title: Osteoarthritic cartilage loses its ability to remain avascular.
abstract: OBJECTIVE
  To determine whether human osteoarthritic (OA) cartilage loses its ability to remain avascular when placed into the in-vivo model of angiogenesis, the chick embryo chorio-allantoic membrane (CAM), and to determine specific changes that occur in the cartilage matrix when the cartilage is exposed to an active vasculature.
  
  
  METHODS
  Articular cartilage from OA and non-OA joints was grafted onto the CAM for up to 5 days before fixing and processing for histological, histochemical and immunological examination for specific changes in proteoglycan and collagen.
  
  
  RESULTS
  OA cartilage, but not non-OA cartilage, showed invasion of its matrix by blood vessels from the CAM to various extents. Associated with these blood vessels was a loss of staining for proteoglycans and cartilage specific glycosaminoglycans (GAG). A deposition of collagen types I and X was also visualized around the invasive vessels.
  
  
  CONCLUSIONS
  OA cartilage loses or has already lost its ability to remain avascular when placed onto the chick CAM. Changes occur in the matrix around the invasive blood vessels, specifically a loss of proteoglycan and GAG, and the deposition of new collagen types, notably I and X.
authors.affiliation: Glenfield Hospital NHS Trust, University of Leicester, Groby Road, Leicester, LE3 9QP.
authors.forename: S A
authors.initials: SA
authors.lastname: Fenwick
authors.forename: P J
authors.initials: PJ
authors.lastname: Gregg
authors.forename: P
authors.initials: P
authors.lastname: Rooney
mesh_terms: D000368:Aged; D000818:Animals; D002358:Cartilage, Articular / Q000098:blood supply* / Q000378:metabolism / Q000637:transplantation; D002642:Chick Embryo; D003094:Collagen / Q000378:metabolism; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology*; D020370:Osteoarthritis, Knee / Q000378:metabolism / Q000473:pathology*; D011509:Proteoglycans / Q000378:metabolism
chemical_list: D006025:Glycosaminoglycans; D011509:Proteoglycans; D003094:Collagen