Porcine Animals Lacking Any Expression of Functional Alpha 1,3 Galactosyltransferase

Abstract

The present invention is a porcine animal, tissue, organ, cells and cell lines, which lack any expression of functional alpha 1,3 galactosyltransferase (alpha1,3GT). These animals, tissues, organs and cells can be used in xenotransplantation and for other medical purposes.

Description

[0001]This application claims priority to U.S. provisional patent application No. 60 / 404,775 filed Aug. 21, 2002.FIELD OF THE INVENTION[0002]The present invention are porcine animals, tissue and organs as well as cells and cell lines derived from such animals, tissue and organs, which lack any expression of functional alpha 1,3 galactosyltransferase (alpha1,3GT). Such animals, tissues, organs and cells can be used in research and in medical therapy, including in xenotransplantation.BACKGROUND OF THE INVENTION[0003]Patients with end stage organ failure require organ transplantation for survival. The major limiting factor in clinical transplantation is the shortage of suitable human donors. Over the past ten years the size of the waiting list of patients for organs has increased dramatically, from approximately 30,000 in 1991 to approximately 80,000 in 2001 (Source: New York Organ Donor Network.; Association of Organ Procurement Organizations' Death Record Review Study from 1997 to 19...

AI Technical Summary

Benefits of technology

[0033]It has for the first time been proven that a viable porcine animal that lacks any expression of functional alpha 1,3 galactosyltransferase can be produced. The present invention provides the complete inactivation of both alleles of the alpha 1,3 galactosyltransferase gene in pigs, thus overcoming this longstanding hurdle and making xenotransplantation a reality. Eliminating the expression of this gene, resulting in a lack of galactose alpha 1,3-galactose epitopes on the cell surface, represents the first and major step in eliminating hyperacute rejection in pig-to-human xenotransplantation therapy. The invention also provides organs, tissues, and cells derived from such porcine animals, which are useful for xenotransplantation.

Problems solved by technology

The major limiting factor in clinical transplantation is the shortage of suitable human donors.

Xenotransplantation, however, presents its own set of problems.

(J Biol. Chem. 276, 39310 (2001)) reported that attempts to block expression of gal epitopes in N-acetylglucosaminyltransferase III transgenic pigs also resulted in only partial reduction of gal epitopes numbers and failed to significantly extend graft survival in primate recipients.

However, there was no evidence that such cells were actually produced prior to the filing date of these applications and the Examples were all prophetic.

Further, since porcine embryonic stem cells have not been available to date, there was and still is no way to use an alpha-1,3-GT homogygous embryonic stem cell to attempt to prepare a live homogygous alpha-1,3-GT knock out pig.

This application does not provide any guidance as to what extent the alpha-1,3-GT must be decreased such that the swine is useful for xenotransplantation.

Further, this application does not provide any proof that the heterozygous pigs that were produced exhibited a decreased expression of functional alpha1,3GT.

Further, while the application refers to homozygous alpha 1,3GT knockout swine, there is no evidence in the application that any were actually produced or producible, much less whether the resultant offspring would be viable or phenotypically useful for xenotransplantation.

In fact, this has been quite difficult as illustrated by the fact that while the first patent application on knock-out porcine cells was filed in 1993, the first homozygous alpha 1,3GT knock out pig was not produced until July 2002 (which was based on the work of the present inventor and described herein).

Based on this extensive experience with mice, it has been learned that transgenic technology has some significant limitations.

Because of developmental defects, many genetically modified mice, especially null mice created by gene knock out technology die as embryos before the researcher has a chance to use the model for experimentation.

Further, it has been learned that it is not possible to predict whether or not a given gene plays a critical role in the development of the organism, and, thus, whether elimination of the gene will result in a lethal or altered phenotype, until the knockout has been successfully created and viable offspring are produced.

However, two phenotypic abnormalities in these mice were apparent.

Second, the elimination of both alleles of the alpha-1,3-GT gene significantly affected the development of the mice.

Indeed, many experts in the field expressed serious doubts as to whether homozygous alpha-1,3-GT knockout pigs would be viable at all, much less develop normally.

Thus, until a viable double alpha-1,3-GT knockout pig is produced, according to those of skill in the art at the time, it was not possible to determine (i) whether the offspring would be viable or (ii) whether the offspring would display a phenotype that allows the use of the organs for transplantation into humans.

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