Transplantation of Gene-Edited Hepatocyte-like Cells Modestly Improves Survival of Arginase-1-Deficient Mice

Abstract

Progress in gene editing research has been accelerated by utilizing engineered nucleases in combination with induced pluripotent stem cell (iPSC) technology. Here, we report transcription activator-like effector nuclease (TALEN)-mediated reincorporation of Arg1 exons 7 and 8 in iPSCs derived from arginase-1-deficient mice possessing Arg1Δ alleles lacking these terminal exons. The edited cells could be induced to differentiate into hepatocyte-like cells (iHLCs) in vitro and were subsequently used for transplantation into our previously described (Sin et al., PLoS ONE 2013) tamoxifen-inducible Arg1-Cre arginase-1-deficient mouse model. While successful gene-targeted repair was achieved in iPSCs containing Arg1Δ alleles, only minimal restoration of urea cycle function could be observed in the iHLC-transplanted mice compared to control mice, and survival in this lethal model was extended by up to a week in some mice. The partially rescued phenotype may be due to inadequate regenerative capacity of arginase-1-expressing cells in the correct metabolic zones. Technical hurdles exist and will need to be overcome for gene-edited iPSC to iHLC rescue of arginase-1 deficiency, a rare urea cycle disorder.

Genome editing technologies to treat rare liver diseases

“…The same research group performed a TALEN-mediated reincorporation of deleted exons in iPSCs from their murine model: successfully edited cells were differentiated in hepatocyte-like cells, and transplanted in the liver of the arginase-1 deficient mouse. Nevertheless, the arginase-1 deficiency phenotype was not adequately rescued, since there were non-optimal engraftment and insufficient hepatic repopulation (26). In summary, these studies constitute a proof-of-principle for gene correction in arginase-1 deficiency, and underline the need for further optimization of hepatocyte-like cells maturation and liver repopulation protocols.…”

Modelling urea cycle disorders using iPSCs

“…The treated mice had increased arginase-1 expression but ureagenesis was not comparable to that of wild-type controls. The inability to fully rescue the phenotype may be caused by the inability for transplanted cells to repopulate the periportal hepatocytes where the urea cycle is expressed, suboptimal hepatocyte differentiation, low engraftment or immunological rejection of transplanted cells 74 .…”

Overcoming Radiation Resistance in Gliomas by Targeting Metabolism and DNA Repair Pathways

“…Transportation of monosaccharides across cell membrane NHEJ and HR [41,125] Hexokinase (HK) Phosphorylation of six-carbon glucose to glucose-6-phosphate NHEJ and HR [125] Succinate dehydrogenase (SDH) Oxidation of succinate to fumarate HR [126] Fumarate Hydratase (FH) Conversion of fumarate to malate NHEJ and HR [62,63] Glutamine synthetase (GS) Production of glutamine HR [78,81] Argininosuccinate synthetase (ASS) Synthesis of argininosuccinate from citrulline and aspartate NHEJ [127] Arginase (ARG) Hydrolysis of arginine to ornithine and urea NHEJ [128] Thymidylate synthase (TS) Production of Thymidylate NHEJ [129] Fatty acid synthase (FASN) Synthesis of fatty acid NHEJ [130] Carnitine palmitoyltransferase 1A (CPT1)…”