Determinants of calcium uptake of bovine pericardium for heart valve replacement: results of in vitro studies.
OBJECTIVE
Reduction of biomaterial calcification is an important aim in the basic research of biological heart valves. An in vitro model was used to investigate the influence of serum calcium concentration and surface coverage with cells or basal proteins on calcium uptake of bovine pericardium.


METHODS
Samples of glutaraldehyde-tanned bovine pericardium, stored in formaldehyde and detoxified with borohydride were incubated for two weeks with cell culture medium containing low (1.0 mmol/l) or physiologic (2.3 mmol Ca/l) calcium concentration. Specimens were either unseeded, completely surface-covered with rat fibrocytes (rf) or fibrin (fi), or incompletely seeded with rabbit cells (re). Quality of surface coverage was assessed by surface scanning electron microscopy and calcium content by atomic absorption spectroscopy.


RESULTS
Serum calcium had a significant influence on calcium uptake (low versus physiological (1.58 +/- 2.45 mg/g versus 8.10 +/- 1.73 mg/g wet wt, p < 0.001). This may explain early calcification of bioimplants in children and patients on dialysis. Surface coverage significantly reduces calcium uptake (fi, 1.20 +/- 0.41 mg/g, rf, 4.20 +/- 1.70 mg/g, p < 0.001) but complete coverage is necessary (re, 6.98 +/- 1.64 mg/g, NS).


CONCLUSIONS
In vitro testing of calcium uptake has proven to be a valuable tool for evaluation of biomaterial calcification.
Dahm
M
M
Department of Cardiothoracic and Vascular Surgery, University Hospital Mainz, Germany.
Dohmen
G
G
Prüfer
D
D
Krummenauer
F
F
Hafner
G
G
Oelert
H
H
D000818:Animals; D001672:Biocompatible Materials; D001705:Bioprosthesis / Q000009:adverse effects*; D002114:Calcinosis / Q000209:etiology / Q000517:prevention & control*; D002118:Calcium / Q000493:pharmacokinetics*; D009202:Cardiomyopathies / Q000209:etiology / Q000517:prevention & control*; D002417:Cattle; D002478:Cells, Cultured; D003470:Culture Media; D004195:Disease Models, Animal; D005337:Fibrin / Q000648:ultrastructure; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D008854:Microscopy, Electron; D010496:Pericardium / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D011474:Prosthesis Design; D011817:Rabbits; D051381:Rats; D012016:Reference Values; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013499:Surface Properties
D001672:Biocompatible Materials; D003470:Culture Media; D005337:Fibrin; D002118:Calcium