Soo-Eun Sung

Chronic effects of losartan on the muscles and the serologic profiles of mdx mice.

AIMS Losartan, an angiotensin II type 1 receptor blocker, attenuates transforming growth factor-β (TGF-β) signaling, which inhibits myogenic regeneration. Although many researchers have demonstrated that losartan has anti-fibrotic and protective effects on cardiac and skeletal muscles, for long-term administration to treat dystrophic disorders, it is essential to demonstrate not only the therapeutic effects of losartan on muscles but also its effects on other organs and on blood biochemistry. MAIN METHODS Mdx mice, an animal model of Duchenne muscular dystrophy (DMD), were fed losartan dissolved in tap water. After 44weeks, the skeletal (gastrocnemius), cardiac, and diaphragm muscles of mdx mice were removed. Tissue and blood samples were collected from all experimental animals. Effects of losartan on muscle regeneration, fibrosis, and blood enzymatic profiles were evaluated. KEY FINDINGS In histopathological findings and serum biochemistry analyses, chronic losartan administration showed muscular protective effects and inhibited fibrosis in skeletal (gastrocnemius), cardiac, and diaphragmatic muscles. In addition, losartan had no effects on other solid organs. Interestingly, losartan had beneficial effects on serum HDL ratio. SIGNIFICANCE This study demonstrates the therapeutic effects of losartan on muscles and its effects on other organs and on blood biochemistry. In conclusion, our results provide useful information for consideration of chronic losartan administration be as a treatment of DMD.

MyoD Overexpressed Equine Adipose-Derived Stem Cells Enhanced Myogenic Differentiation Potential.

Mesenchymal stem cells could potentially be used in the clinical treatment of muscle disorders and muscle regeneration. Adipose-derived stem cells (ADSCs) can be easily isolated from adipose tissue, as opposed to stem cells of other tissues. We believe that cell therapy using ADSCs could be applied to muscle disorders in horses and other species. We sought to improve the myogenic differentiation potential of equine ADSCs (eqADSCs) using a MyoD lentiviral vector. MyoD lentiviruses were transduced into eqADSCs and selected using puromycin. Cells were cultured in differentiation media containing 5% horse serum, and after 5 days the MyoD-transduced cells differentiated into myogenic cells (MyoD-eqADSCs). Using green fluorescent protein (GFP), MyoD-eqADSCs were purified and transplanted into the tibialis anterior muscles of mice after they were injured with the myotoxin notexin. The mice were sacrificed to examine any regeneration in the tibialis anterior muscle 4 weeks after the MyoD-eqADSCs were injected. The MyoD-eqADSCs cultured in growth media expressed murine and equine MyoD; however, they did not express late differentiation markers such as myogenin (MYOG). When cells were grown in differentiation media, the expression of MYOG was clearly observed. According to our reverse transcription polymerase chain reaction and immunocytochemistry results, MyoD-eqADSCs expressed terminal myogenic phase genes, such as those encoding dystrophin, myosin heavy chain, and troponin I. The MyoD-eqADSCs fused to each other, and the formation of myotube-like cells from myoblasts in differentiation media occurred between days 5 and 14 postplating. In mice, we observed GFP-positive myofibers, which had differentiated from the injected MyoD-eqADSCs. Our approaches improved the myogenic differentiation of eqADSCs through the forced expression of murine MyoD. Our findings suggest that limitations in the treatment of equine muscle disorders could be overcome using ADSCs.

Alcohol Induced Hepatic Degeneration in a Hepatitis C Virus Core Protein Transgenic Mouse Model

Hepatitis C virus (HCV) has become a major public health issue. It is prevalent in most countries. HCV infection frequently begins without clinical symptoms, before progressing to persistent viremia, chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) in the majority of patients (70% to 80%). Alcohol is an independent cofactor that accelerates the development of HCC in chronic hepatitis C patients. The purpose of the current study was to evaluate ethanol-induced hepatic changes in HCV core-Tg mice and mutant core Tg mice. Wild type (NTG), core wild-Tg mice (TG-K), mutant core 116-Tg mice (TG-116) and mutant core 99-Tg mice (TG-99) were used in this investigation. All groups were given drinking water with 10% ethanol and 5% sucrose for 13 weeks. To observe liver morphological changes, we performed histopathological and immunohistochemical examinations. Histopathologically, NTG, TG-K and TG-116 mice showed moderate centrilobular necrosis, while severe centrilobular necrosis and hepatocyte dissociation were observed in TG-99 mice with increasing lymphocyte infiltration and piecemeal necrosis. In all groups, a small amount of collagen fiber was found, principally in portal areas. None of the mice were found to have myofibroblasts based on immunohistochemical staining specific for α-SMA. CYP2E1-positive cells were clearly detected in the centrilobular area in all groups. In the TG-99 mice, we also observed cells positive for CK8/18, TGF-β1 and phosphorylated (p)-Smad2/3 and p21 around the necrotic hepatocytes in the centrilobular area (p < 0.01). Based on our data, alcohol intake induced piecemeal necrosis and hepatocyte dissociation in the TG-99 mice. These phenomena involved activation of the TGF-β1/p-Smad2/3/p21 signaling pathway in hepatocytes. Data from this study will be useful for elucidating the association between alcohol intake and HCV infection.

Vitamin C Promoted Liver Regeneration Following Partial Hepatectomy-induced Hepatic Injury in Senescence Marker Protein-30-deficient Mice

The capacity for liver regeneration involves a variety of nutritional factors. Vitamin C has multiple metabolic and antioxidant functions. In this study, we investigated the role of vitamin C in liver regeneration following hepatectomy in senescence marker protein (SMP)-30 knockout (KO) mice. Partial hepatectomy was performed by resecting the median and left lateral lobes of mice. Vitamin C accelerated liver recovery in SMP30 KO mice treated with vitamin C (KV). The livers of the KV mice exhibited lower levels of aspartate aminotransferase and lower injury than those of the KO mice. Increased type II transforming growth factor-β receptor (TGF-βRII)-mediated regeneration signaling was accompanied by HGF and cMet in the KV but not the KO mice. Consistent with this, the expression of cell cycle regulatory proteins, including cyclin D1 and proliferating cell nuclear antigen (PCNA), increased rapidly in the KV mice. Enhanced activation of ERK and GSK-3β proteins and a significantly increased number of binuclear hepatocytes were also detected in the livers of the KV mice. Moreover, the KV mice synthesized the highest levels of albumin. These data suggest that treating SMP30 knockout mice with vitamin C resulted in earlier recovery and liver regeneration by activation of the regeneration system.

Adrenomedullin Deficiency Increases the Susceptibility of Liver Fibrosis Induced by CCl 4

Adrenomedullin (AM) is a peptide expressed in all body tissues, and its related receptors are increased in liver fibrosis. In this study, we evaluated the effect of AM deficiency on liver fibrogenesis induced by CCl 4 using AM heterozygous (HT) mice. The animals received a single injection of CCl 4 or olive oil for the acute experiment, and received CCl 4 or olive oil three times a week for 6 weeks for the chronic experiment. Fibrosis was accessed using histopathological analysis and the western blot. The AM HT mice showed mild pericentrilobular degeneration when compared to the AM wild type (WT) mice. In the acute experiment, there was no significant difference between the AM WT and AM HT mice. However, in the chronic experiment, the CCl 4 -treated AM HT mice showed more severe liver fibrosis than that of the CCl 4 -treated AM WT mice. The AST and ALT levels of the AM HT CCl 4 group were higher than those of the AM WT CCl 4 group. Additionally, the collagen deposition, α-SMA protein and TGF-β protein were increased in the AM HT CCl 4 group when compared to the AM WT CCl 4 group. The AM HT mice also exhibited severe lipid peroxidation through the GSH decrement. Taken together, our data suggest that AM deficiency increases the susceptibility to liver fibrosis induced by CCl 4 , indicating a novel therapeutic target for patients with liver fibrosis.