Small molecule drugs promote repopulation of transplanted hepatocytes by stimulating cell dedifferentiation

BACKGROUND & AIMS: Hepatocyte transplantation has emerged as a possible treatment option for end-stage liver disease. However, an important obstacle to therapeutic success is the low level of engraftment and proliferation of transplanted hepatocytes, which do not survive long enough to exert therapeutic effects. Thus, we aimed to explore the mechanisms of hepatocyte proliferation in vivo and find a way to promote the growth of transplanted hepatocytes. METHODS: Hepatocyte transplantation was performed in Fah(-/-) mice to explore the mechanisms of hepatocyte proliferation in vivo. Guided by in vivo regeneration mechanisms, we identified compounds that promote hepatocyte proliferation in vitro. The in vivo effects of these compounds on transplanted hepatocytes were then evaluated. RESULTS: The transplanted mature hepatocytes were found to dedifferentiate into hepatic progenitor cells (HPCs), which proliferate and then convert back to a mature state at the completion of liver repopulation. The combination of two small molecules Y-27632 (Y, ROCK inhibitor) and CHIR99021 (C, Wnt agonist) could convert mouse primary hepatocytes into HPCs, which could be passaged for more than 30 passages in vitro. Moreover, YC could stimulate the proliferation of transplanted hepatocytes in Fah(-/-) livers by promoting their conversion into HPCs. Netarsudil (N) and LY2090314 (L), two clinically used drugs which target the same pathways as YC, could also promote hepatocyte proliferation in vitro and in vivo, by facilitating HPC conversion. CONCLUSIONS: Our work suggests drugs promoting hepatocyte dedifferentiation may facilitate the growth of transplanted hepatocytes in vivo and may facilitate the application of hepatocyte therapy. IMPACT AND IMPLICATIONS: Hepatocyte transplantation may be a treatment option for patients with end-stage liver disease. However, one important obstacle to hepatocyte therapy is the low level of engraftment and proliferation of the transplanted hepatocytes. Herein, we show that small molecule compounds which promote hepatocyte proliferation in vitro by facilitating dedifferentiation, could promote the growth of transplanted hepatocytes in vivo and may facilitate the application of hepatocyte therapy.