Abstract:The purpose of this study was to develop a strain of canine X-linked muscular dystrophy (CXMD), a model of Duchenne muscular dystrophy, in Japan. A female beagle was artificially inseminated with frozen-thawed spermatozoa derived from an affected golden retriever. Subsequently, two carrier female dogs (G1 carriers) and four normal male littermates were produced. Thereafter, the two G1 carriers were mated with beagle sires. As a result, each bitch whelped three times, and out of 54 pups, 17 affected male descendants, and 11 carrier female descendants (G2 carriers) were detected. One G2 carrier was then mated with a beagle sire and 15 pups in two whelpings were produced, including five affected males and four carrier females (G3 carriers). A total of 10 female beagles were artificially inseminated to evaluate the fertility of the frozen-thawed spermatozoa from the two affected dogs. The whelping rates of the two affected dogs were 4/5 and the litter sizes were 5.0 ± 1.41 and 6.0 ± 0.82, respectively. These results indicate that a canine X-linked muscular dystrophy colony has been established in Japan. We called them CXMD J .

Background: Cardiac mortality in Duchenne muscular dystrophy (DMD) has recently become important, because risk of respiratory failure has been reduced due to widespread use of the respirator. The cardiac involvement is characterized by distinctive electrocardiographic abnormalities or dilated cardiomyopathy, but the pathogenesis has remained obscure. In research on DMD, Golden retriever-based muscular dystrophy (GRMD) has attracted much attention as an animal model because it resembles DMD, but GRMD is very difficult to maintain because of their severe phenotypes. We therefore established a line of dogs with Beagle-based canine X-linked muscular dystrophy in Japan (CXMD J ) and examined the cardiac involvement.

Background Various durations of survival have been observed in the xenotransplantation of life-supporting alpha-1,3-galactosyltransferase knockout (GalT-KO) porcine kidneys into nonhuman primates (NHPs). While others have demonstrated loss of GalT-KO transplanted kidneys within two weeks, we have reported an average survival of 51 days with the co-transplantation of the kidney and vascularized thymus and an average of 29 days with the kidney alone. In order to determine the factors responsible for this difference in survival time, we performed xenogeneic kidney transplantations into cynomolgus monkeys with an anti-CD40L-based regimen using two different strains of GalT-KO swine, one derived from MGH-Miniature swine and the other obtained from Meji University. Materials and Methods Eight cynomolgus moneys received GalT-KO kidneys. Three kidney grafts were from MGH/NIBS GalT-KO pigs and 5 GalT-KO grafts were from MEIJI GalT-KO swine. All cynomolgus recipients were treated identically. Results Recipients of kidneys from the MGH GalT-KO swine, produced by nuclear transfer in Japan, survived an average of 28.7 days, while recipients of MEIJI GalT-KO swine survived an average of 9.2 days. Among the differences between these two groups, one potentially revealing disparity was that the MEIJI swine were positive for porcine-CMV, while the MGH-derived swine were negative. Conclusions This is the first study comparing renal xenotransplantation from two different sources of GalT-KO swine into NHPs at a single center. The results demonstrate that porcine-CMV may be responsible for early loss of GalTKO swine kidney xenografts.

Background-Respiratory support therapy significantly improves life span in patients with Duchenne muscular dystrophy; cardiac-related fatalities, including lethal arrhythmias, then become a crucial issue. It is therefore important to more thoroughly understand cardiac involvement, especially pathology of the conduction system, in the larger Duchenne muscular dystrophy animal models such as dystrophic dogs. Methods and Results-When 10 dogs with canine X-linked muscular dystrophy in Japan (CXMD J ) were examined at the age of 1 to 13 months, dystrophic changes of the ventricular myocardium were not evident; however, Purkinje fibers showed remarkable vacuolar degeneration as early as 4 months of age. The degeneration of CXMD J Purkinje fibers was coincident with overexpression of Dp71 at the sarcolemma and translocation of -calpain to the cell periphery near the sarcolemma or in the vacuoles. Immunoblotting of the microdissected fraction showed that -calpain-sensitive proteins such as desmin and cardiac troponin-I or -T were selectively degraded in the CXMD J Purkinje fibers. Utrophin was highly upregulated in the earlier stage of CXMD J Purkinje fibers, but the expression was dislocated when vacuolar degeneration was recognized at 4 months of age. Nevertheless, the expression of dystrophin-associated proteins ␣-, ␤-, ␥-, and ␦-sarcoglycans and ␤-dystroglycan was well maintained at the sarcolemma of Purkinje fibers. Conclusions-Selective vacuolar degeneration of Purkinje fibers was found in the early stages of dystrophin deficiency.Dislocation of utrophin besides upregulation of Dp71 can be involved with this pathology. The degeneration of Purkinje fibers can be associated with the distinct deep Q waves in ECG and fatal arrhythmia seen in dystrophin deficiency.