A new immortalized rat cell line, hepatic stellate cell-PQ, exhibiting characteristics of hepatic stellate cell.

BACKGROUND: Playing a central role in hepatic fibrosis, hepatic stellate cell (HSC) has made itself the major target of research. The limited supply of HSC, however, can not meet the ever growing need of experiment. Establishment and identification of novel immortalized HSC line thus may be urgently required. METHODS: Primary HSCs were isolated from a normal adult male Sprague-Dawley rat by in situ perfusion with collagenase IV and pronase E, and then were purified by single-step density gradient centrifugation with nycodenz. Once they reached total activation in culture, a new immortalized myofibroblast-like HSC line was established through cellular cloning. Its characteristics were identified by means of immunocytochemical staining, light microscopy, transmission electron microscopy, and growth curve analysis. RESULTS: The novel HSC line, termed HSC-PQ, had a doubling time of about 75 hours in the Dulbecco's modified Eagle medium (DMEM) containing 20% fetal bovine serum. Most of the main morphological characteristics of the differentiated primary HSC could be detected in HSC-PQ cell, while functional features of activated HSC such as alpha-smooth muscle actin, desmin, collagen type I, collagen type III, fibronectin, laminin and other extracellular matrix proteins could also be found in it except for collagen type IV. In contrast, fat droplets and autofluorescence of vitamin A disappeared in the HSC-PQ line. This cell line had been maintained in culture for over 30 passages and more than 1 year with little alternation in biological characteristics. CONCLUSION: A new rat HSC line (HSC-PQ) has been successfully established. It consistently retains the characteristics of activated primary HSC, and has proved to be immortalized.

Relationship between somatostatin receptors and activation of hepatic stellate cells.

BACKGROUND: Somafostatin receptors (SSTRs) have been suggested to involve in mediating the effect of somatostatin on hepatic stellate cells (HSCs) in an activation-dependent way. We, therefore, try to investigate the relationship between expression of SSTRs and activation of rat HSCs. METHODS: HSCs were isolated from rats by in situ perfusion and single-step density gradient centrifugation. SSTR1-5 mRNA levels in the differentiated first passage HSCs were detected by means of a reverse transcription polymerase chain reaction. On the other hand, hepatic fibrosis was induced in adult male Sprague-Dawley rats by carbon tetrachloride intoxication, and the expression of SSTR1-5 in normal as well as fibrotic livers was measured by immunohistochemical staining. RESULTS: SSTR mRNA and SSTR could not be found in freshly isolated rat HSCs or normal rat liver. However, SSTR1-3 mRNA appeared as HSCs became wholly activated, and could also be identified on the membrane of activated HSCs in the perisinusoid space, fibrous septa, etc. CONCLUSION: The expression of SSTR1-3 in the rat HSC is closely related to its activation. This may reflect one of the main negative regulation mechanisms in the course of HSC activation.

Suppressive effects of 17beta-estradiol on hepatic fibrosis in CCl4-induced rat model.

AIM: To investigate the pathway via which 17beta-estradiol (beta-Est) exerts suppressive effects on rat hepatic fibrosis. METHODS: In vivo study was done in CCl4-induced female hepatofibrotic rats. Fibrosis-suppressive effect of beta-Est (20 microg/kg/d) was evaluated in intact and ovariectomized rat models. Six weeks after the treatment, all the rats were sacrificed and specimens of serum or liver tissue were collected for the studies. Serum liver enzymes, fibrosis markers and estradiol levels were determined by standard enzymatic methods, ELISA and RIA, respectively. Degrees of fibrosis and areas of hepatic stellate cells (HSCs) positive for alpha-smooth muscle actin (alpha-SMA) in the liver were determined by van Gieson (VG) stain and immunohistochemistry. In vitro studies, HSCs were isolated by a combination of pronase-collagenase perfusion and density gradient centrifugation. First-passage HSCs were randomly divided into 10 groups, and different concentrations of beta-Est, 2-hydroxyestradiol (2OHE) or 2-methoxyestradiol (2MeOE) were separately added to the cell groups. After incubation for 72 h, the degree of cell proliferation, collagen production, alpha-SMA or estrogen receptor (ER) expression was determined by MTT assay, ELISA and immunohistochemistry, respectively. RESULTS: Beta-Est treatment reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT), hyaluronic acid (HA) and type IV collagen (C IV) in sera, suppressed hepatic collagen content, decreased the areas of HSCs positive for alpha-SMA significantly in both intact and ovariectomized female hepatofibrotic rats. There was a negative correlation between the percentage of fibrotic area of liver tissue and the serum estradiol level; the calculated correlation coefficient was -0.57 (P<0.01). Beta-Est and its metabolites concentration-dependently (10(-9) mol/L-10(-7) mol/L) inhibited HSC proliferation and collagen synthesis. At the concentration of 10(-7) mol/L, they could inhibit alpha-SMA expression. The order of potency was 2MeOE>2OHE>beta-Est. CONCLUSION: Beta-Est may suppress hepatic fibrosis probably via its biologically active metabolites.

Antiproliferative and proapoptotic effects of somatostatin on activated hepatic stellate cells.

AIM: To assess the effects of somatostatin on proliferation and apoptosis of activated rat hepatic stellate cells (HSCs). METHODS: HSCs isolated from the livers of adult Sprague-Dawley rats (weighing 400-500 g) by in situ perfusion and purified by single-step density gradient centrifugation with Nycodenz, became activated after 10 days' cultivation. Then the apoptotic rate of HSCs treated with different doses of somatostatin for 72 h, was assayed by acridine orange/ethidium bromide fluorescent staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, transmission electron microscopy and flow cytometry, while the proliferation of HSCs was measured by MTT assay. Furthermore, the mechanisms of somatostatin were investigated by cytodynamic analysis. RESULTS: Somatostatin at the concentration of 10(-6)-10(-9) mol/L could decrease the proliferative rate, and promote the apoptosis of activated rat HSCs in a dose-dependent way. Its action was most significant when the concentration reached 10(-6) mol/L or 10(-7) mol/L (P<0.05-0.01). An obvious cell-cycle arrest (G(0)/G(1) arrest) was the important way for somatostatin to exert its action. CONCLUSION: Antiproliferative and proapoptotic effects of low-dose somatostatin on activated rat HSCs can be obtained. These findings reveal its potential antifibrotic action.

[Therapeutic effects of octreotide on hepatofibrosis-induced with carbon tetrachloride in rats].

OBJECTIVES: To investigate the therapeutic effects and mechanism of octreotide on experimental hepatic fibrosis in rats. METHODS: Hepatofibrotic rats models were established with carbon tetrachloride. All the experimental rats were divided into four groups: normal control group, pre-and post-treatment model group, and octreotide-treated group in which the rats were injected subcutaneously with octreotide at the dose of 50ng/100g, twice daily, for thirty days. Serum levels of hyaluronic acid (HA), laminin (LN) and pro-collagen type III peptide (PCIII) were detected by radioimmunoassay. Hepatic fibrosis scoring grade was assessed through Van-Gieson staining and observed under light microscope. Protein expression levels of alpha-smooth muscle actin (alpha-SMA) and transforming growth factor beta1 (TGFbeta1) were determined with immunohistochemical staining method. Messenger RNA (mRNA) levels of collagen type I and PCIII were detected by reverse transcription polymerase chain reaction. RESULTS: Serum levels of HA (ng/L), LN (microg/L) and PCIII (ng/L) in pre- and post-treatment model groups were higher than those in normal control group (121.8+/-9.5 and 110.3+/-13.4 vs. 33.1+/-3.7, 85.7+/-12.1 and 78.2+/-7.9 vs. 37.1+/-6.3, 35.9+/-3.5 and 33.7+/-2.6 vs. 15.6+/-2.8, respectively, t > or = 9.41, P<0.05), and there was no significant difference between the two model groups. Concentrations of HA (55.8ng/L+/-7.2ng/L), LN (43.1microg/L+/-3.4microg/L) and PCIII (27.8ng/L+/-3.4ng/L) decreased significantly in octreotide-treated group, compared with those in model groups (t >or=2.76, P<0.05). With histological analysis, fibrotic scoring grade in octreotide-treated group was obviously ameliorated, compared with that in model groups (chi2 > or = 3.97, P<0.05). Imaging analysis revealed that alpha-SMA and TGFbeta1 immunohistological staining areas were markedly shrinked in octreotide-treated group (t > or = 2.47, P < 0.05). In two model groups, PCIII and type I mRNA levels significantly up-regulated as compared with those in normal group (t > or = 9.27, P<0.001), and they were inhibited by octreotide markedly (t > or = 2.47, P<0.05). CONCLUSIONS: Octreotide can inhibit hepatic stellate cells transforming into myofibroblasts, down-regulate TGFbeta1, collagen type I and PCIII transcriptions, so that it has therapeutic effects on experimental hepatic fibrosis.

Effects of AT1 receptor antagonist, losartan, on rat hepatic fibrosis induced by CCl(4).

AIM:To investigate effect of losartan, an AT1 receptor antagonist, on hepatic fibrosis induced by CCl(4); and to determine whether or not AT1 receptors are expressed on hepatic stellate cells. METHODS AND RESULTS:Fifty male Sprague-Dawley rats, weighing (180 plus minus20)g, were randomized into five groups (control group, model group, and three losartan treated groups), in which all rats were given the subcutaneous injection of 40% CCl(4)(every 3 days for 6 weeks) except for rats of control group. Rats of losartan-treated groups were treated with losartan (20 mg/kg, 10 mg/kg, 5 mg/kg, daily gavage). After 6 weeks liver tissue and serum samples of all rats were examined. Serum hyaluronic acid (HA), procollagen type III (PC III) were detected by radioimmunoassays. van Giesion collagen staining was used to evaluate the extracellular matrix of rats with liver fibrosis. The expression of AT1 receptors, transforming growth factor-beta (TGF-beta), and alpha-smooth muscle actinalpha-SMA) in liver tissue were determined by immunohistochemical techniques. Compared with model group, serum ALT and AST of losartan-treated groups were significantly reduced (italic>t = 4.20,P < 0.01 and italic>t = 4.57,P < 0.01). Serum HA and PC III also had significant differences (italic>t = 3.53,P<0.01 and t=2.20, P<0.05). The degree of fibrosis was improved by losartan and correlated with the expressions of AT1 receptors, TGF-beta, and alpha-SMA in liver tissue.CONCLUSION:AT1 receptor antagonist, losartan, could limit the progression of the hepatic fibrosis induced by CCl(4). The mechanism may be related to the decrease in the expression of AT1 receptors and TGF-beta, ameliorating the injury of hepatocytes; activation of local renin-angiotensin system might relate to hepatic fibrosis; and during progression of fibrosis, activated hepatic stellate cells might express AT1 receptors.

The regulatory role of AT 1 receptor on activated HSCs in hepatic fibrogenesis:effects of RAS inhibitors on hepatic fibrosis induced by CCl(4).

AIM:To assess the effect of ACE inhibitor and Ang II type 1 (AT1) receptor antagonist in preventing hepatic fibrosis caused by CCl(4) administration in rats;to investigate whether or not there are expression of AT 1 receptors on hepatic stellate cells; and to observe the effect of Ang II on proliferation and ECM synthesis of cultured HSCs.METHODS:Studies were conducted in male Sprague-Dawley rats. Except for the hepatofibrotic model group and the control group, in three treated groups, either enalapril (5mg/kg), or losartan (10mg/kg), or enalapril + losartan were given to the fibrotic rats by daily gavage, and saline vehicle was given to model and normal control rats. After 6 weeks, liver fibrosis was assessed directly by hepatic morphometric analysis, which has been considered the gold standard for the quantification of fibrosis. The expressions of AT 1 receptors and (alpha-mooth muscle actin,alpha-SMA) in liver tissue or isolated hepatic stellate cells (HSCs) were detected by immunohistochemical techniques. The effect of Ang II on HSC proliferation was determined by MTT method. Effect of Ang II on collagen synthesis of HSCs was determined by (3)H-proline incorporation.RESULTS:Contrasted to the fibrosis in rats of the model group, groups of rats treated with either enalapril or losartan, or a combination of two drugs showed a limited expansion of the interstitium (4.23 plus minus 3.70 vs 11.22 plus minus 4.79, P<0.05), but no difference was observed among three treated groups (5.38 plus minus3.43, 4.96 plus minus 2.96, 4.23 plus minus 2.70, P>0.05). Expression of AT 1 receptors was found in fibrotic interstitium of fibrotic rats, whereas in normal control rats they were limited to vasculature only to a very slight degree. AT 1 receptors were also expressed on activated HSCs in the culture. At concentrations from 10(-9) to 10(-5)mol/L, Ang II stimulated HSC proliferation in culture in a dose dependent manner. Increasing Ang II concentrations produced corresponding increases in (3)H-proline incorporation. Differences among groups were significant.CONCLUSION:Angiotensin converting enzyme inhibitors and AT 1 blocker may slow the progression of hepatic fibrosis;activated HSCs express AT 1 receptors, and Ang II can stimulate the proliferation and collagen synthesis of HSCs in a dose-dependent manner; and activation of RAS may be related to hepatic fibrogenesis induced by CCl(4).