Cardiac xenotransplantation: progress and challenges.

Area of Science:

• Biomedical Engineering
• Transplantation Immunology
• Cardiovascular Surgery

Background:

• Chronic shortage of donor hearts limits treatment options for end-stage cardiac failure.
• Cardiac xenotransplantation (CXTx) offers a potential solution by utilizing animal organs for human transplantation.

Purpose of the Study:

• To review recent advancements in heterotopic and orthotopic CXTx.
• To investigate the role of non-Gal antibodies in xenograft rejection.
• To discuss the challenges associated with clinical orthotopic CXTx.

Main Methods:

• Utilizing genetically modified pigs (GTKO) lacking the α-Gal antigen to mitigate anti-Gal antibody responses.
• Monitoring survival rates and rejection mechanisms in heterotopic and orthotopic xenografts in nonhuman primates.
• Analyzing antibody deposition, complement activation, and inflammatory responses in rejected xenografts.

Main Results:

• GTKO cardiac xenografts demonstrate increased survival in nonhuman primates, with rejection often involving vascular antibody and complement deposition.
• Non-Gal antibody responses to porcine antigens and novel carbohydrate antigens are implicated in rejection, requiring further investigation.
• Orthotopic CXTx faces challenges with early perioperative cardiac xenograft dysfunction (PCXD), though affected hearts can recover function, with some achieving 2-month survival without rejection.

Conclusions:

• CXTx is a promising strategy for addressing end-stage cardiac failure.
• Genetic modification of donor pigs and optimized immunosuppression have significantly extended xenograft survival.
• Further research is needed to overcome antibody-mediated rejection and xenograft dysfunction for successful clinical translation.