Anti-SDC1 monoclonal antibody, clone NJ26 [FITC]

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 mu m (N = 15), as compared with 0.54 +/- 0.12 mu m (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. (C) 2013 Elsevier Inc. All rights reserved.

Stromal fibroblasts of breast carcinomas frequently express the cell surface proteoglycan syndecan-1 (Sdc1). In human breast carcinoma samples, stromal Sdc1 expression correlates with an organized, parallel, extracellular matrix (ECM) fiber architecture. To examine a possible link between stromal Sdc1 and the fiber architecture, we generated bioactive cell-free three-dimensional ECMs from cultures of Sdc1-positive and Sdc1-negative murine and human mammary fibroblasts (termed ECM-Sdc1 and ECM-mock, respectively). Indeed, ECM-Sdc1 showed a parallel fiber architecture that contrasted markedly with the random fiber arrangement of ECM-mock. When breast carcinoma cells were seeded into the fibroblast-free ECMs, ECM-Sdc1, but not ECM-mock, promoted their attachment, invasion, and directional movement. We further evaluated the contribution of the structural/compositional modifications in ECM-Sdc1 on carcinoma cell behavior. By microcontact printing of culture surfaces, we forced the Sdc1-negative fibroblasts to produce ECM with parallel fiber organization, mimicking the architecture observed in ECM-Sdc1. We found that the fiber topography governs carcinoma cell migration directionality. Conversely, an elevated fibronectin level in ECM-Sdc1 was responsible for the enhanced attachment of the breast carcinoma cells. These observations suggest that Sdc1 expression in breast carcinoma stromal fibroblasts promotes the assembly of an architecturally abnormal ECM that is permissive to breast carcinoma directional migration and invasion. (An: J Pathol 2011, 178:325-335; DOI: 10.1016/j.ajpath.2010.11.039)