Transplantation material bovine pericardium: biomechanical and immunogenic characteristics after decellularization vs. glutaraldehyde-fixing

Abstract

Background: Today, bovine pericardium (BP) is extensively investigated as a biomaterial for the generation of various bioimplants. But despite the commercial distribution, and the development of methods either to remove (decellularization) or to mask (chemical cross-linking, for example by glutaraldehyde [GA] treatment) the xenogeneic antigen epitopes, yet questions around the immunogenic reactivity of BP remain. The aim of this study is the comparison of crucial tissue characteristics, that is, biomechanical properties, the presence of αGal epitopes, and residual DNA in acellular vs. GA-fixed BP.

Methods: Bovine pericardium was either cross-linked with 0.6% GA or decellularized according to two common protocols using either sodium dodecyl sulfate (SDS) and desoxycholic acid (DCA) or trypsin and ethylenediaminetetraacetic acid (EDTA). The resulting extracellular matrix was prone to one-dimensional tensile testing. The tissue content for αGal was evaluated by immunoblotting, and residual DNA was determined by a commercial assay. Untreated BP served as control.

Results: In contrast to previous reports, we found a pronounced decrease in the elastic modulus (E-Modulus) for common GA treatment and overall smaller values for the elastic moduli after decellularization (P < 0.05). In parallel, we observed an overall increased ultimate elongation of acellular and cross-linked BP, although ultimate stress values did not significantly differ. SDS/DCA decellularized BP revealed a dramatic reduction in the DNA content and an almost complete removal of αGal epitopes, whereas the trypsin/EDTA protocol retained a residual DNA content of almost 50% and with a great trail of αGal signal. GA-treated tissue had a remarkable content of DNA and αGal.

Conclusions: Although chemically fixated BP is clinically still in wide use, for example, for biological heart valve engineering, our results suggest that an improved biomaterial preparation may be provided by appropriate decellularization. SDS/DCA decellularized BP shows similar biomechanical characteristics as GA treatment, paired with reduced potential immunogenic reactivity. Furthermore, decellularized BP holds the potential of cellular repopulation in vivo or in vitro, to enable an endogenous regenerative capacity in contrast to the toxic effects of GA fixing.