Genetic Correction and Hepatic Differentiation of Hemophilia B-specific Human Induced Pluripotent Stem Cells.

Objective To genetically correct a disease-causing point mutation in human induced pluripotent stem cells (iPSCs) derived from a hemophilia B patient. Methods First, the disease-causing mutation was detected by sequencing the encoding area of human coagulation factor IX (F IX) gene. Genomic DNA was extracted from the iPSCs, and the primers were designed to amplify the eight exons of F IX. Next, the point mutation in those iPSCs was genetically corrected using CRISPR/Cas9 technology in the presence of a 129-nucleotide homologous repair template that contained two synonymous mutations. Then, top 8 potential off-target sites were subsequently analyzed using Sanger sequencing. Finally, the corrected clones were differentiated into hepatocyte-like cells, and the secretion of F IX was validated by immunocytochemistry and ELISA assay. Results The cell line bore a missense mutation in the 6th coding exon (c.676 C>T) of F IX gene. Correction of the point mutation was achieved via CRISPR/Cas9 technology in situ with a high efficacy at about 22% (10/45) and no off-target effects detected in the corrected iPSC clones. F IX secretion, which was further visualized by immunocytochemistry and quantified by ELISA in vitro, reached about 6 ng/ml on day 21 of differentiation procedure. Conclusions Mutations in human disease-specific iPSCs could be precisely corrected by CRISPR/Cas9 technology, and corrected cells still maintained hepatic differentiation capability. Our findings might throw a light on iPSC-based personalized therapies in the clinical application, especially for hemophilia B.

Chronic toxicity of a novel recombinant human granulocyte colony-stimulating factor in rats.

OBJECTIVE: To assess the severity and reversibility of the chronic toxicity of a novel recombinant human granulocyte colony-stimulating factor (rhG-CSFa) in rats and the dose-effect relationship. METHODS: A total of 100 Sprague-Dawley rats (equal numbers of male and female) were randomly divided into five groups (20 rats in each group): four groups were treated with rhG-CSFa at 500, 100, 10, 1 µg/kg, respectively, and one group was treated with vehicle only to serve as the control. The rats were received subcutaneous injections of rhG-CSFa or vehicle daily for 13 weeks. During the course of the chronic toxicity study, the physical status, body weight, and food consumption were monitored. Half of the rats in each group (n = 10) were sacrificed after the last rhG-CSFa administration, and the other half were sacrificed at five weeks after the last rhG-CSFa administration. Urinalyses, blood biochemistry, hematological analysis, histopathological examination, and immunological tests were performed for each of the rats. RESULTS: The hematological analyses revealed that the mean white blood cells count, neutrophils count, and neutrophils percentage were increased in male rats at the dose of 10 µg/kg or higher, and these were related with the biological activity of rhG-CSFa. Some small abnormalities were observed in the spleen of a few rats when used highest dose (500 µg/kg, a dosage of 200 folds higher than the normal clinical dosage), but these abnormalities were recovered within 5-week recovery period. No other rhG-CSFa-related abnormalities were observed in this chronic toxicity study. CONCLUSION: No significant toxicity and immunogenicity are observed with rhG-CSFa administration to rats in the chronic toxicity studies.

Pharmacokinetic study of a novel recombinant human granulocyte colony-stimulating factor in rats.

OBJECTIVE: To study the pharmacokinetics of a novel recombinant human granulocyte colony-stimulating factor (rhG-CSFa) in rats and to determine the proteolytic rates of rhG-CSFa in the whole blood and serum of rats in vitro. METHODS: The pharmacokinetics of rhG-CSFa and conventional (wild type, WT) granulocyte colony-stimulating factor (G-CSF) were investigated in Sprague-Dawley rats which received either intravenous or subcutaneous injection of rhG-CSFa or WT G-CSF at three different doses (20, 50, or 100 microg/kg). The blood samples of rats were collected at multiple time points (from 0.08 to 12 h) and the concentrations of rhG-CSFa and WT G-CSF in serum were determined with a sandwich enzyme-linked immunosorbent assay (ELISA). For the study of proteolytic rates in vitro, the concentrations of rhG-CSFa or WT G-CSF were determined at 3-minute intervals after addition of the respective drug to rat's whole blood or serum. RESULTS: Pharmacokinetic analysis of serum rhG-CSFa or WT G-CSF levels indicated that, at each dose tested, for either route of drug administration, the area under concentration-time curve values and the maximum serum concentration of rhG-CSFa were higher than those of WT G-CSF, and the serum half life of rhG-CSFa was longer than that of WT G-CSF. Subsequent in vitro whole blood and serum stability study showed that the rates of drug degradation in WT G-CSF were 1.8 folds and 1.5 folds higher than those in rhG-CSFa, respectively. CONCLUSION: rhG-CSFa has better serum and whole blood stability in vitro and higher bioavailability in vivo as compared to WT G-CSF.

Protection of chickens against highly lethal H5N1 and H7N1 avian influenza viruses with a recombinant fowlpox virus co-expressing H5 haemagglutinin and N1 neuraminidase genes.

Inactivated whole avian influenza virus (AIV) vaccine provides protection against homologous haemagglutinin (HA) subtype virus, but poor protection against a heterologous HA virus. Moreover, it induces chickens to produce antibodies to cross-reactive antigens, especially nucleoprotein, which is limits AIV serological surveillance. In this study, a recombinant fowlpox virus co-expressing HA (H5 subtype) and NA (NI subtype)genes of AIV was evaluated for its ability to protect chickens against intramuscular challenge with a lethal dose of highly pathogenic (HP) AIV. Susceptible chickens were also vaccinated by wing-web puncture with the parent fowlpox vaccine virus. Following challenge 4 weeks later with HPAIV, all chickens vaccinated with recombinant virus were protected, while the chickens vaccinated with either the unaltered parent fowlpox vaccine virus or unvaccinated controls experienced 100% mortality following challenge. This protection was accompanied by the high levels of specific antibody to the respective components of the recombinant vaccine. The above results showed that rFPV-HA-NA could be a potential vaccine to replace current inactivated vaccines for preventing AI.