Donor MHC-specific thymus vaccination allows for immunocompatible allotransplantation

Area of Science:

• Immunology
• Transplantation Biology
• Gene Therapy

Background:

• Organ transplantation is a life-saving treatment for organ failure, but limited by the scarcity of major histocompatibility complex (MHC)-matched donor organs.
• T cell allorecognition is the primary cause of graft rejection, significantly hindering transplantation success rates.
• Current organ donation systems face a critical mismatch between available organs and recipients, with 25%-80% of donated organs remaining unmatched.

Purpose of the Study:

• To introduce a novel "donor MHC-specific thymus vaccination" (DMTV) strategy to induce recipient tolerance to both autologous and allogeneic donor MHC.
• To overcome the critical shortage of MHC-matched donor organs for patients requiring organ transplantation.

Main Methods:

• Adeno-associated virus-mediated delivery was used to express allogeneic MHC molecules within the recipient's thymus, alongside autologous MHC.
• This process facilitated T cell education, leading to the depletion of T cells recognizing either self or donor MHC.
• The DMTV strategy was validated in C57BL/6-MHC and BALB/c-MHC dual immunocompatible mouse models and a humanized BLT mouse model.

Main Results:

• Stable expression of both autologous and allogeneic MHC was achieved in the engineered thymus, promoting T cell tolerance.
• Long-term graft tolerance was observed in mice receiving C57BL/6 skin and embryonic stem cells after DMTV vaccination.
• The DMTV strategy demonstrated efficacy in a humanized mouse model, enabling immunocompatible allotransplantation of human embryonic stem cells.

Conclusions:

• The DMTV strategy represents a potent method for establishing a donor-compatible immune system in recipients.
• This approach effectively addresses the clinical challenge posed by the severe shortage of MHC-matched donor organs.
• DMTV holds significant promise for improving outcomes in organ transplantation for patients with end-stage organ failure.