Regulation of cerebral endothelial cell morphology by extracellular calcium

Abstract

Cerebral endothelial cells interconnected by tight and adherens junctions constitute the structural basis of the blood-brain barrier. Extracellular calcium ions have been reported to play an important role in the formation and maintenance of the junctional complex. However, little is known about the action of calcium depletion on the structural characteristics of cerebral endothelial cells. Using atomic force microscopy we analyzed the effect of calcium depletion and readdition on the shape and size of living brain endothelial cells. It was found that the removal of extracellular calcium from confluent cell cultures induced the dissociation of the cells from each other accompanied by an increase in their height. After readdition of calcium a gradual recovery was observed until total confluency was regained. We have also demonstrated that Rho-kinase plays an important role in the calcium-depletion-induced disassembly of endothelial tight and adherens junctions. The Rho-kinase inhibitor Y27632 could prevent the morphological changes induced by a lack of calcium as well. Our results suggest that calcium depletion induces Rho-kinase-dependent cytoskeletal changes that may be partly responsible for the disassembly of the junctional complex.

The effect of cross-linking on the microstructure, mechanical properties and biocompatibility of electrospun polycaprolactone–gelatin/PLGA–gelatin/PLGA–chitosan hybrid composite

“…These results indicate that the chitosan-chitosan and gelatin-gelatin fibers interacted and bonded during the cross-linking process. Previous reports described a phenomenon in which the fibers were curled and conglutinated with each other after cross-linking [26,30]. The inset images show the morphology of the ABV scaffold before and after cross-linking at the failure section.…”

Nano-biomechanical investigation of living endothelial cells

“…These proteins can be divided into four families: the immunoglobulin-like adhesion molecules, integrins, cadherins and selectins (Buckley et al 1998). Except the first, all are calcium dependent, hence extracellular calcium plays key role in cell-cell adhesion (Wilhelm et al 2007). …”

“…CECs are very sensitive to environmental changes (Wilhelm et al 2008;Wilhelm et al 2007), therefore in some pathological cases their mechanical modulation can reversibly open the BBB (Bálint et al 2007a). Circulating factors within the blood can alter their mechanical properties (Lee et al 2011).…”

“…Human cerebral endothelial cells (hCMEC/D3 -shortly D3) were grown on rat tail collagen-coated dishes in EBM-2 medium (Lonza) supplemented with EGM-2 Bullet Kit (Lonza) and 2.5% FBS from Sigma (Wilhelm et al 2008;Wilhelm et al 2007). B16/F10 melanoma cells were kept in RPMI medium (Sigma) supplemented with Glutamax and 5% of Fetal Bovine Serum (FBS) from Lonza.…”

Endothelial-melanoma cell interactions in the formation of brain metastases

“…Brain endothelial tight junction proteins, which were shown to be involved in the transmigration of melanoma cells, are linked to the actin cytoskeleton and are influenced by ROCKs. Inhibition of Rho/ROCK signaling has been shown to prevent Ca 2+ -induced junctional disassembly in both epithelial and brain endothelial cells (Samarin et al 2007, Wilhelm et al 2007). ROCK enhances BBB permeability via disruption of tight junction proteins in subarachnoid hemorrhage (Fujii et al 2012), while inhibition of ROCK was found to attenuate the HIV-1 Tat protein-induced decrease in occludin levels in brain endothelial cells (Xu et al 2012).…”