No Tumorigenicity of Allogeneic Induced Pluripotent Stem Cells in Major Histocompatibility Complex-matched Cynomolgus Macaques.

Tumorigenicity of induced pluripotent stem cells (iPSCs) is anticipated when cells derived from iPSCs are transplanted. It has been reported that iPSCs formed a teratoma in vivo in autologous transplantation in a nonhuman primate model without immunosuppression. However, there has been no study on tumorigenicity in major histocompatibility complex (MHC)-matched allogeneic iPSC transplantation with immune-competent hosts. To examine the tumorigenicity of allogeneic iPSCs, we generated four iPSC clones carrying a homozygous haplotype of the MHC. Two clones were derived from female fibroblasts by using a retrovirus and the other two clones were derived from male peripheral blood mononuclear cells by using Sendai virus (episomal approach). The iPSC clones were transplanted into allogenic MHC-matched immune-competent cynomolgus macaques. After transplantation of the iPSCs into subcutaneous tissue of an MHC-matched female macaque and into four testes of two MHC-matched male macaques, histological analysis showed no tumor, inflammation, or regenerative change in the excised tissues 3 months after transplantation, despite the results that iPSCs formed teratomas in immune-deficient mice and in autologous transplantation as previously reported. The results in the present study suggest that there is no tumorigenicity of iPSCs in MHC-matched allogeneic transplantation in clinical application.

First Successful Delivery after Uterus Transplantation in MHC-Defined Cynomolgus Macaques.

Delivery following uterus transplantation (UTx)-an approach for treating uterine factor infertility-has not been reported in nonhuman primate models. Here, six female major histocompatibility complex (MHC)-defined cynomolgus macaques that underwent allogeneic UTx were evaluated. Antithymocyte globulin and rituximab were administered to induce immunosuppression and a triple maintenance regimen was used. Menstruation resumed in all animals with long-term survival, except one, which was euthanized due to infusion associated adverse reaction to antithymocyte globulin. Donor-specific antibodies (DSA) were detected in cases 2, 4, and 5, while humoral rejection occurred in cases 4 and 5. Post-transplant lymphoproliferative disorder (PTLD) developed in cases 2 and 3. Pregnancy was attempted in cases 1, 2, and 3 but was achieved only in case 2, which had haploidentical donor and recipient MHCs. Pregnancy was achieved in case 2 after recovery from graft rejection coincident with DSA and PTLD. A cesarean section was performed at full-term. This is the first report of a successful livebirth following allogeneic UTx in nonhuman primates, although the delivery was achieved via UTx between a pair carrying haploidentical MHCs. Experimental data from nonhuman primates may provide important scientific knowledge needed to resolve unsolved clinical issues in UTx.

Long-Term Outcome and Rejection After Allogeneic Uterus Transplantation in Cynomolgus Macaques.

Uterus transplantation (UTx) is an option for women with uterine factor infertility to have a child, but is still in the experimental stage. Therefore, allogeneic animal models of UTx are required for resolution of clinical issues. In this study, long-term outcomes were evaluated in four recipients (cases 1-4) after allogeneic UTx in cynomolgus macaques. Immunosuppression with antithymocyte globulin induction and a triple maintenance regimen was used. Postoperative ultrasonography and biopsy of the transplanted uterus and immunoserological examinations were performed. All four recipients survived for >3 months after surgery, but continuous menstruation did not resume, although temporary menstruation occurred (cases 1 and 2). All animals were euthanized due to irreversible rejection and no uterine blood flow (cases 1, 2 and 4) and post-transplant lymphoproliferative disorder (case 3). Donor-specific antibodies against MHC class I and II were detected in cases 1, 2 and 4, but not in case 3. Peripheral lymphocyte counts tended to elevate for CD3+, CD20+ and NK cells in conjunction with uterine rejection, and all animals had elevated stimulation indexes of mixed lymphocyte reaction after surgery. Establishment of allogeneic UTx in cynomolgus macaque requires further exploration of immunosuppression, but the clinicopathological features of uterine rejection are useful for development of human UTx.

Transplantation of iPS-Derived Tumor Cells with a Homozygous MHC Haplotype Induces GRP94 Antibody Production in MHC-Matched Macaques.

Immune surveillance is a critical component of the antitumor response in vivo, yet the specific components of the immune system involved in this regulatory response remain unclear. In this study, we demonstrate that autoantibodies can mitigate tumor growth in vitro and in vivo We generated two cancer cell lines, embryonal carcinoma and glioblastoma cell lines, from monkey-induced pluripotent stem cells (iPSC) carrying a homozygous haplotype of major histocompatibility complex (MHC, Mafa in Macaca fascicularis). To establish a monkey cancer model, we transplanted these cells into monkeys carrying the matched Mafa haplotype in one of the chromosomes. Neither Mafa-homozygous cancer cell line grew in monkeys carrying the matched Mafa haplotype heterozygously. We detected in the plasma of these monkeys an IgG autoantibody against GRP94, a heat shock protein. Injection of the plasma prevented growth of the tumor cells in immunodeficient mice, whereas plasma IgG depleted of GRP94 IgG exhibited reduced killing activity against cancer cells in vitro These results indicate that humoral immunity, including autoantibodies against GRP94, plays a role in cancer immune surveillance. Cancer Res; 77(21); 6001-10. ©2017 AACR.