Recent advances in xenotransplantation

The major barrier to clinically successful pig-to-human xenotransplantation is antibody- and complement-dependent hyperacute rejection, known to be du e to host antiGal alpha(1,3)Gal antibodies. Strategies aimed at eliminating hyperacute rejection involve transgenic approaches to eliminate or reduce expression of Gal alpha(1,3)Gal or to reduce complement activation; some of these are now in clinical trials in primates. Another important role of Ga l alpha(1,3)Gal that is becoming more evident is in antibody-dependent and -independent xenograft rejection that is mediated by natural killer cells a nd monocytes.