In summary this report demonstrates another successful appli

In summary, this report demonstrates another successful application of gene editing in iPSCs. Despite the lack of efficient metabolic functional repair after transplantation, the application of gene correction into HLCs might still be a realistic goal for ex vivo gene therapy of liver diseases with further experimental optimization. To our knowledge, these results represent the first description of transplantation using ahr pathway derived from HDR-mediated repair of iPSCs for arginase-1 deficiency. The development of efficient targeted gene editing using TALENs and CRISPR/Cas9 systems could open exciting new avenues for arginase-1 gene therapy.
Materials and Methods
Author Contributions
Conflicts of Interest
Acknowledgments Y.Y.S. is supported by a fellowship from the Urea Cycle Disorders Consortium (UCDC; U54HD061221), which is a part of the NIH Rare Disease Clinical Research Network (RDCRN), supported through collaboration between the Office of Rare Diseases Research (ORDR), the National Center for Advancing Translational Science (NCATS), and the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). This work was supported by a microgrant from the Rare Disease Foundation and the BC Children’s Hospital Foundation (BCCHF) (#18-19 to Y.Y.S.). C.D.F. is supported by the Canada Research Chairs program and the Canadian Institutes of Health Research (CIHR) (MOP-341036).
Introduction Arginaseis an important regulator of nitric oxide (NO) production, and an increase ofarginase activity reduces the availability of l-arginine for NO synthase, thus reducing NO production, and leading to endothelial dysfunction (Pernow and Jung, 2013). Increased activity of arginase has been demonstrated in several pathological conditions including cardiovascular dysfunction and other vascular diseases (Pernow and Jung, 2013). Hypercholesterolemia (HC) induces lipemic stress due to extra cholesterol deposition into the membranes of vascular cells and erythrocytes, and this triggers reactive oxygen species (ROS) production, and membrane aberration (Uydu et al., 2012). Furthermore, lipemic stress is associated with disruption of l-arginine transport into cells and inactivation of nitric oxide synthase (NOS), while arginase activity is increased. Additionally, l-arginine analogues increase, particularly asymmetric dimethylarginine and symmetric dimethylarginine (Eligini et al., 2013, Yang et al., 2013, Porro et al., 2014). The net result of these events is the decrease of NO levels as a key player in the regulation of homeostasis, vasodilation, neurotransmission, free radicals scavenging and erythrocytes function (Eligini et al., 2013). In past decades, several studies reported that vascular NO is mostly produced from endothelial cells by endothelial NO synthase (eNOS); however nowadays, erythrocytes were listed as another major source of NO in vascular lumen (Eligini et al., 2013, Ramírez-Zamora et al., 2013, Porro et al., 2014). For NO biosynthesis, NOS utilizes l-arginine as substrate; flavoproteins and tetrahydrobiopterin were used as coenzymes (Eligini et al., 2013, Porro et al., 2014). Conversely, arginase competes with NOS on l-arginine as common substrate; therefore, it NO production (Yang et al., 2013, Li and Förstermann, 2013). The proper balance between NOS and arginase is essential for maintenance of NO homeostasis (Porro et al., 2014, Yang et al., 2013). Functional erythrocytes have antioxidant machinery that neutralizes ROS generated in the vasculature; however, malfunctioned erythrocytes can act as a source of ROS (Minetti et al., 2007). Moreover, such erythrocytes release arginase that limits NO production (Porro et al., 2014, Yang et al., 2013). Therefore, oxidized erythrocytes act as pro-oxidant bombs to vascular endothelium. Although, several studies reported that erythrocyte’s arginase activity was augmented by oxidative stress (Yang et al., 2013, Porro et al., 2014, Li and Förstermann, 2013), no enough published data address this topic, and further research are necessary to address this issue.