66 Neural Stem Cell Transplantation Restored the Delayed Gastric Emptying in Apolipoprotein E-Knockout Mice

Abstract

Background. Although the pathogenesis of delayed gastric emptying, namely gastroparesis, is still unclear, diabetes mellitus is major etiology of gastroparesis. Decreased neuronal nitric oxide synthase (nNOS), which induces relaxation of gastric smooth muscle through the production of nitric oxide, is supposed to be one of the mechanisms of gastroparesis (Gastroenterology 113:1535, 1997). However, the effective treatment for gastroparesis has not been developed. While dyslipidemia is a risk factor of diabetic neuropathy, the defect of apolipoprotein E (apoE), a lipid transporter secreted from glial cell, decreased the expression of nNOS in the stomach (Dig Dis Sci. 57:1504, 2012). Furthermore, transplantion of neural stem cell into gastric antral wall was reported to improve delayed gastric emptying in nNOS knockout mouse (Gastroenterology 129:1817, 2005). The aim of the present study is to explore the role of apoE on gastric emptying and evaluate the effect of neural stem cell transplantation against the model of gastroparesis. Methods. The model of type2 diabetes, db/db mice, and apoE knockout mice, which is the model of arteriosclerosis and hyperlipidemia, were used. For measurement of gastric emptying, 0.48 mg of 13C-acetic acid with 0.15 ml liquid meal (Lacol®) was orally administered. The gastric half emptying time (t1/2) measured by 13C breath test was used for evaluation. The expression levels of nNOS, pan-neuronal marker, PGP 9.5, glial fibrillary acidic protein (GFAP), and glia derived neurotrophic factor (GDNF) were examined by immunohistochemistry andWestern blotting. Neural stem cells were isolated from ffLuc-transgenic mouse, which fluorescent protein, venus, and luciferase gene was fused (BBRC 419; 188, 2012). After tertiary neurosphere was formed, it was injected into gastric antral wall by glass needle. Results. Delayed gastric emptying was observed in 27% of db/db mice, while the levels of blood glucose and body weight were not significantly different. The expression of nNOS in gastric antrum and serum level of apoE were significantly decreased in db/db mice which presented delayed gastric emptying. In apoE knockout mice, the gastric emptying was also delayed compared with control. Although, the expression of PGP 9.5 was not changed, the expression of nNOS was significantly decreased in apoE knockout mice. Furthermore, the expression levels of GFAP and GDNF were significantly decreased in apoE knockout mice. Transplantation of neural stem cell significantly improved the delayed gastric emptying in apoE knockout mice. Conclusion. Neural stem cell transplantation restored the delayed gastric emptying in apoE knockout mice, suggesting a promising application of regenerative therapy against gastroparesis.