Decellularization and engineered crosslinking: a promising dual approach towards bioprosthetic heart valve longevity

Abstract

OBJECTIVES While decellularization has previously significantly improved the durability of bioprosthetic tissue, remnant immunogenicity may yet necessitate masking through crosslinking. To alleviate the fears of reintroducing the risk of calcific degeneration, we investigated the application of rationally designed crosslinking chemistry, capable of abrogating mineralization in isolation, in decellularized tissue. METHODS Bovine and porcine pericardium were decellularized using the standard Triton X/sodium deoxycholate/DNAse/RNAse methodology and thereafter combined incrementally with components of a four-stage high-density dialdehyde-based fixation regimen. Mechanical properties prior to, and calcium levels following, subcutaneous implantation for 6 and 10 weeks in rats were assessed. RESULTS Enhanced four-stage crosslinking, independent of decellularization, or decellularization followed by any of the crosslinking regimens, achieved sustained, near-elimination of tissue calcification. Decellularization additionally resulted in significantly lower tissue stiffness and higher fatigue resistance in all groups compared to their non-decellularized counterparts. CONCLUSIONS The dual approach of combining decellularization with enhanced crosslinking chemistry in xenogeneic pericardial tissue offers much promise in extending bioprosthetic heart valve longevity.

The Technological Basis of a Balloon-Expandable TAVR System: Non-occlusive Deployment, Anchorage in the Absence of Calcification and Polymer Leaflets

“…Stresses were optimized using FEA on the basis of isotropic hyperelastic materials ( Figure 3 ). Decellularized, sandwich-crosslinked Namibian bovine pericardium (porcine for the “universal” stent) was processed as previously described ( 26 ). The potential longevity of leaflets was assessed in the rat subcutaneous model.…”

Residual Bioprosthetic Valve Immunogenicity: Forgotten, Not Lost

“…Clearly, a “marriage of convenience” between decellularization and chemical cross-linking is required to adequately address residual immunogenicity, especially of the ECM. Despite concerns to the contrary, the use of GA, long thought to promote bioprosthetic mineralization, as an adjunct to decellularization of bovine pericardium, failed to undo the anti-calcification benefit of decellularization in our hands ( 44 ). Whether this suggests that leaching of monomeric GA is diminished in acellular tissue, or perhaps is confounded by the presence of the cellular compartment in intact tissue, or both, remains to be determined.…”

“…With regard to the latter, we have advocated an engineered approach toward cross-linking decellularized xenogenic pericardium with GA, specifically through incorporation of extender diamine molecules, such as L-Lysine, and reduction of labile Schiff bases to avoid monomer leaching ( 44 ) which may again lead to exposure of epitopes over time. While GA remains the principal cross-linking agent used in contemporary bioprosthetic valves, alternatives, including genipin, which has shown potential for reduction of calcification ( 68 ), have been explored.…”

Engineering in-plane mechanics of electrospun polyurethane scaffolds for cardiovascular tissue applications

“…Every sample (n≥3/group) was preconditioned and then tested in Lagrangian equi-stress control to peak stress of 418.9 kPa. This value was identified [34] as appropriate to elicit physiologically relevant strain levels (1.2 for left ventricle wall [35,36], 1.6 for heart valve leaflets [37], 1.5 for large blood vessels [38,39]). During the biaxial test, a constant ratio of loads was maintained between the two directions (circumferential and longitudinal).…”