Effects Of Simulated Microgravity On Morphology Of Human Brain Nervous Tissue

During spaceflight, space microgravity effects on astronauts problems were moreprominent, especially the nervous system problems should be solved. To establish possiblelinks with astronauts’ neurophysiological changes in flights, better understand andsafeguard human, and provide some research data for the human space exploration, aground simulated microgravity study on nerve tissue morphology was carried out.Experimental methods: Mechanically separated the nervous tissues obtained fromsurgical brain cancer patients, then cultured following by cell and tissue explant methods.After7days, cultured plates were randomly divided into two groups, one group for staticculture, and another for rotary processing1day,3days,5days,7days and14days. Aftertreatment, Cultures of the two groups were thereafter collected at each time point forsubsequent detection. The morphology and ultrastructure changes of cells and tissue blockswere observed under inverted microscope and transmission electron microscopy, and thecell surface micro topography and attachment situation were watched by scanning electronmicroscopy. The distribution of cytoskeleton with immunofluorescence analysis werevisualized by laser confocal scanning microscope, using TRITC-conjugated secondaryantibody detected β-tubulin, and the cytochemical labeling phalloidin-FITC for F-actin.Moreover, Hoechst-PI double staining measured cell apoptosis and TMR-Red Tunneldetection for paraffin sections. The cells were stained with Annexin-V Labeled FITC, andthe apoptotic rate was detected by flowcytometry.Results: Inverted microscope revealed that, short-time treatment for1day and3days,cells and tissue explants morphologies have not changed obviously. When the rotary timeextended to7days and14days, cell somas became significantly larger, adhesion abilitywas decline. And that, the substrate accompanied by small cell fragments. Explant culturelost radial ‘growth halo’ around tissues, the arrangement of cells migrated from tissue blockwas disorganized, and the migration distance was shorter. The14days rotary group undertransmission electron microscopy showed that, organelle structures became fewer incytoplasm, mitochondrial cristae were clear and disassociated with each other, and largevacuoles produced.14days rotation scanning images showed, cells completely lost triangleshapes, and only a layer of membrane remaining attached to the substrate. Laser scanningconfocal microscopy showed that the β-tubulin and F-actin were expressed abundantly of control group, appearing as thick tubulin filaments organized into bundles, while F-actinand β-tubulin in rotary group were highly disorganized, and significantly decreased inexpression. F-actin formed a loop around the nucleus. Even, the nucleus dissociated intoseveral micronuclei. Advanced cell apoptosis was examined by flow cytometry, showedthat, the apoptotic cells rate in14days rotary group (24.7%) was higher than that ofsynchronous control group (10.5%).Conclusions: Simulated microgravity treatment for a week affects the morphologyand ultrastructure of nervous tissue cells, and cause highly disorganized distribution ofcytoskeleton, with the increasing of cell apoptosis. These morphological changes could beone of the mechanisms for subsequent apoptosis induced by simulated microgravity effects.