Organ transplantation is the standard treatment for terminal organ disease. The success of that treatment has led to an acute shortage of human donor organs, and projections suggest that the shortage will become more serious in the future. Xenotransplantation constitutes the only long term solution to this problem using organs from animals specifically modified as donors including the MHC haplotype-specific mini swine. One major barrier that currently precludes the use of mini swine organs is due to human natural antibodies recognizing pig-specific epitopes causing hyperacute rejection. The major epitope expressed on all pig cells comprises a disaccharide termed Gal alpha 1,3 Gal, generated by an enzymatic process which includes the alpha 1,3 galactosyltransferase. lnactivation of that gene in pig would, as suggested by the mouse model, remove that barrier. Here, we propose to evaluate strategies to knockout the alpha 1,3 galactosyltransferase in the pig in the absence of ES cells by focusing on structural features of mutant DNA constructions (isogenic DNA) to inactivate at high frequency that gene in cultured cells from mini swine (Phase l), and in transgenic animals (Phase Il) using the strategies that prove successful in the Phase I-study.Proposed commercial application:There are 32,000 individuals currently awaiting life saving organ transplants in the U.S. The number of people on waiting lists is estimated to further increase to around 50,000 by the year 2000. The current approaches to increasing donor supply, while they will help, are inadequate and will continue to be so. Xenotransplantation represents the only long-term solution to this imbalance between organ need and supply.National Center for Research Resources (NCRR)
