Chronic rejection models for vascularized composite tissue allotransplantation

Area of Science:

• Transplantation immunology
• Preclinical research models

Background:

• Vascularized composite tissue allotransplantation (VCA) offers life-changing reconstructive options, but chronic rejection remains a significant barrier to long-term success.
• Current preclinical models inadequately replicate the complexities of chronic rejection, hindering the development of effective treatments.

Purpose of the Study:

• To develop and characterize novel mouse models that accurately mimic chronic rejection following hind limb VCA.
• To provide a platform for evaluating new therapeutic strategies for chronic graft rejection.

Main Methods:

• Heterotopic hind limb VCA in CD8 knockout mice using varying MHC mismatches (BALB/c or B6 H2-Ab1bm12 donors).
• Transient CD4 T cell depletion to facilitate graft maturation.
• Comprehensive evaluation including gross pathology, immune status, donor-specific antibodies (DSA), C4d deposition, and histopathology.

Main Results:

• Two models successfully replicated key features of clinical chronic graft rejection, including skin changes, fibrosis, and mast cell infiltration, without acute necrotic changes.
• Recipients exhibited increased donor-specific antibodies (DSA) and C4d deposition, mirroring findings in human chronic rejection.
• Expansion of activated B and plasma cells was observed in the recipient immune system.

Conclusions:

• The developed mouse models closely recapitulate the immunological and histopathological hallmarks of chronic rejection after VCA.
• These models offer a valuable preclinical platform for testing novel therapeutic interventions before clinical application in VCA patients.