title: Fine characterization of mitral valve glycosaminoglycans and their modification with degenerative disease.
abstract: BACKGROUND
  The levels and fine structure of complex polysaccharides, glycosaminoglycans (GAGs), were determined in segments of the posterior mitral valve leaflet (MVL) taken from 15 patients affected by mitral regurgitation and degenerative disease and were compared with segments from 15 multiorgan donors.
  
  
  METHODS
  MVL GAGs were analyzed by agarose gel electrophoresis, and by HPLC and fluorophore-assisted carbohydrate electrophoresis to evaluate disaccharide patterns after treatment with chondroitinase ABC.
  
  
  RESULTS
  GAGs from the control group were composed of approximately 37% hyaluronic acid and 63% chondroitin sulfate/dermatan sulfate with a charge density of approximately 0.61. Chondroitin sulfate/dermatan sulfate polymers contained approximately 23% of the disaccharide sulfated in position 6 on N-acetyl-galactosamine, approximately 38% of the 4-sulfated disaccharide and approximately 2% of the non-sulfated disaccharide (with a 4-sulfated/6-sulfated ratio of 1.7). The total amount of GAGs was 0.66 microg/mg tissue. The total amount of GAGs in patients suffering from mitral regurgitation and degenerative disease was approximately 51.5% higher (although the difference was not significant, probably because of the low number of subjects enrolled in the study). However, significantly higher hyaluronic acid content (approx. +38%, p<0.05) and lower sulfated GAG content (approx. -21%, p<0.005) were demonstrated. As a consequence, the total charge density decreased by approximately 23% (p<0.005). This macro-modification of GAG composition was also followed by a micro-alteration of the structure of the sulfated polysaccharides, in particular with a significant decrease in the 4-sulfated disaccharide (and a parallel increase in hyaluronic acid content) with no modification of the percentage of the 6-sulfated and non-sulfated disaccharides (with a significant decrease in the 4-/6-sulfated ratio).
  
  
  CONCLUSIONS
  We assume that changes in the relative amount and distribution of GAGs in posterior MVL in subjects suffering from mitral regurgitation and degenerative disease are consistent with a decrease in the tension to which these tissues are subjected and with an abnormal matrix microstructure capable of influencing the hydration and of conditioning the mechanical weakness of these pathological tissues.
authors: Department of Cardiac and Vascular Surgery, Centro Cardiologico Monzino, IRCCS University of Milan, Milan, Italy.
authors: Luca
authors: L
authors: Dainese
authors: Gianluca
authors: G
authors: Polvani
authors: Fabio
authors: F
authors: Barili
authors: Francesca
authors: F
authors: Maccari
authors: Anna
authors: A
authors: Guarino
authors: Francesco
authors: F
authors: Alamanni
authors: Marco
authors: M
authors: Zanobini
authors: Paolo
authors: P
authors: Biglioli
authors: Nicola
authors: N
authors: Volpi
mesh_terms: D002809:Chondroitin Sulfates / Q000032:analysis / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D003871:Dermatan Sulfate / Q000032:analysis / Q000302:isolation & purification; D004586:Electrophoresis; D004587:Electrophoresis, Agar Gel; D006025:Glycosaminoglycans / Q000032:analysis* / Q000302:isolation & purification; D006801:Humans; D006820:Hyaluronic Acid / Q000032:analysis / Q000302:isolation & purification; D008943:Mitral Valve / Q000737:chemistry*; D012016:Reference Values
chemical_list: D006025:Glycosaminoglycans; D003871:Dermatan Sulfate; D006820:Hyaluronic Acid; D002809:Chondroitin Sulfates