CELL THERAPY AND STEM CELLS

K. Ohashi¹, K. Kosai², T. Okano^1
1Inst. Adv. Biomed. Eng. And Sci., Tokyo Womens Medical University, Tokyo Womens Medical University/JAPAN, ², Kagoshima University Faculty of Medicine, Kagoshima University Faculty of Medicine/JAPAN

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[Background]: Liver tissue engineering using isolated hepatocytes is an emerging field in which a functional liver system is created in vivo toward the treatment of liver diseases. Our lab hasrecently developed procedures to create liver tissues under the kidney capsule spaces, however, we have realized that significant portion of transplanted hepatocytes underwent the process of celldeath during the first 48 hours period after transplantation to the ectopic sites. These findings led us to develop a procedure that could protect the hepatocytes from the cell death process. In thepresent study, we attempted to transduce hepatocyte growth factor (HGF) gene, a potent anti-apoptotic gene, to the primary hepatocytes and the transduced cells were used for the purpose of livertissue engineering. We investigated whether the HGF-transduced hepatocytes could survive at higher rates resulting in a creation of larger liver tissue. We also assessed therapeutic effects of thisliver tissue engineering approach on liver failure. [Method]: Donor hepatocytes were isolated and purified from human alpha-1 antitrypsin (A1AT) transgenic mice. The HGF gene transduction to thehepatocytes was carried out using adenoviral vectors (Ad), either Ad-CAG-HGF or Ad-CAG-null (for control), based on our previously developed non-culture Ad-infection system (Cell Transpl 15: 1-12,2006). After this vector infection step, liver tissue engineering procedures were performed to the wild FVB/N mice by transplanting the hepatocyte with EHS-matrix under the kidney capsule spaces.Functional volume of the engineered liver tissues was assessed by periodic measurement of serum A1AT levels of the recipients and histological examination. In order to assess therapeutic potential,acute and lethal liver failure was induced to the tissue engineered or sham-operated mice by performing 2/3 hepatectomy combined with a ligation of right portal pedicles. [Results]: Tunnel stainingof the transplanted hepatocytes revealed that the number of apoptotic hepatocytes was significantly fewer in the HGF-hepatocyte group as compared with control (Ad-CAG-null) group. The serum A1ATlevels in the HGF-hepatocyte group were significantly higher than those in the control group at any time points throughout the experimental period. Histological examination revealed thatHGF-transduced hepatocytes created thicker liver tissues compared with control group. When the HGF-hepatocyte recipient mice developed liver failure, the mice showed significantly higher survivalrates compared to those in the sham-operation group. [Conclusions]: The data presented in this report demonstrated that HGF-transduced hepatocyte is a valuable cell source for liver tissueengineering approaches. The present study also provided evidences that liver tissue engineering could provide therapeutic benefits on the individuals with acute liver failures.

Disclosure: All authors have declared no conflicts of interest.