Effects of granulocyte-colony stimulating factor (G-CSF) on diabetic cardiomyopathy in Otsuka Long-Evans Tokushima Fatty rats

BACKGROUND: Diabetic cardiomyopathy (CMP) is a common and disabling disease in diabetic patients, however no effective treatments have been developed. Although granulocyte-colony stimulating factor (G-CSF) improves heart function in myocardial infarction, its effect on non-ischemic CMP such as diabetic CMP is unknown. In the present study, we investigated the effects of G-CSF on diabetic CMP in a rat model of type II diabetes. METHODS: Twenty 7-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF: a rat model of diabetes) rats and 10 male Long-Evans Tokushima Otsuka (LETO: normal controls) rats were used. All of the LETO and 8 OLETF rats were fed on tap water while the rest were fed on sucrose-containing water. After 10 weeks, saline or recombinant human G-CSF (100 μg/kg/day) was injected intraperitoneally for 5 days. Blood levels of glucose, total cholesterol and triglyceride, and Doppler echocardiograms for diastolic dysfunction were obtained just before and 4 weeks after the saline or G-CSF treatment. Light microscopy, electron microscopy (EM) and immunohistochemistry for transforming growth factor-β were employed to examine myocardial histology 4 weeks after the saline or G-CSF treatment. RESULTS: Diastolic dysfunction developed at 17 weeks (before the saline or G-CSF treatment) in the OLETF rats whether or not they were fed sucrose water, but were more severe in those fed sucrose water. Four weeks after saline or G-CSF treatment, diastolic function had recovered in the G-CSF-treated group regardless of sucrose water feeding, and perivascular and/or interstitial fibrosis in the G-CSF-treated group had decreased significantly. TGF-β immunoreactivity in the interstitial and perivascular tissue was also reduced in the G-CSF-treated group, and EM studies revealed less severe disruption of myofilaments and mitochondrial cristae, and decreased collagen deposition. CONCLUSIONS: G-CSF can ameliorate cardiac diastolic dysfunction and morphological damage, especially fibrosis of the myocardium, in OLETF rats with diabetic CMP.