Community Research and Development Information Service - CORDIS

Human intervertebral disc aggrecan inhibits endothelial cell adhesion and cell migration

Study Design.
The effect of human intervertebral disc aggrecan on endothelial cell growth was examined using cell culture assays.

Objectives.
To determine the response of endothelial cells to human intervertebral disc aggrecan and whether the amount and type of aggrecan present in the intervertebral disc may be implicated in disc vascularisation.

Summary of Background Data.
Intervertebral disc degeneration has been associated with a loss of proteoglycan and the ingrowth of blood vessels and nerves. Neovascularisation is a common feature also of disc herniation. Intervertebral disc aggrecan is inhibitory to sensory nerve growth, but the effects of disc aggrecan on endothelial cell growth are not known.

Methods.
Aggrecan monomers were isolated separately from the anulus fibrosi (AF) and nucleus pulposi (NP) of human lumbar intervertebral discs and characterised to determine the amount and type of glycosaminoglycan (GAG) sidechains present. The effects of these aggrecan isolates on the cellular adhesion and migration of the human endothelial cell lines, HMEC-1 and EAhy-926, were examined in vitro.

Results.
Homogenous substrata of disc aggrecan inhibited endothelial cell adhesion and cell spreading in a concentration-dependent manner. In substrata choice assays, endothelial cells seeded onto collagen type I migrated over the collagen until they encountered substrata of disc aggrecan, where they either stopped migrating, retreated onto the collagen, or, more commonly, changed direction to align along the collagen: aggrecan border. The inhibitory effect of aggrecan on endothelial cell migration was concentration-dependent and reduced by enzymic deglycosylation of the aggrecan monomers. AF aggrecan was more inhibitory to endothelial cell adhesion than NP aggrecan. This difference did not relate, however, to the extent to which the different aggrecan isolates were glycosylated or to marked differences in the relative levels of the GAG sidechains, chondroitin sulphate and keratan sulphate.

Conclusions.
Human intervertebral disc aggrecan is inhibitory to endothelial cell migration and this inhibitory effect appears to depend, in part, on the presence of GAG sidechains on the aggrecan monomer.

Reported by

THE ROBERT JONES AND AGNES HUNT ORTHOPAEDIC AND DISTRICT HOSPITAL NHS TRUST
Shropshire
SY10 7AG OSWESTRY
United Kingdom
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