Abstract
One of the big problems in xenotransplantation from pigs to humans is the hyperacute immune reaction due to the carbohydrate epitope of Galα1-3Gal. Based on the porcine α-1, 3-galactosyltransferase cDNA sequence, several antisense oligonucleotide DNAs (20-base pair phosphorothioates) were chemically synthesized and used to suppress the expression of the Galα1-3Gal carbohydrate epitope on the surface of a porcine kidney cell line. One of the antisense oligonucleotide cDNAs including the stop colon of the sequences, caused a significant 30 to 35% decrease in the level of expression compared to in untreated cells. However, the treatment had no effect on cell growth and exhibited no toxicity. In contrast, the corresponding sense oligonucleotide or other antisense oligonucleotides containing the 5'-start colon had no effect on the carbohydrate expression. The binding of cells to human serum was investigated after the effective antisense oligonucleotide treatment. Cells thus treated were less reactive to human IgG or IgM. This evidence strongly supported that natural antibodies contained in human serum became less reactive with these cells due to suppression of Galα1-3Gal carbohydrate epitope expression on the cell surface by antisense oligonucleotide treatment. These findings provide a basis for and a means of genetic manipulation of porcine α-1, 3-galactosyltransferase for future xenotransplantation studies.
