Stem cell origins and animal models of hepatocellular carcinoma

Modified transarterial chemoembolization with locoregional administration of sorafenib for treating hepatocellular carcinoma: feasibility, efficacy, and safety in the VX-2 rabbit liver tumor model

PURPOSE

We aimed to assess the feasibility, efficacy and safety of a local application of sorafenib within a conventional transarterial chemoembolization in the VX-2 tumor-bearing rabbit model.

METHODS

VX-2 tumors were induced in the left liver lobe of 10 New Zealand White rabbits. After two weeks, growth was verified by contrast-enhanced computed tomography (CT). Five rabbits were treated by transarterial chemoembolization using an emulsion of sorafenib and ethiodized oil (referred to as SORATACE; n=5). Rabbits receiving oral sorafenib for two weeks (n=2) and untreated rabbits (n=3) served as controls. After two weeks, contrast-enhanced CT was performed, followed by animal necropsy.

RESULTS

The change in tumor diameter between baseline and follow-up was significantly different in the SORATACE group compared with the other groups; tumor shrinkage was observed in the SORATACE group only (P = 0.016). In both control groups, preserved hypervascularity was seen in the follow-up CT in all but one tumor. All tumors in the SORATACE group were devascularized in the follow-up CT. Importantly, substantial parenchymal damage in nontargeted areas of the tumor-bearing liver lobe was seen in rabbits treated with SORATACE.

CONCLUSION

SORATACE demonstrated high efficacy in the treatment of experimental VX-2 liver tumors but was also associated with substantial liver parenchymal toxicity.

Molecular bioluminescence imaging as a noninvasive tool for monitoring tumor growth and therapeutic response to MRI-guided laser ablation in a rat model of hepatocellular carcinoma

OBJECTIVES

The objective of this study was to quantitatively compare tumor imaging by magnetic resonance imaging (MRI) and molecular bioluminescence imaging (BLI) and test the feasibility of monitoring the effect of MRI-guided laser ablation on tumor viability by 2-dimensional BLI and 3-dimensional diffuse luminescence tomography (3D DLIT) in an orthotopic rat model of hepatocellular carcinoma.

MATERIALS AND METHODS

This study was approved by the animal care committee. Rats underwent injection of N1S1 cells stably transfected with an empty vector (n = 3) or a heat shock element luciferase reporter (HSE-luc; n = 4) into the liver. All rats underwent MRI to assess tumor establishment and volume and 2-dimensional BLI to assess tumor luminescence at day 7 with subsequent MRI and 2D BLI and 3D DLIT in select animals at days 14 and 21. Magnetic resonance imaging-guided laser ablation of the tumor was performed with preablation and postablation 2D BLI and/or 3D DLIT (n = 2). The tumors underwent histopathologic analysis to assess tumor viability.

RESULTS

The MRI scans demonstrated hyperintense T2-weighted lesions at 3 of 3 and 4 of 4 sites in the empty vector and HSE-luc rats, respectively. Two-dimensional BLI quantitation demonstrated 23.0-fold higher radiance in the HSE-luc group compared with the empty vector group at day 7 (P < 0.01) and a significant correlation with tumor volume by MRI (r = 0.86; P < 0.03). Tumor dimensions by 3D DLIT and MRI demonstrated good agreement. Three-dimensional DLIT quantitation demonstrated better agreement with the percentage of nonviable tumor by histopathology than did 2D BLI quantitation after the MRI-guided laser ablation.

CONCLUSIONS

Bioluminescence imaging is feasible as a noninvasive, quantitative tool for monitoring tumor growth and therapeutic response to thermal ablation in a rat model of hepatocellular carcinoma.

Dynamic morphological examination and evaluation of biological characteristics of a multinodular liver cancer model in mice

Compared with single nodular liver cancer, the prominent biological characteristics of multinodular liver cancer include rapid progression and short survival. Here, we developed a multinodular liver cancer model in mice and assessed the biological characteristics of the resulting neoplasms. H22 hepatoma cells at a dose of 2 × 10(5)/mouse, suspended in 1.6 mL, 0.8 mL, or 200 µL saline were injected via the tail vein of BALB/c mice at a velocity of 200 µL per second. The mice were sacrificed at different time points after injection. And at the time of death the liver, lungs, spleen, kidneys and heart were removed for morphological study. The biological characteristics of the tumor nodules were evaluated by immunohistochemistry. In the mice treated with a large volume injection of H22 cells, by day 7, there was a 100% occurrence of multinodular tumors in the livers, determined by histology. At the time of death, there were 100%, 100%, 37.5% and 37.5% occurrences of tumors in the lungs, kidneys, spleen and heart, respectively. The neoplastic cells in the liver nodules showed pleomorphism, and exhibited high expression of proliferating cell nuclear antigen (PCNA), c-myc, vascular endothelial growth factor (VEGF) and matrix metalloproteinase 2 (MMP-2). In mice treated with a small or medium volume injection, no tumor cells were identified in the livers, spleen, kidneys or heart at any of the examined time points. By day 7 and at the time of death, there was a 100% occurrence of tumor in the lungs. A multinodular liver cancer model in mice was achieved using a large volume injection of H22 cells.

Novel mouse models of hepatocarcinogenesis with stepwise accumulation of genetic alterations

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Various risk factors are involved in hepatocarcinogenesis. Among them, chronic inflammation, including chronic hepatitis and cirrhosis mainly caused by hepatitis B virus and/or hepatitis C virus infection, plays an important role in HCC development. On the other hand, comprehensive genetic analyses of HCC using whole genome and exome sequencing revealed that cancer cells possess a large number of somatic mutations, suggesting that a wide variety of genetic alterations and the resultant dysregulated molecular pathways contribute to the development of HCC. Activation-induced cytidine deaminase (AID) is a nucleotide-editing enzyme, and aberrant expression of AID induced by inflammatory responses contributes to hepatocarcinogenesis via the accumulation of genetic alterations in various tumor-related genes. Constitutive expression of AID in hepatocyte-lineage cells provides novel mouse models that recapitulate the tumorigenesis of human HCC through stepwise accumulation of genetic alterations.

Seven-tesla magnetic resonance imaging accurately quantifies intratumoral uptake of therapeutic nanoparticles in the McA rat model of hepatocellular carcinoma: preclinical study in a rodent model

OBJECTIVES

After inducing McA tumors in Sprague-Dawley rats (McA-SD), the following hypotheses were tested: first, that hypervascular McA tumors grown in Sprague-Dawley rats provide a suitable platform to investigate drug delivery; and second, that high-field MRI can be used to measure intratumoral uptake of DOX-SPIOs.

MATERIALS AND METHODS

McA cells were implanted into the livers of 18 Sprague-Dawley rats. In successfully inoculated animals, 220-μL DOX-SPIOs were delivered to tumors via the intravenous or intra-arterial route. Pretreatment and posttreatment T2*-weighted images were obtained using 7-T MRI, and change in R2* value (ΔR2*) was obtained from mean signal intensities of tumors in these images. Tumor iron concentration ([Fe]), an indicator of DOX-SPIO uptake, was measured using mass spectroscopy. The primary outcome variable was the Pearson correlation between ΔR2* and [Fe].

RESULTS

Tumors grew successfully in 13 of the 18 animals (72%). Mean (SD) maximum tumor diameter was 0.83 (0.25) cm. The results of phantom studies revealed a strong positive correlation between ΔR2* and [Fe], with r = 0.98 (P < 0.01). The results of in vivo drug uptake studies demonstrated a positive correlation between ΔR2* and [Fe], with r = 0.72 (P = 0.0004).

CONCLUSIONS

The McA tumors grown in the Sprague-Dawley rats demonstrated uptake of nanoparticle-based therapeutic agents. Magnetic resonance imaging quantification of intratumoral uptake strongly correlated with iron concentrations in pathological specimens, suggesting that MRI may be used to quantify uptake of iron-oxide nanotherapeutics.

AS30D model of hepatocellular carcinoma: tumorigenicity and preliminary characterization by imaging, histopathology, and immunohistochemistry

PURPOSE

This study was designed to determine the tumorigenicity of the AS30D HCC cell line following orthotopic injection into rat liver and preliminarily characterize the tumor model by both magnetic resonance imaging (MRI) and ultrasound (US) as well as histopathology and immunohistochemistry.

MATERIALS

AS30D cell line in vitro proliferation was assessed by using MTT assay. Female rats (N = 5) underwent injection of the AS30D cell line into one site in the liver. Rats subsequently underwent MR imaging at days 7 and 14 to assess tumor establishment and volume. One rat underwent US of the liver at day 7. Rats were euthanized at day 7 or 14 and livers were subjected to gross, histopathologic (H&E), and immunohistochemical (CD31) analysis to assess for tumor growth and neovascularization.

RESULTS

AS30D cell line demonstrated an in vitro doubling time of 33.2 ± 5.3 h. MR imaging demonstrated hyperintense T2-weighted and hypointense T1-weighted lesions with tumor induction in five of five and three of three sites at days 7 and 14, respectively. The mean (SD) tumor volume was 126.1 ± 36.2 mm(3) at day 7 (N = 5). US of the liver demonstrated a well-circumscribed, hypoechoic mass and comparison of tumor dimensions agreed well with MRI. Analysis of H&E- and CD31-stained sections demonstrated moderate-high grade epithelial tumors with minimal tumor necrosis and evidence of diffuse intratumoral and peritumoral neovascularization by day 7.

CONCLUSIONS

AS30D HCC cell line is tumorigenic following orthotopic injection into rat liver and can be used to generate an early vascularizing, slower-growing rat HCC tumor model.

Development and preliminary testing of a translational model of hepatocellular carcinoma for MR imaging and interventional oncologic investigations

PURPOSE

To develop a translational rat hepatocellular carcinoma (HCC) disease model for magnetic resonance (MR) imaging and image-guided interventional oncologic investigations.

MATERIALS AND METHODS

Male rats underwent sham control surgery (n = 6), selective bile duct ligation (SBDL; n = 4), or common bile duct ligation (CBDL; n = 6), with procedure optimization in four rats and N1S1 hepatoma cell injection into two or three sites in the livers of 12 rats. All rats subsequently underwent MR imaging to assess tumor establishment and volume. Mesenteric angiography and percutaneous MR-guided laser ablation of the liver were performed in a subgroup of animals (n = 4). Animal weight and liver test results were monitored. After harvesting, the livers were subjected to gross and microscopic analysis. Tumor volume and laboratory parameters were assessed between ligation groups.

RESULTS

MR imaging demonstrated hyperintense T2 and hypointense T1 lesions with tumor induction in five of 10 (50.0%), seven of eight (87.5%), and 12 of 12 (100%) sites in the control, SBDL, and CBDL groups, respectively. Tumor volumes differed significantly by group (P < .02). Mesenteric angiography demonstrated an enhancing tumor stain. Clinical and laboratory assessment revealed a significant decrease in weight (P = .01) and albumin level (P < .01) and an increase in total bilirubin level (P = .02) in CBDL rats but not SBDL rats (P = 1.0). Histologic examination showed high-grade HCCs with local and vascular invasion within the context of early fibrosis in CBDL and SBDL rats. MR-guided laser ablation generated a 1-2-cm ablation zone with histologic findings consistent with reversible and irreversible injury.

CONCLUSIONS

A biologically relevant rat HCC disease model has been developed for MR imaging and preliminary interventional oncologic applications.

Hepatocellular carcinoma: insight from animal models

Hepatocellular carcinoma (HCC) ranks as the third most common cause of death from cancer worldwide. Although major risk factors for the development of HCC have been defined, many aspects of the evolution of hepatocellular carcinogenesis and metastasis are still unknown. Suitable animal models are, therefore, essential to promote our understanding of the molecular, cellular and pathophysiological mechanisms of HCC and for the development of new therapeutic strategies. This Review provides an overview of animal models that are relevant to HCC development, metastasis and treatment. For HCC development, this Review focuses on transgenic mouse models of HBV and HCV infection, which provide experimental evidence that viral genes could initiate or promote liver carcinogenesis. Animal models of HCC metastasis provide platforms to elucidate the mechanisms of HCC metastasis, to study the interaction between the microenvironment and HCC invasion and to conduct intervention studies. In addition, animal models have been developed to investigate the effects of new treatment modalities. The criteria for establishing ideal HCC animal models are also discussed.

Progress in stem cell-derived technologies for hepatocellular carcinoma

Primary hepatocellular carcinoma (HCC) is a common malignancy that has a poor prognosis because it is often diagnosed at an advanced stage. HCC normally develops as a consequence of underlying liver disease and is most often associated with cirrhosis. Surgical resection and liver transplantation are the current best options to treat liver cancer. However, problems associated with liver transplantation, such as shortage of donors, risk of immune rejection, and tissue damage following surgery provided the impetus for development of alternative therapies. The emerging field of stem cell therapy has raised hopes for finding curative options for liver cancer. Stem cells have the ability not only to proliferate after transplantation but also to differentiate into most mammalian cell types in vivo. In this review, progress on stem cell-derived technologies for the treatment of liver cancer is discussed.