Background: Recent studies highlighted the presence of
anti--Gal antibodies in patients implanted with commercial
bioprosthetic heart valves (BHVs). BHVs expose residual -Gal
xenoantigen and their recognition by the circulating anti-Gal antibodies leads to
opsonization of the device’s tissue component with the consequent triggering of a
deterioration pathway that culminates with calcification. Small animal models
such as mice and rats have been broadly involved in the in vivo testing
of biomaterials by subcutaneous implantation, especially for the effectiveness of
BHVs anti-calcific treatments. However, since models employed for this purpose
express -Gal antigen, the implantation of BHVs’ leaflets does not
elicit a proper immunological response, so the calcification propensity may be
dramatically underestimated. Methods: An -Gal knockout (KO)
mouse model has been created, using the CRISP/Cas9 approach, and adopted to
assess the calcification potential of commercial BHVs leaflets through the
surgical implantation in the back subcutis area. Calcium quantification was
performed by inductively coupled plasma analysis; immune response against the
BHVs leaflets and -Gal silencing was evaluated through immunological
assays. Results: Two months after the implantation of commercial BHV
leaflets, the anti-Gal antibody titers in KO mice doubled when compared with
those found in wild-type (WT) ones. Leaflets explanted from KO mice, after one
month, showed a four-time increased calcium deposition concerning the ones
explanted from WT. The degree of silencing of -Gal varied, depending on
the specific organ that was assessed. In any case, the animal model was suitable
for evaluating implanted tissue responses. Conclusions: Such mouse model
proved to be an accurate tool for the study of the calcific propensity of
commercial BHVs leaflets than those hitherto used. Given its reliability, it
could also be successfully used to study even other diseases in which the
possible involvement of -Gal has been observed.