A Novel Approach to Increase Glial Cell Populations in Brain Microphysiological Systems

Abstract

Brain microphysiological systems (bMPS) recapitulate human brain cellular architecture and functionality more closely than traditional monolayer cultures and have become increasingly relevant for the study of neurological function in health and disease. Existing 3D brain models vary in reflecting the relative populations of different cell types present in the human brain. Most models consist mainly of neurons, while glial cells represent a smaller portion of the cell populations. Here, by means of a chemically defined glial‐enriched medium (GEM), an improved method to expand the population of astrocytes and oligodendrocytes without compromising neuronal differentiation in bMPS, is presented. An important finding is that astrocytes also change in morphology when cultured in GEM, more closely recapitulating primary culture astrocytes. GEM bMPS are electro‐chemically active and show different patterns of calcium staining and flux. Synaptic vesicles and terminals observed by electron microscopy are also present. No significant changes in neuronal differentiation are observed by gene expression, however, GEM enhanced neurite outgrowth and cell migration, and differentially modulated neuronal maturation in two different cell lines. These results have the potential to significantly improve functionality of bMPS for the study of neurological diseases and drug discovery, contributing to the unmet need for safe human models.

Human Glial Cells as Innovative Targets for the Therapy of Central Nervous System Pathologies

“…Another study implemented a chemically defined glial-enriched medium (GEM) to expand the population of astrocytes and oligodendrocytes without compromising neuronal differentiation in brain organoids. GEM enhanced neurite outgrowth and cell migration, and modulated neuronal maturation, showing its potential to significantly improve the functionality of brain organoids for the study of neurological diseases and drug discovery [93]. Very recently, a glia-enriched cortical organoid model displayed accelerated astrogliogenesis.…”

Revolutionizing developmental neurotoxicity testing – a journey from animal models to advanced in vitro systems

“…These models are spontaneously electrophysiologically active, and they include most of the brain cells we know except for microglia, which can be added. This includes all types of neurons we looked for, as well as astrocytes, oligodendrocytes, even in reasonable proportions -the standard model has about 40% glial cells, and we have just developed protocols to increase them to physiological levels of 50% (Morales Pantoja et al, 2023b). One of the key features is myelination, with about 30% of the axons being myelinated (Pamies et al, 2017;Chesnut et al, 2021a,b;Romero et al, 2023).…”

Identity and Maturity of iPSC-Derived Oligodendrocytes in 2D and Organoid Systems

“…In their most recent study [69], the same group further optimized the bMPS protocol to promote the expansion of astrocyte and oligodendrocyte populations through the enrichment of the previously described differentiation medium [68] with the components of the glial medium (weeks 2 to 8) and signaling molecules essential for the terminal differentiation media (weeks 8-15, see Figure 1). This optimization resulted in an expansion of astrocytes and oligodendrocytes as was evident from the elevated levels of O4, MBP, and GFAP as well as enhanced myelin ensheathment of axons.…”