Hypoimmune induced pluripotent stem cells survive long term in fully immunocompetent, allogeneic rhesus macaques.

Genetic engineering of allogeneic cell therapeutics that fully prevents rejection by a recipient's immune system would abolish the requirement for immunosuppressive drugs or encapsulation and support large-scale manufacturing of off-the-shelf cell products. Previously, we generated mouse and human hypoimmune pluripotent (HIP) stem cells by depleting HLA class I and II molecules and overexpressing CD47 (B2M-/-CIITA-/-CD47+). To determine whether this strategy is successful in non-human primates, we engineered rhesus macaque HIP cells and transplanted them intramuscularly into four allogeneic rhesus macaques. The HIP cells survived unrestricted for 16 weeks in fully immunocompetent allogeneic recipients and differentiated into several lineages, whereas allogeneic wild-type cells were vigorously rejected. We also differentiated human HIP cells into endocrinologically active pancreatic islet cells and showed that they survived in immunocompetent, allogeneic diabetic humanized mice for 4 weeks and ameliorated diabetes. HIP-edited primary rhesus macaque islets survived for 40 weeks in an allogeneic rhesus macaque recipient without immunosuppression, whereas unedited islets were quickly rejected.

Human hypoimmune primary pancreatic islets avoid rejection and autoimmunity and alleviate diabetes in allogeneic humanized mice.

Transplantation of allogeneic pancreatic donor islets has successfully been performed in selected patients with difficult-to-control insulin-dependent diabetes and impaired awareness of hypoglycemia (IAH). However, the required systemic immunosuppression associated with this procedure prevents this cell replacement therapy from more widespread adoption in larger patient populations. We report the editing of primary human islet cells to the hypoimmune HLA class I- and class II-negative and CD47-overexpressing phenotype and their reaggregation into human HIP pseudoislets (p-islets). Human HIP p-islets were shown to survive, engraft, and ameliorate diabetes in immunocompetent, allogeneic, diabetic humanized mice. HIP p-islet cells were further shown to avoid autoimmune killing in autologous, diabetic humanized autoimmune mice. The survival and endocrine function of HIP p-islet cells were not impaired by contamination of unedited or partially edited cells within the p-islets. HIP p-islet cells were eliminated quickly and reliably in this model using a CD47-targeting antibody, thus providing a safety strategy in case HIP cells exert toxicity in a future clinical setting. Transplantation of human HIP p-islets for which no immunosuppression is required has the potential to lead to wider adoption of this therapy and help more diabetes patients with IAH and history of severe hypoglycemic events to achieve insulin independence.