Experimental Model for Successful Liver Cell Therapy by Lenti TTR-YapERT2 Transduced Hepatocytes with Tamoxifen Control of Yap Subcellular Location.

Mladen Yovchev,Liang Zhu,Zhonglei Lu,Shachi Patel,Marius Sudol,Fadi L Jaber,Joseph Locker,David A Shafritz,Mariana D Dabeva,Leslie E Rogler,John W Murray

doi:10.1038/srep19275

Abstract

Liver repopulation by transplanted hepatocytes has not been achieved previously in a normal liver microenvironment. Here we report that adult rat hepatocytes transduced ex vivo with a lentivirus expressing a human YapERT2 fusion protein (hYapERT2) under control of the hepatocyte-specific transthyretin (TTR) promoter repopulate normal rat liver in a tamoxifen-dependent manner. Transplanted hepatocytes expand very slowly but progressively to produce 10% repopulation at 6 months, showing clusters of mature hepatocytes that are fully integrated into hepatic parenchyma, with no evidence for dedifferentiation, dysplasia or malignant transformation. Thus, we have developed the first vector designed to regulate the growth control properties of Yap that renders it capable of producing effective cell therapy. The level of liver repopulation achieved has significant translational implications, as it is 2-3x the level required to cure many monogenic disorders of liver function that have no underlying hepatic pathology and is potentially applicable to diseases of other tissues and organs.

Highlights

The only effective therapy currently available for end stage liver disease is liver transplantation
We previously reported that bipotential rat fetal liver epithelial cells, referred to as fetal liver stem/progenitor cells (FLSPC), repopulate the normal liver after transplantation in conjunction with two-thirds partial hepatectomy (PH)[15,16]
After liver regeneration is completed, transplanted FLSPC continue to proliferate at a level 4–6 times greater than that observed in adjacent host hepatocytes and replace 20–25% of hepatocyte mass within 6 months[16]

Summary

Introduction

The only effective therapy currently available for end stage liver disease is liver transplantation. Extensive liver repopulation by transplanted hepatocytes has been reported in animal model systems, but this occurs only under highly adverse conditions in which there is massive and continuous liver injury induced in the host by genetic manipulation, as in uPA transgenic mice[3] or Fah null mice[4], or host hepatocytes have been subjected to extensive, long-lasting damage, rendering them incapable of cell division, as in retrorsine or monocrotaline treated or x-irradiated rats or mice[5,6,7] Under these circumstances, there is a strong selective advantage for proliferation and/or survival of transplanted hepatic cells vs host cells in the massively injured liver. This level of liver repopulation is sufficient to cure many genetic-based liver disorders, including those in which there is no underlying or ongoing liver injury

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