A Novel Anti-Calcification Strategy of Bovine Pericardium Using Sodium Bisulfite Modification

Background and aim of the study: Calcification is the major contributory factor of clinical failure of glutaraldehyde (GA)-fixed bioprosthetic heart valves. The study aim was to evaluate a novel approach to prevent calcification using a sodium bisulfite (SB) modification. Methods: A series of bovine pericardium samples was fixed in 0.625% (w/v) GA and stored in 0.3% GA solution. One half of these samples were used as a control group; the second half were transferred into SB solution for 24 h and served as the experimental group. Both groups were analyzed with Fourier transform infrared (FTIR) spectroscopy, and characterized on the basis of their shrinkage temperature, mechanical properties and resistance to collagenase digestion. In addition, samples from each group were implanted subcutaneously into 10 juvenile Sprague-Dawley rats for 21 and 60 days, respectively. The calcium content of the explanted tissues was assessed using atomic absorption spectrometry, and calcium deposition demonstrated histologically with von Kossa staining. Results: SB-modified bovine pericardium samples demonstrated a slightly lower shrinkage temperature than GA-treated samples. FTIR demonstrated an alternation in aldehyde banding among the bands from bovine pericardial tissues. The resistance to enzymic digestion was comparable in both groups, but the biomechanical properties of the SB-modified samples were superior to those of controls. Calcium deposition was significantly lower in the SB group at both 21 days (3.5 +/- 0.6 versus 63.3 +/- 0.1 mg/g tissue) and 60 days (5.1 +/- 0.1 versus 79.8 +/- 7.4 mg/g) (p <0.001). These quantitative data were confirmed histologically with von Kossa staining. Conclusion: The additional SB modification of GA-fixed bovine pericardium resulted in an increased pericardial extensibility and strength. SB treatment also led to a significant reduction in pericardial calcification in a subcutaneous rat model.