Sang Woo Lee

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

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 100× 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 400× 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.

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.

Gene Expression Profiling of Hepatocellular Carcinoma Derived Cancer Stem Like Cell under Hypoxia

Purpose Cancer stem like cells (CSCs), with unlimited self-renewal potential and other stem cell characteristics, occur in several cancers including hepatocellular carcinoma (HCC). Although CSCs can initiate tumors, malignant proliferation, relapse and multi-drug resistance, the ways how to activate them still remain unknown. This study aims to evaluate whether CSC acquire tumorigenic characters under tumor hypoxia, analyzed by microarray analysis. Materials and Methods CSCs were purified from HCC patients and Affymetrix microarray was used to investigate their gene expression profiles. The results were validated by real-time polymerase chain reaction (PCR). Results The results of the microarray indicated that 18 genes were up-regulated and 10 genes were down-regulated in CSCs. Several genes were identified to be significantly involved in the regulation of CSCs such as HCC. Furthermore, the up-regulated genes were related with metabolism, angiogenesis and hypoxia, whereas the down-regulated genes were related with apoptosis and inflammation. Conclusion The results may help to understand the mechanisms of tumor development through CSCs which acquired their distinctive tumorogenic properties by hypoxic stimulation.

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

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)-1β expression was 2-fold greater in the TI group than in the C group. In the IC group, IL-1α/β expression increased by 2.5-fold, and Na+/K+ ATPase β1 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 β1 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.