Wang, Xuehao

Abstract Acute rejection is commonly encountered for long-term survival in liver transplant (LT) recipients and may impact their long-term survival if rejection is severe or recurrent. The aim of this study is to examine the therapeutic potential of transforming growth factor (TGF-β)-overexpressing mesenchymal stem cells (MSCs) in inducing a local immunosuppression in liver grafts after transplantation. MSCs were transduced with a lentiviral vector expressing the human TGF-β1 gene; TGF-β1-overexpressing MSCs (designated as TGF/MSCs) were then transfused into the liver grafts via the portal vein of a rat LT model of acute rejection. Rejection severity was assessed by clinical and histologic analysis. The immunity suppression effects and mechanism of TGF/MSCs were tested, focusing on their ability to induce generation of regulatory T cells (Tregs) in the liver grafts. Our findings demonstrate that transfusion of TGF/MSCs prevented rejection, reduced mortality, and improved survival of rats after LT. The therapeutic effects were associated with the immunosuppressive effects of MSCs and TGF-β1. Their reciprocal effects on Tregs induction and function resulted in more CD4 + Foxp3 + Helios- induced Tregs, fewer Th17 cells, and improved immunosuppressive effects in local liver grafts. Thus, TGF/MSCs can induce a local immunosuppressive effect in liver grafts after transplantation. The immunomodulatory activity of TGF-β1 modified MSCs may be a gateway to new therapeutic approaches to prevent organ rejection in clinical transplantation.

Tens of millions of patients are affected by liver disease worldwide. Many of these patients can benefit from cell therapy involving living metabolically active cells, either by treatment of their liver disease, or by prevention of their disease phenotype. Cell therapies, including hepatocyte transplantation and bioartificial liver (BAL) devices, have been proposed as therapeutic alternatives to the shortage of transplantable livers. Both BAL and hepatocyte transplantation are cellular therapies that avoid use of a whole liver. Hepatocytes are also widely used in drug screening and liver disease modelling. However, the demand for human hepatocytes, heavily outweighs their availability by conventional means. Induced pluripotent stem cells (iPSCs) technology brings together the potential benefits of embryonic stem cells (ESCs) (i.e., self-renewal, pluripotency) and addresses the major ethical and scientific concerns of ESCs: embryo destruction and immune-incompatibility. It has been shown that hepatocyte-like cells (HLCs) can be generated from iPSCs. Furthermore, human iPSCs (hiPSCs) can provide an unlimited source of human hepatocytes and hold great promise for applications in regenerative medicine, drug screening and liver diseases modelling. Despite steady progress, there are still several major obstacles that need to be overcome before iPSCs will reach the bedside. This review will focus on the current state of efforts to derive hiPSCs for potential use in modelling and treatment of liver disease.

Tens of millions of patients are affected by liver disease worldwide. Many of these patients can benefit from therapy involving hepatocyte transplantation. Liver transplantation is presently the only proven treatment for many medically refractory liver diseases including end-stage liver failure and inherited metabolic liver disease. However, the shortage in transplantable livers prevents over 40% of listed patients per year from receiving a liver transplant; many of these patients die before receiving an organ offer or become too sick to transplant. Therefore, new therapies are needed to supplement whole-organ liver transplantation and reduce mortality on waiting lists worldwide. Furthermore, the remarkable regenerative capacity of hepatocytes in vivo is exemplified by the increasing number of innovative cell-based therapies and animal models of human liver disorders. Induced pluripotent stem cells (iPSCs) have similar properties to those of embryonic stem cells (ESCs) but bypass the ethical concerns of embryo destruction. Therefore, generation of hepatocyte-like cells (HLCs) using iPSC technology may be beneficial for the treatment of severe liver diseases, screening of drug toxicities, basic research of several hepatocytic disorders, and liver transplantation. Here we briefly summarize the growing number of potential applications of iPSCs for treatment of liver disease.