SummaryImmunodeficient non-obese diabetic (NOD)-severe combined immunedeficient (scid) mice bearing a targeted mutation in the gene encoding the interleukin (IL)-2 receptor gamma chain gene (IL2rg null ) engraft readily with human peripheral blood mononuclear cells (PBMC). Here, we report a robust model of xenogeneic graft-versus-host-like disease (GVHD) based on intravenous injection of human PBMC into 2 Gy conditioned NOD-scid IL2rg null mice. These mice develop xenogeneic GVHD consistently (100%) following injection of as few as 5 ¥ 10 6 PBMC, regardless of the PBMC donor used. As in human disease, the development of xenogeneic GVHD is highly dependent on expression of host major histocompatibility complex class I and class II molecules and is associated with severely depressed haematopoiesis. Interrupting the tumour necrosis factor-a signalling cascade with etanercept, a therapeutic drug in clinical trials for the treatment of human GVHD, delays the onset and progression of disease. This model now provides the opportunity to investigate in vivo mechanisms of xenogeneic GVHD as well as to assess the efficacy of therapeutic agents rapidly.

Limb-girdle muscular dystrophy 2B, Miyoshi myopathy, and distal myopathy of anterior tibialis are severely debilitating muscular dystrophies caused by genetically determined dysferlin deficiency. In these muscular dystrophies, it is the repair, not the structure, of the plasma membrane that is impaired. Though much is known about the effects of dysferlin deficiency in skeletal muscle, little is known about the role of dysferlin in maintenance of cardiomyocytes. Recent evidence suggests that dysferlin deficiency affects cardiac muscle , leading to cardiomyopathy when stressed. However, neither the morphological location of dysferlin in the cardiomyocyte nor the progression of the disease with age are known. In this study, we examined a mouse model of dysferlinopathy using light and electron microscopy as well as echocardiography and conscious electrocardiography. We determined that dysferlin is normally localized to the intercalated disk and sarcoplasm of the cardiomyocytes. In the absence of dysferlin, cardiomyocyte membrane damage occurs and is localized to the intercalated disk and sarcoplasm. This damage results in transient functional deficits at 10 months of age, but, unlike in skeletal muscle, the cell injury is sublethal and causes only mild cardiomyopathy even at advanced

The spontaneous mouse mutation "thrombocytopenia and cardiomyopathy" (trac) causes macrothrombocytopenia, prolonged bleeding times, anemia, leukopenia, infertility, cardiomyopathy, and shortened life span.

Immunodeficient mice have been used as recipients of human peripheral blood mononuclear cells (PBMC) for in vivo analyses of human xeno-graft-versus-host disease (GVHD). This xeno-GVHD model system in many ways mimics the human disease. The model system is established by intravenous or intraperitoneal injection of human PBMC or spleen cells into unconditioned or irradiated immunodeficient recipient mice. Recently, the development of several stocks of immunodeficient Prkdcscid (scid), or recombination activating 1 or 2 gene (Rag1 or Rag2) knockout mice bearing a targeted mutation in the gene encoding the IL2 receptor gamma chain (IL2rγ) have been reported. The addition of the mutated IL2rγ gene onto an immunodeficient mouse stock facilitates heightened engraftment with human PBMC. Stocks of mice with mutations in the IL2rγ gene have been studied in several laboratories on NOD-scid, NOD-Rag1null, BALB/c-Rag1null, BALB/c-Rag2null, and Stock-H2d-Rag2null strain backgrounds. Parameters to induce human xeno-GVHD in H2d-Rag2null IL2rγnull mice have been published, but variability in the frequency of disease and kinetics of GVHD were observed. The availability of the NOD-scid IL2rγnull stock that engrafts more readily with human PBMC than does the Stock-H2d-Rag2null IL2rγnull stock should lead to a more reproducible humanized mouse model of GVHD and for the use in drug evaluation and validation. Furthermore, GVHD in human PBMC-engrafted scid mice has been postulated to result predominately from a human anti-mouse major histocompatibility complex (MHC) class II reactivity. Our recent development of NOD-scid IL2rγnull β2mnull and NOD-scid IL2rγnull Abnull stocks of mice now make it possible to investigate directly the role of host MHC class I and class II in the pathogenesis of GVHD in humanized mice using NOD-scid IL2rγnull stocks that engraft at high levels with human PBMC and are deficient in murine MHC class I, class II, or both classes of MHC molecules.

Aims/hypothesis To develop and validate a new immunodeficient mouse strain that spontaneously develops a nonautoimmune hyperglycaemia to serve as a diabetic host for human islets and human beta stem and progenitor cells without the need for induction of hyperglycaemia by toxic chemicals with their associated side effects. Methods We generated and characterised a new strain of immunodeficient spontaneously hyperglycaemic mice, the NOD-Rag1 null Prf1 null Ins2 Akita strain and compared this strain with the NOD-scid Il2rγ null (also known as Il2rg) immunodeficient strain rendered hyperglycaemic by administration of a single dose of streptozotocin. Hyperglycaemic mice were transplanted with human islets ranging from 1,000 to 4,000 islet equivalents (IEQ) and were monitored for normalisation of blood glucose levels. Results NOD-Rag1 null Prf1 null Ins2 Akita mice developed spontaneous hyperglycaemia, similar to Ins2 Akita -harbouring strains of immunocompetent mice. Histological examination of islets in the host pancreas validated the spontaneous loss of beta cell mass in the absence of mononuclear cell infiltration. Human islets transplanted into spontaneously diabetic NOD-Rag1 null Prf1 null Ins2 Akita and chemically diabetic NOD-scid Il2rγ null mice resulted in a return to euglycaemia that occurred with transplantation of similar beta cell masses. Conclusions/interpretation The NOD-Rag1 null Prf1 null Ins2 Akita mouse is the first immunodeficient, spontaneously hyperglycaemic mouse strain described that is based on the Ins2 Akita mutation. This strain is suitable as hosts for human islet and human beta stem and progenitor cell transplantation in the absence of the need for pharmacological induction of diabetes. This strain of mice also has low levels of innate immunity and can be engrafted with a human immune system for the study of human islet allograft rejection.