Distinct characteristics of microglia from neurogenic and non-neurogenic regions of the human brain in patients with Mesial Temporal Lobe Epilepsy.

The study of microglia isolated from adult human brain tissue provides unique insight into the physiology of these brain immune cells and their role in adult human brain disorders. Reports of microglia in post-mortem adult human brain tissue show regional differences in microglial populations, however, these differences have not been fully explored in living microglia. In this study biopsy tissue was obtained from epileptic patients undergoing surgery and consisted of both cortical areas and neurogenic ventricular and hippocampal (Hp) areas.

The amyotrophic lateral sclerosis-linked protein TDP-43 regulates interleukin-6 cytokine production by human brain pericytes.

Amyotrophic lateral sclerosis (ALS) is a fatal movement disorder involving degeneration of motor neurons through dysfunction of the RNA-binding protein TDP-43. Pericytes, the perivascular cells of the blood-brain, blood-spinal cord, and blood-CSF barriers also degenerate in ALS. Indeed, pericytes are among the earliest cell types to show gene expression changes in pre-symptomatic animal models of ALS.

Characterisation of PDGF-BB:PDGFRβ signalling pathways in human brain pericytes: evidence of disruption in Alzheimer's disease.

Platelet-derived growth factor-BB (PDGF-BB):PDGF receptor-β (PDGFRβ) signalling in brain pericytes is critical to the development, maintenance and function of a healthy blood-brain barrier (BBB). Furthermore, BBB impairment and pericyte loss in Alzheimer's disease (AD) is well documented. We found that PDGF-BB:PDGFRβ signalling components were altered in human AD brains, with a marked reduction in vascular PDGFB.

Identifying Neural Progenitor Cells in the Adult Human Brain.

The discovery, in 1998, that the adult human brain contains at least two populations of progenitor cells and that progenitor cells are upregulated in response to a range of degenerative brain diseases has raised hopes for their use in replacing dying brain cells. Since these early findings, the race has been on to understand the biology of progenitor cells in the human brain, and they have now been isolated and studied in many major neurodegenerative diseases. Before these cells can be exploited for cell replacement purposes, it is important to understand how to (1) locate them, (2) label them, (3) determine what receptors they express, (4) isolate them, and (5) examine their electrophysiological properties when differentiated.

Single-cell image analysis reveals a protective role for microglia in glioblastoma.

Background: Microglia and tumor-associated macrophages (TAMs) constitute up to half of the total tumor mass of glioblastomas. Despite these myeloid populations being ontogenetically distinct, they have been largely conflated. Recent single-cell transcriptomic studies have identified genes that distinguish microglia from TAMs.

Human in vitro systems for examining synaptic function and plasticity in the brain.

The human brain shows remarkable complexity in its cellular makeup and function, which are distinct from nonhuman species, signifying the need for human-based research platforms for the study of human cellular neurophysiology and neuropathology. However, the use of adult human brain tissue for research purposes is hampered by technical, methodological, and accessibility challenges. One of the major problems is the limited number of in vitro systems that, in contrast, are readily available from rodent brain tissue.

Unique and shared inflammatory profiles of human brain endothelia and pericytes.

Background: Pericytes and endothelial cells are critical cellular components of the blood-brain barrier (BBB) and play an important role in neuroinflammation. To date, the majority of inflammation-related studies in endothelia and pericytes have been carried out using immortalised cell lines or non-human-derived cells. Whether these are representative of primary human cells is unclear and systematic comparisons of the inflammatory responses of primary human brain-derived pericytes and endothelia has yet to be performed.

Modelling physiological and pathological conditions to study pericyte biology in brain function and dysfunction.

Background: Brain pericytes ensheathe the endothelium and contribute to formation and maintenance of the blood-brain-barrier. Additionally, pericytes are involved in several aspects of the CNS immune response including scarring, adhesion molecule expression, chemokine secretion, and phagocytosis. In vitro cultures are routinely used to investigate these functions of brain pericytes, however, these are highly plastic cells and can display differing phenotypes and functional responses depending on their culture conditions.

Interferon-γ blocks signalling through PDGFRβ in human brain pericytes.

Background: Neuroinflammation and blood-brain barrier (BBB) disruption are common features of many brain disorders, including Alzheimer's disease, epilepsy, and motor neuron disease. Inflammation is thought to be a driver of BBB breakdown, but the underlying mechanisms for this are unclear. Brain pericytes are critical cells for maintaining the BBB and are immunologically active.

Cultured pericytes from human brain show phenotypic and functional differences associated with differential CD90 expression.

The human brain is a highly vascular organ in which the blood-brain barrier (BBB) tightly regulates molecules entering the brain. Pericytes are an integral cell type of the BBB, regulating vascular integrity, neuroinflammation, angiogenesis and wound repair. Despite their importance, identifying pericytes amongst other perivascular cell types and deciphering their specific role in the neurovasculature remains a challenge.

TGF-beta1 regulates human brain pericyte inflammatory processes involved in neurovasculature function.

Background: Transforming growth factor beta 1 (TGFβ1) is strongly induced following brain injury and polarises microglia to an anti-inflammatory phenotype. Augmentation of TGFβ1 responses may therefore be beneficial in preventing inflammation in neurological disorders including stroke and neurodegenerative diseases. However, several other cell types display immunogenic potential and identifying the effect of TGFβ1 on these cells is required to more fully understand its effects on brain inflammation.

Isolation of highly enriched primary human microglia for functional studies.

Microglia, the resident macrophages of the central nervous system play vital roles in brain homeostasis through clearance of pathogenic material. Microglia are also implicated in neurological disorders through uncontrolled activation and inflammatory responses. To date, the vast majority of microglial studies have been performed using rodent models.

An anti-inflammatory role for C/EBPδ in human brain pericytes.

Neuroinflammation contributes to the pathogenesis of several neurological disorders and pericytes are implicated in brain inflammatory processes. Cellular inflammatory responses are orchestrated by transcription factors but information on transcriptional control in pericytes is lacking. Because the transcription factor CCAAT/enhancer binding protein delta (C/EBPδ) is induced in a number of inflammatory brain disorders, we sought to investigate its role in regulating pericyte immune responses.

A role for human brain pericytes in neuroinflammation.

Background: Brain inflammation plays a key role in neurological disease. Although much research has been conducted investigating inflammatory events in animal models, potential differences in human brain versus rodent models makes it imperative that we also study these phenomena in human cells and tissue.

Methods: Primary human brain cell cultures were generated from biopsy tissue of patients undergoing surgery for drug-resistant epilepsy.

Adult human glia, pericytes and meningeal fibroblasts respond similarly to IFNy but not to TGFβ1 or M-CSF.

The chemokine Interferon gamma-induced protein 10 (IP-10) and human leukocyte antigen (HLA) are widely used indicators of glial activation and neuroinflammation and are up-regulated in many brain disorders. These inflammatory mediators have been widely studied in rodent models of brain disorders, but less work has been undertaken using human brain cells. In this study we investigate the regulation of HLA and IP-10, as well as other cytokines and chemokines, in microglia, astrocytes, pericytes, and meningeal fibroblasts derived from biopsy and autopsy adult human brain, using immunocytochemistry and a Cytometric Bead Array.

Identifying neural progenitor cells in the adult human brain.

The discovery, in 1998, that the adult human brain contains at least two populations of progenitor cells and that progenitor cells are upregulated in response to a range of degenerative brain diseases has raised hopes for their use in replacing dying brain cells. Since these early findings the race has been on to understand the biology of progenitor cells in the human brain and they have now been isolated and studied in many major neurodegenerative diseases. Before these cells can be exploited for cell replacement purposes it is important to understand how to: (1) find them, (2) label them, (3) determine what receptors they express, (4) isolate them, and (5) examine their electrophysiological properties when differentiated.

M-CSF increases proliferation and phagocytosis while modulating receptor and transcription factor expression in adult human microglia.

Background: Microglia are the primary immune cells of the brain whose phenotype largely depends on their surrounding micro-environment. Microglia respond to a multitude of soluble molecules produced by a variety of brain cells. Macrophage colony-stimulating factor (M-CSF) is a cytokine found in the brain whose receptor is expressed by microglia.

The transcription factor PU.1 is critical for viability and function of human brain microglia.

Microglia are the predominant resident immune cells of the brain and can assume a range of phenotypes. They are critical for normal brain development and function but can also contribute to many disease processes. Although they are widely studied, the transcriptional control of microglial phenotype and activation requires further research.

Adult human brain neural progenitor cells (NPCs) and fibroblast-like cells have similar properties in vitro but only NPCs differentiate into neurons.

The ability to culture neural progenitor cells from the adult human brain has provided an exciting opportunity to develop and test potential therapies on adult human brain cells. To achieve a reliable and reproducible adult human neural progenitor cell (AhNPC) culture system for this purpose, this study fully characterized the cellular composition of the AhNPC cultures, as well as the possible changes to this in vitro system over prolonged culture periods. We isolated cells from the neurogenic subventricular zone/hippocampus (SVZ/HP) of the adult human brain and found a heterogeneous culture population comprised of several types of post-mitotic brain cells (neurons, astrocytes, and microglia), and more importantly, two distinct mitotic cell populations; the AhNPCs, and the fibroblast-like cells (FbCs).

Valproic acid induces microglial dysfunction, not apoptosis, in human glial cultures.

Valproic acid (VPA) is widely used for the treatment of mood disorders and epilepsy, but its mechanism of action is unclear. In vivo and in vitro studies using rodent models have demonstrated that VPA has both neuroprotective and neurotrophic effects. These beneficial effects are, in part, through modulation of glial cell function.

Cellular composition of human glial cultures from adult biopsy brain tissue.

Microglia and astrocytes play vital roles in normal human brain function and in neurological disorders. To study their physiological and pathological roles it is desirable to establish in vitro systems that are derived from the adult human brain. Although several groups have successfully cultured cells from the human brain, the composition of these cultures remains controversial.

High throughput quantification of cells with complex morphology in mixed cultures.

Automated image-based and biochemical assays have greatly increased throughput for quantifying cell numbers in in vitro studies. However, it has been more difficult to automate the counting of specific cell types with complex morphologies in mixed cell cultures. We have developed a fully automated, fast, accurate and objective method for the quantification of primary human GFAP-positive astrocytes and CD45-positive microglia from images of mixed cell populations.