**5. Concluding remarks**

This chapter collectively delivers information about the DEN-induced liver fibrosis/cirrhosis in a small amount (0.014%) of water drinking diet chemical (DEN)-induced hepatic fibrosis, cirrhosis and carcinogenesis mouse model and clinical implications, and provides additional insights into the liver possibility of the positive effect of CD8+ T cells in the animal model-associated pathogenesis. The sequence of pathophysiological alterations in the model has a high similarity to what happens in humans. In comparison to other mouse models, the DEN-induced liver fibrosis-cirrhosis-HCC model on a natural genetic background C57BL/6 inbred mice sounds favorable, and prolonged application of DEN to induce hepatic inflammatory response and immune CD8+ T cell activation after a period of latency are beneficial for endogenous HSP cells (NG2+ HSP) mobilization and survival. Based on our experience and on a multitude of independent studies in the field, we recommend that for treatment strategies not inhibit but regulate inflammation and immune CD8<sup>+</sup> T-cells during liver fibrosis/cirrhosis development. Alternatively, the use of male mice at middle age (approximately 8–10 weeks old) and body weight of the animals should be regularly measured and documented (approximately 22–25 g), and the extent of pathological features (evolution from homeostasis to fibrosis to cirrhosis to HCC formation) should always be histologically proven and documented. Further studies are warranted to identify the specific signaling or molecules that contribute to the development of hepatic homeostasis to fibrosis, then cirrhosis and finally cancer (HCC) in the liver.

### **Acknowledgements**

This work was supported by grants from the National Natural Science Foundation of China (81873586) and the Army Medical University of China (2021-20180-52).
