Thorac Cardiovasc Surg 2020; 68(S 01): S1-S72
DOI: 10.1055/s-0040-1705474
Short Presentations
Sunday, March 1st, 2020
Cardiovascular Basic Sciences
Georg Thieme Verlag KG Stuttgart · New York

Hypoimmunogenic Derivatives of Induced Pluripotent Stem Cells Evade Immune Rejection in Fully Immunocompetent Allogeneic Recipients

T. Deuse
1   San Francisco, California, United States
,
X. Hu
2   Hamburg, Germany
,
A. Gravina
1   San Francisco, California, United States
,
D. Wang
2   Hamburg, Germany
,
G. Tediashvili
2   Hamburg, Germany
,
H. Reichenspurner
2   Hamburg, Germany
,
M. M. Davis
3   Stanford, California, United States
,
L. L. Lanier
1   San Francisco, California, United States
,
S. Schrepfer
2   Hamburg, Germany
› Author Affiliations
Further Information

Publication History

Publication Date:
13 February 2020 (online)

Objectives: Autologous induced pluripotent stem cells (iPSCs) constitute an unlimited cell source for patient-specific cell-based organ repair strategies. Many of the current challenges in this field could be overcome by using prefabricated allogeneic cell or tissue products, but the vigorous immune response against histo-incompatible cells has prevented the successful implementation of this approach. We envisioned engineering hypoimmunogenic iPSCs as a source for universally compatible cell or tissue grafts not requiring any immunosuppression.

Methods: C57BL/6 wild-type (WT) miPSCs give rise to classical teratomas with ectodermal, mesodermal, and endodermal features in SCID-beige mice. To achieve hypoimmunogenicity, these miPSCs underwent a three-step gene-editing process. First, CRISPR guide RNAs targeting the coding sequence of the mouse β2-microglobulin (B2m) gene were used to yield B2m−/− miPSCs. Second, these were transfected with a CRISPR-Cas9 vector targeting Ciita, the master regulator of MHC class II molecules. Third, a Cd47 transgene (tg) was introduced by a lentiviral vector yielding B2m−/−Ciita−/− Cd47 tg-expressing miPSCs. Finally, we transplanted WT miPSCs or engineered miPSCs into syngeneic C57BL/6 (H2b) and allogeneic (H2d) BALB/c recipients without immunosuppression.

Results: WT miPSCs showed 100% teratoma growth in syngeneic recipients, but all cell grafts were rejected in allogeneic BALB/c mice. After 5 days, splenocytes from allogeneic BALB/c recipients showed a strong IFN-γ and a moderate IL-4 response relative to baseline responder cell activity; syngeneic mice showed no responsiveness. Only allogeneic BALB/c recipients mounted a strong IgM antibody response against the WT miPSCs relative to baseline MFI. Engineered miPSCs developed comparable teratomas to WT miPSCs in syngeneic recipients, with enhanced survival in allogeneic recipients that depended on their level of hypoimmunogenicity and increased with every engineering step. Our final B2m−/−Ciita−/− Cd47 tg miPSC line showed 100% teratoma formation and induced no IFN-γ or antibody responses.

Conclusion: We show that murine iPSCs lose their immunogenicity when major histocompatibility complex (MHC) class I and II genes are inactivated and CD47 is over-expressed. These hypoimmunogenic iPSCs retain their pluripotent stem cell potential and differentiation capacity and reliably evade immune rejection in fully MHC-mismatched allogeneic recipients.