AIM:To investigate the cellular mechanisms of action of Yiguanjian(YGJ) decoction in treatment of chronic hepatic injury.METHODS:One group of mice was irradiated,and received enhanced green fluorescent protein(EGFP)positive bone marrow transplants followed by 13 wk of CCl4 injection and 6 wk of oral YGJ administration.A second group of Institute for Cancer Research mice was treated with 13 wk of CCl4 injection and 6 wk of oral YGJadministration.Liver function,histological changes in the liver,and Hyp content were analyzed.The expression of-smooth muscle actin(-SMA),F4/80,albumin(Alb),EGFP,mitogen-activated protein kinase-2(PKM2),Ki-67,fetoprotein(AFP),monocyte chemotaxis protein-1 and CC chemokine receptor 2 were assayed.RESULTS:As hepatic damage progressed,EGFP-positive marrow cells migrated into the liver and were mainly distributed along the fibrous septa.They showed a conspicuous coexpression of EGFP with-SMA and F4/80 but no coexpression with Alb.Moreover,the expression of PKM2,AFP and Ki-67 was enhanced dynamically and steadily over the course of liver injury.YGJ abrogated the increases in the number of bone marrow-derived fibrogenic cells in the liver,inhibited expression of both progenitor and mature hepatocyte markers,and reduced fibrogenesis.CONCLUSION:YGJ decoction improves liver fibrosis by inhibiting the migration of bone marrow cells into the liver as well as inhibiting their differentiation and suppressing the proliferation of both progenitors and hepatocytes in the injured liver. AIM: To investigate the cellular mechanisms of action of Yiguanjian (YGJ) decoction in treatment of chronic hepatic injury. METHODS: One group of mice was irradiated, and received enhanced green fluorescent protein (EGFP) positive bone marrow transplants followed by 13 wk of CCl4 injection and 6 wk of oral YGJ administration. A second group of Institute for Cancer Research mice was treated with 13 wk of CCl4 injection and 6 wk of oral YGJ administration. Liver function, histological changes in the liver, and Hyp content were analyzed. expression of-smooth muscle actin (-SMA), F4 / 80, albumin (Alb), EGFP, mitogen-activated protein kinase 2 (PKM2), Ki- 67, fetoprotein (AFP), monocyte chemotaxis protein- 1 and CC chemokine receptor 2 were assayed. Results: As hepatic damage progressed, EGFP-positive marrow cells migrated into the liver and were mainly distributed along the fibrous septa. They showed a conspicuous coexpression of EGFP with-SMA and F4 / 80 but no coexpression with Alb. Moreover , the expression of PKM2, AF P and Ki-67 was enhanced dynamically and steadily over the course of liver injury. YGJ abrogated the increases in the number of bone marrow-derived fibrogenic cells in the liver, inhibited expression of both progenitor and mature hepatocyte markers, and reduced fibrogenesis. CONCLUSION : YGJ decoction improves liver fibrosis by inhibiting the migration of bone marrow cells into the liver as well as inhibiting their differentiation and suppressing the proliferation of both progenitors and hepatocytes in the injured liver.