Freeze-drying and gamma irradiation are the techniques widely use in tissue banking for preservation and sterilization of tissue grafts respectively. However, the effect of these techniques on biomechanical properties of bovine pericardium is poorly known. A total of 300 strips of bovine pericardium each measured 4 cm x 1 cm were used in this study to evaluate the effect of freeze-drying on biomechanical properties of fresh bovine pericardium and the effect of gamma irradiation on biomechanical properties of freeze-dried bovine pericardium. The strips were divided into three equal groups, which consist of 100 strips each group. The three groups were fresh bovine pericardium, freeze-dried bovine pericardium and irradiated freeze-dried bovine pericardium. The biomechanical properties of the pericardial strips were measured by a computer controlled instron tensiometer while the strips thickness was measured by Mitutoyo thickness gauge. The results of the study revealed that freeze-drying has no significant (p > 0.05) effect on the tensile strength, Young's modulus (stiffness) and elongation rate of fresh bovine pericardium. Irradiation with 25 kGy gamma rays caused significant decreased in the tensile strength, Young's modulus and elongation rate of the freeze-dried pericardium. However, gamma irradiation has no significant effect on the thickness of freeze-dried bovine pericardium, while freeze-drying caused significant decreased in the thickness of the fresh bovine pericardium. The outcome of this study demonstrated that freeze-drying has no significant effect on the biomechanical properties of fresh bovine pericardium, and gamma irradiation caused significant effect on the biomechanical properties of freeze-dried bovine pericardium.

The aim of the present study was to evaluate the lyophilized and glycerolized bovine parietal tunica vaginalis for repair of a full-thickness abdominal wall defect and to compare their effectiveness with expanded polytetrafluoroethylene (ePTFE) Mycro Mesh (Gore-Tex MYCRO MESH; Gore and Designs, W. L. Gore & Associates, Flagstaff, AZ, USA) in a rat model. Fresh bovine parietal tunica vaginalis sacs collected from an abattoir were processed and preserved by freeze-drying and by using 99.5% glycerol. Full-thickness abdominal wall defects (3 x 2.5 cm) created surgically in 90 male Sprague-Dawley rats (300-400 g) were repaired with the same size of lyophilized, glycerolized or ePTFE Mycro Mesh with 30 rats in each group. Six rats from each group were killed at post-implantation intervals of 1, 3, 6, 9 and 18 weeks for macroscopic, microscopic and tensiometric evaluations. All rats survived the procedure, except for one rat in the ePTFE Mycro Mesh group. Implants of bovine origin were gradually resorbed and replaced with recipient fibrous tissue, whereas the mesh implant was encapsulated with fibrous tissue and remained without any marked changes throughout the study period. Adhesions between the implant and underlying visceral organs were encountered in 10, 6.6 and 3.3% of rats implanted with lyophilized, glycerolized or ePTFE Mycro Mesh, respectively. Foreign body giant cells and calcification were demonstrated in fibrous capsule and mesh matrix, respectively, in rats implanted with ePTFE Mycro Mesh. Neither of these characteristics were observed in rats implanted with processed bovine tunica vaginalis. Macrophages engorged with lipofuchsin pigments were observed in the recipient tissue that replaced the implants of bovine origin at 3-18 weeks post-implantation. There were no significant (P > 0.05) differences in total mean values of healing tensile strength, load at break and Young's modulus of elasticity between the three implant groups. The results of the present study encourage further investigation into the use of processed bovine parietal tunica vaginalis in clinical practice.

This study investigates the effect of preservation methods on the performance of bovine parietal pericardium grafts in a rat model. Mid-ventral full thickness abdominal wall defects of 3 x 2.5 cm in size were created in 90 male Sprague-Dawley rats (300-400 g), which were divided into three groups of 30 rats each. The abdominal defects of group one and two were repaired with lyophilized and glycerolized bovine pericardium grafts, while the defects of group three were repaired with expanded polytetrafluoroethylene (ePTFE) Mycro Mesh as a positive control. Another group of 30 rats underwent sham operation and was used for comparison as negative control. Each group of rats (n = 30) was divided into five subgroups (n = 6) and killed at 1, 3, 6, 9 and 18 weeks post-surgery for gross and morphological evaluations. The rats tolerated the surgical procedure well with a total mortality of 0.05%. No serious post-operative clinical complications or signs of rejection were encountered. Adhesions between the grafts and the underlying visceral organs observed in the study were mostly results of post-surgical complications. Glycerol preservation delayed degradation and replacement of the grafts, whereas lyophilization caused early resorption and replacement of the grafts. The glycerolized grafts were replaced with thick dense fibrous tissue, and the lyophilized grafts were replaced with thin loose fibrous tissue. The healing characteristic of the bovine pericardium grafts was similar to those of the sham-operated group, and quite different from those of the ePTFE Mycro Mesh. The outcome of the present study confirmed the superiority of glycerolized bovine pericardium grafts over its lyophilized counter part.