Impaired induction of blood-brain barrier properties in aortic endothelial cells by astrocytes from GFAP-deficient mice.
Cell culture models have been extensively used for studies of blood-brain barrier (BBB) function. However, most in vitro models fail to reproduce the peculiar physiological and morphological properties of in situ brain microvascular endothelial cells. A recently developed, tridimensional and dynamic model of the BBB has permitted studies of glial-endothelial interactions in hollow fibers exposed to intraluminal flow. We have taken advantage of this technique and have investigated the ability of glial fibrillary acidic protein (GFAP)-deficient (GFAP-/-) astrocytes to induce BBB properties in aortic endothelial cells (BAEC) cultured in vitro. BAEC exposed to flow were seeded intraluminally in hollow fibers and co-cultured with extraluminally seeded mouse astrocytes. Under these conditions, astrocytes have been shown to induce blood-brain barrier properties in non-brain endothelial cells. We followed induction of a BBB phenotype by measuring the transendothelial resistance, as well as endothelial permeability to potassium, theophylline, 8-sulphophenyl-theophylline (8-SPT), sucrose, and Evans blue. Wild-type mouse astrocytes induced BBB properties in aortic endothelial cells following 3-4 weeks of co-culturing. Thus, these endothelial cells restricted passage of K+ ions into the extracapillary space and selectively excluded hydrophilic molecules, such as 8-SPT and 14C-sucrose. GFAP-/- astrocytes failed to induce a significant restriction to the passage of potassium and hydrophilic drugs (sucrose, 8-SPT), failed to induce transendothelial resistance values comparable to control co-cultures, but were capable of inducing exclusion of Evans blue by endothelial cells. These results suggest that GFAP (and intermediate filaments) may play a role in the induction of BBB properties in non-BBB endothelial cells.
Pekny
M
M
Department of Medical Biochemistry, University of Göteborg, Sweden.
Stanness
K A
KA
Eliasson
C
C
Betsholtz
C
C
Janigro
D
D
D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000502:physiology; D001253:Astrocytes / Q000502:physiology*; D001812:Blood-Brain Barrier / Q000502:physiology*; D002417:Cattle; D002463:Cell Membrane Permeability / Q000502:physiology; D004553:Electric Conductivity; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D005070:Evans Blue; D005904:Glial Fibrillary Acidic Protein / Q000172:deficiency*; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D011188:Potassium / Q000378:metabolism
D005904:Glial Fibrillary Acidic Protein; D005070:Evans Blue; D011188:Potassium