Published online Apr 14, 2015. doi: 10.3748/wjg.v21.i14.4184
Peer-review started: September 29, 2014
First decision: October 29, 2014
Revised: December 16, 2014
Accepted: January 16, 2015
Article in press: January 16, 2015
Published online: April 14, 2015
Processing time: 200 Days and 12.6 Hours
AIM: To test whether hepatic stellate cells (HSCs) at different activation stages play different roles in acetaminophen (APAP)-induced acute liver injury (ALI).
METHODS: HSCs were isolated from mouse liver and cultured in vitro. Morphological changes of initiation HSCs [HSCs (5d)] and perpetuation HSCs [HSCs (p3)] were observed by immunofluorescence and transmission electron microscopy. The protective effects of HSC-derived molecules, cell lysates and HSC-conditioned medium (HSC-CM) were tested in vivo by survival and histopathological analyses. Liver injury was determined by measuring aminotransferase levels in the serum and by histologic examination of tissue sections under a light microscope. Additionally, to determine the molecular mediators of the observed protective effects of initiation HSCs, we examined HSC-CM using a high-density protein array.
RESULTS: HSCs (5d) and HSCs (p3) had different morphological and phenotypic traits. HSCs (5d) presented a star-shaped appearance with expressing α-SMA at non-uniform levels between cells. However, HSCs (p3) evolved into myofibroblast-like cells without lipid droplets and expressed a uniform and higher level of α-SMA. HSC-CM (5d), but not HSC-CM (p3), provided a significant survival benefit and showed a dramatic reduction of hepatocellular necrosis and panlobular leukocyte infiltrates in mice exposed to APAP. However, this protective effect was abrogated at higher cell masses, indicating a therapeutic window of effectiveness. Furthermore, the protein array screen revealed that HSC-CM (5d) was composed of many chemokines and growth factors that correlated with inflammatory inhibition and therapeutic activity. When compared with HSC-CM (p3), higher levels of monocyte chemoattractant protein-1, macrophage inflammatory protein-1γ, hepatocyte growth factor, interleukin-10, and matrix metalloproteinase-2, but lower levels of stem cell factor and Fas-Ligand were observed in HSC-CM (5d).
CONCLUSION: These data indicated that initiation HSCs and perpetuation HSCs were different in morphology and protein expression, and provided the first experimental evidence of the potential medical value of initiation HSC-derived molecules in the treatment of ALI.
Core tip: In this study, we isolated hepatic stellate cells (HSCs) from mice by in situ perfusion of the liver and created primary and secondary cultures in plastic tissue culture dishes. Then, we observed different morphologies and phenotypes between initiation HSCs and perpetuation HSCs and described the first use of molecules secreted from HSCs in acetaminophen-induced acute liver injury. Initiation HSC-derived molecules showed hepatocyte-protective effects. Our findings provide novel insight into the mechanisms of HSCs in liver injury therapy. Whether the potential value of initiation HSC-derived molecular therapy is derived from the effect of a single cytokine or a combination of cytokines should be explored in future.