Humanized Mouse Models of Diabetic Nephropathy
Small immunodeficient animal models of diabetic nephropathy are needed to assess the impact of human cell populations on diabetic kidney complications. Immunocompetent mice bearing a mutated leptin receptor gene, leprdb-5J/db-5J (abbreviated db/db), develop obesity, insulin resistance, and chronic hyperglycemia as they age. However, they fail to develop robust nephropathy. It has been reported that endothelial nitric oxide synthase deficiency caused by introduction of a mutated Nos3 gene leads to accelerated and robust nephropathy in immunocompetent diabetic mice. However, these immuncomponent mice will reject human cells and cannot be used to test the potential of human cell-based therapies to impact diabetic complications. We have recently developed immunodeficient NOD-scid IL2r?null (NSG) mice that readily engraft with human cells and tissues, including hematopoietic stem cells, mesenchymal stem cells, and embryonic stem cells - cell populations under consideration as treatment for diabetic complications. We propose to develop three new immunodeficient stocks of mice that represent type 2 diabetes, nephropathy, and diabetic nephropathy, and can be readily engrafted with human cells: 1) NSG mice bearing a mutation in the leptin receptor (leprdb/db, abbreviated db/db, type 2 diabetes model), and 2) NSG mice bearing a mutated Nos3 gene (NOS3null, nephropathy model). We will then intercross these two NSG stocks of mice to 3) generate NSG-Nos3null db/db (diabetic nephropathy model) mice. We have recently generated NSG-db/db mice that are now available and propose to generate NSG-Nos3null mice using a speed congenic marker assisted backcrossing approach. At the end of the first year of this P&F, we will have 1) characterized the development of obesity, diabetes, and nephropathy (or lack thereof) in NSG-db/db/ mice, validating this new model of type 2 diabetes, 2) be at the n3 backcross generation of NSG-Nos3null mice. In year 2, we will finish the backcross, and intercross with NSG-db/db mice to generate the stock of most interest, the NSG-Nos3null db/db mouse. This mouse will be available to the AMDCC for screening for the development of diabetic nephropathy and for its ability to support human cell engraftment and cell-based therapy.