Decellularization of heart valve matrices : search for the ideal balance

Objective: Currently used decellularization procedures have negative effects on extracellular matrix (ECM) integrity. The objective of this study is to evaluate four decellularization methods and their effect on the collagen ultrastructure, mechanical behavior and antigenicity of porcine aortic valves. Methods: Aortic valves were placed in a trypsin, osmotic, trypsin-osmotic or detergent-osmotic solution. Leaflets were processed for histology and mechanical testing. Matrices were implanted subdermally in rats to evaluate immune reaction and calcification. Results: Trypsin-osmotic methodology effected near-complete decellularization. Trypsin treatment resulted in cell removal only in the spongiosa layer. Osmotic and detergent-osmotic treatments did not remove any cells from the cusps. Mechanical strength was significantly inferior in the trypsin (p = 0,03) and trypsin-osmotic treated group (p = 0,04). Trypsin and trypsin-osmotic decellularized matrices evoked a strong CD3+ inflammatory cell infiltration. Conclusion: Enzymatic-osmotic decellularization appears to be the only effective method to remove cellular components. However, the near cell free scaffolds still evokes a strong CD3+ T-cell inflammatory reaction