Changes induced by hyperosmotic mannitol in cerebral endothelial cells: an atomic force microscopic study

• Published in: European biophysics journal 2007-02, Vol.36 (2), p.113-120
• Main Authors: Bálint, Zoltán, Krizbai, István A, Wilhelm, Imola, Farkas, Attila E, Párducz, Arpád, Szegletes, Zsolt, Váró, György
• Format: Article
• Language: English
• Subjects: Animals; Atomic force microscopes; Atomic force microscopy; Blood-brain barrier; Brain - cytology; Brain - drug effects; Brain - physiology; Cell culture; Cell Size - drug effects; Cells; Cells, Cultured; Dose-Response Relationship, Drug; Elasticity; Endothelial cells; Endothelial Cells - cytology; Endothelial Cells - drug effects; Endothelial Cells - physiology; Force measurement; Imaging techniques; Mannitol; Mannitol - administration & dosage; Mechanical properties; Membrane Fluidity - drug effects; Membrane Fluidity - physiology; Microscopy, Atomic Force - methods; Modulus of elasticity; Neuroimaging; Osmotic Pressure - drug effects; Proteins; Rats; Stress, Mechanical; Surface structure
• ISSN: 0175-7571; 1432-1017
• DOI: 10.1007/s00249-006-0112-4

Understanding the reaction of living cells in response to different extracellular stimuli, such as hyperosmotic stress, is of primordial importance. Mannitol, a cell-impermeable non-toxic alcohol, has been used successfully for reversible opening of the blood-brain barrier in hyperosmotic concentrations. In this study we analyzed the effect of hyperosmotic mannitol on the shape and surface structure of living cerebral endothelial cells by atomic force microscope imaging technique. Addition of clinically relevant concentrations of mannitol to the culture medium of the confluent cells induced a decrease of about 40% in the observed height of the cells. This change was consistent both at the nuclear and peripheral region of the cells. After mannitol treatment even a close examination of the contact surface between the cells did not reveal gap between them. We could observe the appearance of surface protrusions of about 100 nm. By force measurements the elasticity of the cells were estimated. While the Young's modulus of the control cells appeared to be 8.04 +/- 0.12 kPa, for the mannitol-treated cells it decreased to an estimated value of 0.93 +/- 0.04 kPa which points to large structural changes inside the cell.