BIOLOGIC DETERMINANTS OF DYSTROPHIC CALCIFICATION AND OSTEOCALCIN DEPOSITION IN GLUTARALDEHYDE-PRESERVED PORCINE AORTIC-VALVE LEAFLETS IMPLANTED SUBCUTANEOUSLY IN RATS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 113  (2) , 143-155
Abstract
Bioprosthetic cardiac valve calcification is a frequent complication after long-term valve replacement. The biologic determinants of this type of dystrophic calcification were examined using subcutaneous implants of glutaraldehyde-preserved porcine aortic valve leaflets (GPV) in rats. GPV and clinical valvular bioprostheses were prepared identically. Retrieved implants were examined for calcification and the deposition of osteocalcin (OC), a vitamin K-dependent, bone-derived protein, that is found in other dystrophic and ectopic calcifications. GPV implanted in 3 wk old rats calcified progressively (GPV Ca2+, 122.9 .+-. 6.0 .mu.g/mg) after 21 days, with mineral deposition occurring in a morphologic pattern comparable to that noted in clinical retrievals. Calcified GPV accumulated osteocalcin (OC, 183.4 .+-. 19.4 ng/mg); Nonpreserved porcine aortic leaflet implants did not calcify (Ca2+ + 5.6 .+-. 1.0 .mu.g/mg). Millipore diffusion chamber (0.45-.mu. pore size) enclosed GPV implants, accumulated Ca and adsorbed osteocalcin despite the absence of attached host cells. GPV implanted for 21 days in 8 mo. old rats calcified less (GPV Ca2+, 22.4 .+-. 5.0 .mu.g/mg) than did GPV implanted in 3 wk old rats. High-dose warfarin therapy (80 mg/kg) did not alter GPV calcification (GPV Ca2+, 39.6 .+-. 2.9 .mu.g/mg) in 72 h subcutaneous implants in 3 wk old male rats, compared with control rats (GPV Ca2+, 40.8 .+-. 4.8 .mu.g/mg).