Auxiliary liver xenotransplantation technique in a transgenic pig-to-non-human primate model: A surgical approach to prolong survival

Public Attitudes Toward Xenotransplantation in South Korea: A 2023 Survey Study

BACKGROUND

Xenotransplantation is a promising field to solve the problem of insufficient allograft and has been actively studied in Korea. However, there are a number of ethical, legal, and social issues to consider, and it is necessary to know the public attitudes regarding them.

METHODS

A Computer Aided Web Interview consisting of 22 questionnaire items was conducted to investigate the attitudes of Korean related to xenotransplantation. Participants were selected from Hankook Research MS (Master Sample) panel. A total of 1007 sets of data were finally collected and analyzed with SPSS. A statistical analysis was performed using an independent t-test and chi-square method.

RESULTS

72.9% of the respondents were positive about xenotransplantation, while 22.2% negative. 61.7% said that they would accept xenotransplantation for incurable diseases. 64.4% agreed with genetically modified pigs for organ resource. 61% agreed that the brain dead could be transplanted first for research purpose, while 32.7% disagreed. The ratio of response that the risk of zoonotic infection is important was 97.2%; the safety issue due to immunosuppression 98.7%; the human identity issue after transplantation 67.4%; and the animal right issue 51.6%. Men were more favorable to xenotransplantation than women on all but one item (stigmatization). There was no significant difference between religions except for the human identity issue.

CONCLUSION

Korean people are favorable to xenotransplantation as a therapeutic option and also positive with the use of pig even genetically modified in spite of the issue of animal rights. They are also positive with the idea of using the brain dead as study subject for xenotransplantation, which is currently forbidden in Korea.

Innovations to Expand the Liver Donor Pool: Machine Perfusion and Xenotransplantation

The number of patients awaiting liver transplant exceeds the number of liver grafts available. However, emerging technologies offer hope. Machine perfusion enhances the preservation, graft quality, and utilization of marginal livers, thereby reducing unnecessary graft discards. Xenotransplantation provides an alternative organ source, augmenting the donor supply or serving as a bridge for critically ill patients. These innovations are described in this review, as the recent clinical applications of these technologies promise to alleviate organ scarcity, improve transplant outcomes, and save lives.

Addressing glycan and hematological barriers in pig-to-nonhuman primate liver xenotransplantation: challenges and future directions

Achieving long-term survival in pig-to-primate liver xenotransplantation has proven highly challenging due to significant hematological issues. This paper investigates the primary obstacles from a hematological perspective, focusing on coagulation disorders caused by molecular incompatibility between species. It also examines the mismatched glycan structures on the surfaces of platelets and red blood cells, which lead to sequestration and phagocytosis by recipient macrophages. These mismatches underscore the need for improved glycan and molecular compatibility to overcome immunological and physiological barriers. Moreover, the liver's unique role in synthesizing a wide array of proteins, especially those involved in blood coagulation, introduces additional challenges of molecular incompatibility compared to other organs, such as the heart and kidneys. This study highlights the importance of addressing these challenges to improve the outcomes of liver xenotransplantation and suggests the necessity of strategies like glycan matching and the development of gene-edited pigs specifically tailored for liver transplantation.

Research on gene editing and immunosuppressants in kidney xenotransplantation

Gene-edited pig organ transplantation can solve the serious shortage of human donor organs. Currently, xenotransplantation is rapidly developing and has made significant breakthroughs. The use of GTKO (Gal knockout) pigs is an important step forward. The subsequent knockout of three genes combined with the transfer of immune-related genes effectively prolonged the survival time of non-human primate (NHP) transplantation in xenotransplantation. Due to the success of allogeneic kidney transplantation on NHP, this gene editing protocol was recently applied to clinical patients. Two patients underwent allogeneic kidney transplantation and survived for 51 days and 47 days. Exceeding the hyperacute rejection period proves that appropriate gene editing strategies and the combination of immunosuppressive agents contribute to the success of xenotransplantation. To further enhance the feasibility of pig kidney xenograft, this article mainly explores the effects of the NHP xenograft gene editing scheme and immunosuppressants on prolonging transplant survival time.

Systematic Review and Comparative Outcomes Analysis of NHP Liver Allotransplants and Xenotransplants

Patients with fulminant liver failure ineligible for transplantation have a high mortality rate. With recent progress in genetic modifications and clinical achievements, using pig livers as a bridge-to-transplant has regained popularity. Preclinical testing has been done in small cohorts of nonhuman primates (NHP), and maximum survival is limited to 1-month. We conducted a systematic review and comparative outcomes analysis of NHP-liver xenotransplantation and gathered 203 pig-to-NHP and NHP-to-NHP transplants reported in 23 studies. Overall, NHP survival after pig-liver xenotransplantation was limited (1, 3, 4 weeks: 18.0%, 5.6%, 1.1%), compared to NHPs after allotransplantation (1, 3, 4 weeks: 60.6%, 47.4%, 45.4%). A focus on pigs with genetic modifications evidenced some short-term survival benefits (1, 3, 4 weeks: 29.1%, 9.1%, 1.8%). The use of the auxiliary transplant technique was also associated with better short-term results (1, 3, 4 weeks: 40.9%, 9.1%, 4.5%). Causes of graft and animal loss were mostly rejection and liver failure in allotransplants, while bleeding, liver, and respiratory failure predominated in xenotransplants. Notably, the 1-month survival rate for NHP-allotransplants was significantly lower than the national > 98% rate for human liver transplants. This data confirms the short-term improvements brought by genetic modifications and auxiliary implantation in the NHP model, which remains imperfect.

Bridging Therapies-Ex Vivo Liver Xenoperfusion and the Role of Machine Perfusion: An Update

Advancements in xenotransplantation intersecting with modern machine perfusion technology offer promising solutions to patients with liver failure providing a valuable bridge to transplantation and extending graft viability beyond current limitations. Patients facing acute or acute chronic liver failure, post-hepatectomy liver failure, or fulminant hepatic failure often require urgent liver transplants which are severely limited by organ shortage, emphasizing the importance of effective bridging approaches. Machine perfusion is now increasingly used to test and use genetically engineered porcine livers in translational studies, addressing the limitations and costs of non-human primate models. Current reports about artificial and bioartificial liver support combined with xenografts showcase the potential in ex vivo xenogeneic perfusion. Breakthroughs, such as the perfusion of genetically modified porcine liver with FDA-approved machine perfusion systems connected to human blood circulation, underscore the interest and potential feasibility of a "liver dialysis" bridge to allotransplantation or recovery. This review provides an overview of the past and current research in the field of ex vivo pig liver xenoperfusion.

Xenotransplantation literature update March 2023-November 2023

We present an updated report highlighting significant developments in the field of xenotransplantation since March 2023. The past six months have witnessed significant strides in the field and the emergence of novel research that is expected to facilitate the journey towards clinical trials. We are reviewing here the most pertinent findings from March 2023 to November 2023.