Confirmation of HIF-1α Independent Pathway in the Progression of HepG2 Cells by Hypoxic Condition

BACKGROUND/AIMS: When hepatocellular carcinoma (HCC) is exposed to hypoxic condition, HIF-1α is activated and results in angiogenesis and increased tumor burden. Although inhibition of HIF-1α may reduce tumor growth, there are some limitations to control tumor growth completely. For a more effective therapy for HCC, we investigated HIF-1α independent pathway related tumor growth with angiogenesis. METHODS: We cultured HepG2 cells (HCC cell line) in both normoxia and hypoxia conditions. These cells were divided into three groups: a echinomycin treated group, a echinomycin and quinazoline treated group and a control group without any treatments. Growth morphologies of cells were observed with a microscope after 24 hours. Immunocytochemistry assay was done to detect the angiogenesis during inhibition of HIF-1α and/or NF-κB in hypoxia condition, and compared with results in normoxia condition. RESULTS: In normoxia, the expression of HIF-1α on tumor growth was not found. In hypoxia, inhibition of HIF-1α reduced the tumor growth compared to the control group. But, inhibition of both HIF-1α and NF-κB did not show apparent reduction of tumor growth as shown in HIF-1α only group. CONCLUSIONS: Signaling pathways related to cancer cell growth exist through a vast network. Inhibition of one target molecule may result in over-expression of other molecules related to the tumor growth. For an effective therapy in blocking of the tumor growth, more comprehensive understanding of the network related to signaling pathways on tumor growth is necessary.

Toward angiogenesis of implanted bio-artificial liver using scaffolds with type I collagen and adipose tissue-derived stem cells

BACKGROUNDS/AIMS: Stem cell therapies for liver disease are being studied by many researchers worldwide, but scientific evidence to demonstrate the endocrinologic effects of implanted cells is insufficient, and it is unknown whether implanted cells can function as liver cells. Achieving angiogenesis, arguably the most important characteristic of the liver, is known to be quite difficult, and no practical attempts have been made to achieve this outcome. We carried out this study to observe the possibility of angiogenesis of implanted bio-artificial liver using scaffolds. METHODS: This study used adipose tissue-derived stem cells that were collected from adult patients with liver diseases with conditions similar to the liver parenchyma. Specifically, microfilaments were used to create an artificial membrane and maintain the structure of an artificial organ. After scratching the stomach surface of severe combined immunocompromised (SCID) mice (n=4), artificial scaffolds with adipose tissue-derived stem cells and type I collagen were implanted. Expression levels of angiogenesis markers including vascular endothelial growth factor (VEGF), CD34, and CD105 were immunohistochemically assessed after 30 days. RESULTS: Grossly, the artificial scaffolds showed adhesion to the stomach and surrounding organs; however, there was no evidence of angiogenesis within the scaffolds; and VEGF, CD34, and CD105 expressions were not detected after 30 days. CONCLUSIONS: Although implantation of cells into artificial scaffolds did not facilitate angiogenesis, the artificial scaffolds made with type I collagen helped maintain implanted cells, and surrounding tissue reactions were rare. Our findings indicate that type I collagen artificial scaffolds can be considered as a possible implantable biomaterial.

Immediately transcripted genes in various hepatic ischemia models / 대한외과학회지

PURPOSE: To elucidate the characteristic gene transcription profiles among various hepatic ischemia conditions, immediately transcribed genes and the degree of ischemic injury were compared among total ischemia (TI), intermittent clamping (IC), and ischemic preconditioning (IPC). METHODS: Sprague-Dawley rats were equally divided into control (C, sham-operated), TI (ischemia for 90 minutes), IC (ischemia for 15 minutes and reperfusion for 5 minutes, repeated six times), and IPC (ischemia for 15 minutes, reperfusion for 5 minutes, and ischemia again for 90 minutes) groups. A cDNA microarray analysis was performed using hepatic tissues obtained by partial hepatectomy after occluding hepatic inflow. RESULTS: The cDNA microarray revealed the following: interleukin (IL)-1beta expression was 2-fold greater in the TI group than in the C group. In the IC group, IL-1alpha/beta expression increased by 2.5-fold, and Na+/K+ ATPase beta1 expression decreased by 2.4-fold. In the IPC group, interferon regulatory factor-1, osteoprotegerin, and retinoblastoma-1 expression increased by approximately 2-fold compared to that in the C group, but the expression of Na+/K+ ATPase beta1 decreased 3-fold. CONCLUSION: The current findings revealed characteristic gene expression profiles under various ischemic conditions. However, additional studies are needed to clarify the mechanism of protection against IPC.

Ideal Experimental Rat Models for Liver Diseases

There are many limitations for conducting liver disease research in human beings due to the high cost and potential ethical issues. For this reason, conducting a study that is difficult to perform in humans using appropriate animal models, can be beneficial in ascertaining the pathological physiology, and in developing new treatment modalities. However, it is difficult to determine the appropriate animal model which is suitable for research purposes, since every patient has different and diverse clinical symptoms, adverse reactions, and complications due to the pathological physiology. Also, it is not easy to reproduce identically various clinical situations in animal models. Recently, the Guide for the Care and Use of Laboratory Animals has tightened up the regulations, and therefore it is advisable to select the appropriate animals and decide upon the appropriate quantities through scientific and systemic considerations before conducting animal testing. Therefore, in this review article the authors examined various white rat animal testing models and determined the appropriate usable rat model, and the pros and cons of its application in liver disease research. The authors believe that this review will be beneficial in selecting proper laboratory animals for research purposes.

The effect of preconditioning on liver regeneration after hepatic resection in cirrhotic rats / 대한간학회지

BACKGROUND/AIMS: Ischemic preconditioning (IP) decreases severity of liver necrosis and has anti-apoptotic effects in previous studies using liver regeneration in normal rats. This study assessed the effect of IP on liver regeneration after hepatic resection in cirrhotic rats. METHODS: To induce liver cirrhosis, thioacetamide (300 mg/kg) was injected intraperitoneally into Sprague-Dawley rats twice per week for 16 weeks. Animals were divided into four groups: non-clamping (NC), total clamping (TC), IP, and intermittent clamping (IC). Ischemic injury was induced by clamping the left portal pedicle including the portal vein and hepatic artery. Liver enzymes alanine transaminase (ALT) and aspartate aminotransferase (AST) were measured to assess liver damage. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining for apoptosis and proliferating cell nuclear antigen (PCNA) staining for cell replication were also performed. RESULTS: Day-1 ALT and AST were highest in IP, however, levels in NC and IC were comparably low on days 1-7. There was no significant correlation of AST or ALT with experimental groups (P=0.615 and P=0.186). On TUNEL, numbers of apoptotic cells at 100x magnification (cells/field) were 31.8+/-24.2 in NC, 69.0+/-72.3 in TC, 80.2+/-63.1 in IP, and 21.2+/-20.8 in IC (P<0.05). When regeneration capacity was assessed by PCNA staining, PCNA-positive cells (cells/field) at 400x were 3.4+/-6.0 in NC, 16.9+/-69 in TC, 17.0+/-7.8 in IP and 7.4+/-7.6 in IC (P<0.05). CONCLUSIONS: Although regeneration capacity in IP is higher than IC, the liver is vulnerable to ischemic damage in cirrhotic rats. Careful consideration is needed in applying IP in the clinical setting.

The Factors Affecting Transplanted Hepatocytes Repopulation in Rats with Liver Fibrosis

PURPOSE: Cell therapy for various diseases has gained wide acceptance. Because most patients with chronic liver failure have mild-to-severe liver cirrhosis, there are many limitations to clinical applications. We analyzed how to increase cell engraftment in rats with liver fibrosis. METHODS: We used analbuminemic SD rats (NARs) as recipients of syngeneic CAG-EGFP SD hepatocytes obtained by the 2 perfusion method. Hepatic fibrosis was induced with thioacetamide in drinking water for 6 weeks in the recipient NARs. NARs were pre-treated with gadolinium, doxorubicin, and gliotoxin before hepatocyte transplantation. We evaluated the degree of cell engraftment by RT-PCR and immunofluorescent staining for GFP and albumin. The transplanted cells were detected by immunostaining for albumin, and serum albumin was also measured. RESULTS: Although detection of GFP by RT-PCR was variable, albumin was detected in all groups 4 wks after hepatocyte transplantation. GFP and albumin were also detected by immunofluorescent staining 1 and 4 wks after cell transplantation. In control rats, albumin production was maximal at 3 wks, and after that it rapidly decreased. In the gadolinium and doxorubicin-treated group, albumin production was increased up to 4 wks. Albumin production in the gadolinium-treated group was superior to that of the doxorubicin-treated group. CONCLUSION: Kupffer cells play the most important role in cell engraftment in hepatic fibrosis. Therefore, perturbation of kupffer cells in hepatic fibrosis is needed to increase cell engraftment.

The Factors Affecting Transplanted Hepatocytes Repopulation in Rats with Liver Fibrosis

PURPOSE: Cell therapy for various diseases has gained wide acceptance. Because most patients with chronic liver failure have mild-to-severe liver cirrhosis, there are many limitations to clinical applications. We analyzed how to increase cell engraftment in rats with liver fibrosis. METHODS: We used analbuminemic SD rats (NARs) as recipients of syngeneic CAG-EGFP SD hepatocytes obtained by the 2 perfusion method. Hepatic fibrosis was induced with thioacetamide in drinking water for 6 weeks in the recipient NARs. NARs were pre-treated with gadolinium, doxorubicin, and gliotoxin before hepatocyte transplantation. We evaluated the degree of cell engraftment by RT-PCR and immunofluorescent staining for GFP and albumin. The transplanted cells were detected by immunostaining for albumin, and serum albumin was also measured. RESULTS: Although detection of GFP by RT-PCR was variable, albumin was detected in all groups 4 wks after hepatocyte transplantation. GFP and albumin were also detected by immunofluorescent staining 1 and 4 wks after cell transplantation. In control rats, albumin production was maximal at 3 wks, and after that it rapidly decreased. In the gadolinium and doxorubicin-treated group, albumin production was increased up to 4 wks. Albumin production in the gadolinium-treated group was superior to that of the doxorubicin-treated group. CONCLUSION: Kupffer cells play the most important role in cell engraftment in hepatic fibrosis. Therefore, perturbation of kupffer cells in hepatic fibrosis is needed to increase cell engraftment.

The Extracellular Matrix Affected Proliferation and Cell Adhesion of Human Adipose Tissue Derived Mesenchymal Stem Cells in vitro

PURPOSE: Human mesenchymal stem cells (hMSCs) have the potency for self-renewal and differentiation into various kinds of cells. The hMSCs are obtained from the various tissues, including adipose tissue, bone marrow and cord blood. The extracellular matrix (ECM) is an important factor that affects cell adherence, growth, migration, apoptosis and differentiation both in vitro and vivo. The adipose-derived mesenchymal stem cells (AD-MSCs) have CD29 (integrin) on the cell surface, which is the receptor for fibronectin. The aim of this study is to validate the efficacy of ECM, and especially fibronectin, for cell expansion. METHODS: The AD-MSCs were obtained from the abdominal fat of humans. These cells were seeded onto culture plates coated with fibronectin-Human (FN) and plates without ECM (control). The cells were incubated for 3 passages and the cellular morphology was simultaneously observed with microscopy. CCK-8 assay was performed to compare the proliferation ability in each condition at the same passage. Immunocytochemistry staining for integrin-beta1 was performed to observe the cell to cell interaction. RESULTS: The hAD-MSCs in the FN-coated and non-coated plates exhibited cytoplasm staining for integrin-beta1. In all the cultures, extended fibroblastic-shaped cells that turned into rhomboid cells were most frequently observed. The cell growth rates for the non coated culture plate were lower than those for the FN coated plates. After 72 hour culture under the different coated concentrations of FN and the non coated condition (control), the control group had a lower growth rate. In the culture with a FN coated plate, a significant change was observed as compared with that of the control group. We observed an increase in cell proliferation, with a maximum of 140%, on the FN coated plate by performing CCK-8 assay. In comparison, integrin beta1 on the cells was more expressed in the FN-coated plates than that in the non-coated plates. CONCLUSION: The cell morphology can be changed faster in the FN coated culture plates than that in the non coated culture plates. Because proliferation and adhesion with FN can enhance the expansion, the culture within a FN coated plate is needed to encourage hAD-MSCs to proliferate in vitro.

The Extracellular Matrix Affected Proliferation and Cell Adhesion of Human Adipose Tissue Derived Mesenchymal Stem Cells in vitro

PURPOSE: Human mesenchymal stem cells (hMSCs) have the potency for self-renewal and differentiation into various kinds of cells. The hMSCs are obtained from the various tissues, including adipose tissue, bone marrow and cord blood. The extracellular matrix (ECM) is an important factor that affects cell adherence, growth, migration, apoptosis and differentiation both in vitro and vivo. The adipose-derived mesenchymal stem cells (AD-MSCs) have CD29 (integrin) on the cell surface, which is the receptor for fibronectin. The aim of this study is to validate the efficacy of ECM, and especially fibronectin, for cell expansion. METHODS: The AD-MSCs were obtained from the abdominal fat of humans. These cells were seeded onto culture plates coated with fibronectin-Human (FN) and plates without ECM (control). The cells were incubated for 3 passages and the cellular morphology was simultaneously observed with microscopy. CCK-8 assay was performed to compare the proliferation ability in each condition at the same passage. Immunocytochemistry staining for integrin-beta1 was performed to observe the cell to cell interaction. RESULTS: The hAD-MSCs in the FN-coated and non-coated plates exhibited cytoplasm staining for integrin-beta1. In all the cultures, extended fibroblastic-shaped cells that turned into rhomboid cells were most frequently observed. The cell growth rates for the non coated culture plate were lower than those for the FN coated plates. After 72 hour culture under the different coated concentrations of FN and the non coated condition (control), the control group had a lower growth rate. In the culture with a FN coated plate, a significant change was observed as compared with that of the control group. We observed an increase in cell proliferation, with a maximum of 140%, on the FN coated plate by performing CCK-8 assay. In comparison, integrin beta1 on the cells was more expressed in the FN-coated plates than that in the non-coated plates. CONCLUSION: The cell morphology can be changed faster in the FN coated culture plates than that in the non coated culture plates. Because proliferation and adhesion with FN can enhance the expansion, the culture within a FN coated plate is needed to encourage hAD-MSCs to proliferate in vitro.

Mesenchymal Stem Cells: The Promotion of Endodermal-Induction Using Activin A

PURPOSE: The most important consideration for therapy using MSCs is the differentiation of the target organ's cell type. For in-vitro hepatogenic differentiation of MSCs, the main focus is efficient induction of the MSCs into the endoderm stage. Activin A, which is a signaling molecule that is similar to Nodal, promotes the induction of definitive endoderm from both ESs and MSCs. The protocols for induction into definitive endoderm have shown different efficiency and reproducibility depending on the researchers or the sources of the MSCs. Thus, a study on the various conditions of Activin A is needed to efficiently differentiate MSCs into the definitive endoderm lineage of MSCs. METHODS: MSCs were isolated from human adipose tissues and these were cultured in MCM (MSCs Culture Medium) on a human fibronectin coated plate. At 70~80% confluence, the MSCs were harvested and cultured in MCM supplemented with Activin A, at a 50 ng/mL concentration, and FGF4. The expression of the genes related with MSCs or primitive endoderm were analyzed by RT-PCR. The changes of cell morphology for differentiation were also observed by a light microscope & a SEM. RESULTS: The expression of genes related with primitive foregut endoderm was seen in the groups that were treated with a higher concentration of Activin A. The morphology of the cells that differentiated into definitive endoderm were not different from those of the undifferentiated MSCs. The expression of genes related with functional primitive hepatocytes was seen in the early phase during hepatic differentiation. The cell morphology was changed to a similar cuboidal form in a time-dependent manner. CONCLUSION: Activin A promotes a more rapid induction of definitive endoderm. It also makes an efficient condition for the differentiation into primitive foregut endoderm at a higher concentration.

Mesenchymal Stem Cells: The Promotion of Endodermal-Induction Using Activin A

PURPOSE: The most important consideration for therapy using MSCs is the differentiation of the target organ's cell type. For in-vitro hepatogenic differentiation of MSCs, the main focus is efficient induction of the MSCs into the endoderm stage. Activin A, which is a signaling molecule that is similar to Nodal, promotes the induction of definitive endoderm from both ESs and MSCs. The protocols for induction into definitive endoderm have shown different efficiency and reproducibility depending on the researchers or the sources of the MSCs. Thus, a study on the various conditions of Activin A is needed to efficiently differentiate MSCs into the definitive endoderm lineage of MSCs. METHODS: MSCs were isolated from human adipose tissues and these were cultured in MCM (MSCs Culture Medium) on a human fibronectin coated plate. At 70~80% confluence, the MSCs were harvested and cultured in MCM supplemented with Activin A, at a 50 ng/mL concentration, and FGF4. The expression of the genes related with MSCs or primitive endoderm were analyzed by RT-PCR. The changes of cell morphology for differentiation were also observed by a light microscope & a SEM. RESULTS: The expression of genes related with primitive foregut endoderm was seen in the groups that were treated with a higher concentration of Activin A. The morphology of the cells that differentiated into definitive endoderm were not different from those of the undifferentiated MSCs. The expression of genes related with functional primitive hepatocytes was seen in the early phase during hepatic differentiation. The cell morphology was changed to a similar cuboidal form in a time-dependent manner. CONCLUSION: Activin A promotes a more rapid induction of definitive endoderm. It also makes an efficient condition for the differentiation into primitive foregut endoderm at a higher concentration.