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DOI: 10.1055/s-0031-1297861
Residual alpha-gal epitope content and elasticity of crosslinked vs. decellularized bovine pericardium
Objective: 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 to either remove (decellularization) or to mask (chemical cross-linking, e.g. by glutaraldehyde [GA] treatment) the xenogenic antigen epitopes, yet questions around the immunogenic reactivity of BP remain. The aim of this study is the comparison of crucial tissue characteristics i.e. biomechanical properties, the presence of alpha-gal epitopes and residual DNA in acellular vs. GA fixed bovine pericardium.
Methods: BP 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 EDTA. The resulting extracellular matrix (ECM) was prone to one-dimensional tensile testing. The tissue content for alpha-gal was evaluated by immuno-blotting 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 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 of DNA content and an almost complete removal of alpha-gal epitopes whereas the trypsin/EDTA protocol retained a residual DNA content of almost 50% and with a great trail of alpha-gal signal. GA treated tissue had a remarkable content of DNA and alpha-gal.
Conclusions: Although chemically fixated BP is clinically still in wide use, e.g. 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 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 known toxic effects of GA fixation.