ALBERT

Description:    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 β 1-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. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00418-012-1045-x Authors Angela Maria Falchi, Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria Monserrato, 09042 Monserrato, CA, Italy Valeria Sogos, Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria Monserrato, 09042 Monserrato, CA, Italy Francesca Saba, Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria Monserrato, 09042 Monserrato, CA, Italy Monica Piras, Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria Monserrato, 09042 Monserrato, CA, Italy Terenzio Congiu, Department of Surgical and Morphological Sciences, University of Insubria, 21100 Varese, Italy Marco Piludu, Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria Monserrato, 09042 Monserrato, CA, Italy Journal Histochemistry and Cell Biology Online ISSN 1432-119X Print ISSN 0948-6143