Complement activation in discordant hepatic xenotransplantation

Area of Science:

• Transplantation Immunology
• Xenotransplantation
• Complement System

Background:

• Hyperacute rejection mechanisms in hepatic xenotransplantation remain largely unknown.
• Clinical xenoperfusion data suggest hepatic xenografts may exhibit less vigorous rejection compared to kidney or heart xenografts.
• Understanding the immediate immune response is critical for successful xenotransplantation.

Purpose of the Study:

• To investigate the roles of the classical and alternate complement pathways in the immediate response to hepatic xenotransplantation.
• To determine the contribution of each complement pathway to xenograft injury using an in vitro model.
• To elucidate the complement-mediated mechanisms underlying hyperacute rejection in liver xenotransplantation.

Main Methods:

• Utilized an in vitro model involving porcine hepatic sinusoidal endothelial cells (PHEC).
• Incubated PHEC with human serum that was either complement-replete or complement-deficient.
• Assessed the activation of classical and alternate complement pathways and subsequent cellular injury.

Main Results:

• Both the classical and alternate pathways of complement activation were independently capable of initiating a response upon exposure to PHEC.
• Either pathway alone could activate the complement cascade.
• Each pathway was capable of inducing injury to a similar degree as the entire complement cascade.

Conclusions:

• Both the classical and alternate complement pathways play significant roles in the immediate response to hepatic xenotransplantation.
• Either pathway is sufficient to trigger substantial injury to porcine liver endothelial cells.
• Targeting either the classical or alternate complement pathways could be a viable strategy to prevent hyperacute rejection in liver xenotransplantation.