Thyroid Hormone Levels Correlate With the Maturation of Implanted Pancreatic Endoderm Cells in Patients With Type 1 Diabetes

BACKGROUND

Macroencapsulated pancreatic endoderm cells (PECs) can reverse diabetes in rodents and preclinical studies revealed that thyroid hormones in vitro and in vivo bias PECs to differentiate into insulin-producing cells. In an ongoing clinical trial, PECs implanted in macroencapsulation devices into patients with type 1 diabetes were safe but yielded heterogeneous outcomes. Though most patients developed meal responsive C-peptide, levels were heterogeneous and explanted grafts had variable numbers of surviving cells with variable distribution of endocrine cells.

METHODS

We measured circulating triiodothyronine and thyroxine levels in all patients treated at 1 of the 7 sites of the ongoing clinical trial and determined if thyroid hormone levels were associated with the C-peptide or glucagon levels and cell fate of implanted PECs.

RESULTS

Both triiodothyronine and thyroxine levels were significantly associated with the proportion of cells that adopted an insulin-producing fate with a mature phenotype. Thyroid hormone levels were inversely correlated to circulating glucagon levels after implantation, suggesting that thyroid hormones lead PECs to favor an insulin-producing fate over a glucagon-producing fate. In mice, hyperthyroidism led to more rapid maturation of PECs into insulin-producing cells similar in phenotype to PECs in euthyroid mice.

CONCLUSION

These data highlight the relevance of thyroid hormones in the context of PEC therapy in patients with type 1 diabetes and suggest that a thyroid hormone adjuvant therapy may optimize cell outcomes in some PEC recipients.

Human A2-CAR T Cells Reject HLA-A2 + Human Islets Transplanted Into Mice Without Inducing Graft-versus-host Disease

BACKGROUND

Type 1 diabetes is an autoimmune disease characterized by T-cell-mediated destruction of pancreatic beta-cells. Islet transplantation is an effective therapy, but its success is limited by islet quality and availability along with the need for immunosuppression. New approaches include the use of stem cell-derived insulin-producing cells and immunomodulatory therapies, but a limitation is the paucity of reproducible animal models in which interactions between human immune cells and insulin-producing cells can be studied without the complication of xenogeneic graft-versus-host disease (xGVHD).

METHODS

We expressed an HLA-A2-specific chimeric antigen receptor (A2-CAR) in human CD4 + and CD8 + T cells and tested their ability to reject HLA-A2 + islets transplanted under the kidney capsule or anterior chamber of the eye of immunodeficient mice. T-cell engraftment, islet function, and xGVHD were assessed longitudinally.

RESULTS

The speed and consistency of A2-CAR T-cell-mediated islet rejection varied depending on the number of A2-CAR T cells and the absence/presence of coinjected peripheral blood mononuclear cells (PBMCs). When <3 million A2-CAR T cells were injected, coinjection of PBMCs accelerated islet rejection but also induced xGVHD. In the absence of PBMCs, injection of 3 million A2-CAR T cells caused synchronous rejection of A2 + human islets within 1 wk and without xGVHD for 12 wk.

CONCLUSIONS

Injection of A2-CAR T cells can be used to study rejection of human insulin-producing cells without the complication of xGVHD. The rapidity and synchrony of rejection will facilitate in vivo screening of new therapies designed to improve the success of islet-replacement therapies.

Human A2-CAR T cells reject HLA-A2+ human islets transplanted into mice without inducing graft versus host disease

Background

Type 1 diabetes (T1D) is an autoimmune disease characterised by T cell mediated destruction of pancreatic beta-cells. Islet transplantation is an effective therapy, but its success is limited by islet quality and availability along with the need for immunosuppression. New approaches include use of stem cell-derived insulin-producing cells and immunomodulatory therapies, but a limitation is the paucity of reproducible animal models in which interactions between human immune cells and insulin-producing cells can be studied without the complication of xenogeneic graft- versus -host disease (xGVHD).

Methods

We expressed an HLA-A2-specific chimeric antigen receptor (A2-CAR) in human CD4+ and CD8+ T cells and tested their ability to reject HLA-A2+ islets transplanted under the kidney capsule or anterior chamber of the eye of immunodeficient mice. T cell engraftment, islet function and xGVHD were assessed longitudinally.

Results

The speed and consistency of A2-CAR T cells-mediated islet rejection varied depending on the number of A2-CAR T cells and the absence/presence of co-injected peripheral blood mononuclear cells (PBMCs). When <3 million A2-CAR T cells were injected, co-injection of PBMCs accelerated islet rejection but also induced xGVHD. In the absence of PBMCs, injection of 3 million A2-CAR T cells caused synchronous rejection of A2+ human islets within 1 week and without xGVHD for 12 weeks.

Conclusions

Injection of A2-CAR T cells can be used to study rejection of human insulin-producing cells without the complication of xGVHD. The rapidity and synchrony of rejection will facilitate in vivo screening of new therapies designed to improve the success of isletreplacement therapies.

The impact of different implantation sites and sex on the differentiation of human pancreatic endoderm cells into insulin-secreting cells in vivo

Few studies have examined the differentiation of human embryonic stem cell (hESC)-derived pancreatic endoderm cells (PECs) in different implantation sites. Here, we investigate the influence of implantation site and recipient sex on the differentiation of hESC-derived PECs in vivo. Male and female mice were implanted with 5x106 hESC-derived PECs either under the kidney capsule, in the gonadal fat pad, or subcutaneously within macroencapsulation (TheraCyteTM) devices. Mice that received PECs within TheraCyteTM devices developed glucosestimulated human C-peptide secretion faster than cells implanted under the kidney capsule or in the gonadal fat pad. Interestingly, hESC-derived PECs implanted under the kidney capsule in females developed glucose-stimulated human C-peptide faster than in males, and secreted higher levels of arginine-stimulated glucagon and GLP-1 than other implantation sites. Furthermore, hESC-derived grafts collected from the kidney capsule and gonadal fat pad sites displayed a mix of endocrine and ductal cells as well as contained cysts whereas TheraCyteTM device grafts displayed mostly endocrine cells and cysts were not observed. Here we demonstrate that the macroencapsulated subcutaneous site and the female recipient can promote faster differentiation of hESC-derived PECs to endocrine cells in mice.

Sex Differences in Maturation of Human Embryonic Stem Cell-Derived β Cells in Mice

Pancreatic progenitors derived from human embryonic stem cells (hESCs) are now in clinical trials for insulin replacement in patients with type 1 diabetes. Animal studies indicate that pancreatic progenitor cells can mature into a mixed population of endocrine cells, including glucose-responsive β cells several months after implantion. However, it remains unclear how conditions in the recipient may influence the maturation and ultimately the function of these hESC-derived cells. Here, we investigated the effects of (1) pregnancy on the maturation of human stage 4 (S4) pancreatic progenitor cells and (2) the impact of host sex on both S4 cells and more mature stage 7 (S7) pancreatic endocrine cells implanted under the kidney capsule of immunodeficient SCID-beige mice. Pregnancy led to increased proliferation of endogenous pancreatic β cells, but did not appear to affect proliferation or maturation of S4 cells at midgestation. Interestingly, S4 and S7 cells both acquired glucose-stimulated C-peptide secretion in females before males. Moreover, S4 cells lowered fasting blood glucose levels in females sooner than in males, whereas the responses with S7 cells were similar. These data indicate that the host sex may impact the maturation of hESC-derived cells in vivo and that this effect can be minimized by more advanced differentiation of the cells before implantation.

Hypothyroidism Impairs Human Stem Cell-Derived Pancreatic Progenitor Cell Maturation in Mice

Pancreatic progenitors derived from human embryonic stem cells (hESCs) are a potential source of transplantable cells for treating diabetes and are currently being tested in clinical trials. Yet, how the milieu of pancreatic progenitor cells, including exposure to different factors after transplant, may influence their maturation remains unclear. Here, we examined the effect of thyroid dysregulation on the development of hESC-derived progenitor cells in vivo. Hypothyroidism was generated in SCID-beige mice using an iodine-deficient diet containing 0.15% propyl-2-thiouracil, and hyperthyroidism was generated by addition of L-thyroxine (T4) to drinking water. All mice received macroencapsulated hESC-derived progenitor cells, and thyroid dysfunction was maintained for the duration of the study ("chronic") or for 4 weeks posttransplant ("acute"). Acute hyperthyroidism did not affect graft function, but acute hypothyroidism transiently impaired human C-peptide secretion at 16 weeks posttransplant. Chronic hypothyroidism resulted in severely blunted basal human C-peptide secretion, impaired glucose-stimulated insulin secretion, and elevated plasma glucagon levels. Grafts from chronic hypothyroid mice contained fewer β-cells, heterogenous MAFA expression, and increased glucagon(+) and ghrelin(+) cells compared to grafts from euthyroid mice. Taken together, these data suggest that long-term thyroid hormone deficiency may drive the differentiation of human pancreatic progenitor cells toward α- and ε-cell lineages at the expense of β-cell formation.