Hepatic parenchymal changes following transcatheter embolization and chemoembolization in a rabbit tumor model

Abstract

Objective: To compare the effects of transcatheter arterial chemoembolization (TACE) with transcatheter arterial embolization (TAE) on liver function, hepatic damage, and hepatic fibrogenesis in a rabbit tumor model.

Materials and methods: Thirty-nine New Zealand white rabbits implanted with VX2 tumors in the left liver lobes were randomly divided into three groups: TAE, TACE, and control group. In the TAE group (n = 15), polyvinyl alcohol particles (PVAs) were used for left hepatic artery embolization. In the TACE group (n = 15), the tumors were treated with left hepatic arterial infusions of a suspension of 10-hydroxycamptothecin and lipiodol, followed by embolization with PVAs. In the control group (n = 9), the animals received sham treatment with distilled water. Serum and liver samples were collected at 6 hours, 3 days and 7 days after treatment. Liver damage was measured using a liver function test and histological analyses. Liver fibrogenesis and hepatic stellate cell (HSC) activation were evaluated using Sirius Red and anti-alpha-smooth muscle actin (α-SMA) immunohistochemical stains.

Results: TACE caused liver injury with greater increases in serum alanine aminotransferase and aspartate aminotransferase levels on day 3 (P<0.05). Histological analyses revealed increased hepatic necrosis in adjacent non-tumorous liver tissue from day 3 compared to the TAE group (Suzuki score of 2.33±1.29 versus 1.13±1.18, P = 0.001). HSC activation and proliferation were significantly increased in the TACE group compared to the control group at 3 and 7 days after treatment (0.074±0.014 vs. 0.010±0.006, and 0.088±0.023 vs. 0.017±0.009, P<0.05). Sirius Red staining demonstrated a statistically significant increase in collagen deposition in the livers in the TACE group 7 days after embolization compared to the control group (0.118±0.012 vs. 0.060±0.017, P = 0.05).

Conclusion: The results of this animal study revealed that TACE induced prominent hepatocellular damage and hepatic fibrogenesis, which compromised liver function and may be responsible for chronic liver decompensation.

Figure 1. Postoperative changes in serum ALT, AST and bilirubin levels.

(A and B) ALT and AST peaked on day 3 in the TAE and TACE groups. (C) Serum bilirubin levels increased slightly after all of the procedures, but these increases were not significant. *P<0.05 compared to the control group; **P<0.05 compared to the TAE and control groups.

Figure 2. Histologic analyses on postoperative day 7.

Hematoxylin and eosin stained livers adjacent to tumors from rabbits (100X). The lobular architecture in the control group was well preserved, and no edema, congestion, or centrilobular necrosis was observed (A). The TAE group displayed focal hepatocyte necrosis and the infiltration of inflammatory cells (B). The TACE group displayed severe sinusoidal congestion and hepatocyte necrosis. Diffuse infiltration of inflammatory cells (lymphocytes and granulocytes) and sinusoidal dilatation/atrophic trabeculae were observed (C).

Figure 3. HSC activation following TAE and TACE at different time points after treatment.

Areas that stained positive for α-SMA using immunohistochemistry were measured using a computerized image analysis system and expressed as a percentage of the total analyzed area. *P<0.05 vs. control.

Figure 4. Immunohistochemical staining was used to determine HSC activation using α-SMA.

Liver samples (embolized non-tumorous liver tissue) from the control, TAE and TACE groups 3 days after treatment. No positive α-SMA expression was observed in the control group, with the exception of the blood vessels (A). Significant positive α-SMA expression was mainly localized to the hepatic parenchymal cells near the portal tracts in the TAE group (B), and α-SMA expression was higher in the TACE group than in the TAE group (C).

Figure 5. Liver fibrogenesis following TAE and TACE at different time points after treatment.

Sirius Red stained areas were measured using a computerized image analysis system and expressed as a percentage of the total analyzed area. *P<0.05 vs. control.

Figure 6. Picro-Sirius Red staining for liver fibrogenesis.

Liver samples (embolized non-tumorous liver tissue) from the control, TAE and TACE groups 7 days after treatment. Picro-Sirius Red stains collagen red on a yellow background under a bright-field microscope, whereas under a polarization microscope, collagen appears bright yellow-red (mainly type I collagen), and/or bright green (mainly type III collagen). Seven days after treatment, Picro-Sirius Red staining was observed to be concentrated mainly around the portal tracts in the control group (A), and type I and III collagen fibrils were confined to the portal area (D). Seven days after embolization, liver fibrogenesis was detected in the TAE group (B). However, collagen fiber staining around the portal tracts was increased in the TACE group (C). In the TAE and TACE groups, dramatic increases in the levels of collagen fibrils, type I in particular, were observed (E and F).