Contribution of Mature Hepatocytes to Biliary Regeneration in Rats with Acute and Chronic Biliary Injury

Abstract

Whether hepatocytes can convert into biliary epithelial cells (BECs) during biliary injury is much debated. To test this concept, we traced the fate of genetically labeled [dipeptidyl peptidase IV (DPPIV)-positive] hepatocytes in hepatocyte transplantation model following acute hepato-biliary injury induced by 4,4’-methylene-dianiline (DAPM) and D-galactosamine (DAPM+D-gal) and in DPPIV-chimeric liver model subjected to acute (DAPM+D-gal) or chronic biliary injury caused by DAPM and bile duct ligation (DAPM+BDL). In both models before biliary injury, BECs are uniformly DPPIV-deficient and proliferation of DPPIV-deficient hepatocytes is restricted by retrorsine. We found that mature hepatocytes underwent a stepwise conversion into BECs after biliary injury. In the hepatocyte transplantation model, DPPIV-positive hepatocytes entrapped periportally proliferated, and formed two-layered plates along portal veins. Within the two-layered plates, the hepatocytes gradually lost their hepatocytic identity, proceeded through an intermediate state, acquired a biliary phenotype, and subsequently formed bile ducts along the hilum-to-periphery axis. In DPPIV-chimeric liver model, periportal hepatocytes expressing hepatocyte nuclear factor-1β (HNF-1β) were exclusively DPPIV-positive and were in continuity to DPPIV-positives bile ducts. Inhibition of hepatocyte proliferation by additional doses of retrorsine in DPPIV-chimeric livers prevented the appearance of DPPIV-positive BECs after biliary injury. Moreover, enriched DPPIV-positive BEC/hepatic oval cell transplantation produced DPPIV-positive BECs or bile ducts in unexpectedly low frequency and in mid-lobular regions. These results together suggest that mature hepatocytes but not contaminating BECs/hepatic oval cells are the sources of periportal DPPIV-positive BECs. We conclude that mature hepatocytes contribute to biliary regeneration in the environment of acute and chronic biliary injury through a ductal plate configuration without the need of exogenously genetic or epigenetic manipulation.

From Hepatocyte to Cholangiocyte: The Remarkable Potential of Transdifferentiation to Treat Cholestatic Diseases

“…In rodent models, mature hepatocytes transdifferentiate into biliary cells when there is extensive injury and loss of functional biliary cells, and resident cholangiocyte proliferative capabilities are unable to adequately compensate. (4)(5)(6) The novelty of the current study lies in the replenishment of functional intrahepatic biliary ducts without injury and, notably, without previous biliary tissue being present. Hepatic organoids (of rat origin) have also been used to study hepatocyte transdifferentiation into biliary cells, (7,8) which demonstrate the requirement of hepatocyte growth factor (HGF) and endothelial growth factor (EGF) in this system to induce the phenotypic change.…”

“…(2,3) The liver normally produces a large amount of lymph (estimated at 1-3 liters per day, comprising 25%-50% of flow in the thoracic duct (4) ). This enormous traffic passing through the space of Mall (5,6) deserves further study with modern methodologies. 2.…”

“…These prior studies primarily focus on rat and mouse models of injury (acute and chronic) and manipulation of the proliferative capabilities of the original cells. In rodent models, mature hepatocytes transdifferentiate into biliary cells when there is extensive injury and loss of functional biliary cells, and resident cholangiocyte proliferative capabilities are unable to adequately compensate . The novelty of the current study lies in the replenishment of functional intrahepatic biliary ducts without injury and, notably, without previous biliary tissue being present.…”

Role of ErbB/HER family of receptor tyrosine kinases in cholangiocyte biology

“…If a drastic loss of hepatocytes occurs, cholangiocytes can transdifferentiate into hepatocytes to regenerate the liver parenchyma . Conversely, hepatocytes can contribute to biliary regeneration in case of acute hepatobiliary or chronic biliary injuries in order to restore the biliary epithelium's structure and function . Although the involvement of an ErbB‐dependent signaling has not been reported in the conversion of cholangiocyte into hepatocyte, EGFR may contribute to the conversion of hepatocyte into cholangiocyte‐like phenotype .…”

“…(17) Conversely, hepatocytes can contribute to biliary regeneration in case of acute hepatobiliary or chronic biliary injuries in order to restore the biliary epithelium's structure and function. (18) Although the involvement of an ErbB-dependent signaling has not been reported in the conversion of cholangiocyte into hepatocyte, EGFR may contribute to the conversion of hepatocyte into cholangiocyte-like phenotype. (19) In rat organoid cultures, EGF, through kinase B protein (AKT)-independent phosphoinositide 3 kinase (PI3K) activation, was the only growth factor, along with hepatocyte growth factor (HGF), capable of promoting hepatocyte transdifferentiation into cholangiocytes.…”