G-CSF-primed hematopoietic stem cells or G-CSF per se accelerate recovery and improve survival after liver injury, predominantly by promoting endogenous repair programs.

OBJECTIVE: On the basis of the recently recognized potential of bone marrow (BM) cells to give rise to hepatocytes, we investigated the possibility that granulocyte colony-stimulating factor (G-CSF)-mobilized BM cells could home to the injured liver and promote tissue repair. We also examined the origin of cells (endogenous or BM) reconstituting liver after damage.

METHODS: Acute and chronic liver injury models were generated by injecting CCl4 in C57Bl6 mice and G-CSF was administered in hematopoietic stem cell (HSC) mobilization doses. After sex-mismatched BM transplantation into lethally irradiated recipients and treatment with CCl4 +/- G-CSF, sry (sex-determining region for Y chromosome) protein was detected by immunohistochemistry in liver sections. Double immunohistochemistry for sry and ki-67 protein was used to define the origin of proliferating cells reconstituting liver after injury.

RESULTS: In both acute and chronic liver injury model, G-CSF administration ameliorated the histological damage and accelerated the regeneration process. This was accompanied by a strong survival benefit in G-CSF-treated group vs CCl4 group. Quantitative analysis showed higher percentage of BM-origin hepatocytes in the CCl4+G-CSF group compared with the CCl4 group, although the liver engraftment rate still remained rather low. Double staining for ki-67 and sry demonstrated that the recovery acceleration after chemical injury and G-CSF treatment was mainly mediated by increased proliferation of host hepatocytes (ki-67(+)/sry(-)) with less support from BM-origin cells (ki-67(+)/sry(+)).

CONCLUSION: G-CSF treatment significantly improved survival and liver histology in chemically injured mice, predominantly by promoting endogenous repair mechanisms. Therefore, mobilization with G-CSF might offer a novel therapeutic approach for the treatment of acute and chronic liver diseases in humans.