CRISPR-targeted genome editing of human induced pluripotent stem cell-derived hepatocytes for the treatment of Wilson's disease.

BACKGROUND & AIMS: Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism caused by loss-of-function mutations in ATP7B, which encodes a copper-transporting protein. It is characterized by excessive copper deposition in tissues, predominantly in the liver and brain. We sought to investigate whether gene-corrected patient-specific induced pluripotent stem cell (iPSC)-derived hepatocytes (iHeps) could serve as an autologous cell source for cellular transplantation therapy in WD. METHODS: We first compared the in vitro phenotype and cellular function of ATP7B before and after gene correction using CRISPR/Cas9 and single-stranded oligodeoxynucleotides (ssODNs) in iHeps (derived from patients with WD) which were homozygous for the ATP7B R778L mutation (ATP7BR778L/R778L). Next, we evaluated the in vivo therapeutic potential of cellular transplantation of WD gene-corrected iHeps in an immunodeficient WD mouse model (Atp7b -/- / Rag2 -/- / Il2rg -/- ; ARG). RESULTS: We successfully created iPSCs with heterozygous gene correction carrying 1 allele of the wild-type ATP7B gene (ATP7BWT/-) using CRISPR/Cas9 and ssODNs. Compared with ATP7BR778L/R778L iHeps, gene-corrected ATP7BWT/- iHeps restored i n vitro ATP7B subcellular localization, its subcellular trafficking in response to copper overload and its copper exportation function. Moreover, in vivo cellular transplantation of ATP7BWT/- iHeps into ARG mice via intra-splenic injection significantly attenuated the hepatic manifestations of WD. Liver function improved and liver fibrosis decreased due to reductions in hepatic copper accumulation and consequently copper-induced hepatocyte toxicity. CONCLUSIONS: Our findings demonstrate that gene-corrected patient-specific iPSC-derived iHeps can rescue the in vitro and in vivo disease phenotypes of WD. These proof-of-principle data suggest that iHeps derived from gene-corrected WD iPSCs have potential use as an autologous ex vivo cell source for in vivo therapy of WD as well as other inherited liver disorders. LAY SUMMARY: Gene correction restored ATP7B function in hepatocytes derived from induced pluripotent stem cells that originated from a patient with Wilson's disease. These gene-corrected hepatocytes are potential cell sources for autologous cell therapy in patients with Wilson's disease.

Development of new versions of anti-human CD34 monoclonal antibodies with potentially reduced immunogenicity.

Despite the widespread clinical use of CD34 antibodies for the purification of human hematopoietic stem/progenitor cells, all the current anti-human CD34 monoclonal antibodies (mAbs) are murine, which have the potential to elicit human antimouse antibody (HAMA) immune response. In the present study, we developed three new mouse anti-human CD34 mAbs which, respectively, belonged to class I, class II and class III CD34 epitope antibodies. In an attempt to reduce the immunogenicity of these three murine mAbs, their chimeric antibodies, which consisted of mouse antibody variable regions fused genetically to human antibody constant regions, were constructed and characterized. The anti-CD34 chimeric antibodies were shown to possess affinity and specificity similar to that of their respective parental murine antibodies. Due to the potentially better safety profiles, these chimeric antibodies might become alternatives to mouse anti-CD34 antibodies routinely used for clinical application.

Humanization of an anti-CD34 monoclonal antibody by complementarity-determining region grafting based on computer-assisted molecular modelling.

4C8 is a new mouse anti-human CD34 monoclonal antibody (mAb), which recognizes class II CD34 epitopes and can be used for clinical hematopoietic stem/progenitor cell selection. In an attempt to improve its safety profiles, we have developed a humanized antibody of 4C8 by complementarity-determining region (CDR) grafting method in this study. Using a molecular model of 4C8 built by computer-assisted homology modelling, framework region (FR) residues of potential importance to the antigen binding were identified. A humanized version of 4C8, denoted as h4C8, was generated by transferring these key murine FR residues onto a human antibody framework that was selected based on homology to the mouse antibody framework, together with the mouse CDR residues. The resultant humanized antibody was shown to possess antigen-binding affinity and specificity similar to that of the original murine antibody, suggesting that it might be an alternative to mouse anti-CD34 antibodies routinely used clinically.

Generation of Human Liver Chimeric Mice with Hepatocytes from Familial Hypercholesterolemia Induced Pluripotent Stem Cells.

Familial hypercholesterolemia (FH) causes elevation of low-density lipoprotein cholesterol (LDL-C) in blood and carries an increased risk of early-onset cardiovascular disease. A caveat for exploration of new therapies for FH is the lack of adequate experimental models. We have created a comprehensive FH stem cell model with differentiated hepatocytes (iHeps) from human induced pluripotent stem cells (iPSCs), including genetically engineered iPSCs, for testing therapies for FH. We used FH iHeps to assess the effect of simvastatin and proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies on LDL-C uptake and cholesterol lowering in vitro. In addition, we engrafted FH iHeps into the liver of Ldlr-/-/Rag2-/-/Il2rg-/- mice, and assessed the effect of these same medications on LDL-C clearance and endothelium-dependent vasodilation in vivo. Our iHep models recapitulate clinical observations of higher potency of PCSK9 antibodies compared with statins for reversing the consequences of FH, demonstrating the utility for preclinical testing of new therapies for FH patients.

Systematic Comparative Evaluation of Methods for Investigating the TCRß Repertoire.

High-throughput sequencing has recently been applied to profile the high diversity of antibodyome/B cell receptors (BCRs) and T cell receptors (TCRs) among immune cells. To date, Multiplex PCR (MPCR) and 5'RACE are predominately used to enrich rearranged BCRs and TCRs. Both approaches have advantages and disadvantages; however, a systematic evaluation and direct comparison of them would benefit researchers in the selection of the most suitable method. In this study, we used both pooled control plasmids and spiked-in cells to benchmark the MPCR bias. RNA from three healthy donors was subsequently processed with the two methods to perform a comparative evaluation of the TCR ß chain sequences. Both approaches demonstrated high reproducibility (R2 = 0.9958 and 0.9878, respectively). No differences in gene usage were identified for most V/J genes (>60%), and an average of 52.03% of the CDR3 amino acid sequences overlapped. MPCR exhibited a certain degree of bias, in which the usage of several genes deviated from 5'RACE, and some V-J pairings were lost. In contrast, there was a smaller rate of effective data from 5'RACE (11.25% less compared with MPCR). Nevertheless, the methodological variability was smaller compared with the biological variability. Through direct comparison, these findings provide novel insights into the two experimental methods, which will prove to be valuable in immune repertoire research and its interpretation.

Minimal Residual Disease Detection and Evolved IGH Clones Analysis in Acute B Lymphoblastic Leukemia Using IGH Deep Sequencing.

Acute B lymphoblastic leukemia (B-ALL) is one of the most common types of childhood cancer worldwide and chemotherapy is the main treatment approach. Despite good response rates to chemotherapy regiments, many patients eventually relapse and minimal residual disease (MRD) is the leading risk factor for relapse. The evolution of leukemic clones during disease development and treatment may have clinical significance. In this study, we performed immunoglobulin heavy chain (IGH) repertoire high throughput sequencing (HTS) on the diagnostic and post-treatment samples of 51 pediatric B-ALL patients. We identified leukemic IGH clones in 92.2% of the diagnostic samples and nearly half of the patients were polyclonal. About one-third of the leukemic clones have correct open reading frame in the complementarity determining region 3 (CDR3) of IGH, which demonstrates that the leukemic B cells were in the early developmental stage. We also demonstrated the higher sensitivity of HTS in MRD detection and investigated the clinical value of using peripheral blood in MRD detection and monitoring the clonal IGH evolution. In addition, we found leukemic clones were extensively undergoing continuous clonal IGH evolution by variable gene replacement. Dynamic frequency change and newly emerged evolved IGH clones were identified upon the pressure of chemotherapy. In summary, we confirmed the high sensitivity and universal applicability of HTS in MRD detection. We also reported the ubiquitous evolved IGH clones in B-ALL samples and their response to chemotherapy during treatment.

IMonitor: A Robust Pipeline for TCR and BCR Repertoire Analysis.

The advance of next generation sequencing (NGS) techniques provides an unprecedented opportunity to probe the enormous diversity of the immune repertoire by deep sequencing T-cell receptors (TCRs) and B-cell receptors (BCRs). However, an efficient and accurate analytical tool is still on demand to process the huge amount of data. We have developed a high-resolution analytical pipeline, Immune Monitor ("IMonitor") to tackle this task. This method utilizes realignment to identify V(D)J genes and alleles after common local alignment. We compare IMonitor with other published tools by simulated and public rearranged sequences, and it demonstrates its superior performance in most aspects. Together with this, a methodology is developed to correct the PCR and sequencing errors and to minimize the PCR bias among various rearranged sequences with different V and J gene families. IMonitor provides general adaptation for sequences from all receptor chains of different species and outputs useful statistics and visualizations. In the final part of this article, we demonstrate its application on minimal residual disease detection in patients with B-cell acute lymphoblastic leukemia. In summary, this package would be of widespread usage for immune repertoire analysis.

Exome-wide association analysis reveals novel coding sequence variants associated with lipid traits in Chinese.

Blood lipids are important risk factors for coronary artery disease (CAD). Here we perform an exome-wide association study by genotyping 12,685 Chinese, using a custom Illumina HumanExome BeadChip, to identify additional loci influencing lipid levels. Single-variant association analysis on 65,671 single nucleotide polymorphisms reveals 19 loci associated with lipids at exome-wide significance (P<2.69 × 10(-7)), including three Asian-specific coding variants in known genes (CETP p.Asp459Gly, PCSK9 p.Arg93Cys and LDLR p.Arg257Trp). Furthermore, missense variants at two novel loci-PNPLA3 p.Ile148Met and PKD1L3 p.Thr429Ser-also influence levels of triglycerides and low-density lipoprotein cholesterol, respectively. Another novel gene, TEAD2, is found to be associated with high-density lipoprotein cholesterol through gene-based association analysis. Most of these newly identified coding variants show suggestive association (P<0.05) with CAD. These findings demonstrate that exome-wide genotyping on samples of non-European ancestry can identify additional population-specific possible causal variants, shedding light on novel lipid biology and CAD.

A potyvirus P1 protein interacts with the Rieske Fe/S protein of its host.

ABSTRACT Yeast two-hybrid (Y2H) screens were used to test for interactions between the P1 protein of Soybean mosaic virus Pinellia isolate (SMV-P) and a cDNA expression library of its host, the aroid Pinellia ternata. Of the 13 independent interacting clones identified, ten were identical and had an open reading frame predicted to encode a 23.7-kDa protein closely related to the cytochrome b6/f complex Rieske Fe/S genes of plants. The interaction between SMV-P-P1 and the mature Rieske Fe/S protein (without transit peptide) of the host was confirmed by in vitro co-immunoprecipitation of the two proteins. Y2H assays using different parts of the two proteins showed that only the N-terminal part (amino acids 1-82) of SMV-P P1 was responsible for the interaction with the Rieske Fe/S protein and that amino acids 1-33 interacted only with the transit peptide, while amino acids 34-82 could interact with the entire Rieske Fe/S protein. SMV-P P1 also interacted moderately with the Rieske Fe/S protein of its other hosts, soybean and Zantedeschia aethiopica, but weakly with that of the non-host Arabidopsis thaliana. The P1-Rieske Fe/S protein interactions are likely to be involved in symptom development, and the very variable N-terminus of P1 may play an important role in host adaptation.