title: The endothelial glycocalyx in syndecan-1 deficient mice.
abstract: The existence of a hydrodynamically relevant endothelial glycocalyx has been established in capillaries, venules, and arterioles in vivo. The glycocalyx is thought to consist primarily of membrane-bound proteoglycans with glycosaminoglycan side-chains, membrane-bound glypicans, and adsorbed plasma proteins. The proteoglycans found on the luminal surface of endothelial cells are syndecans-1, -2, and -4, and glypican-1. The extent to which any of these proteins might serve to anchor the glycocalyx to the endothelium has not yet been determined. To test whether syndecan-1, in particular, is an essential anchoring protein, we performed experiments to determine the hydrodynamically relevant glycocalyx thickness in syndecan-1 deficient (Sdc1(-/-)) mice. Micro-particle image velocimetry data were collected using a previously described method. Microviscometric analysis of these data consistently revealed the existence of a hydrodynamically relevant endothelial glycocalyx in Sdc1(-/-) mice in vivo. The mean glycocalyx thickness found in Sdc1(-/-) mice was 0.45±0.10 μm (N=15), as compared with 0.54±0.12 μm (N=11) in wild-type (WT) mice (p=0.03). The slightly thinner glycocalyx observed in Sdc1(-/-) mice relative to WT mice may be due to the absence of syndecan-1. These findings show that healthy Sdc1(-/-) mice are able to synthesize and maintain a hydrodynamically relevant glycocalyx, which indicates that syndecan-1 is not an essential anchoring protein for the glycocalyx in Sdc1(-/-) mice. This may also be the case for WT mice; however, Sdc1(-/-) mice might adapt to the lack of syndecan-1 by increasing the expression of other proteoglycans. In any case, syndecan-1 does not appear to be a prerequisite for the existence of an endothelial glycocalyx.
authors: Boston University, Department of Biomedical Engineering, Boston, MA 02215, USA. mdsavery@gmail.com
authors: Michele D
authors: MD
authors: Savery
authors: John X
authors: JX
authors: Jiang
authors: Pyong Woo
authors: PW
authors: Park
authors: Edward R
authors: ER
authors: Damiano
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D002448:Cell Adhesion; D042783:Endothelial Cells / Q000378:metabolism*; D019276:Glycocalyx / Q000378:metabolism*; D057446:Hydrodynamics; D016018:Least-Squares Analysis; D007962:Leukocytes / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D017711:Nonlinear Dynamics; D012039:Regional Blood Flow; D053668:Syndecan-1 / Q000172:deficiency* / Q000235:genetics; D014699:Venules / Q000166:cytology / Q000378:metabolism*
chemical_list: C508242:Sdc1 protein, mouse; D053668:Syndecan-1