The microenvironment in hepatocyte regeneration and function in rats with advanced cirrhosis

Abstract

In advanced cirrhosis, impaired function is caused by intrinsic damage to the native liver cells and from the abnormal microenvironment in which the cells reside. The extent to which each plays a role in liver failure and regeneration is unknown. To examine this issue, hepatocytes from cirrhotic and age-matched control rats were isolated, characterized, and transplanted into the livers of noncirrhotic hosts whose livers permit extensive repopulation with donor cells. Primary hepatocytes derived from livers with advanced cirrhosis and compensated function maintained metabolic activity and the ability to secrete liver-specific proteins, whereas hepatocytes derived from cirrhotic livers with decompensated function failed to maintain metabolic or secretory activity. Telomere studies and transcriptomic analysis of hepatocytes recovered from progressively worsening cirrhotic livers suggest that hepatocytes from irreversibly failing livers show signs of replicative senescence and express genes that simultaneously drive both proliferation and apoptosis, with a later effect on metabolism, all under the control of a central cluster of regulatory genes, including nuclear factor κB and hepatocyte nuclear factor 4α. Cells from cirrhotic and control livers engrafted equally well, but those from animals with cirrhosis and failing livers showed little initial evidence of proliferative capacity or function. Both, however, recovered more than 2 months after transplantation, indicating that either mature hepatocytes or a subpopulation of adult stem cells are capable of full recovery in severe cirrhosis. Conclusion Transplantation studies indicate that the state of the host microenvironment is critical to the regenerative potential of hepatocytes, and that a change in the extracellular matrix can lead to regeneration and restoration of function by cells derived from livers with end-stage organ failure.

Immunohistochemical Analysis of the Stem Cell Marker Lgr5 in Pediatric Liver Disease

“…Of note, similar HPC incapacitation was recently reported in liver explants from patients with severe alcoholic hepatitis compared to those with cirrhosis (28). Previous studies in rodents have also demonstrated that the regenerative capacity of cirrhotic hepatocytes can be restored if they are transplanted into healthy livers, suggesting that the microenvironment impairs effective proliferation in response to chronic injury (15)(16)(17). When we further compared neonatal liver biopsies and childhood explants from the same patients with A1ATD, we found increased expression of LGR5 at time of biopsy, suggesting recruitment of a predominantly LGR5+ regenerative response early on, before end-stage cirrhosis.…”

“…RSPO1 and ZNF3/RNF43 act to inversely module Wnt receptor turnover at them membrane, and these are potential mechanisms to explore in liver (15,45). Of note, recent studies in human and mouse livers also suggest a role for both RSPO1 and RSPO2 in hepatic stellate cell activation and liver fibrosis (27,46).…”

“…In humans with acute liver failure, >50% hepatocyte loss is required for significant activation of HPCs, and the number of HPCs is also inversely correlated with the number of Ki67+ hepatocytes, suggesting that unlike some animal models, human HPC activation depends on both hepatocyte loss and decreased proliferation (13,14). Furthermore, in cirrhotic liver, the microenvironment plays a significant role in determining the proliferation response of hepatocytes, as demonstrated by cell transplantation and repopulation studies in rodents (15)(16)(17). Understanding the spatiotemporal expression of these signals may provide histologic clues into the regenerative capacity of hepatocytes in response to liver damage.…”

Resetting the transcription factor network reverses terminal chronic hepatic failure

“…Using this chronic injury model, we show that hepatocyte network transcription factors -HNF4α, FOXA2, C/EBPα, PPARα, and HNF1α -are stably downregulated in end-stage hepatocytes from animals with cirrhosis and terminal hepatic failure (13). Since recent studies have shown that somatic cells can be reprogrammed into pluripotent stem cells or other mature cell lineages following forced expression of selected transcription factors (17,18), we examined whether reprogramming the disrupted transcription factor network in degenerative disease could reverse the acute decompensated and fatal organ failure mediated by chronic injury.…”

“…With chronic injury, there is a decrease in hepatocyte mass, and the remaining hepatocytes have ongoing oxidative damage (9,10), impaired mitochondrial function (11,12), altered cellular energy production (13), telomere shortening (14,15), and a decrease in regeneration capacity (13)(14)(15). Over the last decade, we developed a unique model in rats, using chronic administration of CCl 4 to produce a syndrome of progressive injury and irreversible and fatal chronic liver failure that greatly resembles human disease (13,16). While the latter has different etiologies -including HBV, HCV, alcohol, or nonalcoholic steatohepatitis (NASH)/ metabolic syndrome -this CCl 4 -injured rat model reproduces the most important feature of advanced degenerative liver disease, the irreversibly decompensated hepatocyte.…”