Shinichiro Yamamoto

Comparison of therapeutic effects between radiofrequency ablation and percutaneous microwave coagulation therapy for small hepatocellular carcinomas

Background:  Although thermal ablation therapies have gained fairly wide acceptance as an effective treatment for small hepatocellular carcinoma (HCC), there have been only a few clinical studies comparing the response to radiofrequency ablation (RFA) and percutaneous microwave coagulation therapy (PMCT). We evaluated the therapeutic efficacy and safety of these two procedures for the treatment of small HCC measuring ≤ 2 cm in diameter.

Establishment of immortalized human hepatic stellate scavenger cells to develop bioartificial livers

Background. Maintenance of liver-specific functions has been shown to be stabilized by co-cultivation of hepatocytes with hepatic stellate cells (HSC). Because the limited lifespan of human HSC is a major hurdle to their use, the authors report here the amplification of human HSC populations in vitro by retroviral transfer of human telomerase reverse transcriptase (hTERT). Methods. Human HSC strain LI 90 cells were transduced with a retroviral vector SSR#197 expressing hTERT and green fluorescent protein (GFP) cDNA flanked by a pair of loxP. TWNT-1, one of SSR#197-immortalized HSC, was characterized. Differentiated liver functions were evaluated in an immortalized human hepatocyte NKNT-3–TWNT-1 co-culture system. Results. TWNT-1 cells showed differential functions of HSC, including uptake of acetylated low-density lipoproteins and synthesis of collagen type I and hepatocyte growth factor. Efficient excision of the retrovirally transferred hTERT and GFP cDNAs was achieved by TAT-mediated expression of the Cre recombinase and subsequent GFP-negative cell sorting. When co-cultured with TWNT-1 cells, NKNT-3 increased protein expression of the detoxifying cytochrome P450-associated protein isoenzymes 3A4 and 2C9 and urea synthesis. Conclusions. TWNT-1 cells could be valuable in the study of integrated liver functions and contribute to the optimization of liver cell therapies and bioartificial livers.

Establishment of an immortalized human-liver endothelial cell line with SV40T and hTERT.

Background and Aims. Liver endothelial cells (LECs) perform an essential role in important pathophysiologic functions in the liver. Establishment of a human LEC line facilitates advances in LEC research. Here, we present immortalization of human LECs using retroviral gene transfer of simian virus 40 large T antigen (SV40T) and human telomerase reverse transcriptase (hTERT). We also demonstrate excision of SV40T and hTERT with TAT-mediated Cre/loxP recombination and subsequent cell sorting. Methods. First, human LECs were transduced with a retroviral vector somatostatin receptor (SSR)#69 expressing SV40T and hygromycin-resistance genes flanked by a pair of loxA recombination targets. Then, cells were retrovirally superinfected with SSR#197 encoding hTERT and green fluorescent protein (GFP) cDNAs that were intervened by two loxBs. One SV40T-and hTERT-immortalized LEC clone, TMNK-1, was established and analyzed for its biologic characteristics. Results. The cells were hygromycin-resistant and uniformly positive for GFP expression. TMNK-1 expressed EC markers, including factor VIII, vascular endothelial growth factor receptors (flt-1, KDR/Flk-1), and CD34, showed uptake of Di-I-acetylated-low-density lipoprotein and angiogenic potential in Matrigel assays. After lipopolysaccharide treatment, TMNK-1 produced tumor necrosis factor (TNF)-&agr; and interleukin (IL)-6 and exhibited increased expression of intra-cellular adhesive molecule-1, vascular cellular adhesive molecule-1, and VE-cadherin. After treatment with TAT-Cre recombinase fusion protein, approximately 60% of TMNK-1 was negative for GFP expression, and subsequent cell sorting of this population for GFP allowed for collection of the reverted form of TMNK-1. Conclusions. This study demonstrates the utility and efficiency of the reversible immortalization procedure to expand primary human LECs for basic studies.

Establishment of an immortalized human hepatic stellate cell line to develop antifibrotic therapies.

Because human hepatic stellate cells (HSCs) perform a crucial role in the progress of hepatic fibrosis, it is of great value to establish an immortalized human cell line that exhibits HSC characteristics and grows well in tissue cultures for the development of antifibrotic therapies. Thus, we engineered an immortalized human hepatic stellate cell (HSC) line TWNT-4 by retrovirally inducing human telomerase reverse transcriptase (hTERT) into LI 90 cells established from a human liver mesenchymal tumor. Parental LI 90 entered replicative senescence, whereas TWNT-4 showed telomerase activity and proliferated for more than population doubling level (PDL) 200 without any crisis. TWNT-4 expressed platelet-derived growth factor-β receptor (PDGF-βR), α-smooth muscle actin (α-SMA), and type I collagen (α1) and was considered to be an activated form of HSCs. Treatment of TWNT-4 cells with either 100 U/ml of IFN-γ or 1 ng/ml of rapamycin (Rapa) for 14 days led to lower expression of type I collagen (α1) at RNA and protein levels. Exposure of TWNT-4 cells to both of IFN-γ (10 U/ml) and Rapa (0.1 ng/ml) for 14 days effectively decreased the expression of type I collagen (α1), PDGF-βR, and α-SMA expression and suppressed TGF-β1 secretion of TWNT-4 cells. We successfully induced apoptosis by transducing TNF-related apoptosis-inducing ligand (TRAIL) into TWNT-4 cells using adenovirus vectors Ad/GT-TRAIL and Ad/PGK-GV-17. These findings suggested that immortalized activated HSC line TWNT-4 would be a useful means to develop antifibrotic therapies.

Cryopreservation of primarily isolated porcine hepatocytes with UW solution.

Development of liver-targeted cell therapies, such as hepatocyte transplantation and bioartificial livers, requires a large amount of functional hepatocytes as needed. To achieve this development, establishing an excellent cryopreservation method of hepatocytes is an extremely important issue. Therefore, we performed a comparative review of cryoprotective effects of various cryopreservation solutions using primarily isolated porcine hepatocytes. Porcine hepatocytes were isolated with a four-step dispase and collagenase perfusion method. The obtained hepatocytes with the initial viabilities of 76%, 84%, and 96% were assigned to the following four groups for cryopreservation at −80°C: Dulbeccos modified Eagles medium (DMEM) + 10% fetal bovine serum (FBS) + 12% dimethyl sulfoxide (DMSO) (group A), University of Wisconsin (UW) solution + 12% DMSO (group B), Cell Banker 1 (group C), and Cell Banker 2 (group D). The hepatocytes in each group were thawed at 3 days, 10 days, and 5 months of cryopreservation and subjected to comparative analyses, including viability, plating efficiency, LDH release, ammonia removal test, and lentiviral gene transfer. These parameters were the most favorable in the hepatocytes cryopreserved with UW solution. Approximately 5% of thawed cryopreserved porcine hepatocytes expressed LacZ activity after lentiviral transduction. Intrasplenic transplantation of UW solution-cryopreserved hepatocytes improved the survival of rats treated with D-galactosamine. UW solution maintained the functions of cryopreserved porcine hepatocytes.

Long-term effect of bezafibrate on parameters of hepatic fibrosis in primary biliary cirrhosis

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Spontaneous regression of focal nodular hyperplasia of the liver

Focal nodular hyperplasia (FNH) of the liver is a rare benign lesion that probably reflects a local hyperplastic response of hepatocytes to a vascular abnormality. Currently, the natural history of the disease remains largely unknown. We present a patient with FNH of the liver who was followed up for 4 years. A 22-year-old woman with a 3-year history of oral contraceptive use was referred to our hospital in September 1996 for further examination of a liver tumor. A diagnosis of FNH was made using various imaging methods, such as ultrasonography, enhanced computed tomography (CT) scanning, MR imaging, and hepatic angiography, as well as fine-needle biopsy. A decrease in the size of the lesion was observed by enhanced CT scanning during the 4-year observation period. In this patient, oral contraceptive use and its discontinuation may have influenced the natural history of FNH. The present case suggests that an accurate diagnosis is of the utmost importance, and a patient with FNH should be managed conservatively rather than by resection, because FNH has the potential for spontaneous regression with the discontinuation of oral contraceptives.

Maintenance of cold-preserved porcine hepatocyte function with UW solution and ascorbic acid-2 glucoside.

Normal human hepatocytes are an ideal source of liver-targeted cell therapies, such as hepatocyte transplantation and bioartificial livers, but availability of human donor livers for liver cell isolation is severely limited. To effectively utilize scarce donor organs for cell therapies, it is of extreme importance to establish an efficient isolation technique and an effective cold preservation solution for transportation of isolated cells. A lateral segment of the liver was surgically resected from pigs weighing 10 kg and a four-step collagenase and dispase digestion was conducted. Isolated hepatocytes were subjected to 8-h cold storage on ice. The following preservation solutions were tested: 1) University of Wisconsin (UW) solution, 2) UW with 100 μg/ml of ascorbic acid-2 glucoside (AA2G), 3) 100% fetal bovine serum (FBS), and 4) Dulbeccos modified Eagles medium (DMEM) supplemented with 100% FBS. The mean viability of porcine hepatocytes was 95.5 ± 2.5% when isolated in three independent experiments. Viability, plating efficiency, membrane stability, and ammonia metabolic capacity of cold-preserved hepatocytes were significantly better maintained by the use of UW solution. When AA2G (100 μg/ml) was combined with UW solution, such parameters were further improved. It was explained by inhibition of caspase-3 activation and retention of ATP at high levels of hepatocytes preserved with UW solution containing AA2G. The present work demonstrates that a combination of UW solution with AA2G (100 μg/ml) would be a useful cold preservation means for the development of cell therapies.

Improved Prognosis of Cirrhosis Patients with Esophageal Varices and Thrombocytopenia Treated by Endoscopic Variceal Ligation Plus Partial Splenic Embolization

The aim of this study was to assess the efficacy of the combination of endoscopic variceal ligation (EVL) and partial splenic embolization (PSE) compared with EVL alone in cirrhosis patients with thrombocytopenia. In a prospective study, 84 cirrhosis patients with esophageal varices and thrombocytopenia (platelet count < 50,000/mm3) underwent EVL plus PSE (N = 42) or EVL alone (N = 42). Primary end points assessed during the follow-up period included the recurrence of varices, progression to variceal bleeding, and death. Comparison between combined treatment and variceal ligation alone by multivariate analysis showed a hazard ratio of 0.44 for the recurrence of varices (P = 0.02), 0.19 for progression to variceal bleeding (P = 0.01), and 0.31 for death (P = 0.04). These results suggest that the combination of EVL plus PSE can prevent the recurrence of varices, progression to variceal bleeding, and death in cirrhosis patients with esophageal varices and thrombocytopenia.

Association of Fatty Liver with Increased Ratio of Visceral to Subcutaneous Adipose Tissue in Obese Men

We studied the association of fatty liver with subcutaneous and visceral obesity in 46 male and 36 female patients with body mass index (BMI) over 22 kg/m2. The correlation coefficient between the ratio of the visceral adipose tissue to the subcutaneous adipose tissue (V/S) and the computed tomography (CT) number of the liver was -0.299 (P < 0.05) and that between the V/S ratio and the ratio of the CT number of the liver to that of the spleen (CT-L/CT-S) was -0.335 (P < 0.05) in the males. Partial correlation analysis after making correction for BMI showed an increased correlation coefficient of -0.485 (P < 0.05) between the V/S ratio and the CT-L/CT-S ratio in the males. The odds ratio in the males for CT-L/CT-S below 1.0 and V/S above 1.0 was 3.25 with a 95% confidence interval of 1.02 to 9.39. No such association between the V/S ratio and the CT-L/CT-S ratio was present in the female patients. Multiple regression analysis with serum level of alanine aminotransferase, a marker of fatty liver, as an independent variable revealed a partial regression coefficient of -17.7 for CT-L/CT-S (P < 0.05) in the males and -21.7 (P < 0.05) in the females, validating the CT-L/CT-S ratio as an index of fatty liver. The results indicate the association of fatty liver as determined by the CT-L/CT-S ratio with visceral obesity in males.