Chemically-induced liver progenitors (CLiPs) have promising applications in liver regenerative medicine. We aimed to clarify the efficacy of CLiPs for ameliorating fibrosis in a diet-induced nonalcoholic steatohepatitis rat model, since nonalcoholic fatty liver disease is currently recognized as the most common form of chronic liver disease in developed countries. Methods: Primary mature hepatocytes were isolated from 7-week-old male Wistar rats. To establish CLiPs, isolated hepatocytes were cultured in differentiation medium composed of Y-27632, A-83-01, and CHIR99021 (YAC medium). As an animal model that reproduces NASH pathophysiology, 6-week-old severe combined immunodeficient (SCID) mice were carefully selected and prepared and fed with choline-deficient, L-amino acid-defined, high-fat diet (HFD). After 12 weeks’ HFD feeding, the mice were assigned to continue HFD with or without the administration of rat CLiPs (HFD + CLiPs and HFD-CLiPs, respectively). Rat CLiPs were administered from the spleen. Hepatic fibrosis was semi-quantitatively evaluated according to histology. Liver parenchyma and blood samples were collected for biochemical analyses. Results: Rat CLiPs were positive for CK19 and EpCAM were successfully delivered to the liver. At 8 weeks after CLiPs transplantation, the HFD + CLiPs group showed significantly less positive staining than the HFD-CLiPs group. Alanine aminotransferase significantly improved in the HFD + CLiPs group, as demonstrated by Azan staining and αSMA immunostaining. RT qPCR showed that the liver expression of MMP2 and 9 tended to be higher in the HFD + CLiPs group. Conclusions: The anti-fibrotic effect of CLiPs was demonstrated in the immunodeficient NASH animal model and may have therapeutic applications in humans.

Cell sheets consisting of adipose-derived stem cells (ADSCs) have been reported to be effective for wound healing. We conducted this study to clarify the efficacy of ADSC sheets in wound healing at the duct-to-duct biliary anastomotic site in pigs. Eleven female pigs (20-25 kg) were divided into two groups: biliary anastomosis with an ADSC sheet (n = 6) or without an ADSC sheet (n = 5). To follow the transplanted ADSCs, PKH26GL-labeled sheets were used in one of the ADSC pigs. Two weeks prior to laparotomy, ADSCs were isolated from the lower abdominal subcutaneous adipose tissue. After three passages, ADSCs were seeded on temperature-responsive culture dishes and collected as cell sheets. ADSC sheets were gently transplanted on the anastomotic site. We evaluated specimens by PKH26GL labeling, macroscopic changes, infiltration of inflammatory cells, and collagen content. Labeled ADSCs remained around the bile duct wall. In the no-ADSC group, more adhesion developed at the hepatic hilum as observed during relaparotomy. Histopathological examination showed that the diameter and cross-sectional area of the bile duct wall were decreased in the ADSC group. In the no-ADSC group, a large number of inflammatory cells and more collagen fibers were identified in the bile duct wall. The present study demonstrated that autologous ADSC sheet transplantation reduced hypertrophic changes in the bile duct wall at the anastomotic site. A long-term follow-up is required to evaluate the efficacy of this mechanism in prevention of biliary anastomotic strictures.