title: Astrocytes shed large membrane vesicles that contain mitochondria, lipid droplets and ATP.
abstract: Various cells types, including stem and progenitor cells, can exchange complex information via plasma membrane-derived vesicles, which can carry signals both in their limiting membrane and lumen. Astrocytes, traditionally regarded as mere supportive cells, play previously unrecognized functions in neuronal modulation and are capable of releasing signalling molecules of different functional significance. In the present study, we provide direct evidence that human fetal astrocytes in culture, expressing the same feature as immature and reactive astrocytes, release membrane vesicles larger than the microvesicles described up to now. We found that these large vesicles, ranging from 1-5 to 8 μm in diameter and expressing on their surface β1-integrin proteins, contain mitochondria and lipid droplets together with ATP. We documented vesicle content with fluorescent-specific dyes and with the immunocytochemistry technique we confirmed that mitochondria and lipid droplets were co-localized in the same vesicle. Scanning electron microscopy and transmission electron microscopy confirmed that astrocytes shed from surface membrane vesicles of the same size as the ones detected by fluorescence microscopy. Our results report for the first time that cultured astrocytes, activated by repetitive stimulation of ATP released from neighboring cells, shed from their surface large membrane vesicles containing mitochondria and lipid droplets.
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria Monserrato, 09042 Monserrato, CA, Italy. amfalchi@unica.it
authors.forename: Angela Maria
authors.initials: AM
authors.lastname: Falchi
authors.forename: Valeria
authors.initials: V
authors.lastname: Sogos
authors.forename: Francesca
authors.initials: F
authors.lastname: Saba
authors.forename: Monica
authors.initials: M
authors.lastname: Piras
authors.forename: Terenzio
authors.initials: T
authors.lastname: Congiu
authors.forename: Marco
authors.initials: M
authors.lastname: Piludu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D022162:Cytoplasmic Vesicles / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008055:Lipids / Q000737:chemistry*; D008928:Mitochondria / Q000378:metabolism*; D010316:Particle Size
chemical_list: D008055:Lipids; D000255:Adenosine Triphosphate