Circuit integration by transplanted human neurons.

Transplantation-based cell therapy holds the potential to offer sustained and physiological repair for neurological diseases and injuries, which requires the integration of transplanted neurons into the neural circuits of the human brain. Recent studies involving transplantation of human pluripotent stem cell-derived neural progenitors into the brain of model animals reveal the remarkable capacity of grafted immature human neurons to mature, project axons in a long distance, and form both pre- and postsynaptic connections with host neurons, corresponding to functional recovery. Strikingly, this circuit integration depends largely on the identity of the transplanted cells and may be modified by external stimuli.

3D Bioprinting of Human Neural Tissues with Functional Connectivity.

Probing how the human neural networks operate is hindered by the lack of reliable human neural tissues amenable for dynamic functional assessment of neural circuits. We developed a 3D bioprinting platform to assemble tissues with defined human neural cell types in a desired dimension using a commercial bioprinter. The printed neuronal progenitors differentiate to neurons and form functional neural circuits in and between tissue layers with specificity within weeks, evidenced by the cortical-to-striatal projection, spontaneous synaptic currents and synaptic response to neuronal excitation.

3D bioprinting of human neural tissues with functional connectivity.

Probing how human neural networks operate is hindered by the lack of reliable human neural tissues amenable to the dynamic functional assessment of neural circuits. We developed a 3D bioprinting platform to assemble tissues with defined human neural cell types in a desired dimension using a commercial bioprinter. The printed neuronal progenitors differentiate into neurons and form functional neural circuits within and between tissue layers with specificity within weeks, evidenced by the cortical-to-striatal projection, spontaneous synaptic currents, and synaptic response to neuronal excitation.

Preclinical long-term safety of intraspinal transplantation of human dorsal spinal GABA neural progenitor cells.

Human pluripotent stem cell (hPSC)-derived neurons have shown promise in treating spinal cord injury (SCI). We previously showed that hPSC-derived dorsal spinal γ-aminobutyric acid (GABA) neurons can alleviate spasticity and promote locomotion in rats with SCI, but their long-term safety remains elusive. Here, we characterized the long-term fate and safety of human dorsal spinal GABA neural progenitor cells (NPCs) in naive rats over one year.

Generation of locus coeruleus norepinephrine neurons from human pluripotent stem cells.

Central norepinephrine (NE) neurons, located mainly in the locus coeruleus (LC), are implicated in diverse psychiatric and neurodegenerative diseases and are an emerging target for drug discovery. To facilitate their study, we developed a method to generate 40-60% human LC-NE neurons from human pluripotent stem cells. The approach depends on our identification of ACTIVIN A in regulating LC-NE transcription factors in dorsal rhombomere 1 (r1) progenitors.

Enabling Survival of Transplanted Neural Precursor Cells in the Ischemic Brain.

There is no effective therapy for ischemic stroke following the acute stage. Neural transplantation offers a potential option for repairing the ischemic lesion. However, this strategy is hindered by the poor survival of the neural precursor cells (NPCs) that are transplanted into the inflammatory ischemic core.

Generation of Cerebral Cortical Neurons from Human Pluripotent Stem Cells in 3D Culture.

Human forebrain cortical neurons are essential for fundamental functions like memory and consciousness. Generation of cortical neurons from human pluripotent stem cells provides a great source for creating models specific to cortical neuron diseases and for developing therapeutics. This chapter describes a detailed and robust method for generating human mature cortical neurons from stem cells in 3D suspension culture.

Neuronal Senescence in the Aged Brain.

Cellular senescence is a highly complicated cellular state that occurs throughout the lifespan of an organism. It has been well-defined in mitotic cells by various senescent features. Neurons are long-lived post-mitotic cells with special structures and functions.

Real-time trajectory guide tracking for intraoperative MRI-guided neurosurgery.

Purpose: In current intraoperative MRI (IMRI) methods, an iterative approach is used to aim trajectory guides at intracerebral targets: image MR-visible features, determine current aim by fitting model to image, manipulate device, repeat. Infrequent updates are produced by such methods, compared to rapid optically tracked stereotaxy used in the operating room. Our goal was to develop a real-time interactive IMRI method for aiming.

Grafted hPSC-derived GABA-ergic interneurons regulate seizures and specific cognitive function in temporal lobe epilepsy.

Interneuron loss/dysfunction contributes to spontaneous recurrent seizures (SRS) in chronic temporal lobe epilepsy (TLE), and interneuron grafting into the epileptic hippocampus reduces SRS and improves cognitive function. This study investigated whether graft-derived gamma-aminobutyric acid positive (GABA-ergic) interneurons directly regulate SRS and cognitive function in a rat model of chronic TLE. Human pluripotent stem cell-derived medial ganglionic eminence-like GABA-ergic progenitors, engineered to express hM4D(Gi), a designer receptor exclusively activated by designer drugs (DREADDs) through CRISPR/Cas9 technology, were grafted into hippocampi of chronically epileptic rats to facilitate the subsequent silencing of graft-derived interneurons.

Altered patterning of trisomy 21 interneuron progenitors.

Individuals with Down syndrome (DS; Ts21), the most common genetic cause of intellectual disability, have smaller brains that reflect fewer neurons at pre- and post-natal stages, implicating impaired neurogenesis during development. Our stereological analysis of adult DS cortex indicates a reduction of calretinin-expressing interneurons. Using Ts21 human induced pluripotent stem cells (iPSCs) and isogenic controls, we find that Ts21 progenitors generate fewer COUP-TFII+ progenitors with reduced proliferation.

Comparative efficacy of surgical approaches to disease modification in Parkinson disease.

Parkinson's disease (PD) may optimally be treated with a disease-modifying therapy to slow progression. We compare data underlying surgical approaches proposed to impart disease modification in PD: (1) cell transplantation therapy with stem cell-derived dopaminergic neurons to replace damaged cells; (2) clinical trials of growth factors to promote survival of existing dopaminergic neurons; (3) subthalamic nucleus deep brain stimulation early in the course of PD; and (4) abdominal vagotomy to lower risk of potential disease spread from gut to brain. Though targeted to engage potential mechanisms of PD these surgical approaches remain experimental, indicating the difficulty in translating therapeutic concepts into clinical practice.

Anastasis Drives Senescence and Non-Cell Autonomous Neurodegeneration in the Astrogliopathy Alexander Disease.

Anastasis is a recently described process in which cells recover after late-stage apoptosis activation. The functional consequences of anastasis for cells and tissues are not clearly understood. Using , rat and human cells and tissues, including analyses of both males and females, we present evidence that glia undergoing anastasis in the primary astrogliopathy Alexander disease subsequently express hallmarks of senescence.

Chemically induced senescence in human stem cell-derived neurons promotes phenotypic presentation of neurodegeneration.

Modeling age-related neurodegenerative disorders with human stem cells are difficult due to the embryonic nature of stem cell-derived neurons. We developed a chemical cocktail to induce senescence of iPSC-derived neurons to address this challenge. We first screened small molecules that induce embryonic fibroblasts to exhibit features characteristic of aged fibroblasts.

Autologous transplant therapy alleviates motor and depressive behaviors in parkinsonian monkeys.

Degeneration of dopamine (DA) neurons in the midbrain underlies the pathogenesis of Parkinson's disease (PD). Supplement of DA via L-DOPA alleviates motor symptoms but does not prevent the progressive loss of DA neurons. A large body of experimental studies, including those in nonhuman primates, demonstrates that transplantation of fetal mesencephalic tissues improves motor symptoms in animals, which culminated in open-label and double-blinded clinical trials of fetal tissue transplantation for PD.

Impaired lipid metabolism in astrocytes underlies degeneration of cortical projection neurons in hereditary spastic paraplegia.

Hereditary spastic paraplegias (HSPs) are caused by a length-dependent axonopathy of long corticospinal neurons, but how axons of these cortical projection neurons (PNs) degenerate remains elusive. We generated isogenic human pluripotent stem cell (hPSC) lines for two ATL1 missense mutations associated with SPG3A, the most common early-onset autosomal dominant HSP. In hPSC-derived cortical PNs, ATL1 mutations resulted in reduced axonal outgrowth, impaired axonal transport, and accumulated axonal swellings, recapitulating disease-specific phenotypes.

Human Stem Cell-Derived Neurons Repair Circuits and Restore Neural Function.

Although cell transplantation can rescue motor defects in Parkinson's disease (PD) models, whether and how grafts functionally repair damaged neural circuitry in the adult brain is not known. We transplanted hESC-derived midbrain dopamine (mDA) or cortical glutamate neurons into the substantia nigra or striatum of a mouse PD model and found extensive graft integration with host circuitry. Axonal pathfinding toward the dorsal striatum was determined by the identity of the grafted neurons, and anatomical presynaptic inputs were largely dependent on graft location, whereas inhibitory versus excitatory input was dictated by the identity of grafted neurons.

[F]FEPPA PET imaging for monitoring CD68-positive microglia/macrophage neuroinflammation in nonhuman primates.

Purpose: The aim of this study was to examine whether the translocator protein 18-kDa (TSPO) PET ligand [F]FEPPA has the sensitivity for detecting changes in CD68-positive microglial/macrophage activation in hemiparkinsonian rhesus macaques treated with allogeneic grafts of induced pluripotent stem cell-derived midbrain dopaminergic neurons (iPSC-mDA).

Methods: In vivo positron emission tomography (PET) imaging with [F]FEPPA was used in conjunction with postmortem CD68 immunostaining to evaluate neuroinflammation in the brains of hemiparkinsonian rhesus macaques (n = 6) that received allogeneic iPSC-mDA grafts in the putamen ipsilateral to MPTP administration.

Results: Based on assessment of radiotracer uptake and confirmed by visual inspection of the imaging data, nonhuman primates with allogeneic grafts showed increased [F]FEPPA binding at the graft sites relative to the contralateral putamen.

PAX6D instructs neural retinal specification from human embryonic stem cell-derived neuroectoderm.

PAX6 is essential for neural retina (NR) and forebrain development but how PAX6 instructs NR versus forebrain specification remains unknown. We found that the paired-less PAX6, PAX6D, is expressed in NR cells during human eye development and along human embryonic stem cell (hESC) specification to retinal cells. hESCs deficient for PAX6D failed to enter NR specification.

Plasticity of Synaptic Transmission in Human Stem Cell-Derived Neural Networks.

Long-term potentiation and depression, inferred from analysis on brain slices, are considered the cellular processes underlying learning and memory formation. They have not so far been demonstrated in human stem cell-derived neurons. By expressing channelrhodopsin in hESCs-derived glutamate neurons and co-culturing them with GABA neurons, we found that blue light stimulation increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) and decreased the ratio of paired pulse facilitation (PPF) in non-ChR2-expressing GABA neurons, indicating a facilitating action at the presynaptic terminals.

Regionally specified human pluripotent stem cell-derived astrocytes exhibit different molecular signatures and functional properties.

Astrocytes display diverse morphologies in different regions of the central nervous system. Whether astrocyte diversity is attributable to developmental processes and bears functional consequences, especially in humans, is unknown. RNA-seq of human pluripotent stem cell-derived regional astrocytes revealed distinct transcript profiles, suggesting differential functional properties.

Generation of seven induced pluripotent stem cell lines from neonates of different ethnic backgrounds.

Seven human induced pluripotent stem cell (iPSC) lines were generated from fibroblasts from three neonatal individuals using non-integrative reprogramming. Most control iPSCs are derived from adults, so these iPSCs meet the need for control iPSCs from young individuals. Donors were from different ethnicities and these lines provide unique genetic profiles.