Reduction in Gal‐α1,3‐Gal epitope expression in transgenic mice expressing human H‐transferase

Abstract

There is now considerable evidence implicating anti‐Gal xenoantibodies as a key instigator in the hyperacute rejection of discordant xenografts. As a consequence it is generally held that elimination or reduction of the Gal/anti‐Gal component is critical to overcoming hyperacute rejection. We have recently shown that in mice inactivation of the GalT gene by homologous recombination completely eliminates the expression of the Gal‐epitope and that hearts from these mice demonstrate prolonged survival when perfused ex vivo with human plasma. Unfortunately this strategy is currently not feasible in pigs because the technology to isolate porcine embryonic stem cells, which are critical for homologous recombination, is not yet available. This study investigates an alternative competition‐based transgenic strategy to suppress the level of the Gal epitope by expression of H‐transferase (α1,2‐fucosyltransferase) an enzyme which has the same substrate specificity (lactobiose) as α1,3‐galactosyltransferase. In vitro transfection of murine cells with H‐transferase reduced Gal‐epitope expression by 80–90%. A similar reduction in Gal expression was observed on PBL and thymocytes from H‐transferase transgenic mice. This reduction in Gal epitope expression resulted in a marked reduction in the reactivity of these cells with human serum. In tissues from these mice the reduction in Gal expression was inversely proportional to the endogenous level of Gal. The results of this study support pursuing this strategy as a means to reduce the xenoantigenicity of porcine tissues.

Thromboregulatory manifestations in human CD39 transgenic mice and the implications for thrombotic disease and transplantation

“…Similar numbers of the dense granules that contain adenine nucleotides were present in both (data not shown). Consistent with our previous results using the H-2K b promoter (24,25), transgene expression was widespread in all tissues examined, including heart, lung, and pancreas, and was particularly strong on endothelium ( Figure 1B). Correct processing of hCD39 in the tissues of transgenic mice was confirmed by Western blot analysis ( Figure 1C).…”

Altered Glycosylation in Donor Mice Causes Rejection of Strain-Matched Skin and Heart Grafts

“…As part of our xenotransplantation program, we generated hFUT1 transgenic mice expressing human α1,2‐fucosyltransferase , also known as H‐transferase (HTF) because it is responsible for the synthesis of H substance (blood group O). The rationale for this strategy was that HTF reduces the expression of the major porcine xenoantigen galactose‐α1,3‐galactose (αGal) by competing for the substrate of α1,3‐galactosyltransferase .…”

Candidemia in women with breast carcinoma treated with high‐dose chemotherapy and autologous bone marrow transplantation

“…Our results indicate that there is no direct competition between mouse α1,3GT and human α1,2fucosyltransferase or α2,3sialyltransferase, which are more or less expressed in parental BxPC‐3 and Panc‐1 cells,16 for the same acceptor substrate. Many studies on the hyperacute rejection of xenografts have shown a reduction of the level of αGal epitope in transgenic mice and pigs due to the expression of an α1,2fucosyltransferase,42, 43, 44, 45 suggesting that α1,2fucosyltransferase activity could be dominant over that of the α1,3GT in the Golgi subcompartmentation. These data corroborate results reported by Osman et al 46.…”