The Evaluation Of The Mechanics In Vitro And Anti-calcification Feature Of Bovine Pericardium With Different Treatment

Objective:To compare the mechanics in vitro and anti-calcification feature of bovine pericardium treated with four different methods(group A-glutaraldehyde-fixed, group B-ethanol and aluminum treated,group C-epoxy compound fixation,group D-dye-mediated photooxidation).Methods:Twenty pieces of precordium of fresh bovine pericardium(BP)were obtained.Each piece was divided into four parts and randomized into four groups.Group A:BP was tanned with HEPES buffer solution of 0.625%GA for 24 h,then reserved in HEPES of 0.3%GA in refrigerator of 4℃.Group B:BP was tanned with HEPES buffer solution of 0.625%GA for 24h,then post-treated with 0.1 mol/l aluminum trichloride for 45 min and reserved in 80%ethanol with 25℃thermostatic waterbath.Group C:BP was tanned with 4%Ethylene glycol diglycidyl ether(pH 10.5)for 3d and reserved in 50%ethanol.Group D:BP was tanned in hyperosmosis PBS(pH:7.6;Osm:680 mosm)for 4 h and post-treated with PBS of 0.1%methylene blue.Then BP was exposed to incandescent lamp of 500w for 48 h.The mechanical properties of bovine pericardium in the 4 groups,including ultimate tensile strength, extensibility at break,heat shrink temperature were measured.The rat subcutaneous model for the assessment of tissue calcification was used. The calcium content in bovine pericardium was determined by flame atomic absorption spectrophotometer after two months.Hematoxyline and eosin von Kossa stains was used.Results:Ultimate tensile strength:group A(17.35±1.71 MN/M2),group B(21.27±1.53 MN/M2),group C(17.77±1.19 MN/M2),group D (11.66±0.66 MN/M2);Extensibility at break:group A(34.16±2.08%),group B(42.37±1.48%),group C(51.60±3.18%),group D(48.78±3.43 %)(n=20);Heat shrink temperature:group A(88.86±0.58℃),group B(86.41±0.85℃),group C(80.43±1.02℃),group D(73.96±0.66℃) (n=10)(P＜0.05)。The calcium content:group A(96.82±7.08μg/mg),group B(17.96±7.87μg/mg),group C(29.59±3.18μg/mg),group D (2.26±0.34μg/mg).Hematoxyline and eosin stains show that there is great mass of lysis and degeneration of collagen and no nucleus remains in group A;in group B there is little lysis of collagen and no nucleus remains; in group C collagen and tissue structures reserve integrity,similar to group D.There is little nucleus remain in group C and mass cellular infiltration in group D.VON KOSSA'S stains shows that there is great amount of calcium salt deposition in group A;in group B there is light black calcium salt in trabs form;there is one lump of calcium salt deposition in group C; no obvious calcified tissue in group D.Conclusions:The bovine pericardial tissue treated with ethanol and aluminum after fixed by glutaraldehyde is best in the extent of tissue cross-link and mechanic strength.In the extent of tissue flexibility,the treatment of epoxy compound fixation and dye-mediated photooxidation appears superiority.In the evaluation of anti-calcification feature,dye-mediated photooxidation＞treatment ethanol and aluminum＞epoxy compound fixation＞＞glutaraldehyde-fixed.