Acellular porcine and kangaroo aortic valve scaffolds show more intense immune-mediated calcification than cross-linked Toronto SPV valves in the sheep model.
OBJECTIVE
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.


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.


CONCLUSIONS
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.
Department of Cardiac Surgery, 5K12, University Hospital Ghent, De Pintelaan 185, BE-9000 Ghent, Belgium. guido.vannooten@ugent.be
Guido
G
Van Nooten
Pamela
P
Somers
Maria
M
Cornelissen
Stefaan
S
Bouchez
Frank
F
Gasthuys
Eric
E
Cox
Lisa
L
Sparks
Kishan
K
Narine