRRK2, PINK1, Parkin, DJ-1, VPS35 and GBA1) linked to PD, discuss the potential mechanisms for the loss of dopaminergic neurons (dopamine metabolism, mitochondrial dysfunction, endoplasmic reticulum stress, impaired autophagy, and deregulation of immunity) in PD, and expect the development direction for treatment of PD.
148 citations
References
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TL;DR: This work presents DESeq2, a method for differential analysis of count data, using shrinkage estimation for dispersions and fold changes to improve stability and interpretability of estimates, which enables a more quantitative analysis focused on the strength rather than the mere presence of differential expression.
Abstract: In comparative high-throughput sequencing assays, a fundamental task is the analysis of count data, such as read counts per gene in RNA-seq, for evidence of systematic changes across experimental conditions. Small replicate numbers, discreteness, large dynamic range and the presence of outliers require a suitable statistical approach. We present DESeq2, a method for differential analysis of count data, using shrinkage estimation for dispersions and fold changes to improve stability and interpretability of estimates. This enables a more quantitative analysis focused on the strength rather than the mere presence of differential expression. The DESeq2 package is available at http://www.bioconductor.org/packages/release/bioc/html/DESeq2.html
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47,038 citations
TL;DR: Induction of pluripotent stem cells from mouse embryonic or adult fibroblasts by introducing four factors, Oct3/4, Sox2, c-Myc, and Klf4, under ES cell culture conditions is demonstrated and iPS cells, designated iPS, exhibit the morphology and growth properties of ES cells and express ES cell marker genes.
23,959 citations
TL;DR: Noggin/SB431542-based neural induction should facilitate the use of hES and hiPS cells in regenerative medicine and disease modeling and obviate the need for protocols based on stromal feeders or embryoid bodies.
Abstract: Current neural induction protocols for human embryonic stem (hES) cells rely on embryoid body formation, stromal feeder co-culture or selective survival conditions. Each strategy has considerable drawbacks, such as poorly defined culture conditions, protracted differentiation and low yield. Here we report that the synergistic action of two inhibitors of SMAD signaling, Noggin and SB431542, is sufficient to induce rapid and complete neural conversion of >80% of hES cells under adherent culture conditions. Temporal fate analysis reveals the appearance of a transient FGF5(+) epiblast-like stage followed by PAX6(+) neural cells competent to form rosettes. Initial cell density determines the ratio of central nervous system and neural crest progeny. Directed differentiation of human induced pluripotent stem (hiPS) cells into midbrain dopamine and spinal motoneurons confirms the robustness and general applicability of the induction protocol. Noggin/SB431542-based neural induction should facilitate the use of hES and hiPS cells in regenerative medicine and disease modeling and obviate the need for protocols based on stromal feeders or embryoid bodies.
3,152 citations
TL;DR: In this paper, a combination of three transcription factors, Ascl1, Brn2 (also called Pou3f2) and Myt1l, was used to convert mouse embryonic and postnatal fibroblasts into functional neurons in vitro.
Abstract: Cellular differentiation and lineage commitment are considered to be robust and irreversible processes during development. Recent work has shown that mouse and human fibroblasts can be reprogrammed to a pluripotent state with a combination of four transcription factors. This raised the question of whether transcription factors could directly induce other defined somatic cell fates, and not only an undifferentiated state. We hypothesized that combinatorial expression of neural-lineage-specific transcription factors could directly convert fibroblasts into neurons. Starting from a pool of nineteen candidate genes, we identified a combination of only three factors, Ascl1, Brn2 (also called Pou3f2) and Myt1l, that suffice to rapidly and efficiently convert mouse embryonic and postnatal fibroblasts into functional neurons in vitro. These induced neuronal (iN) cells express multiple neuron-specific proteins, generate action potentials and form functional synapses. Generation of iN cells from non-neural lineages could have important implications for studies of neural development, neurological disease modelling and regenerative medicine.
2,730 citations
TL;DR: Large-scale single-cell RNA sequencing is used to classify cells in the mouse somatosensory cortex and hippocampal CA1 region and found 47 molecularly distinct subclasses, comprising all known major cell types in the cortex.
Abstract: The mammalian cerebral cortex supports cognitive functions such as sensorimotor integration, memory, and social behaviors. Normal brain function relies on a diverse set of differentiated cell types, including neurons, glia, and vasculature. Here, we have used large-scale single-cell RNA sequencing (RNA-seq) to classify cells in the mouse somatosensory cortex and hippocampal CA1 region. We found 47 molecularly distinct subclasses, comprising all known major cell types in the cortex. We identified numerous marker genes, which allowed alignment with known cell types, morphology, and location. We found a layer I interneuron expressing Pax6 and a distinct postmitotic oligodendrocyte subclass marked by Itpr2. Across the diversity of cortical cell types, transcription factors formed a complex, layered regulatory code, suggesting a mechanism for the maintenance of adult cell type identity.
2,675 citations