(500a) A Transplantable Liver Graft with Improved Blood Compatibility

The only definitive treatment for end-stage liver disease is orthotopic liver transplantation and it is limited by the shortage of available donor organs. To address the issue, we recently developed a novel method to prepare transplantable liver grafts using perfusion decellularized liver matrix (DLM). While we successfully showed that the engineered liver grafts were functional in vitro and could be transplanted in rats, the post-transplantation survival time of the recipient animals was significantly low (~8 h) due to complications related to the high thrombogenicity of the grafts. An ideal engineered liver graft should be anti-thrombogenic and should enable undisrupted blood circulation through the graft in order to allow for its therapeutic testing in a liver failure model. Therefore, we hypothesized that the immobilization of active heparin, an anti-thrombogenic molecule, on the DLM scaffold surface will render the DLM blood compatible, hence will prevent blood clotting when exposed to blood upon transplantation and prolong the post transplantation survival time of the recipient animal. In this study, we deposited heparin on the DLM scaffold surface using layer-by-layer polyelectrolyte multilayer deposition technique. Heparin deposition was confirmed by histological and chemical assays.  The ability of the heparinized DLM (hDLM) to prevent blood coagulation was tested via 2-h ex vivo diluted blood perfusion and there was significant reduction in the blood clot formation in hDLM scaffolds. The macroscopic observation indicated that the extent of reduction was proportional to the amount of heparin deposited. Heparin deposition on the DLM did not appear to affect the function of engineered grafts as evident by sustained secretion of albumin and urea during 5 d of perfusion culture.  The heterotopic transplantation using hDLM and recellularized hDLM is under investigation in order to assess the feasibility of the tissue-engineered liver graft as a potential replacement for liver transplantation. In the preliminary study the survival over 2-wk period was observed post-transplantation in our animal model; that is much more promising than 8-h survival limited in the previous study. The generation of transplantable and functional engineered liver grafts that can serve as a reliable alternative for liver transplantation will offer a new avenue for treatment of liver diseases.