Modeling and Targeting Neuroglial Interactions with Human Pluripotent Stem Cell Models

The role of glial cells in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) has traditionally been considered a neuron-centric disease. This view is now outdated, with increasing recognition of cell autonomous and non-cell autonomous contributions of central and peripheral nervous system glia to ALS pathomechanisms. With glial research rapidly accelerating, we comprehensively interrogate the roles of astrocytes, microglia, oligodendrocytes, ependymal cells, Schwann cells and satellite glia in nervous system physiology and ALS-associated pathology. Moreover, we highlight the inter-glial, glial-neuronal and inter-system polylogue which constitutes the healthy nervous system and destabilises in disease. We also propose classification based on function for complex glial reactive phenotypes and discuss the pre-requisite for integrative modelling to advance translation. Given the paucity of life-enhancing therapies currently available for ALS patients, we discuss the promising potential of harnessing glia in driving ALS therapeutic discovery.

Asteroid impact: the potential of astrocytes to modulate human neural networks within organoids

Astrocytes are a vital cellular component of the central nervous system that impact neuronal function in both healthy and pathological states. This includes intercellular signals to neurons and non-neuronal cells during development, maturation, and aging that can modulate neural network formation, plasticity, and maintenance. Recently, human pluripotent stem cell-derived neural aggregate cultures, known as neurospheres or organoids, have emerged as improved experimental platforms for basic and pre-clinical neuroscience compared to traditional approaches. Here, we summarize the potential capability of using organoids to further understand the mechanistic role of astrocytes upon neural networks, including the production of extracellular matrix components and reactive signaling cues. Additionally, we discuss the application of organoid models to investigate the astrocyte-dependent aspects of neuropathological diseases and to test astrocyte-inspired technologies. We examine the shortcomings of organoid-based experimental platforms and plausible improvements made possible by cutting-edge neuroengineering technologies. These advancements are expected to enable the development of improved diagnostic strategies and high-throughput translational applications regarding neuroregeneration.

Neuroprotective Potential of L-Glutamate Transporters in Human Induced Pluripotent Stem Cell-Derived Neural Cells against Excitotoxicity

Human induced pluripotent stem cell (hiPSC)-derived neural cells have started to be used in safety/toxicity tests at the preclinical stage of drug development. As previously reported, hiPSC-derived neurons exhibit greater tolerance to excitotoxicity than those of primary cultures of rodent neurons; however, the underlying mechanisms remain unknown. We here investigated the functions of L-glutamate (L-Glu) transporters, the most important machinery to maintain low extracellular L-Glu concentrations, in hiPSC-derived neural cells. We also clarified the contribution of respective L-Glu transporter subtypes. At 63 days in vitro (DIV), we detected neuronal circuit functions in hiPSC-derived neural cells by a microelectrode array system (MEA). At 63 DIV, exposure to 100 μM L-Glu for 24 h did not affect the viability of neural cells. 100 µM L-Glu in the medium decreased to almost 0 μM in 60 min. Pharmacological inhibition of excitatory amino acid transporter 1 (EAAT1) and EAAT2 suppressed almost 100% of L-Glu decrease. In the presence of this inhibitor, 100 μM L-Glu dramatically decreased cell viability. These results suggest that in hiPSC-derived neural cells, EAAT1 and EAAT2 are the predominant L-Glu transporters, and their uptake potentials are the reasons for the tolerance of hiPSC-derived neurons to excitotoxicity.

hiPSC-Derived Cells as Models for Drug Discovery 2.0

Human-induced pluripotent stem cells (hiPSCs) serve as a sustainable resource for studying the molecular foundation of disease development, including initiation and deterioration [...]

Applications of Induced Pluripotent Stem Cell-Derived Glia in Brain Disease Research and Treatment

Glia are integral components of neural networks and are crucial in both physiological functions and pathological processes of the brain. Many brain diseases involve glial abnormalities, including inflammatory changes, mitochondrial damage, calcium signaling disturbance, hemichannel opening, and loss of glutamate transporters. Induced pluripotent stem cell (iPSC)-derived glia provide opportunities to study the contributions of glia in human brain diseases. These cells have been used for human disease modeling as well as generating new therapies. This chapter introduces glial involvement in brain diseases, then summarizes different methods of generating iPSC-derived glia disease models of these cells. Finally, strategies for treating disease using iPSC-derived glia are discussed. The goal of this chapter is to provide an overview and shed light on the applications of iPSC-derived glia in brain disease research and treatment.

Morphological Characterization of Astrocytes in a Xenograft of Human iPSCDerived Neural Precursor Cells

Transplantation of a mixed astrocyte and neuron culture is of interest in the development of cell therapies for neurodegenerative diseases. In this case, an assessment of engraftment requires a detailed morphological characterization, in particular an analysis of the neuronal and glial populations. In the experiment performed, human iPSC-derived neural progenitors transplanted into a rat striatum produced a mixed neuron and astrocyte population in vivo by the sixth month after transplantation. The morphological characteristics and neurochemical profile of the xenografted astrocytes were similar to those of mature human astroglia. Unlike neurons, astrocytes migrated to the surrounding structures and the density and pattern of their distribution in the striatum and cerebral cortex differed, which indicates that the microenvironment affects human glia integration. The graft was characterized by the zonal features of glial cell morphology, which was a reflection of cell maturation in the central area, glial shaft formation around the transplanted neurons, and migration to the surrounding structures.

Cell-Autonomous Processes That Impair Xenograft Survival into the Cerebellum

In immunocompetent animals, numerous factors including the immune system of the host regulate the survival of neuro-glial precursors transplanted into the cerebellum. We transplanted human neuro-glial precursors derived in vitro from partial differentiation of IPS cells into the developing cerebellum of mice and rats before maturation of the host immune system. These approaches should facilitate the development of immune-tolerance for the transplanted cells. However, we found that human cells survived the engraftment and integrated into the host cerebellum and brain stem up to about 1 month postnatally when they were rejected in both species. On the contrary, when we transplanted the same cells in NOD-SCID mice, they survived indefinitely. Our findings are consistent with the hypothesis that the slower pace of differentiation of human neural precursors compared to that of rodents restricts the induction of immune-tolerance to human antigens expressed before completion of the maturation of the immune system. As predicted by our hypothesis, when we engrafted the human neuro-glial precursor cells either in a more mature state or mixed with extracts from adult cerebellum, we prolonged the survival of the graft.