title: Human astrocytes develop physiological morphology and remain quiescent in a novel 3D matrix.
abstract: Astrocytes are the most abundant glial cells in the brain and are responsible for diverse functions, from modulating synapse function to regulating the blood-brain barrier. In vivo, these cells exhibit a star-shaped morphology with multiple radial processes that contact synapses and completely surround brain capillaries. In response to trauma or CNS disease, astrocytes become activated, a state associated with profound changes in gene expression, including upregulation of intermediate filament proteins, such as glial fibrillary acidic protein (GFAP). The inability to recapitulate the complex structure of astrocytes and maintain their quiescent state in vitro is a major roadblock to further developments in tissue engineering and regenerative medicine. Here, we characterize astrocyte morphology and activation in various hydrogels to assess the feasibility of developing a matrix that mimics key aspects of the native microenvironment. We show that astrocytes seeded in optimized matrix composed of collagen, hyaluronic acid, and matrigel exhibit a star-shaped morphology with radial processes and do not upregulate GFAP expression, hallmarks of quiescent astrocytes in the brain. In these optimized gels, collagen I provides structural support, HA mimics the brain extracellular matrix, and matrigel provides endothelial cell compatibility and was found to minimize GFAP upregulation. This defined 3D microenvironment for maintaining human astrocytes in vitro provides new opportunities for developing improved models of the blood-brain barrier and studying their response to stress signals.
authors.affiliation: Department of Materials Science and Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA; Institute for Nanobiotechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Placone
authors.affiliation: Department of Materials Science and Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: McGuiggan
authors.affiliation: Institute for Nanobiotechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, 855 North Wolfe Street, Baltimore, MD 21218, USA.
authors.forename: Dwight E
authors.initials: DE
authors.lastname: Bergles
authors.affiliation: Department of Neurosurgery, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Hugo
authors.initials: H
authors.lastname: Guerrero-Cazares
authors.affiliation: Department of Neurosurgery, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Quiñones-Hinojosa
authors.affiliation: Department of Materials Science and Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA; Institute for Nanobiotechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA. Electronic address: searson@jhu.edu.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Searson
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D060833:Cellular Microenvironment / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology; D004338:Drug Combinations; D055119:Elastic Modulus / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D006820:Hyaluronic Acid / Q000494:pharmacology; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology; D007797:Laminin / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D011509:Proteoglycans / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
chemical_list: D004338:Drug Combinations; D005904:Glial Fibrillary Acidic Protein; D007797:Laminin; D011509:Proteoglycans; C059485:matrigel; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D006820:Hyaluronic Acid; D003094:Collagen
keywords: Activation; Astrocytes; Extracellular matrix; GFAP expression; Hydrogel