Initial experimental experience of triple‐knockout pig red blood cells as potential sources for transfusion in alloimmunized patients with sickle cell disease

Abstract

Background: Blood transfusion remains important in the treatment of patients with sickle cell disease (SCD). However, alloimmunization after blood transfusion is associated with patient morbidity and mortality. Triple-knockout (TKO) pigs (i.e., pigs in which the three known xenoantigens to which humans have anti-pig antibodies have been deleted) may be an alternative source of RBCs for these patients because many humans have no preformed antibodies to TKO pig RBCs (pRBCs). Methods and materials: In an in vitro study, plasma from alloimmunized (n = 12) or non-alloimmunized (n = 12) SCD patients was used to determine IgM/IgG binding to, and CDC of, TKO pRBCs. In an in vivo study, after an estimated 25% of blood volume was withdrawn from two capuchin monkeys, CFSE-labeled TKO pRBCs were transfused. Loss of TKO pRBCs was monitored by flow cytometry, and 7 weeks later, 25% of blood was withdrawn, and CFSE-labeled monkey RBCs were transfused. Results:The in vitro study demonstrated that plasma from neither alloimmunized nor non-alloimmunized SCD patients bound IgM/IgG to, or induced CDC of, TKO pRBCs. In the in vivo study, survival of TKO pRBCs in the two capuchin monkeys was of 5 and 7 days, respectively, whereas after allotransfusion, survival was >28 days. Conclusions:In conclusion, (1) in the present limited study, no antibodies were detected that cross-reacted with TKO pRBCs, and (2) TKO pigs may possibly be an alternate source of RBCs in an emergency if no human RBCs are available.

ABO blood group antigens and differential glycan expression: Perspective on the evolution of common human enzyme deficiencies

“…Anti-α-Gal antibodies can also cause hyperacute rejection of certain xenotransplants, as α-Gal is expressed on common donor animal tissues ( Lantéri et al., 2002 ). To make xenotransplants and xenotransfusions possible ( Yamamoto et al., 2021 ), the α(1,3)-galactosyltransferase gene was knocked out in pigs ( Roux et al., 2007 ). The first successful pig-to-human heart transplant was performed in 2022 using a pig with 10 genetic modifications.…”

What Have We Learned From In Vitro Studies About Pig-to-primate Organ Transplantation?

“…However, (1) their limited size (eg, capuchin <3 kg, squirrel <1 kg) largely prohibits pig organ transplantation and (2) some biological immunosuppressive agents (eg, the anti-CD20 monoclonal antibody, Rituximab) are not active in them, 68 but they may be suitable as recipients of skin, islets, and cell transplants and of pRBC transfusion. 69…”

“…All of these valuable observations have been made rapidly and inexpensively from in vitro assays and have largely predicted what will result from in vivo studies in pig-to-NHP organ transplantation models. 1,2,9,[31][32][33][34]60,[67][68][69] The production of antibodies in OWNHPs is currently a greater barrier to the survival of TKO pig kidneys than of GTKO pig kidneys. Therefore, it is difficult to provide the regulatory authorities with positive data from pig-to-NHP transplant models to support the concept that TKO pig organs will be associated with long-term graft survival in humans.…”

“…All of these valuable observations have been made rapidly and inexpensively from in vitro assays and have largely predicted what will result from in vivo studies in pig-to-NHP organ transplantation models. 1,2,9,31-34,60,67-69,81-108…”

Spatial and Temporal Expression Characteristics of the HBB Gene Family in Six Different Pig Breeds

“…Therefore, it is important to develop animal models to accurately simulate human β-thalassemia for gene therapy or for other more effective therapies. Pig is the optimal experimental animal model for performing clinical research on human disease [ 23 , 24 , 25 , 26 ]. Moreover, pigs have unique advantages in studying β-thalassemia and other related blood diseases, compared with mice and rabbits [ 27 , 28 ].…”