title: Microglia in Glia-Neuron Co-cultures Exhibit Robust Phagocytic Activity Without Concomitant Inflammation or Cytotoxicity.
abstract: A simple method to co-culture granule neurons and glia from a single brain region is described, and microglia activation profiles are assessed in response to naturally occurring neuronal apoptosis, excitotoxin-induced neuronal death, and lipopolysaccharide (LPS) addition. Using neonatal rat cerebellar cortex as a tissue source, glial proliferation is regulated by omission or addition of the mitotic inhibitor cytosine arabinoside (AraC). After 7-8 days in vitro, microglia in AraC(-) cultures are abundant and activated based on their amoeboid morphology, expressions of ED1 and Iba1, and ability to phagocytose polystyrene beads and the majority of neurons undergoing spontaneous apoptosis. Microglia and phagocytic activities are sparse in AraC(+) cultures. Following exposure to excitotoxic kainate concentrations, microglia in AraC(-) cultures phagocytose most dead neurons within 24 h without exacerbating neuronal loss or mounting a strong or sustained inflammatory response. LPS addition induces a robust inflammatory response, based on microglial expressions of TNF-α, COX-2 and iNOS proteins, and mRNAs, whereas these markers are essentially undetectable in control cultures. Thus, the functional effector state of microglia is primed for phagocytosis but not inflammation or cytotoxicity even after kainate exposure that triggers death in the majority of neurons. This model should prove useful in studying the progressive activation states of microglia and factors that promote their conversion to inflammatory and cytotoxic phenotypes.
authors.affiliation: Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.|Department of Pulmonary and Critical Care, Mount Sinai Beth Israel Medical Center, New York, NY, 10003, USA.
authors.forename: Alexandra C
authors.initials: AC
authors.lastname: Adams
authors.affiliation: Department of Neurosurgery, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
authors.forename: Michele
authors.initials: M
authors.lastname: Kyle
authors.affiliation: Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
authors.forename: Carol M
authors.initials: CM
authors.lastname: Beaman-Hall
authors.affiliation: Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.|Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213, USA.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Monaco
authors.affiliation: Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.|Department of Anesthesiology, Phelps Memorial Hospital Center, Sleepy Hollow, NY, 10591, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Cullen
authors.affiliation: Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA. vallanom@upstate.edu.
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Vallano
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D018920:Coculture Techniques / Q000379:methods; D003603:Cytotoxins / Q000633:toxicity*; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003603:Cytotoxins
keywords: Co-cultures; Excitotoxicity; Inflammation; Microglia; Phagocytosis