Engineering human pluripotent stem cell lines to evade xenogeneic transplantation barriers

Area of Science:

• Immunology
• Stem Cell Biology
• Regenerative Medicine

Background:

• Allogeneic human pluripotent stem cell (hPSC)-derived therapies face immunological rejection by recipients.
• Overcoming immune barriers is critical for the clinical success of hPSC-based treatments.

Purpose of the Study:

• To engineer hPSCs with enhanced immune evasion properties.
• To define the specific immune components responsible for rejecting hPSC transplants.
• To develop preclinical models for testing hPSC immunogenicity.

Main Methods:

• Genetically ablated genes (β2M, TAP1, CIITA, CD74, MICA, MICB) in hPSCs to reduce expression of HLA-I, HLA-II, and NK cell activating ligands.
• Engineered hPSCs to express immune-inhibitory factors (Qa1, H2-K^b, CD55, Crry, CD59).
• Transplanted modified hPSCs into immunocompetent and immunodeficient mouse models.

Main Results:

• Transplantation of engineered hPSCs led to persistent teratomas in wild-type mice, indicating successful immune evasion.
• hPSCs lacking HLA expression persisted in mice deficient in complement and NK cells, further supporting immune evasion.
• T cell, NK cell, and complement-mediated responses were identified as key barriers to hPSC engraftment.

Conclusions:

• Comprehensive immune evasion strategies targeting T cells, NK cells, and complement are necessary for successful allogeneic hPSC transplantation.
• Genetically modified hPSCs expressing immune evasion factors can serve as valuable tools for studying immune barriers.
• These findings facilitate preclinical testing of hPSC-derived therapies in immunocompetent models.