Synchronized Synergism Using Ethanol, L-lysine and NaBH4 in Glutaraldehyde Treated Porcine Pericardium

Kim, Kwan Chang; Kim, Yong Jin; Kim, Soo Hwan; Choi, Seung Hwa

Abstract

BACKGROUND
Calcification is the most frequent cause of clinical failure of bioprosthetic tissues that are fabricated from Glutaraldehyde (GA)-fixed porcine valve or bovine pericardium. We recently used a multi-factorial approach of employing different mechanisms to investigate how to reduce the calcification of bioprosthetic tissues. The purpose of the present study was to evaluate the synchronized synergism using ethanol, L-lysine and NaBH4 in glutaraldehyde treated porcine pericardium from the standpoint of calcification and tissue elasticity. MATERIAL AND METHOD: Porcine pericardium was fixed with 0.625% GA (commercial fixation). An interim step of ethanol (80%; 1 day at room temperature) or L-lysine (0.1 M; 2 days at 37degrees C) or NaBH4 (0.1 M; 2 days at room temperature) was followed by completion of the GA fixation (2 days at 4degrees C and 7 days at room temperature). The tensile strength and thickness of the samples were measured. The treated pericardiums were implanted subcutaneously into three-week old Sprague-Dawley rats for 8 weeks. The calcium content was assessed by atomic absorption spectroscopy and the histology of the samples. RESULT: The amount of calcium in the pericardium pretreated with ethanol (13.6+/-10.0 ug/mg, p=0.008), L-lysine (15.3+/-1.0 ug/mg, p=0.002) and both (16.1+/-11.1 ug/mg, p=0.012) was significantly reduced compared with the control (51.2+/-8.5 ug/mg). However, NaBH4 pretreatment (65.7+/-61.8 ug/mg, p=0.653) and combined pretreatment that including ethanol, L-lysine and NaBH4 (92.9+/-58.3 ug/mg, p=0.288) were not significantly different from the controls (51.2+/-8.5 ug/mg). Both the combined pretreatment using ethanol and L-lysine (7.60+/-1.55, p=0.76) and the combined pretreatment that included ethanol, L-lysine and NaBH4 (7.47+/-1.85, p=0.33) increased the tensile strength/thickness ratio compared with that of the controls (4.75+/-1.88).
CONCLUSION
The combined pretreatment using ethanol and L-lysine seemed to decrease the calcification of porcine pericardium fixed with glutaraldehyde, as compared to single pretreatment, and it increase the tissue elasticity, but to the degree that showed synchronized synergism. NaBH4 pretreatment seemed to increase the calcification of porcine pericardium, irrespective of whether single or combined pretreatment was used.