Cartography and Evaluation of Native and Decellularized Bovine Pericardium for Use as a Medical Implant

Objectives: Bovine pericardium (BP), native, fixated, or decellularized (DZ), is one of the most common materials in modern cardiovascular surgery. Although, used in everyday surgery, there is no recommendation which part of the BP should be preferred. Therefore, it was the aim of this study, to identify defined areas of BP with solid, durable, and consistent properties.

Methods: BP (n = 20) were collected from a local slaughterhouse. The thicknesses of the native pericardia were measured at 140 spots and fiber orientations were documented. Based on these results, five areas of 8 × 8 cm were defined for DZ and further evaluation. For DZ, BP were washed with detergents (0.5% sodiumdesoxycholate/0.5% sodiumdodecylsulfate), following DNAse incubation. The efficiency of DZ was evaluated by DNA quantification, as well as DAPI, and H&E staining. Biomechanical properties of all samples were determined using tensile tests. For microscopical investigations, scanning electron microscopy, Picrosirius Red and Movat’s Pentachrome staining were used. To investigate the long-term durability patches were tested in a high-cycle system for over 9 mio. cycles (3 months in vivo), applying a mean peak pressure of 120 mm Hg. Commercially available fixated BP patches were used as control group.

Results: The thickness varied across the pericardia, with one thicker area (833 ± 191 μm) and two more homogenous thinner areas (548 ± 121 μm and 605 ± 109 μm). Fibers were arranged unoriented. DZ removed all cell nuclei, proven by negative DAPI and H&E staining, and reduced the DNA amount by 85 ± 18%. Tensile tests showed significant variations, depending on samples localization on BP as well as on strain direction (weakest DZ area: 9.67 ± 7.21 N/mm², strongest DZ area: 17.19 ± 8.31 N/mm²). Still, three areas could be identified, which constantly resisted strong tensile load. Microscopical observations showed, that the appearance of extracellular matrix did not change by DZ. During the long-term testing, most of the BP slowly lost tautness, though none of them was destroyed. Only samples of one DZ area remained macro- and microscopically mostly unchanged.

Conclusion: We could clearly document significant differences within a single BP (native and DC). Especially tensile tests, as well as durability testing, showed a high dependence on the selected area. Only one area showed consistent properties, high resilience and long durability. We highly recommend taking this into account for future implant material selection.