Michihiko Takesue

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.

Hepatocyte isolation and transplantation in the pig.

Hepatocyte transplantation (HTX) has received great expectation for the treatment of a wide spectrum of liver diseases. Considering the severe shortage of human livers for hepatocyte isolation, porcine hepatocytes are an attractive alternative to normal human hepatocytes. To develop such therapy, establishment of an efficient hepatocyte isolation and transplantation model that enables accurate assessment of safety and efficacy of HTX is extremely important. Porcine hepatocytes were isolated from a surgically removed liver segment with a four-step retrograde perfusion using dispase and collagenase. The resultant hepatocytes of > 84% viability were used for transplantation experiment in a pig model of acute liver failure induced by intravenous administration of D-galactosamine (D-gal) (0.5 mg/kg). Twenty-four hours after D-gal injection, transplantation of freshly isolated porcine hepatocytes (1 x 10(9)) was safely conducted and prolonged the survival of D-gal-treated pigs. We describe an efficient porcine hepatocyte isolation and subsequent cell transplantation in pigs with D-gal-induced liver failure.

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.

Transduction of immortalized human hepatocytes with p21 to enhance differentiated phenotypes.

We previously constructed an immortal human hepatocyte line NKNT-3 with a simian virus 40 T antigen (SV40T) to develop cell-based biological therapies. p21 is a molecule that regulates the transition from the G1 phase to the S phase of the cell cycle. Investigators have demonstrated that overexpression of p21 induces differentiation in various cell lines. In the current study we examined the effect of p21 on differentiated phenotypes of SV40T-immortalized NKNT-3 cells. A replication-deficient adenovirus vector expressing a human wild-type p21 cDNA under the control of the CMV promoter (Ad5CMVp21) and a human wild-type p21 protein fused to the protein transduction domain from the human immunodeficiency virus (HIV) TAT protein (TAT/p21) were utilized to achieve efficient delivery of p21 into NKNT-3 cells. Morphological alterations, cell cycle progression, and expression of albumin and p-450 associated enzymes (CYPs) 3A4 and 2C9 were evaluated in NKNT-3 cells treated with Ad5CMVp21 and TAT/p21. Efficient adenovirus-based p21 transfer and TAT-mediated p21 protein delivery were confirmed in NKNT-3 cells in an immuno-fluorescence study and Western blotting analysis. Transduction of NKNT-3 cells with p21 predominantly arrested the cell cycle at the G1 checkpoint, resulting in differentiated hepatic phenotypes in morphology and improvement in protein expression of albumin, CYP 3A4, and CYP C29. We here show that exogenous expression of p21 augments cellular differentiation in immortalized human NKNT-3 cells.

Mechanism for increase in expression of cerebral diazepam binding inhibitor mRNA by nicotine: involvement of L-type voltage-dependent calcium channels.

We investigated the mechanisms underlying the increase in diazepam binding inhibitor (DBI) and its mRNA expression induced by nicotine (0.1 microM) exposure for 24 h using mouse cerebral cortical neurons in primary culture. Nicotine-induced (0.1 microM) increases in DBI mRNA expression were abolished by hexamethonium, a nicotinic acetylcholine (nACh) receptor antagonist. Agents that stabilize the neuronal membrane, including tetrodotoxin (TTX), procainamide (a Na(+) channel inhibitor), and local anesthetics (dibucaine and lidocaine), dose-dependently inhibited the increased expression of DBI mRNA by nicotine. The nicotine-induced increase in DBI mRNA expression was inhibited by L-type voltage-dependent Ca(2+) channel (VDCC) inhibitors such as verapamil, calmodulin antagonist (W-7), and Ca(2+)/calmodulin-dependent protein kinase II (CAM II kinase) inhibitor (KN-62), whereas P/Q- and N-type VDCC inhibitors showed no effects. In addition, nicotine exposure for 24 h induced [3H]nicotine binding to the particulate fractions of the neurons with an increased B(max) value and no changes in K(d). Under these conditions, the 30 mM KCl- and nicotine-induced 45Ca(2+) influx into the nicotine-treated neurons was significantly higher than those into non-treated neurons. These results suggest that the nicotine-stimulated increase in DBI mRNA expression is mediated by CAM II kinase activation resulting from the increase in intracellular Ca(2+) through L-type VDCCs subsequent to the neuronal membrane depolarization associated with nACh receptor activation.

NMDA receptor activation enhances diazepam binding inhibitor and its mRNA expressions in mouse cerebral cortical neurons

Effects of N-methyl-D-aspartate (NMDA) on diazepam binding inhibitor (DBI) and its mRNA expression in mouse cerebral cortical neurons were examined. A significant increase in DBI mRNA expression was observed 1 day after the exposure to 0.1 microM NMDA and the maximal expression occurred 2 days after the exposure, whereas transient exposure to 0.1 microM NMDA for 15 min, 1 and 3 h produced no changes in the expression. Similarly, no changes in the expression were found by the concomitant exposure to NMDA and MK-801, a NMDA receptor antagonist, for 72 h subsequent to the incubation with NMDA alone for 3 h. Such NMDA-induced increases in DBI mRNA expression were dose-dependently inhibited by MK-801. Moreover, neuronal DBI content significantly increased by treatment with NMDA, which was completely abolished by MK-801. These results indicate that continuous activation of NMDA receptors is an essential factor for increasing DBI expression in the neurons.