This research was supported by the National Institutes of Health (K99MH104595) and the NICHD intramural research program to T.J.P. We thank Gord Fishell, in whose lab this approach was originally established.

<ol>
	<li>Bozzi, Y., Casarosa, S., Caleo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epilepsy+as+a+neurodevelopmental+disorder.">Epilepsy as a neurodevelopmental disorder.</a> Front Psychiatry. 3 (19), (2012).</li><li>Takano, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interneuron+Dysfunction+in+Syndromic+Autism:+Recent+Advances.">Interneuron Dysfunction in Syndromic Autism: Recent Advances.</a> Dev Neurosci. , (2015).</li><li>Inan, M., Petros, T. J., Anderson, S. 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P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+spatial+bias+for+the+origins+of+interneuron+subgroups+within+the+medial+ganglionic+eminence.">A spatial bias for the origins of interneuron subgroups within the medial ganglionic eminence.</a> Dev Biol. 314 (1), 127-136 (2008).</li><li>Inan, M., Welagen, J., Anderson, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatial+and+temporal+bias+in+the+mitotic+origins+of+somatostatin-+and+parvalbumin-expressing+interneuron+subgroups+and+the+chandelier+subtype+in+the+medial+ganglionic+eminence.">Spatial and temporal bias in the mitotic origins of somatostatin- and parvalbumin-expressing interneuron subgroups and the chandelier subtype in the medial ganglionic eminence.</a> Cereb Cortex. 22 (4), 820-827 (2012).</li><li>Petros, T. J., Bultje, R. S., Ross, M. E., Fishell, G., Anderson, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apical+versus+Basal+Neurogenesis+Directs+Cortical+Interneuron+Subclass+Fate.">Apical versus Basal Neurogenesis Directs Cortical Interneuron Subclass Fate.</a> Cell Rep. 13 (6), 1090-1095 (2015).</li><li>Taniguchi, H., Lu, J., Huang, Z. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+spatial+and+temporal+origin+of+chandelier+cells+in+mouse+neocortex.">The spatial and temporal origin of chandelier cells in mouse neocortex.</a> Science. 339 (6115), 70-74 (2013).</li><li>Bandler, R. C., Mayer, C., Fishell, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+interneuron+specification:+the+juncture+of+genes,+time+and+geometry.">Cortical interneuron specification: the juncture of genes, time and geometry.</a> Curr Opin Neurobiol. 42, 17-24 (2017).</li><li>Kepecs, A., Fishell, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interneuron+cell+types+are+fit+to+function.">Interneuron cell types are fit to function.</a> Nature. 505 (7483), 318-326 (2014).</li><li>Mayer, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+diversification+of+cortical+inhibitory+interneurons.">Developmental diversification of cortical inhibitory interneurons.</a> Nature. 555 (7697), 457-462 (2018).</li><li>Mi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+emergence+of+cortical+interneuron+diversity+in+the+mouse+embryo.">Early emergence of cortical interneuron diversity in the mouse embryo.</a> Science. 360 (6384), 81-85 (2018).</li><li>Alvarez-Dolado, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+inhibition+modified+by+embryonic+neural+precursors+grafted+into+the+postnatal+brain.">Cortical inhibition modified by embryonic neural precursors grafted into the postnatal brain.</a> J Neurosci. 26 (28), 7380-7389 (2006).</li><li>Baraban, S. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+seizures+by+transplantation+of+cortical+GABAergic+interneuron+precursors+into+Kv1.1+mutant+mice.">Reduction of seizures by transplantation of cortical GABAergic interneuron precursors into Kv1.1 mutant mice.</a> Proc Natl Acad Sci U S A. 106 (36), 15472-15477 (2009).</li><li>De la Cruz, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interneuron+progenitors+attenuate+the+power+of+acute+focal+ictal+discharges.">Interneuron progenitors attenuate the power of acute focal ictal discharges.</a> Neurotherapeutics. 8 (4), 763-773 (2011).</li><li>Gilani, A. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interneuron+precursor+transplants+in+adult+hippocampus+reverse+psychosis-relevant+features+in+a+mouse+model+of+hippocampal+disinhibition.">Interneuron precursor transplants in adult hippocampus reverse psychosis-relevant features in a mouse model of hippocampal disinhibition.</a> Proc Natl Acad Sci U S A. 111 (20), 7450-7455 (2014).</li><li>Larimer, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Caudal+Ganglionic+Eminence+Precursor+Transplants+Disperse+and+Integrate+as+Lineage-Specific+Interneurons+but+Do+Not+Induce+Cortical+Plasticity.">Caudal Ganglionic Eminence Precursor Transplants Disperse and Integrate as Lineage-Specific Interneurons but Do Not Induce Cortical Plasticity.</a> Cell Rep. 16 (5), 1391-1404 (2016).</li><li>Martinez-Cerdeno, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+MGE+precursor+cells+grafted+into+adult+rat+striatum+integrate+and+ameliorate+motor+symptoms+in+6-OHDA-lesioned+rats.">Embryonic MGE precursor cells grafted into adult rat striatum integrate and ameliorate motor symptoms in 6-OHDA-lesioned rats.</a> Cell Stem Cell. 6 (3), 238-250 (2010).</li><li>Quattrocolo, G., Fishell, G., Petros, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterotopic+Transplantations+Reveal+Environmental+Influences+on+Interneuron+Diversity+and+Maturation.">Heterotopic Transplantations Reveal Environmental Influences on Interneuron Diversity and Maturation.</a> Cell Rep. 21 (3), 721-731 (2017).</li><li>Xu, Q., Tam, M., Anderson, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fate+mapping+Nkx2.1-lineage+cells+in+the+mouse+telencephalon.">Fate mapping Nkx2.1-lineage cells in the mouse telencephalon.</a> J Comp Neurol. 506 (1), 16-29 (2008).</li><li>Thompson, L., Bjorklund, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Survival,+differentiation,+and+connectivity+of+ventral+mesencephalic+dopamine+neurons+following+transplantation.">Survival, differentiation, and connectivity of ventral mesencephalic dopamine neurons following transplantation.</a> Prog Brain Res. 200, 61-95 (2012).</li><li>Liang, Y., Agren, L., Lyczek, A., Walczak, P., Bulte, J. 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The authors have nothing to disclose.

One critical aspect of this protocol is maximizing the survivability of the cells. Ensuring that the tissue and cells are always in ice cold carboxygenated sACSF is necessary to promote cell survival. This requires an efficient dissection and dissociation strategy to minimize the length of time that the cells spend in various solution and outside of the brain environment. Depending on the number of brain regions being dissected and transplanted, it can be beneficial to have a partner aid in the dissection and/or transpla...

Proper cortical function requires a balance between excitatory projection neurons and inhibitory GABAergic interneurons, an extremely heterogeneous population with distinct morphologies, electrophysiological properties, connectivity and neurochemical markers. Abnormal development and function of interneurons (and specific interneuron subgroups) has been linked to the pathobiology of psychiatric disorders such as schizophrenia, autism and epilepsy1,2,3. Furthermore, many genes implicated in these brain disorders are strongly enriched in young interneurons4. Thus, a greater understanding of the mechanisms that regulate interneuron fate determination and maturation is needed to understand normal development and potential etiologies of numerous brain diseases.
Forebrain interneurons are born primarily from two transient embryonic structures, the medial and caudal ganglionic eminences (MGE and CGE, respectively). These postmitotic cells (interneuron precursors) then undergo a protracted tangential migration phase to disperse throughout the telencephalon where they integrate into a wide variety of circuits. MGE-derived interneurons consist of three largely non-overlapping, neurochemically defined subgroups: fast spiking parvalbumin (PV+) interneurons, non-fast spiking somatostatin (SST+) interneurons, and late spiking neuronal nitric oxide synthase (nNOS+) interneurons that constitute hippocampal neurogliaform and ivy cells. Numerous labs have identified several mechanisms within the MGE that regulate initial fate decisions into PV+ or SST+ interneurons, including spatial gradients of morphogens, birthdate of interneuron precursors, and the mode of neurogenic division5,6,7,8,9,10. It has been proposed that interneurons initially differentiate into &#39;cardinal classes&#39; and then progressively mature into &#39;definitive classes&#39; as they interact with their environment11. Recent evidence indicates that some mature interneuron subtypes may be genetically hardwired as these cells become postmitotic in the ganglionic eminences, indicating that early defined intrinsic genetic programs may play a larger role than previously appreciated12,13. However, the key question of how the intrinsic genetic programs interact with environmental cues to drive differentiation into distinct interneuron subtypes remains largely unexplored.
Numerous studies have transplanted embryonic MGE cells directly into a variety of brain regions, with the consensus results that grafted cells mature and release GABA to generally inhibit the local endogenous circuitry14,15,16,17,18,19. These promising observations have generated significant interest in using human induced pluripotent stem cell (hIPSC)-derived interneurons to treat a variety of brain diseases. However, very few of these studies assess if these grafted cells mature into the expected types of mature interneurons, a critical component when one thinks about translational approaches.
To address how environment influences interneuron differentiation and maturation, a strategy was devised to transplant immature interneuron precursors into new brain environments in order to examine whether grafted interneurons adopt features of the host environment or retain features from the donor environment20. MGE transplants are not suitable to address this question because the MGE contains a mixed population of interneuron and GABAergic projection cells that disperse throughout numerous brain regions21. Without knowing where these MGE cells would have migrated, one can not fully assess how these transplantations are affected by the brain environment. By harvesting interneuron precursors at early postnatal timepoints, this problem is circumvented by obtaining immature cells that have completed their migration and reached their target brain region but have minimal interaction with the environment. By focusing on specific features of interneurons that are differentially expressed between distinct brain regions, one can then determine how the host environment changes interneuron properties. The general approach outlined in this protocol should be applicable to any investigator that wants to examine how young neurons behave when challenged in a new environment.

<table><tbody><tr><td>Sodium chloride</td><td>Sigma</td><td>S7653</td><td></td></tr><tr><td>Sodium bicarbonate</td><td>Sigma</td><td>S6297</td><td></td></tr><tr><td>Potassium chloride</td><td>Sigma</td><td>P9541</td><td></td></tr><tr><td>Sodium phosphate monobasic</td><td>Sigma</td><td>S0751</td><td></td></tr><tr><td>Calcium chloride</td><td>Sigma</td><td>C5080</td><td></td></tr><tr><td>Magnesium chloride</td><td>Sigma</td><td>M2670</td><td></td></tr><tr><td>Glucose</td><td>Sigma</td><td>G7528</td><td></td></tr><tr><td>Sucrose</td><td>Sigma</td><td>S7903</td><td></td></tr><tr><td>Brain Matrices</td><td>Roboz</td><td>SA-2165</td><td>Only needed if harvesting striatum</td></tr><tr><td>Fine point Dumont Forceps</td><td>Roboz</td><td>RS-4978</td><td></td></tr><tr><td>Microdissecting scissors</td><td>Roboz</td><td>RS-5940</td><td></td></tr><tr><td>Razor blades</td><td>ThermoFisher</td><td>12-640</td><td></td></tr><tr><td>Pasteur pipettes</td><td>ThermoFisher</td><td>1367820C</td><td></td></tr><tr><td>Nanoject III</td><td>Drummond</td><td>3-000-207</td><td></td></tr><tr><td>Manual Manipulator w/ stand</td><td>World Precision Instruments&amp;nbsp;</td><td>M3301R/M10</td><td></td></tr><tr><td>5 ml round bottom plastic tubes</td><td>ThermoFisher</td><td>149591A</td><td></td></tr><tr><td>60 mm Petri dishes</td><td>ThermoFisher</td><td>12556001</td><td></td></tr><tr><td>100 mm Petri dishes</td><td>ThermoFisher</td><td>12565100</td><td></td></tr><tr><td>Pronase</td><td>Sigma</td><td>10165921001</td><td></td></tr><tr><td>Fetal Bovine Serum (FBS)</td><td>ThermoFisher</td><td>16140063</td><td></td></tr><tr><td>DNase I</td><td>Sigma</td><td>4716728001</td><td></td></tr><tr><td>Celltrics 50um filters</td><td>Sysmex</td><td>04-0042327</td><td></td></tr><tr><td>Trypan blue</td><td>ThermoFisher</td><td>15-250-061</td><td></td></tr><tr><td>Hemocytometer</td><td>ThermoFisher</td><td>02-671-6</td><td></td></tr></tbody></table>

homochronic transplantation of interneuron precursors into early postnatal mouse brains

Neuronal fate determination and maturation requires an intricate interplay between genetic programs and environmental signals. However, disentangling the roles of intrinsic vs. extrinsic mechanisms that regulate this differentiation process is a conundrum for all developmental neurobiologists. This issue is magnified for GABAergic interneurons, an incredibly heterogeneous cell population that is born from transient embryonic structures and undergo a protracted migratory phase to disperse throughout the telencephalon. To explore how different brain environments affect interneuron fate and maturation, we developed a protocol for harvesting fluorescently labeled immature interneuron precursors from specific brain regions in newborn mice (P0-P2). At this age, interneuron migration is nearly complete and these cells are residing in their final resting environments with relatively little synaptic integration. Following collection of single cell solutions via flow cytometry, these interneuron precursors are transplanted into P0-P2 wildtype postnatal pups. By performing both homotopic (e.g., cortex-to-cortex) or heterotopic (e.g., cortex-to-hippocampus) transplantations, one can assess how challenging immature interneurons in new brain environments affects their fate, maturation, and circuit integration. Brains can be harvested in adult mice and assayed with a wide variety of posthoc analysis on grafted cells, including immunohistochemical, electrophysiological and transcriptional profiling. This general approach provides investigators with a strategy to assay how distinct brain environments can influence numerous aspects of neuron development and identify if specific neuronal characteristics are primarily driven by hardwired genetic programs or environmental cues.

This protocol demonstrates how to harvest specific brain regions from early postnatal brains (Figure 1-2), collect single cell dissociations of interneuron precursors, and transplant these cells into various brain regions in naive WT postnatal pups (Figure 3). For posthoc analysis, brains that received interneuron precursor grafts were harvested between P30-35 to characterize cell morphology, neurochemical marker...

Watch this Scientific Journal Video about Homochronic Transplantation of Interneuron Precursors into Early Postnatal Mouse Brains at JoVE.com

Homochronic Transplantation of Interneuron Precursors into Early Postnatal Mouse Brains

Challenging young neurons in new brain regions can reveal important insights into how the environment sculpts neuronal fate and maturation. This protocol describes a procedure to harvest interneuron precursors from specific brain regions and transplant them either homotopically or heterotopically into the brain of postnatal pups.

Neuronal fate determination and maturation requires an intricate interplay between genetic programs and environmental signals. However, disentangling the ...

homochronic-transplantation-interneuron-precursors-into-early

Research

JoVE Journal

Neuroscience

7.8K Views.  Norwegian University of Science and Technology. Uitdagende jonge neuronen in nieuwe hersengebieden kan het onthullen van belangrijke inzichten in hoe het milieu neuronale lot en rijping beeldhouwt. Dit protocol beschrijft een procedure om de oogst interneuron precursoren van specifieke hersengebieden en verplant ze ofwel homotopically of heterotopically in de hersenen van postnatale pups.

Video: Homochronic Transplantation of Interneuron Precursors into Early Postnatal Mouse Brains

Intraventricular Transplantation of Engineered Neuronal Precursors for In Vivo Neuroarchitecture Studies

Gene control of neuronal cytoarchitecture is currently the subject of intensive investigation. Described here is a simple method developed to study in vivo gene control of neocortical projection neuron morphology. This method is based on (1) in vitro lentiviral engineering of neuronal precursors as "test" and "control" cells, (2) their co-transplantation into wild-type brains, and (3) paired morphometric evaluation of their neuronal derivatives. Specifically, E12.5 pallial precursors from panneuronal, genetically labeled donors, are employed for this purpose. They are engineered to take advantage of selected promoters and tetON/OFF technology, and they are free-hand transplanted into neonatal lateral ventricles. Later, upon immunofluorescence profiling of recipient brains, silhouettes of transplanted neurons are fed into NeurphologyJ open source software, their morphometric parameters are extracted, and average length and branching index are calculated. Compared to other methods, this one offers three main advantages: it permits achieving of fine control of transgene expression at affordable costs, it only requires basic surgical skills, and it provides statistically reliable results upon analysis of a limited number of animals. Because of its design, however, it is not adequate to address non cell-autonomous control of neuroarchitecture. Moreover, it should be preferably used to investigate neurite morphology control after completion of neuronal migration. In its present formulation, this method is exquisitely tuned to investigate gene control of glutamatergic neocortical neuron architecture. Taking advantage of transgenic lines expressing EGFP in other specific neural cell types, it can be re-purposed to address gene control of their architecture.

Based on in vitro lentiviral engineering of neuronal precursors, their co-transplantation into wild-type brains and paired morphometric evaluation of "test" and "control" derivatives, this method allows accurate modeling of in vivo gene control of neocortical neuron morphology in a simple and affordable way.

Gene control of neuronal cytoarchitecture is currently the subject of intensive investigation. Described here is a simple method developed to study in ...

Genetics

Neonatal Subventricular Zone Electroporation

Neural stem cells (NSCs) line the postnatal lateral ventricles and give rise to multiple cell types which include neurons, astrocytes, and ependymal cells1. Understanding the molecular pathways responsible for NSC self-renewal, commitment, and differentiation is critical for harnessing their unique potential to repair the brain and better understand central nervous system disorders. Previous methods for the manipulation of mammalian systems required the time consuming and expensive endeavor of genetic engineering at the whole animal level2. Thus, the vast majority of studies have explored the functions of NSC molecules in vitro or in invertebrates.
Here, we demonstrate the simple and rapid technique to manipulate neonatal NPCs that is referred to as neonatal subventricular zone (SVZ) electroporation. Similar techniques were developed a decade ago to study embryonic NSCs and have aided studies on cortical development3,4 . More recently this was applied to study the postnatal rodent forebrain5-7. This technique results in robust labeling of SVZ NSCs and their progeny. Thus, postnatal SVZ electroporation provides a cost and time effective alternative for mammalian NSC genetic engineering.

We demonstrate a minimally invasive technique referred to as neonatal subventricular zone electroporation. The technique consists of injecting plasmid DNA into the lateral ventricles of neonatal pups and applying electrical current to deliver and genetically manipulate neural stem cells

Neural stem cells (NSCs) line the postnatal lateral ventricles and give rise to multiple cell types which include neurons, astrocytes, and ependymal ...

Live Imaging of Mitosis in the Developing Mouse Embryonic Cortex

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixed brain sections. This protocol will describe in detail an approach for live imaging of mitosis in ex vivo embryonic brain slices. We will describe the critical steps for this procedure, which include: brain extraction, brain embedding, vibratome sectioning of brain slices, staining and culturing of slices, and time-lapse imaging. We will then demonstrate and describe in detail how to perform post-acquisition analysis of mitosis. We include representative results from this assay using the vital dye Syto11, transgenic mice (histone H2B-EGFP and centrin-EGFP), and in utero electroporation (mCherry-&#945;-tubulin). We will discuss how this procedure can be best optimized and how it can be modified for study of genetic regulation of mitosis. Live imaging of mitosis in brain slices is a flexible approach to assess the impact of age, anatomy, and genetic perturbation in a controlled environment, and to generate a large amount of data with high temporal and spatial resolution. Hence this protocol will complement existing tools for analysis of neural progenitor mitosis.

Neural progenitor mitosis is a critical parameter of neurogenesis. Much of our understanding of neural progenitor mitosis is based on analysis of fixed tissue. Live imaging in embryonic brain slices is a versatile technique to assess mitosis with high temporal and spatial resolution in a controlled environment.

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the ...

Differentiation of Mouse Embryonic Stem Cells into Cortical Interneuron Precursors

GABAergic cortical interneurons are a heterogeneous population of cells that play critical roles in regulating the output of excitatory pyramidal neurons as well as synchronizing the outputs of pyramidal neuron ensembles. Deficits in interneuron function have been implicated in a variety of neuropsychiatric disorders, including schizophrenia, autism, and epilepsy. The derivation of cortical interneurons from embryonic stem cells not only allows for the study of their development and function, but provides insight into the molecular mechanisms underlying the pathogenesis of cortical interneuron-related disorders. Interneurons also have the remarkable capacity to survive, migrate, and integrate into host cortical circuitry post-transplantation, making them ideal candidates for use in cell-based therapies. Here, we present a scalable, highly efficient, modified embryoid body-to-monolayer method for the derivation of Nkx2.1-expressing interneuron progenitors and their progeny from mouse embryonic stem cells (mESCs). Using a Nkx2.1::mCherry:Lhx6::GFP dual reporter mESC line, Nkx2.1 progenitors or their Lhx6-expressing post-mitotic progeny can be isolated via fluorescence-activated cell sorting (FACS) and subsequently used in a number of downstream applications. We also provide methods to enrich for parvalbumin (PV) or somatostatin (SST) interneuron subgroups, which may be helpful for studying aspects of fate determination or for use in therapeutic applications that would benefit from interneuron subgroup-enriched transplantations.

This protocol describes a method for generating cortical interneuron progenitors and post-mitotic interneuron precursors from mouse embryonic stem cells using a modified embryoid body-to-monolayer method. These progenitors/precursors can be used in vitro or fluorescently sorted and transplanted into neonatal neocortex for studying fate determination, or used in therapeutic applications.

GABAergic cortical interneurons are a heterogeneous population of cells that play critical roles in regulating the output of excitatory pyramidal neurons ...

The Mouse Hindbrain As a Model for Studying Embryonic Neurogenesis

The mouse embryo forebrain is the most commonly employed system for studying mammalian neurogenesis during development. However, the highly folded forebrain neuroepithelium is not amenable to wholemount analysis to examine organ-wide neurogenesis patterns. Moreover, defining the mechanisms of forebrain neurogenesis is not necessarily predictive of neurogenesis in other parts of the brain; for example, due to the presence of forebrain-specific progenitor subtypes. The mouse hindbrain provides an alternative model for studying embryonic neurogenesis that is amenable to wholemount analysis, as well as tissue sections to observe the spatiotemporal distribution and behavior of neural progenitors. Moreover, it is easily dissected for other downstream applications, such as cell isolation or molecular biology analysis. As the mouse hindbrain can be readily analyzed in the vast number of cell lineage reporter and mutant mouse strains that have become available, it offers a powerful model for studying the cellular and molecular mechanisms of developmental neurogenesis in a mammalian organism. Here, we present a simple and quick method to use the mouse embryo hindbrain for analyzing mammalian neural progenitor cell (NPC) behavior in wholemount preparations and tissue sections.

This article demonstrates how the mouse embryonic hindbrain can be used as a model for studying developmental neurogenesis in both whole organ and tissue section preparations.

The mouse embryo forebrain is the most commonly employed system for studying mammalian neurogenesis during development. However, the highly folded ...

Transplantation of Chemogenetically Engineered Cortical Interneuron Progenitors into Early Postnatal Mouse Brains

Neuronal development is regulated by a complex combination of environmental and genetic factors. Assessing the relative contribution of each component is a complicated task, which is particularly difficult in regards to the development of &#947;-aminobutyric acid (GABA)ergic cortical interneurons (CIs). CIs are the main inhibitory neurons in the cerebral cortex, and they play key roles in neuronal networks, by regulating both the activity of individual pyramidal neurons, as well as the oscillatory behavior of neuronal ensembles. They are generated in transient embryonic structures (medial and caudal ganglionic eminences -&#160;MGE and CGE) that are very difficult to efficiently target using in utero electroporation approaches. Interneuron progenitors migrate long distances during normal embryonic development, before they integrate in the cortical circuit. This remarkable ability to disperse and integrate into a developing network can be hijacked by transplanting embryonic interneuron precursors into early post-natal host cortices. Here, we present a protocol that allows genetic modification of embryonic interneuron progenitors using focal ex vivo electroporation. These engineered interneuron precursors are then transplanted into early post-natal host cortices, where they will mature into easily identifiable CIs. This protocol allows the use of multiple genetically encoded tools, or the ability to regulate the expression of specific genes in interneuron progenitors, in order to investigate the impact of either genetic or environmental variables on the maturation and integration of CIs.

Here we present a protocol, designed to use chemogenetic tools to manipulate the activity of cortical interneuron progenitors transplanted into the cortex of early postnatal mice.

Neuronal development is regulated by a complex combination of environmental and genetic factors. Assessing the relative contribution of each component is ...

Intracerebral Transplantation and In Vivo Bioluminescence Tracking of Human Neural Progenitor Cells in the Mouse Brain

Cell therapy has long been an emerging treatment paradigm in experimental neurobiology. However, cell transplantation studies often rely on end-point measurements and can therefore only evaluate longitudinal changes of cell migration and survival to a limited extent. This paper provides a reliable, minimally invasive protocol to transplant and longitudinally track neural progenitor cells (NPCs) in the adult mouse brain. Before transplantation, cells are transduced with a lentiviral vector comprising a bioluminescent (firefly-luciferase) and fluorescent (green fluorescent protein [GFP]) reporter. The NPCs are transplanted into the right cortical hemisphere using stereotaxic injections in the sensorimotor cortex. Following transplantation, grafted cells were detected through the intact skull for up to five weeks (at days 0, 3, 14, 21, 35) with a resolution limit of 6,000 cells using in vivo bioluminescence imaging. Subsequently, the transplanted cells are identified in histological brain sections and further characterized with immunofluorescence. Thus, this protocol provides a valuable tool to transplant, track, quantify, and characterize cells in the mouse brain.

Intracerebral Transplantation and In Vivo Bioluminescence Tracking of Human Neural Progenitor Cells in the Mouse Brain

We describe the intraparenchymal transplantation of human neural progenitor cells transduced with a dual reporter vector expressing luciferase-green fluorescent protein (GFP) in the mouse brain. After transplantation, the luciferase signal is repeatedly measured using in vivo bioluminescence and GFP-expressing grafted cells identified in brain sections using fluorescence microscopy.

Cell therapy has long been an emerging treatment paradigm in experimental neurobiology. However, cell transplantation studies often rely on end-point ...

Transplantation of Human Stem Cell-Derived GABAergic Neurons into the Early Postnatal Mouse Hippocampus to Mitigate Neurodevelopmental Disorders

A reduced number or dysfunction of inhibitory interneurons is a common contributor to neurodevelopmental disorders. Therefore, cell therapy using interneurons to replace or mitigate the effects of altered neuronal circuits is an attractive therapeutic avenue. To this end, more knowledge is needed about how human stem cell-derived GABAergic interneuron-like cells (hdINs) mature, integrate, and function over time in the host circuitry. Of particular importance in neurodevelopmental disorders is a better understanding of whether these processes in transplanted cells are affected by an evolving and maturing host brain. The present protocol describes a fast and highly efficient generation of hdINs from human embryonic stem cells based on the transgenic expression of the transcription factors Ascl1 and Dlx2. These neuronal precursors are transplanted unilaterally, after 7 days in vitro, to the hippocampus of neonatal 2-day-old mice. The transplanted neurons disperse in the ipsi- and contralateral hippocampus of a mouse model of cortical dysplasia-focal epilepsy syndrome and survive for up to 9 months after transplantation. This approach allows for investigating the cellular identity, integration, functionality, and therapeutic potential of transplanted interneurons over an extended time in developing healthy and diseased brains.

Transplantation of human pluripotent stem cell-derived GABAergic neurons generated by neuronal programming could be a potential treatment approach for neurodevelopmental disorders. This protocol describes the generation and transplantation of human stem cell-derived GABAergic neuronal precursors into the brains of neonatal mice, allowing long-term investigation of grafted neurons and evaluation of their therapeutic potential.

A reduced number or dysfunction of inhibitory interneurons is a common contributor to neurodevelopmental disorders. Therefore, cell therapy using ...

Visualizing Neuronal and Glial Cell Dynamics in the Developing Mouse Brain

Time-Lapse Imaging of Migrating Neurons and Glial Progenitors in Embryonic Mouse Brain Slices

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain surface. This process is crucial for proper brain function, and its dysregulation can result in neurodevelopmental and psychiatric disorders after birth. In fact, many genes responsible for these diseases have been found to be involved in this process, and therefore, revealing how these mutations affect cellular dynamics is important for understanding the pathogenesis of these diseases. This protocol introduces a technique for time-lapse imaging of migrating neurons and glial progenitors in brain slices obtained from mouse embryos. Cells are labeled with fluorescent proteins using in utero electroporation, which visualizes individual cells migrating from the ventricular zone with a high signal-to-noise ratio. Moreover, this in vivo gene transfer system enables us to easily perform gain-of-function or loss-of-function experiments on the given genes by co-electroporation of their expression or knockdown/knockout vectors. Using this protocol, the migratory behavior and migration speed of individual cells, information that is never obtained from fixed brains, can be analyzed.

Author Spotlight: Exploring Cell Migration and Gene Roles in the Developing Brain

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain surface. Many genes are involved in this process. This protocol introduces the technique for the time-lapse imaging of migrating neurons and glial progenitors.

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain ...

Viral-Mediated Labeling and Transplantation of Medial Ganglionic Eminence Cells for In Vivo Studies

Source: Vogt, D. et al., <a href="https://app.jove.com/v/52740">Viral-mediated Labeling and Transplantation of Medial Ganglionic Eminence (MGE) Cells for In Vivo Studies.</a>&#160;J. Vis. Exp.&#160;(2015).
This video demonstrates the viral labeling and transplantation of medial ganglionic eminence (MGE) cells for in vivo studies. It outlines the steps involved in transducing MGE cells with a viral reporter, transplanting these transduced cells into the cortex of a mouse pup, and enabling reporter expression in specific interneuron subtypes.

Homochronic Transplantation of Interneuron Precursors into Early Postnatal Mouse Brains

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