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Objective: To establish a high efficient human coagulation factor VIII (FVIII) eukaryotic stable expression system using lentiviral vector, and determine its biosafety., Methods: Lentiviral transfer plasmid carrying human B-domain-deleted FVIII(BDDhFVIII)-IRES-GFP(BDDhFVIII/pXZ9)or IRES-GFP(pXZ9) was constructed. Lentivirus particles were produced by transiently co-transfected 3-plasmids into 293FT cells and further concentrated via ultracentrifugation. CHO cells were infected, 72h later, the FVIII antigen (FVIII:Ag) concentration in the medium was examined by ELISA, the activity was detected via one stage coagulation,and the transcription of FVIII in the infected CHO cells was determined by RT-PCR.Virus infection ability in the medium and the gag gene in CHO cells were determined to evaluate the model's biosafety., Results: Lentiviral transfer plasmid BDDhFVIII-IRES-GFP(BDDhFVIII/pXZ9)carrying human B-domain-deleted FVIII or IRES-GFP (pXZ9) was successfully constructed, and high titer lentiviruses has been prepared. The lentivirus could infect CHO cells efficiently, after an additional 72 h, the FVIII:Ag concentration had up to (1724.9±283.7) mU/ml, the FVIII:C level increased to (10.58±1.55)%, and transcripts of BDDhFVIII mRNA could be measured by RT-PCR. Neither the gag gene nor the virus in the supernatant was detected., Conclusion: Lentivirus-mediated human coagulation factor VIII could be expressed efficiently in CHO cells. The system couldn't produce offspring virus, proving a good biosafety.

Objective: To construct mouse CXC chemokine receptor type 4 (Cxcr4) gene overexpressing lentiviral vector and to evaluate its biological effect on mouse mesenchymal stem cells (MSCs)., Methods: Cxcr4 gene was amplified and subcloned into pCR-Blunt vector. Cxcr4 gene and enhanced green fluorescent protein (EGFP) gene expressed bicistronic recombinant lentiviral vector LV-CXCR4-IRES-EGFP and control vector LV-IRES-EGFP were constructed, respectively. Both plasmids were co-transfected into 293FT packaging cell line with packaging plasmid pSPAX2 and enveloping plasmid pMD.2G using Lipofectamine 2000 to produce lentiviral virus, respectively. The recombinant viruses were harvested and the virus titer was determined by limiting dilution. Mouse MSCs were infected with viral supernatant. EGFP expression was visualized using fluorescence microscope and efficiency of infection was determined by flow cytometry (FCM). Cell counting kit-8 (CCK-8) was applied in mixed lymphocyte reaction (MLR) to evaluate the suppressive effect of MSCs on mice splenocyte proliferation in vitro. Wound healing ability of MSCs was measured by scratch experiment and migration capacity by a chemotaxis assay using a transwell assay., Results: The Cxcr4 fragment was amplified by reverse transcription polymerase chain reaction (RT-PCR) and verified by DNA sequencing. The restriction enzyme digestion experiment demonstrated that the recombinant lentiviral vector LV-CXCR4-IRES-EGFP and the control vector LV-IRES-EGFP were successfully constructed. Expression of CXCR4 was detected by fluorescence microscopy, which indicated that the lentiviral particles expressing CXCR4 were packaged. Furthermore, expression of EGFP were detected by fluorescence microscopy in MSCs after infection and the expression of CXCR4 protein on MSCs surface in CXCR4-MSC group was significantly increased comparing to those in the control group(P < 0.05).CXCR4-MSCs group and the control group were (90.3 ± 3.37)% and (1.53 ± 0.34)%, respectively. Meanwhile, overexpression of CXCR4 had no effect on their capacity of immune regulation when co-cultured with splenocyte(P > 0.05). Moreover, overexpression of CXCR4 can not only accelerated the wound healing after scratch, but also enhanced the migration ability of cells in the transwell induced by high concentration of SDF-1 in a dose-dependent manner compared with the EGFP control group., Conclusion: The CXCR4 expressing lentiviral vector LV-CXCR4-IRES-EGFP was successfully constructed. The lentiviral vector can not only efficiently infect mouse MSCs, but also stably express CXCR4 in MSCs. The MSCs modified with CXCR4 have biological characteristic in vitro.

Recently, gene therapy has been become a promising approach to cure hemophilia A, a most common recessive bleeding disease. The aim of this study was to determine the perspective of lentiviral vector in hemophilia A gene therapy in vitro and in NOD/SCID mice. Lentivirus transfer vector pXZ9/BDDFVIII containing human B-domain-deleted Factor VIII-IRES-eGFP coding sequence and mock control pXZ9 were constructed. Lentivirus was prepared by co-transfecting 3 plasmids into 293FT cells. 293FT, HLF, human bone marrow mesenchymal stem cells and Chang-liver cells were transfected with the prepared virus. Coagulant activity of human FVIII, human FVIII antigen, human FVIII mRNA transcription and genomic integration were assayed by ELISA, one-step method, RT-PCR and PCR after infection. Lentiviral particles were concentrated by ultracentrifugation and NOD/SCID mice were transfected via portal vein injection. Human FVIII antigen in mouse blood plasma was analyzed by ELISA. eGFP expression was observed by fluorescent microscopy and human FVIII transcription in mouse liver was analyzed by RT-PCR at one month after transduction. The results showed that the high titer of recombinant virus was prepared and used to efficiently transduce the target cells in vitro. At 72 h after transfection, high levels of FVIII activity and FVIII antigen were detected. Human FVIII gene transcription could be detected in the liver of NOD/SCID mice received lentiviral particles carrying FVIII gene. Mouse hepatocytes were transfected with recombinant lentivirus efficiently in vivo. Human FVIII level in mouse blood plasma reached to (49 ± 6) mU, (54 ± 8) mU and (23 ± 4) mU at 72 h, one week and one month after transfection respectively. It is concluded that the lentiviral particles carrying BDDhFVIII gene can high efficiently transfect the target cells both in vitro and in vivo, and the transfected target cells can secrete hFVIII efficiently. The sustained expression of human FVIII in NOD/SCID mice is observed after lentivirus transfection via portal vein injection.

This study was aimed to clone the gene coding mouse fibroblast growth factor receptor-1 (fgfr1), to construct the recombinant lentiviral vector of truncated form fgfr-1 (Δfgfr1) carrying enhanced green fluorescence protein (EGFP) and to investigate its expression in eukaryotic cells (293FT cells). The full length fgfr1 gene was cloned by RT-PCR using brain tissue of BALB/c fetal mouse as template and inserted into PCR-Blunt vector, a truncated fgfr1 fragment was produced by site-directed mutagenesis for deleting intracellular phosphorylated domain, then was subcloned into a lentiviral vector and cotransfected into 293FT packaging cells together with envelope plasmid and packaging plasmid by lipofectamine 2000. Viruses were gathered and concentrated using ultracentrifuge, and then transfected into 293FT cells. Expression of EGFP was detected by fluorescent microscopy and flow cytometry (FCM), and the truncated FGFR1 protein was detected by Western blot. The results demonstrated that mouse fgfr1 gene was cloned and the lentiviral expression vector LV-IRES-EGFP-Δfgfr1 and control vector LV-IRES-EGFP were successfully constructed. The lentiviral particles were correctly packaged, and the virus titers were above 10(8) TU/ml in the supernatant after concentration. Expression of EGFP was detected by fluorescent microscopy in 293FT cells post transfection, and the transfection efficacy was > 95% determined by FCM. Expression of FGFR1 protein detected by Western blot was significantly higher than that in control group. It is concluded that the truncated gene fgfr1 along with the gene coding EGFP is successfully inserted into a lentiviral vector to construct a recombinant lentiviral vector, which can be expressed in eukaryotic cells.

In order to construct a lentiviral vector carrying human VE-cadherin gene, and to express VE-cadherin in Sup-B15 cells, the VE-cadherin gene was amplified by RT-PCR from the human placenta, and then cloned into pCR-Blunt vector. The VE-cadherin DNA fragment was subcloned into pLB vector to generate a lentiviral vector pLB-VEC. Recombinant lentivirus was generated by co-transfection of three-plasmids into 293FT packing cells using lipofectamine 2000. The Sup-B15 cells were transfected by the lentivirus. The post-transfected Sup-B15 cells were observed by microscopy and flow cytometry. Western blot was used to determine the expression of VE-cadherin. The results showed that the VE-cadherin DNA fragment was amplified from human placenta and was cloned into pCR-Blunt vector, the recombinant lentiviral vector pLB-VEC was successfully constructed. High titer lentivirus was prepared by 3-plasmid packing system, and transfected into Sup-B15 cells in vitro effectively. The obviously morphological changes occurred in transfected cells, the expression of VE-cadherin protein could be detected in Sup-B15 cells via flow cytometry and Western blot. It is concluded that the lentiviral vector pLB-VEC carrying human VE-cadherin gene is successfully constructed; VE-cadherin gene is expressed in Sup-B15 cells via lentiviral vector transfection, which provides an optional tool for further study on the mechanism of VE-cadherin controlling leukemia development.

This study was aimed to construct a lentiviral vector carrying mouse RORγt and glp gene, and to detect the expression of RORγt in the 293FT cells. The RORγt fragment was amplified by RT-PCR from mouse thymus and cloned into PCR 2.1 vector. The RORγt DNA fragment was prepared by digestion and inserted into MigR1 plasmid, then the RORγt-IRES-GFP was directionally linked with lentiviral transfer plasmid pTK208 to generate a lentiviral vector pXZ9-RORγt. The recombinant lentivirus were produced by co-transfected three plasmids into 293FT packing cells using lipofectamine 2000. After transfection, the lentiviral supernatant was collected and concentrated via ultracentrifugation. The 293FT cells were infected by the concentrated lentivirus, GFP expression was examined under a fluorescent microscope and the expression of RORγt protein was detected by Western blot. The results showed that the RORγt fragment was amplified from cDNA of mouse thymus and recombinant lentiviral vector pXZ9-RORγt was constructed successfully. High titer lentivirus were prepared after one round ultracentrifugation. RORγt expression could be detected in 293FT cells after virus infection. It is concluded that the lentiviral vector pXZ9- RORγt containing mouse RORγt-IRES-GFP is successfully constructed; RORγt can express in 293FT cells via lentiviral vector transduction, which provides an optional tool for further research on the mechanism of RORγt controlling Th17 cell differentiation.

Objective: To construct red fluorescent protein (DsRed) and mouse vascular endothelial growth factor (mVEGF) lentiviral expression vector in order to obtain the DsRed and VEGF expression in 293T cells., Methods: The mVEGF was amplified from the lungs of fetal mouse by RT-PCR. The IRES-DsRed was obtained from plasmid pLV-tTRKRAB-red which contains IRES-DsRed sequence by PCR. Then they were cloned into lentiviral expression vector pTK-208. Human embryonic kidney 293T cells were co-transfected with the three plasmids by lipofectamine, and the expression of DsRed was examined under fluorescent microscope 24 h and 48 h after transfection. 48 h and 72 h later the viral supernatant was used to infect 293T cells, the expression of DsRed was examined under fluorescent microscope and Western blot assays was used to examine the expression of mVEGF in cells and the culture medium., Results: The recombinant lentiviral vector pTK208-mVEGF-IRES-DsRed was constructed, the virus titres were above 10(6) PFU/mL in the supernatant. After infection, DsRed and mVEGF proteins were successfully expressed in 293T cells., Conclusion: The lentiviral vector pTK208-mVEGF-IRES-DsRed contains DsRed and mVEGF were successfully constructed and expressed in 293T cells, it could provide a basis for further researches on the pathophysiological mechanism of VEGF and lay the foundation of gene therapy.

This study was purposed to construct a lentiviral vector encoding red fluorescent protein (DsRed) and transfect DsRed into EL4 cells for establishing mouse leukemia/lymphoma model expressing DsRed. The bicistronic SIN lentiviral transfer plasmid containing the genes encoding neo and internal ribosomal entry site-red fluorescent protein (IRES-DsRed) was constructed. Human embryonic kidney 293FT cells were co-transfected with the three plasmids by liposome method. The viral particles were collected and used to transfect EL4 cells, then the cells were selected by G418. The results showed that the plasmid pXZ208-neo-IRES-DsRed was constructed successfully, and the viral titer reached to 10(6) U/ml. EL4 cells were transfected by the viral solution efficiently. The transfected EL4 cells expressing DsRed survived in the final concentration 600 microg/ml of G418. The expression of DsRed in the transfected EL4 cells was demonstrated by fluorescence microscopy and flow cytometry. In conclusion, the EL4/DsRed cell line was established successfully.

Objective: To prepare the genetic engineering regulatory T cells (Treg) via the self-inactivating (SIN) lentiviral vectors carrying Foxp3 gene, and assay the phenotype and abilities of its proliferation and immunosuppression., Methods: The bicistronic SIN lentiviral transfer plasmid containing Foxp3 gene and internal ribosomal entry site-green fluorescent protein gene (IRES-GFP) was constructed. Human embryonic kidney 293T cells were co-transfected using liposome by lentiviral packing system, which included the packaging plasmid Delta NRF, the transfer plasmid and the envelope plasmid VSVG. The efficiency of gene transduction and the expressions of Foxp3, CD25, GITR, CTLA-4 of CD4(+)CD25(-) T cells, which were isolated by magnetic beads from the spleen, and then co-cultured with 293T cells, were detected by flow cytometry (FCM). The proliferative and suppressive capacities of transduced T cells were estimated by Cell Count Kit-8 (CCK-8) and the cytokine production was performed by ELISA., Results: The lentiviral transfer plasmid pXZ208-Foxp3-IRES-GFP was successfully constructed, the virus titers were above 10(6) IU/ml in the supernatant. pXZ208-IRES-GFP was used as control group. After cocultured, the CD4(+)CD25(-) T cells expressed significantly higher Foxp3, CD25, GITR and CTLA-4 in experimental group than in control group. Upon stimulation with anti-CD3 epsilon and APCs, the proliferative capacity of Foxp3-transduced T cells and the production of IL-2, IL-4, IL-10, IFN-gamma were significantly lower than those in control group (P < 0.01); Foxp3-transduced T cells also significantly inhibited the proliferation of CD4(+)CD25(-) T cells., Conclusions: The genetic engineering Treg mediated by SIN lentiviral vectors are successfully constructed and their phenotype and function are similar to natural CD4(+)CD25(+) Treg.

Objective: To construct the self-inactivating lentiviral vector containing murine Foxp3 gene and detect its expression in the CD4+ CD25- T cells., Methods: The bicistronic lentiviral transfer plasmid containing Foxp3 gene and internal ribosomal entry site-green fluorescent protein gene (IRES-GFP) was constructed. Human embryonic kidney 293T cells were co-transfected by lentiviral packing system, which including the packaging plasmid deltaNRF, the transfer plasmid and the envelope plasmid VSVG using liposome. Then manifested the efficiency of gene transduction with Flow Cytometry (FCM) and the expressions of Foxp3 mRNA and protein were assayed by RT-PCR and Western blotting., Results: The lentiviral transfer plasmid pXZ208-Foxp3-IRES-GFP was constructed, the virus titres were above 10(6) IU/mL in the supernatant. After coculture with thus cells, the CD4+ CD25- T cells in experimental group expressed significantly higher amounts of Foxp3 mRNA and protein than control group, and the efficiency of gene transduction was about 55.95%., Conclusions: The self-inactivating lentiviral vector containing murine Foxp3 gene are successfully constructed. This gene delivery system can transduce Foxp3 gene into CD4+ CD25- T cells with highly efficient expression.

Objective: To construct a three plasmids lentiviral vector containing canine coagulation factor IX (cFIX) gene with ubiquinone promoter (PUB) and observe the expression of cFIX gene., Methods: Lentivirus was generated by transient three-plasmid transfection, namely, the VSV-G envelope expression cassette, the delta NRF packaging plasmid and the PTK 164 plasmid. Viral particles were used to infect the target cell, third passage mesenchymal stem cells (MSCs) and 293T cell respectively at MOI 3: 1. The cFIX activity was detected in cultured cells with one-stage clotting assay., Results: The MSCs were obtained in vitro. The lentivirus infected MSCs and 293T cells all expressed the active factor IX with the activity of (26.30 +/- 2.10)% and (19.70 +/- 1.53)%, respectively, which are significantly higher than that of control (1.00 +/- 0.05)%., Conclusions: The lentiviral vector of three plasmids with ubiquinone promoter (PUB) was constructed and can transfect the MSCs and 293T cells.

This study was aimed to construct a lentiviral vector carrying human coagulant factor VIII (FVIII) and to investigate its expression in 293T cells. B-domain-deleted factor VIII gene fragment (BDDhFVIIIcDNA) was obtained by enzyme digestion and cloned into lentiviral vector pXZ208 to establish the expression vector pXZ208-BDDhFVIII. Recombinant viral particles were prepared by cotransfection with packaging plasmid delta NRF and envelope plasmid VSV-G using calcium phosphate precipitation method. 293T cells were transfected by viral supernatant. Coagulant activity of FVIII, BDDhFVIIImRNA and genome integration were assayed by one-step method, RT-PCR and PCR after transfection. The results showed that 293T cells could be transfected by recombinant virus. The transfection rate of 293T was 59.57%. After transfection, the cells expressed FVIII efficiently. Detection confirmed that the activity of FVIII was 12%, 43% and 87% respectively at 24, 48 and 72 hours after infection. BDDhFVIII transcription was detected by RT-PCR from the infected cells. The gene integration in the targeted cells was also observed. It is concluded that the successfully constructed lentiviral vector is able to generate high level expression of human FVIII in 293T cells, which may provide a potential application of gene therapy to haemophilia A.