Neither the hepatocytes nor the BECs express DPPIV in the recipient DPPIV negative rats. Thus, appearance of biliary epithelial cell clusters positive for the hepatocyte marker DPPIV provides strong evidence that BEC find more are derived from hepatocytes. Results Histological and functional bile duct damage after DAPM administration

Biliary toxicity induced by single administration of DAPM (50 mg/kg, ip) was monitored by elevations of serum bilirubin and histopathological observations over a time course. Maximum biliary injury in terms of serum bilirubin was apparent by 24 h and consistently stayed high till 48 h after DAPM (Figure 1A). By day 7, rats appeared to recover from toxicity as indicated by regressing serum bilirubin levels (Figure 1A). Histopathological observations revealed biliary cell necrosis as early as 12 h after DAPM. Necrosis was accompanied by ductular swelling and inflammation. Some damage to the hepatocytes was also observed in the form of bile infarcts. However, the serum ALT elevations were minimal suggesting hepatocyte injury by DAPM was secondary (Additional File 1, Figure S1). Based on the quantitative analysis, 70% bile ducts were injured by DAPM at 24 h after DAPM. At 48 h, the bile ducts appeared to be repairing from injury (Figure

1B). The PCNA analysis indicated that the biliary cells begin cell division at 48 h and continue till day 7 (Figure SC75741 chemical structure 1C). Based on these findings, we chose to administer DAPM (50mg/kg, ip) every 2 days for total 3 times in order to inflict repeated biliary injury and simultaneously impairing their ability to regenerate themselves. It should be noted that it is the same dose of DAPM that was used in our previous study using DAMP + BDL injury model [1]. Figure 1 Biliary injury and regeneration

for following DAPM toxicity. (A) Serum bilirubin levels indicative of biliary injury after DAPM (50 mg/kg) administration in F344 rats over a time course. * indicates XAV-939 purchase statistical difference from the 0h control (P ≤ 0.05). (B) Histopathology of the liver following DAPM toxicity (50 mg/kg) depicted by H&E staining. Arrow points to the biliary injury. (C) Biliary regeneration after DAPM (50 mg/kg) toxicity depicted by PCNA immunohistochemistry. Brown staining indicates PCNA positive cells. Thin arrow indicates regenerating biliary ductules. Arrowhead points to the hepatocyte proliferation. Scale bar = 100 μm. Appearance of DPPIV-positive bile ducts after repeated administration of DAPM The DPPIV chimeric rats were injected with DAPM at day 0, day 2, and day 4 (Figure 2A). On day 30 after the last injection of DAPM the rats were sacrificed and the liver sections from various lobes were examined for DPPIV positivity.