Impaired Hepatocyte Regeneration in Acute Severe Hepatic Injury Enhances Effective Repopulation by Transplanted Hepatocytes

Abstract

Efficient repopulation by transplanted hepatocytes in the severely injured liver is essential for their clinical application in the treatment of acute hepatic failure. We studied here whether and how the transplanted hepatocytes are able to efficiently repopulate the toxin-induced acute injured liver. Male dipeptidyl peptidase IV-deficient F344 rats were randomized to receive retrorsine plus D-galactosamine (R+D-gal) treatment or D-galactosamine-alone (D-gal) to induce acute hepatic injury, and retrorsine-alone. In these models, retrorsine was used to inhibit the proliferation of endogenous hepatocytes while D-galactosamine induced acute hepatocyte damage. Wild-type hepatocytes (1 x 10(7)/ml) were transplanted intraportally 24 h after D-galactosamine or saline injection. The kinetics of proliferation and repopulation of transplanted cells and the kinetics of cytokine response, hepatic stellate cell (HSC) activation, and matrix metalloproteinase (MMP2) expression were analyzed. We observed that early entry of transplanted hepatocytes into the hepatic plates and massive repopulation of the liver by transplanted hepatocytes occurred in acute hepatic injury induced by R+D-gal treatment but not by D-gal-alone or retrorsine-alone. The expressions of transforming growth factor-alpha and hepatocyte growth factor genes in the R+D-gal injured liver were significantly upregulated and prolonged up to 4 weeks after hepatocyte transplantation. The expression kinetics were parallel with the efficient proliferation and repopulation of transplanted hepatocytes. HSC was activated rapidly, markedly, and prolongedly up to 4 weeks after hepatocyte transplantation, when the expression of HGF gene and repopulation of transplanted hepatocytes were reduced afterward. Furthermore, the expression kinetics of MMP2 and its specific distribution in the host areas surrounding the expanding clusters of transplanted hepatocytes are consistent with those of activated HSC. Impaired hepatocyte regeneration after acute severe hepatic injury may initiate serial compensatory repair mechanisms that facilitate the extensive repopulation by transplanted hepatocytes that enter early the hepatic plates.

Contribution of mature hepatocytes to small hepatocyte-like progenitor cells in retrorsine-exposed rats with chimeric livers

“…The rats with DPPIV chimeric livers were generated according to our previous studies 18. Male DPPIV‐deficient rats received two treatments of retrorsine (30 mg/kg, intraperitoneal; Sigma, St. Louis, MO) 2 weeks apart, at 6 and 8 weeks of age.…”

“…We took advantage of the chimeric genetic status of hepatic parenchyma in repopulated dipeptidyl peptidase IV (DPPIV)‐deficient rats. The DPPIV chimeric livers display stable repopulation by two kinds of hepatocytes, endogenous DPPIV‐deficient hepatocytes and transplanted DPPIV‐positive hepatocytes 18. Rats with DPPIV chimeric livers were subjected to retrorsine/PH treatment.…”

Prospects for stem cell transplantation in the treatment of hepatic disease

“…Certainly, direct hepatocyte administration has shown promise in treating metabolic disease, in which a low percentage of cell engraftment can still result in clinical improvement 57. In acute liver failure, the presence of strong regenerative demand may provide favorable conditions under which liver repopulation by exogenous cell lines can be facilitated 58, 59. However, in the presence of cirrhosis, the severely disrupted liver architecture may present a hostile target for effective cell engraftment, differentiation, and function.…”

Repeated transplantation of hepatocytes prevents fulminant hepatitis in a rat model of Wilson's disease

“…Therefore, the proliferation of donor cells has been stimulated in several animal models with genetic, chemical, or physical perturbations within the host liver before transplantation; this is a limitation in the clinical setting. The regimens used to treat recipient livers before transplantation, which are often called preconditioning, can be effectively induced by, for example, agents such as retrorsine that alkylate DNA and proteins, radiation, partial hepatectomy, and temporary liver embolization 24‐27. Although these regimens have significantly helped with exploring and explaining important mechanisms involved in cell transplantation, the transfer of these treatments to the clinical setting is difficult because of possibly detrimental effects (eg, the oncogenic potential of drugs).…”

“…The regimens used to treat recipient livers before transplantation, which are often called preconditioning, can be effectively induced by, for example, agents such as retrorsine that alkylate DNA and proteins, radiation, partial hepatectomy, and temporary liver embolization. [24][25][26][27] Although these regimens have significantly helped with exploring and explaining important mechanisms involved in cell transplantation, the transfer of these treatments to the clinical setting is difficult because of possibly detrimental effects (eg, the oncogenic potential of drugs). A single hepatocyte transplant in LEC rats was shown to cure WD when a combination of treatments was used for preconditioning (eg, retrorsine and partial hepatectomy, radiation and ischemia reperfusion, or radiation and cholic acid).…”