Hepatocellular carcinoma (HCC) is the fifth most common malignant tumour, with a high mortality rate. Radiofrequency ablation (RFA) is a therapeutic option for patients, which cannot be treated with resection or transplantation. We aimed to characterise the effect of RFA on HCC and healthy liver tissue in this study with the main focus on cell culture experiments simulating different grades of fibrosis and cirrhosis. Moreover, we evaluated the effect of RFA in a porcine model to monitor changes in and around the affected area. In our cell culture experiments, we established an in vitro fibrosis model to investigate the heat sensitivity and cell survival on different cell lines. MRC-5 or LX-1 cells were heated with HepG2 cells in co-culture and transwells from 55°C to 100°C for different time spans. Thereafter, we measured the metabolic activity immediately, after 24 h and 48 h using MTS test to assess how many cells survived heating. Furthermore, we investigated LX-1 and HepG2 cells after heat exposure using Flow Cytometry to distinguish between apoptosis and necrosis. In the large animal model we performed RFA in pigs and euthanized them after different time spans (0d, 1d, 2d, 1w, 2 w, 1m, 2m, 3m). At each time point we gain one large and one standard paraffin block, which were sliced and stained for CAB, MB, Caspase 3, Hsp70, Ki-67, Calprotectin, GFAP and α-SMA to investigate the changes in the transition zone after RFA. We demonstrated that fibrosis has a wide influence on the shape and the size of a RFA lesion. To prevent further tumour growth or alteration a temperature of at least 75°C has to be reached in the border area. High temperatures cause a necrotic and thermally fixed lesion, which appears to resist tissue repair and resolution. In the transition zone, apoptotic cells are replaced by fibroblasts producing a fibrous capsule over time. This capsule acts as inflammatory border and causes mainly foreign body reaction, which leads to a chronic local inflammation. Generally, RFA causes acute inflammatory reaction due to wounding of liver tissue. A capsule is formed around the ablation zone, which reacts as inflammatory border and causes foreign body reaction. If the tumour cells are killed completely within the RFA, the ablated area will vanish over years and will cause no further complications.
Impact of Hyperthermia caused by Radiofrequency Ablation on Liver Cell Lines and Tissue
Mayrhauser, U. (Author). 2012
Student thesis: Doctoral thesis