Effectiveness of bioengineered islet cell sheets for the treatment of diabetes mellitus

Transplantation of human cells into Interleukin-2 receptor gamma gene knockout pigs under several conditions

Introduction

Previously, we performed gene knockout (KO) of interleukin-2 receptor gamma (IL2RG) in porcine fetal fibroblasts using zinc finger nuclease-encoding mRNAs, subsequently generating IL2RG KO pigs using these cells through somatic cell nuclear transfer. The IL2RG KO pigs lacked a thymus and were deficient in T lymphocytes and natural killer cells, similar to human X-linked severe combined immunodeficiency (SCID) patients. The present study aimed to evaluate whether pigs can support the growth of xenografted human cells and have the potential to be an effective animal model.

Methods

The IL2RG X^KOY pigs used in this study were obtained by mating IL2RG X^KOX females with wild-type boars. This permitted the routine production of IL2RG KO pigs via natural breeding without complicated somatic cell cloning procedures; therefore, a sufficient number of pigs could be prepared. We transplanted human HeLa S3 cells expressing the tandem dimer tomato into the ears and pancreas of IL2RG KO pigs. Additionally, a newly developed method for the aseptic rearing of SCID pigs was used in case of necessity.

Results

Tumors from the transplanted cells quickly developed in all pigs and were verified by histology and immunohistochemistry. We also transplanted these cells into the pancreas of designated pathogen-free pigs housed in novel biocontainment facilities, and large tumors were confirmed.

Conclusions

IL2RG KO pigs have the potential to become useful animal models in a variety of translational biology fields.

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The present study aimed to evaluate whether IL2RG KO SCID-like pigs can host and support the growth of xenografted human cells under several conditions.

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Tumors from transplanted cells quickly developed in all pigs, as verified by histology and immunohistochemistry.

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IL2RG KO pigs have the potential to become extremely useful animal models in a variety of translational biology fields.

Feasibility of large experimental animal models in testing novel therapeutic strategies for diabetes

Diabetes is among the top 10 causes of death in adults and caused approximately four million deaths worldwide in 2017. The incidence and prevalence of diabetes is predicted to increase. To alleviate this potentially severe situation, safer and more effective therapeutics are urgently required. Mice have long been the mainstay as preclinical models for basic research on diabetes, although they are not ideally suited for translating basic knowledge into clinical applications. To validate and optimize novel therapeutics for safe application in humans, an appropriate large animal model is needed. Large animals, especially pigs, are well suited for biomedical research and share many similarities with humans, including body size, anatomical features, physiology, and pathophysiology. Moreover, pigs already play an important role in translational studies, including clinical trials for xenotransplantation. Progress in genetic engineering over the past few decades has facilitated the development of transgenic animals, including porcine models of diabetes. This article discusses features that attest to the attractiveness of genetically modified porcine models of diabetes for testing novel treatment strategies using recent technical advances.

Genetically engineered pigs manifesting pancreatic agenesis with severe diabetes

INTRODUCTION

Pancreatic duodenum homeobox 1 (Pdx1) expression is crucial for pancreatic organogenesis and is a key regulator of insulin gene expression. Hairy and enhancer of split 1 (Hes1) controls tissue morphogenesis by maintaining undifferentiated cells. Hes1 encodes a basic helix loop helix (bHLH) transcriptional repressor and functionally antagonizes positive bHLH genes, such as the endocrine determination gene neurogenin-3. Here, we generated a new pig model for diabetes by genetic engineering Pdx1 and Hes1 genes.

RESEARCH DESIGN AND METHODS

A transgenic (Tg) chimera pig with germ cells carrying a construct expressing Hes1 under the control of the Pdx1 promoter was used to mate with wild-type gilts to obtain Tg piglets.

RESULTS

The Tg pigs showed perinatal death; however, this phenotype could be rescued by insulin treatment. The duodenal and splenic lobes of the Tg pigs were slender and did not fully develop, whereas the connective lobe was absent. β cells were not detected, even in the adult pancreas, although other endocrine cells were detected, and exocrine cells functioned normally. The pigs showed no irregularities in any organs, except diabetes-associated pathological alterations, such as retinopathy and renal damage.

CONCLUSION

Pdx1-Hes1 Tg pigs were an attractive model for the analysis of pancreatic development and testing of novel treatment strategies for diabetes.