Transplantation of chemically induced liver progenitors in Nagase analbuminemic rats under liver regenerative stimulus.

We have explored chemically induced liver progenitors (CLiP) as a potential therapeutic agent for liver diseases because their proliferative capacity in vitro. Therefore, we hypothesized the potential treatment with CLiP transplantation (Tx) could be effective and be enhanced with liver regenerative stimulus for metabolic liver diseases. METHODS: Male Sprague Dawley rats were used for mature hepatocytes (HEP) isolation to induce CLiP using 3 small molecules cocktail (ROCK-inhibitor, TGF beta-1 inhibitor, GSK3 inhibitor). Harvested rat CLiP (1 × 10(6)) were transplanted to the posterior lobe of the liver (30 % of whole liver) of Nagase analbuminemic rats (NAR) through portal vein injection. One week later, portal venous branch to non-transplanted lobe was ligated to induce liver regeneration in CLiP bearing liver lobe (portal branch ligation: PBL). Only CLiP Tx or HEP Tx of same dose were used as control groups. Serial measurement of serum albumin level was measured by ELISA method. All NARs were subject to immunosuppression therapy using tacrolimus s.q. 3 days per week. RESULTS: After HEP Tx especially with PBL, serum albumin level was significantly elevated. However, even with PBL, CLiP Tx group did not show significant increase in serum albumin. CLiP were surrounded by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) positive cells in portal veins suggesting that CLiP were exposed to the risk of innate immunity. CONCLUSION: Although CLiP respond to growth factors and proliferate better than HEP in vitro, their behavior in vivo in response to liver regenerative stimulus were not similar to in vitro probably because of less immaturity of receptors and/or high immunogenicity as compared to HEP.