IDENTIFICATION OF HOST AND DONOR CELLS IN PORCINE HOMOGRAFT HEART-VALVE EXPLANTS BY FLUORESCENCE IN-SITU HYBRIDIZATION

The pathogenesis of the primary tissue degeneration that limits the li fe-span of aortic and pulmonary homografts has still not been revealed . Histopathological studies on homograft explants have not given defin itive insight into the eventual fate of donor cells, nor have they dem onstrated the assumed importance of host cell ingrowth into the graft tissue, In this experimental study, fluorescence in sih hybridization (FISH) is introduced as a new approach to examine the distribution of host and donor cells in homograft explants, Aortic valve replacement w as performed,vith a cryopreserved porcine aortic homograft in three pi gs; donor and recipient were of opposite sex, After 4 months, the graf ts were explanted and examined by FISH using a biotinylated porcine Y- chromosome-specific library probe, Following probe detection with FITC -conjugated avidin, a clear distinction could be made between cells of host and donor origin without distorting the histological integrity o f the explants, There was ingrowth of donor cells into the graft aorti c mall and into the valve leaflet, to some extent, In all explants, re maining donor cells were present, though decreased in number. The intr oduction of FISH in homograft heart valve research provides a powerful tool to study the fate of recipient and donor cellular elements in si tu, and may therefore contribute to a better understanding of the hist opathological processes that take place in transplanted homograft valv es. (C) 1997 by John Wiley & Sons, Ltd.