Amplification of Engrafted Hepatocytes by Preparative Manipulation of the Host Liver

Abstract

Scarcity of donor livers is a major obstacle to the general application of hepatocytes for the development of bioartificial liver assist devices as well as intracorporeal engraftment of hepatocytes for the treatment of inherited metabolic diseases. The number of hepatocytes that can be transplanted into the liver safely in a single sitting also limits the utility of this procedure. These limitations could be addressed by providing preferential proliferative advantage to the transplanted cells. Studies using transgenic mouse recipients or donors have indicated that massive repopulation of the host liver by engrafted hepatocytes requires that the transplanted cells are subjected to a proliferative stimulus to which the host hepatocytes cannot respond. Prevention of host hepatocyte proliferation has been achieved by treatment with a plant alkaloid, retrorsine. Because retrorsine is carcinogenic, we have evaluated preparative irradiation for this purpose. The proliferative stimulus may consist of the loss of hepatic mass (e.g., partial hepatectomy, reperfusion injury or induction of Fas-mediated apoptosis by gene transfer) or administration of stimulants of hepatocellular mitosis (e.g., growth factors or thyroid hormone). Potential applications of these preparative manipulations of the host liver include the treatment of inherited metabolic disorders by transplantation of allogeneic hepatocytes, hepatocyte-mediated ex vivo gene therapy, rescuing liver cancer patients from radiation-induced liver damage, and expansion of human hepatocytes in animal livers.

Hepatic injury and the kinetics of bone marrow-derived hepatocyte transgene expression

“…Although most BMdHs have been observed in the mouse FAH −/− model of fatal tyrosinemia, it appears that this phenomenon is not restricted to this particular experimental group of mice. Indeed, other groups have reported this finding in various mouse models including nontransgenic strains [29]. Common to all groups has been the use of liver injury to promote the process of BMdHs.…”

“…Whole body irradiation causes a diffuse oxidative injury to hepatocytes resulting in cell cycle arrest that has been previously demonstrated to result in a persistent inhibition of hepatocyte proliferation [29]. This injury is acute and the mice recover within 10 days if there is no other intervention.…”

Correction of Hyperoxaluria by Liver Repopulation With Hepatocytes in a Mouse Model of Primary Hyperoxaluria Type-1

“…Therefore, we and others have explored various approaches to inhibit the proliferative response of host hepa- tocytes, so that transplanted hepatocytes can proliferate preferentially in response to mitotic stimuli (10,21). These studies have revealed that death of the host hepatocytes or loss of hepatic mass is not a prerequisite for hepatic repopulation.…”

Proliferation of L02 human hepatocytes in tolerized genetically immunocompetent rats

“…With an exogenous growth stimulus, such as partial hepatectomy, the recipient hepatocytes can not only regenerate but the transplanted hepatocytes can also proliferate [5] . If restraining the regeneration of recipient hepatocytes with 2-acetaminofluorene (2-AAF), Retrorsine(Rts), dipin, furan, or 3'5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) [6][7][8] , followed by an exogenous growth stimulus such as carbon tetrachloride(CCl4) or partial hepatectomy (PH) [9][10][11] , the proliferation of transplanted hepatocytes can be improved significantly. We investigate whether human hepatocytes could repopulate after transplantation to rats with a normal immune system treated with 2-acetaminofluorene (2-AAF) or Retrorsine (Rts) and partial hepatectomy (PH).…”