Generation of genetic modified pigs devoid of GGTA1 and expressing the human leukocyte antigen-G5 / 生物工程学报

Pigs are considered as ideal donors for xenotransplantation because they have many physiological and anatomical characteristics similar to human beings. However, antibody-mediated immunity, which includes both natural and induced antibody responses, is a major challenge for the success of pig-to-primate xenotransplantation. Various genetic modification methods help to tailor pigs to be appropriate donors for xenotransplantation. In this study, we applied transcription activator-like effector nuclease (TALEN) to knock out the porcine α-1, 3-galactosyltransferase gene GGTA1, which encodes Gal epitopes that induce hyperacute immune rejection in pig-to-human xenotransplantation. Meanwhile, human leukocyte antigen-G5 gene HLA-G5, which acts as an immunosuppressive factor, was co-transfected with TALEN into porcine fetal fibroblasts. The cell colonies of GGTA1 biallelic knockout with positive transgene for HLA-G5 were chosen as nuclear donors to generate genetic modified piglets through a single round of somatic cell nuclear transfer. As a result, we successfully obtained 20 modified piglets that were positive for GGTA1 knockout (GTKO) and half of them expressed the HLA-G5 protein. Gal epitopes on the cell membrane of GTKO/HLA-G5 piglets were completely absent. Western blotting and immunofluorescence showed that HLA-G5 was expressed in the modified piglets. Functionally, the fibroblasts from the GTKO/HLA-G5 piglets showed enhanced resistance to complement-mediated lysis ability compared with those from GTKO-only or wild-type pigs. These results indicate that the GTKO/HLA-G5 pigs could be a valuable donor model to facilitate laboratory studies and clinics for xenotransplantation.

Knockdown the expression of ku70 and lig4 in HEK293T cells by CRISPR/Cas13 system / 生物工程学报

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) system is a hotspot of gene editing and gene expression research, in which CRISPR/Cas13 system provides a new direction for RNA interference and editing. In this study, we designed and synthesized the corresponding gRNAs of CRISPR/Cas13a and CRISPR/Cas13b systems in non-homologous end joining (NHEJ) pathway, such as Ku70 and Lig4, and then detected the expression of ku70 and lig4 in HEK293T cells. The CRISPR/Cas13a system could efficiently knockdown the mRNA expression of ku70 and lig4 more than 50%, and CRISPR/Cas13b system also suppressed ku70 and lig4 about 92% and 76%, respectively. Also, CRISPR/Cas13a, b systems could down-regulate Ku70 and Lig4 proteins level to 68% and 53%, respectively. The study demonstrates that the CRISPR/Cas13 system could effectively knockdown the expression of RNA and protein in HEK293T cells, providing a new strategy for gene function and regulation research.

Construction of a prokaryotic expression vector of human tau multi-epitope peptide and immunogenicity of the expressed product / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a prokaryotic expression vector of human tau multiepitope peptide for examining the immunogenicity of a TauP1/P2 DNA vaccine in mice using the expressed product.</p><p><b>METHODS</b>The coding sequence of Tau multiepitope peptide gene was amplified from the plasmid pVAX1-Tau by PCR and inserted into the prokaryotic expression vector pGEX-4T-2 to construct the recombinant plasmid pGEX-4T-2-TauP1/P2. The positive recombinants were transformed into E.coli BL21 cells, and the expression of fusion protein GST-TauP1/P2 was induced by IPTG and identified by SDS-PAGE. Mice was immunized with TauP1/P2 DNA vaccine and the production of the specific antibodies was detected by Dot-blot analysis using the purified fusion protein.</p><p><b>RESULTS</b>A gene fragment 300 bp in length was amplified. Enzyme digestion and DNA sequencing verified correct construction of the prokaryotic expression plasmid pGEX-4T-2-TauP1/P2. The expression of target fusion protein GST-TauP1/P2 was detected by SDS-PAGE. Specific antibodies against TauP1/P2 were detected in the serum of mice immunized with the DNA vaccine using GST-TauP1/P2 fusion protein.</p><p><b>CONCLUSION</b>The constructed prokaryotic expression plasmid of human Tau multiepitope peptide is capable of expressing the target fusion protein, which specifically recognizes the specific antibodies against TauP1/P2 in mice immunized with TauP1/P2 DNA vaccine.</p>

Umbilical cord blood mesenchymal stem cell transplantation for treatment of a child with spinal muscular atrophy / 中国组织工程研究

BACKGROUND: Many animal and clinical studies have reported that the safe and effective usage of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) transplantation for treatment of neurological genetic diseases.OBJECTIVE: To investigate the feasibility and effect of UCB-MSCs transplantation in the treatment of spinal muscular atrophy (SMA).METHODS: A child admitted at January 2010 had been confirmed as having SMA, and drug and rehabilitation therapies were invalid. Then, the child received UCB-MSCs transplantation via the first intravenous infusion and three times of subarachnoid injection, once a week, (4-6)×107 cells once and four times as a course. Neurological physical examination, biochemical test, muscle enzymes detection, FIM scoring and electromyography (EMG) examination were conducted. RESULTS AND CONCLUSION: Compared with prior to transplantation, the level of muscle enzymes decreased, FIM scores were increased from 68 to 93 points, EMG results showed that the motor units with re-contraction in each 10.0 ms were increased that the motor function was improved, the lower extremity muscle strength elevated, and the self-care ability was improved in the SMA child at 6 months after transplantation. During the 10-month follow-up, the child had no adverse effects. It is indicated that UCB-MSCs transplantation is effective to treat SMA, and the neurological function has a remarkable restoration.

Literature review on treatment of type 2 diabetic foot cases with umbilical cord blood mesenchymal stem cell transplantation / 中国综合临床

Objective To observe the clinical effect and safety of umbilical cord blood mesenchymal stem cell(UCB-MSC) transplantation in the treatment of diabetic foot. Methods UCB-MSC suspension (cell concentration (3 -7) × 107/L,0.3 -0.5 ml per point) was injected into multiple spots on affected lower limb with a 3 cm × 3 cm istance among each point. Demixing injection could be performed in regions with multilayer muscles. Clinical symptoms and related index were routinely observed from the first day to three months after operation. Results After three months of UCB-MSC transplantation, pain of patients was relieved, skin temperature increased, intermittent claudication ameliorated, ulcer healed, ankle-brachial index and transcutaneous partial pressure of oxygen increased. The lower extremity lesions showed an abundant collateral vessel formation after the treatment in 2 patients by angiography. Both patients had no severe complications and adverse reactions, none underwent amputation. Conclusions Umbilical cord blood mesenchymal stem cell transplantation is a safe and effective treatment of diabetic lower limb ischemic disease, which can exempt the patient from amputation and improve their quality of life.

Rescued influenza A virus with codon deoptimized NS1 gene is attenuated both in vitro and in vivo / 生物工程学报

Abstract: To develop novel live attenuated influenza vaccine, we explored the feasibility to attenuate influenza virus by codon deoptimization of NS1. According to the codon usage bias in influenza A virus, we designed and synthesized a condon-deoptimized NS gene by substituting codons of 110 amino acids in the NS1 gene of A/Puerto Rico/8/34(H1N1) with unpreferred synonymous codons. The influenza A virus with the codon deoptimized NS1 gene (deoNS virus) was rescued by reverse genetics. Plaque forming assay and virus growth curve showed that the growth of deoNS virus was reduced about 1000 times in MDCK cells compared to that of the wild-type virus. Intranasal inoculation with deoNS virus did not cause death or evident disease in infected BALB/c mice. Furthermore, the virus titer in the lungs of mice infected with deoNS virus was significantly lower (i.e. 100-1000 times) than that of wild-type virus. Our results indicated that influenza virus could be effectively attenuated by synonymous codon deoptimization of NS1 gene. This strategy will be useful to develop new attenuated candidates for the production of live attenuated influenza vaccines.

Construction of a Novel Eukaryotic Expression Plasmid pcDNA6/myc-his-EGFP Band Its Applications in Expression of Recombinant Genes / 中国生物工程杂志

Enhanced green fluorescent protein( EGFP), myc epitope and polyhistidine metal-binding tag are often used as a marker for recombinant fusion protein in many gene expression vectors, each marker has its own function, EGFP emits green fluorescence for direct detection, myc epitope facilitates recombinant fusion protein detection using its antibodies, polyhistidine tag allows purification of recombinant fusion protein using resin.Hitherto, no a plasmid vector can integrate all of these functions. In this study we constructed a novel eukaryotic expressive plasmid, designated as pcDNA6/myc-his-EGFP B, which integrated the functions of EGFP, myc epitope and polyhistidine tag. Importantly, a linker octo - peptide in N terminal of EGFP was designed using LINKER program. A DNA fragment encoding a putative protein containing a signal peptide of human interleukin 2(IL-2) in N terminal was cloned into pcDNA6/myc-his-EGFP B in frame with the C-terminal peptide to construct pMHES. 2.2.15 Cells were transfected with pcDNA6/myc-his-EGFP B and pMHES, and Balb/c mice were intravenously injected with pcDNA6/myc-his-EGFP B by tails, results revealed that both of the plasmids worked in 2.2.15 Cells and livers of Balb/c mice. Assuming gene of the IL-2 was inserted into pcDNA6/myc-his -EGFP B in frame with EGFP, myc and 6 × His, three-dimensional structure for this putative expression product was simulated using Modeller8V2, results revealed that IL-2, EGFP, myc and 6 × his did not interfere each other and octo- peptide linker owned certain flexibility. The results suggest that pcDNA6/myc-his-EGFP B may be useful as a genetic tool for mammalian cells and a vector for gene therapy.