Aim Of The Study: A major limitation of currently available bioprosthetic valves is their propensity to calcify. At present, one approach in tissue-engineering, uses decellularized, xenogenic scaffolds that are implanted, with the expectation of complete matrix repopulation in vivo. Whether or not such a decellularized matrix will be sufficiently endowed to prevent calcification is unknown.
Materials And Methods: This study examines the calcification potential of xenogenic biological scaffolds from two species, namely pigs (n=3) and kangaroos (n=3) in the sheep model and compared them to a commercially available glutaraldehyde treated porcine bioprosthetic valve (Toronto SPV) (n=3).
Results: Valves and matrices were explanted after 120 days. Histologically (H&E and Von Kossa stain) more calcium was found in the acellular matrices. The mean calcium content (mg/g-dw) of the Toronto SPV valve leaflets was 2.63 mg/g-dw compared to 43.81 mg/g-dw (P=0.12) in kangaroo and 105.08 mg/g-dw (P=0.004) in porcine matrices. On electron microscopy calcific deposits were located between as well as in close association with the collagen fibers in all tissue. In contrast to the cross-linked gluteraldehyde fixed bioprostheses both matrices showed strong immune IgG reaction.
Conclusion: Toronto SPV valves calcified significantly less than the tested biological matrices irrespective of species of origin. Surprisingly, xenogenic decelullarized scaffolds are inherently prone to calcification due to a strong immunogenicity.
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