Loss of chondroitin 6-sulfate and hyaluronan from failed porcine bioprosthetic valves.
Explanted porcine bioprosthetic valves have a thinned spongiosa, partially because of an overall loss of glycosaminoglycans (GAGs). We measured the concentrations of specific GAG classes in explanted bioprosthetic valves (n = 14, implanted 12.0 +/- 4.7 years) compared with glutaraldehyde-fixed porcine controls. After extraction with NaOH, GAGs were analyzed using either a hexuronic acid assay or fluorophore-assisted carbohydrate electrophoresis to quantify the individual GAG classes. The total GAG concentration in explants was 198 +/- 95 pmol/mg wet weight-93% less than freshly fixed controls. Explants also contained altered proportions of the different GAG classes relative to controls. The proportions of hyaluronan and chondroitin/dermatan-6-sulfate were reduced from 39 to 7% and 34 to 18% of total GAGs, respectively. The predominant explant GAG class was chondroitin/dermatan-4-sulfate (proportion elevated from 14 to 70%). This GAG is commonly found in the collagen-associated proteoglycan decorin, which is likely well crosslinked by glutaraldehyde. Chondroitin-6-sulfate is commonly found in the water- and hyaluronan-binding proteoglycan versican, which is likely poorly crosslinked. The loss of versican and its associated water-binding capacity is consistent with the thinned spongiosa. The resultant compromise of hydration, compressive resistance, and viscoelasticity may be responsible for the deterioration of the bioprosthesis in vivo.
Grande-Allen
K Jane
KJ
Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Mako
W John
WJ
Calabro
Anthony
A
Shi
Yaling
Y
Ratliff
Norman B
NB
Vesely
Ivan
I
D000818:Animals; D001705:Bioprosthesis; D002809:Chondroitin Sulfates / Q000737:chemistry*; D004586:Electrophoresis; D006025:Glycosaminoglycans / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006820:Hyaluronic Acid / Q000737:chemistry*; D008422:Materials Testing; D023421:Models, Animal; D011475:Prosthesis Failure; D015203:Reproducibility of Results; D013552:Swine
D006025:Glycosaminoglycans; D006820:Hyaluronic Acid; D002809:Chondroitin Sulfates