Nyberg, Scott L.

Share 35 was implemented in 2013 to direct livers to the most urgent candidates by prioritizing Model for End‐Stage Liver Disease (MELD) ≥ 35 patients. We aim to evaluate this policy's impact on costs and mortality. Our study includes 834 wait‐listed patients and 338 patients who received deceased donor, solitary liver transplants at Mayo Clinic between January 2010 and December 2014. Of these patients, 101 (30%) underwent transplantation after Share 35. After Share 35, 29 (28.7%) MELD ≥ 35 patients received transplants, as opposed to 46 (19.4%) in the pre–Share 35 era (P = 0.06). No significant difference in 90‐day wait‐list mortality (P = 0.29) nor 365‐day posttransplant mortality (P = 0.68) was found between patients transplanted before or after Share 35. Mean costs were $3,049 (P = 0.30), $5226 (P = 0.18), and $10,826 (P = 0.03) lower post‐Share 35 for the 30‐, 90‐, and 365‐day pretransplant periods, and mean costs were $5010 (P = 0.41) and $5859 (P = 0.57) higher, and $9145 (P = 0.54) lower post‐Share 35 for the 30‐, 90‐, and 365‐day posttransplant periods. In conclusion, the added cost of transplanting more MELD ≥ 35 patients may be offset by pretransplant care cost reduction. Despite shifting organs to critically ill patients, Share 35 has not impacted mortality significantly. Liver Transplantation 23:11–18 2017 AASLD.

AbstractCulture conditions that induce hepatic spheroidal aggregates sustain liver cells with metabolism that mimics in vivo hepatocytes. Here we present an array of elastin‐like polypeptide conjugate coating materials (Aminated‐ELPs) that are biocompatible, have spheroid‐forming capacity, can be coated atop traditional culture surfaces, and maintain structural integrity while ensuring adherence of spheroids over long culture period. The Aminated‐ELPs were synthesized either by direct conjugation of ELP and various polyelectrolytes or by conjugating both ELP and various small electrolytes to the reactive polymer poly(2‐vinyl‐4,4‐dimethyl azlactone) (PVDMA). Spheroid morphology, cellular metabolic function, and liver‐specific gene expression over the long‐term, 20‐day culture period were assessed through optical microscopy, measurement of total protein content and albumin and urea production, and quantitative real‐time (qRT) PCR. We found that the amine content of the Aminated‐ELP coatings dictated the initial hepatocyte attachment, but not the subsequent hepatocyte spheroid formation and their continued attachment. A lower amine content was generally found to sustain higher albumin production by the spheroids. Out of the 19 Aminated‐ELP coatings tested, we found that the lysine‐containing substrates comprising ELP‐polylysine or ELP‐PVDMA‐butanediamine proved to consistently culture productive spheroidal hepatocytes. We suggest that the incorporation of lysine functional groups in Aminated‐ELP rendered more biocompatible surfaces, increasing spheroid attachment and leading to increased liver‐specific function. Taken together, the Aminated‐ELP array presented here has the potential to create in vitro hepatocyte culture models that mimic in vivo liver functionality and thus, lead to better understanding of liver pathophysiology and superior screening methods for drug efficacy and toxicity. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 377–388, 2017.

Abstract Donor organ shortage is the main limitation to liver transplantation as a treatment for end-stage liver disease and acute liver failure. Liver regenerative medicine may in the future offer an alternative form of therapy for these diseases, be it through cell transplantation, bioartificial liver (BAL) devices, or bioengineered whole organ liver transplantation. All three strategies have shown promising results in the past decade. However, before they are incorporated into widespread clinical practice, the ideal cell type for each treatment modality must be found, and an adequate amount of metabolically active, functional cells must be able to be produced. Research is ongoing in hepatocyte expansion techniques, use of xenogeneic cells, and differentiation of stem cell-derived hepatocyte-like cells (HLCs). HLCs are a few steps away from clinical application, but may be very useful in individualized drug development and toxicity testing, as well as disease modeling. Finally, safety concerns including tumorigenicity and xenozoonosis must also be addressed before cell transplantation, BAL devices, and bioengineered livers occupy their clinical niche. This review aims to highlight the most recent advances and provide an updated view of the current state of affairs in the field of liver regenerative medicine.

Transplantation of gene-corrected autologous hepatocytes can cure metabolic disease in a preclinical pig model of hereditary tyrosinemia type 1.

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.

Cell therapy is an emerging form of treatment for several liver diseases, but is limited by the availability of donor livers. Stem cells hold promise as an alternative to the use of primary hepatocytes. We performed an exhaustive review of the literature, with a focus on the latest studies involving the use of stem cells for the treatment of liver disease. Stem cells can be harvested from a number of sources, or can be generated from somatic cells to create induced pluripotent stem cells (iPSCs). Different cell lines have been used experimentally to support liver function and treat inherited metabolic disorders, acute liver failure, cirrhosis, liver cancer, and small-for-size liver transplantations. Cell-based therapeutics may involve gene therapy, cell transplantation, bioartificial liver devices, or bioengineered organs. Research in this field is still very active. Stem cell therapy may, in the future, be used as a bridge to either liver transplantation or endogenous liver regeneration, but efficient differentiation and production protocols must be developed and safety must be demonstrated before it can be applied to clinical practice.

Use of the Molecular Adsorbent Recirculating System (MARS) as a liver support device continues to grow worldwide. Various components of the MARS circuit remove both protein‐bound and water‐soluble molecules. Little is known about the extent of the enhanced clearance mechanisms used in MARS therapy on drug elimination. Of particular interest to acute care practitioners is the impact of MARS on antibiotic clearance, as suboptimal concentrations of such drugs can negatively impact patient outcomes. The properties of piperacillin/tazobactam suggest that elimination may be enhanced in the setting of MARS therapy. We describe two cases in which this was studied. Piperacillin concentrations were determined at various points within the MARS circuit, and patient serum concentrations were reported throughout the dosing interval while receiving MARS therapy. Piperacillin concentrations in both cases were in excess of the desired goal minimum inhibitory concentrations for treatment of gram‐negative infections. Use of an extended‐infusion strategy of piperacillin/tazobactam 3.375 or 4.5 g given every 8 hours maintained desired serum levels throughout the dosing interval. To our knowledge, this is the second published report on the use of piperacillin/tazobactam during MARS therapy. These case reports reveal successful dosing strategies for patients requiring piperacillin/tazobactam while receiving MARS therapy, as well as quantify the influence of individual MARS elements on drug extraction.

Abstract Congenital heart diseases (CHDs) requiring surgical palliation mandate new treatment strategies to optimize long-term outcomes. Despite the mounting evidence of cardiac regeneration, there are no long-term safety studies of autologous cell-based transplantation in the pediatric setting. We aimed to establish a porcine pipeline to evaluate the feasibility and long-term safety of autologous umbilical cord blood mononuclear cells (UCB-MNCs) transplanted into the right ventricle (RV) of juvenile porcine hearts. Piglets were born by caesarean section to enable UCB collection. Upon meeting release criteria, 12 animals were randomized in a double-blinded fashion prior to surgical delivery of test article (n = 6) or placebo (n = 6). The UCB-MNC (3 × 106 cells per kilogram) or control (dimethyl sulfoxide, 10%) products were injected intramyocardially into the RV under direct visualization. The cohorts were monitored for 3 months after product delivery with assessments of cardiac performance, rhythm, and serial cardiac biochemical markers, followed by terminal necropsy. No mortalities were associated with intramyocardial delivery of UCB-MNCs or placebo. Two animals from the placebo group developed local skin infection after surgery that responded to antibiotic treatment. Electrophysiological assessments revealed no arrhythmias in either group throughout the 3-month study. Two animals in the cell-therapy group had transient, subclinical dysrhythmia in the perioperative period, likely because of an exaggerated response to anesthesia. Overall, this study demonstrated that autologous UCB-MNCs can be safely collected and surgically delivered in a pediatric setting. The safety profile establishes the foundation for cell-based therapy directed at the RV of juvenile hearts and aims to accelerate cell-based therapies toward clinical trials for CHD.

Cell transplantation is a potential treatment for the many liver disorders that are currently only curable by organ transplantation. However, one of the major limitations of hepatocyte (HC) transplantation is an inability to monitor cells longitudinally after injection. We hypothesized that the thyroidal sodium iodide symporter (NIS) gene could be used to visualize transplanted HCs in a rodent model of inherited liver disease: hereditary tyrosinemia type 1. Wild‐type C57Bl/6J mouse HCs were transduced ex vivo with a lentiviral vector containing the mouse Slc5a5 (NIS) gene controlled by the thyroxine‐binding globulin promoter. NIS‐transduced cells could robustly concentrate radiolabeled iodine in vitro, with lentiviral transduction efficiencies greater than 80% achieved in the presence of dexamethasone. Next, NIS‐transduced HCs were transplanted into congenic fumarylacetoacetate hydrolase knockout mice, and this resulted in the prevention of liver failure. NIS‐transduced HCs were readily imaged in vivo by single‐photon emission computed tomography, and this demonstrated for the first time noninvasive 3‐dimensional imaging of regenerating tissue in individual animals over time. We also tested the efficacy of primary HC spheroids engrafted in the liver. With the NIS reporter, robust spheroid engraftment and survival could be detected longitudinally after direct parenchymal injection, and this thereby demonstrated a novel strategy for HC transplantation. This work is the first to demonstrate the efficacy of NIS imaging in the field of HC transplantation. We anticipate that NIS labeling will allow noninvasive and longitudinal identification of HCs and stem cells in future studies related to liver regeneration in small and large preclinical animal models. Liver Transpl 21:442–453, 2015. © 2015 AASLD.