Xenogeneic rejection mechanisms shown by intravital microscopy

Area of Science:

• Transplantation immunology
• Vascular biology
• Hepatology

Background:

• Xenogeneic liver transplantation faces challenges with hyperacute rejection.
• Understanding microvascular perfusion dynamics is crucial for successful xenotransplantation.
• Previous models lacked precision in localizing xenogeneic damage within the liver.

Purpose of the Study:

• To investigate the precise location and dynamics of microvascular damage in a xenogeneic liver perfusion model.
• To assess the impact of perfusion failure on sinusoidal blood flow.
• To evaluate the efficacy of interventions in mitigating xenogeneic rejection.

Main Methods:

• Utilized an innovative in vivo microscopy (IVM) model for real-time observation of liver microcirculation.
• Quantified sinusoidal perfusion and calculated the ratio of perfused to unperfused sinusoids.
• Assessed the effects of various interventions, including platelet inhibitors and apheresis.

Main Results:

• Perfusion failure was localized to the periportal fields, where leukocytes first interact with foreign endothelium.
• During xenoperfusion, only 65% of sinusoids maintained blood flow, a significant reduction.
• Combined platelet inhibitors and apheresis demonstrated remarkable improvement in acinar perfusion.

Conclusions:

• The developed IVM model accurately analyzes microvascular and sinusoidal perfusion dynamics in xenogeneic settings.
• Early xenogeneic rejection involves non-specific interactions of leukocytes and thrombocytes, leading to microcirculatory collapse.
• Targeting these early cellular interactions may be key to improving xenograft survival.