Targeting lentiviral vectors to primordial germ cells(PGCs):An efficient strategy for generating transgenic chickens

Recent advances in avian transgenic studies highlight the possibility of utilizing lentiviral vectors as tools to generate transgenic chickens. However, low rates of gonadal chimerism and germ line transmission efficiency still limit the broad usage of this method in creating transgenic chickens. In this study, we implemented a simple strategy using modified lentiviral vectors targeted to chicken primordial germ cells(PGCs) to generate transgenic chickens. The lentiviral vectors were pseudotyped with a modified Sindbis virus envelope protein(termed M168) and conjugated with an antibody specific to PGC membrane proteins. We demonstrated that these optimized M168-pseudotyped lentiviral vectors conjugated with SSEA4 antibodies successfully targeted transduction of PGCs in vitro and in vivo. Compared with the control, 50.0%–66.7% of chicken embryos expressed green fluorescent protein(GFP) in gonads transduced by the M168-pseudotyped lentivirus. This improved the targeted transduction efficiency by 30.0%–46.7%. Efficient chimerism of exogenous genes was also observed. This targeting technology could improve the efficiency of germ line transmission and provide greater opportunities for transgenic poultry studies.

Differentiation Character of Adult Mesenchymal Stem Cells andTransfection of MSCs with Lentiviral Vectors

This study examined the differentiation character and pluripotency of mesenchymal stem cells (MSCs) under different conditions. Adult MSCs were initially isolated from the bone marrow of rats, cultured in vitro and identified by flow cytometry. After MSCs were transferred to osteogenic and adipogenic medium respectively, the morphological characterization of induced cells was observed. The expression of marker genes was detected by RT-PCR analysis. Then MSCs were transfected with lenti- viral vectors pGC-FU-Sox9-EGFP. Enhanced green fluorescence protein (EGFP) expression and trans- fection efficiency were determined by fluorescence microscopy. The results demonstrated that EGFP caused no effect on the multilineage potential of adult MSCs. Sox9 gene expression of high level was maintained stable in the transfected MSCs and induced MSCs to differentiate into chondrocytes. Ag- gracan was positive in chondrogenic lineages and the expression of aggracan and type Ⅱ collagenwas significantly increased during MSCs chondrogenic differentiation. It was concluded that Sox9 gene-modified adult MSCs may be promising candidate cells for further studies on tissue engineering. EGFP facilitates the research on MSCs physiological behavior and application in tissue engineering during differentiation both in vitro and in vivo.

Efficient production of transgenic chickens using self-inactive HIV-based lentiviral vectors

We demonstrated the simple and effective production of transgenic chickens, in which the enhanced green fluorescence protein （EGFP） was expressed by using third-generation self-inactive HIV-based lentiviral vectors. In our experiments, lentiviruses were injected into 204 fertilized eggs, from which 30 （15%） chickens were hatched. The exogenous gene was detected in the genomes of 16 out of 30 （53%） chickens. The green fluorescence signal was observed directly in various body parts, and was particularly significant in the testes. The transgenes were also found in the offspring of these chickens. The results indicate that HIV-based lentiviral vectors can be used to generate transgenic birds economically and effectively [ Current Zoology 55 （5）： 383 - 387,2009].

Pseudotyped lentiviral vectors:Ready for translation into targeted cancer gene therapy?

Gene therapy holds great promise for curing cancer by editing the deleterious genes of tumor cells,but the lack of vector systems for efficient delivery of genetic material into specific tumor sites in vivo has limited its full therapeutic potential in cancer gene therapy.Over the past two decades,increasing studies have shown that lentiviral vectors(LVs)modified with different glycoproteins from a donating virus,a process referred to as pseudotyping,have altered tropism and display cell-type specificity in transduction,leading to selective tumor cell killing.This feature of LVs together with their ability to enable high efficient gene delivery in dividing and non-dividing mammalian cells in vivo make them to be attractive tools in future cancer gene therapy.This review is intended to summarize the status quo of some typical pseudotypings of LVs and their applications in basic anti-cancer studies across many malignancies.The opportunities of translating pseudotyped LVs into clinic use in cancer therapy have also been discussed.

Isolation and cultivation of murine hematopoietic stem cells and expression of hFIX mediated by recombinant lentiviral vectors in vitro

Hematopoietic stem cells(HSCs)are an attractive target for gene therapy,especially for inherited blood diseases.Moreover,recombinant lentiviral vectors are considered to be prospective in HSCs gene therapy for the high efficiency of infection.In this study,murine mononuclear cells(MNCs)were isolated from bone marrow and cultured in suspension,and then Lin−CD117+HSCs were isolated by immunomagnetic beads.During culturing,cells and colonies increased in HSCs supplied with cytokines while no change was observed in the control group without cytokines.FUXW recombinant lentiviral vectors were produced by calcium phosphate-mediated transient cotransfection infected MNCs from ICR and C57 mice.The hFIX expressions were 41.7±4.2 ng/mL and 34.5±6.6 ng/mL in supernatant on 7d.The hFIX expressions of HSCs infected by FUXW recombinant lentiviral vectors were 46.6±5.7 ng/mL(with cytokines)and 33.3±4.8 ng/mL(without cytokines)in supernatant on 7d.Results indicate that recombinant lentiviral vectors can infect murine MNCs and Lin−CD117+HSCs efficiently,and expression of the transgene can be improved when supplied with cytokines.

Recent advances in lentiviral vectors for gene therapy

Lentiviral vectors(LVs), derived from human immunodeficiency virus, are powerful tools for modifying the genes of eukaryotic cells such as hematopoietic stem cells and neural cells. With the extensive and in-depth studies on this gene therapy vehicle over the past two decades, LVs have been widely used in both research and clinical trials. For instance, third-generation and selfinactive LVs have been used to introduce a gene with therapeutic potential into the host genome and achieve targeted delivery into specific tissue. When LVs are employed in leukemia, the transduced T cells recognize and kill the tumor B cells;in β-thalassemia, the transduced CD34^(+) cells express normal β-globin;in adenosine deaminase-deficient severe combined immunodeficiency, the autologous CD34^(+) cells express adenosine deaminase and realize immune reconstitution. Overall, LVs can perform significant roles in the treatment of primary immunodeficiency diseases, hemoglobinopathies, B cell leukemia, and neurodegenerative diseases. In this review, we discuss the recent developments and therapeutic applications of LVs. The safe and efficient LVs show great promise as a tool for human gene therapy.

Understanding the role of transmembrane 9 superfamily member 1 in bladder cancer pathogenesis

In this editorial we comment on the article by Wei et al,published in the recent issue of the World Journal of Clinical Oncology.The authors investigated the role of Transmembrane 9 superfamily member 1(TM9SF1)protein in bladder cancer(BC)carcinogenesis.Lentiviral vectors were used to achieve silencing or overexpression of TM9SF1 gene in three BC cell lines.These cell lines were then subject to cell counting kit 8,wound-healing assay,transwell assay,and flow cytometry.Proliferation,migration,and invasion of BC cells were increased in cell lines subjected to TM9SF1 overexpression.TM9SF1 silencing inhibited proliferation,migration and invasion of BC cells.The authors conclude that TM9SF1 may be an oncogene in bladder cancer pathogenesis.

Phase I clinical trial of intracerebral injection of lentiviral-ABCD1 for the treatment of cerebral adrenoleukodystrophy

This was a single-arm,multicenter,open-label phase I trial.Lentiviral vectors(LV)carrying the ABCD1 gene(LV-ABCD1)was directly injected into the brain of patients with childhood cerebral adrenoleukodystrophy(CCALD),and multi-site injection was performed.The injection dose increased from 200 to 1600 lL(vector titer:1×10^(9) transduction units per mL(TU/mL)),and the average dose per kilogram body weight ranges from 8 to 63.6 lL/kg.The primary endpoint was safety,dose-exploration and immunogenicity and the secondary endpoint was initial evaluation of efficacy and the expression of ABCD1 protein.A total of 7 patients participated in this phase I study and were followed for 1 year.No injectionrelated serious adverse event or death occurred.Common adverse events associated with the injection were irritability(71%,5/7)and fever(37.2-38.5℃,57%,4/7).Adverse events were mild and selflimited,or resolved within 3 d of symptomatic treatment.The maximal tolerable dose is 1600 lL.In 5 cases(83.3%,5/6),no lentivirus associated antibodies were detected.The overall survival at 1-year was 100%.The ABCD1 protein expression was detected in neutrophils,monocytes and lymphocytes.This study suggests that the intracerebral injection of LV-ABCD1 for CCALD is safe and can achieve successful LV transduction in vivo;even the maximal dose did not increase the risk of adverse events.Furthermore,the direct LV-ABCD1 injection displayed low immunogenicity.In addition,the effectiveness of intracerebral LV-ABCD1 injection has been preliminarily demonstrated while further investigation is needed.This study has been registered in the Chinese Clinical Trial Registry(https://www.chictr.org.cn/,registration number:ChiCTR1900026649).

Recombinant HIV to kill latent reservoir cells: a hypothetical therapeutic strategy

Latency is the pivotal factor that governs the long-term pathogenecity and persistence of HIV-1 infection.It is also the primary impediment to cure and successful treatment,resulting in patient death.Latency of HIV-1 infection promotes failure of the conventional antiretroviral therapy(ART).Cessation of ART immediately leads to viral reactivation and attainment of viral load in peripheral circulation.ART comes with severe side effects and is ineffective at treating latent infection.To eliminate latent infection,alternate therapeutic strategies such as Shock and Kill,Block and Lock,gene editing and vaccination have been proposed.Although these strategies have experimentally been proven successful,they possess major limitations.Hence,in this hypothesis,an alternate therapeutic strategy has been proposed to solve the threat of HIV-latency.The proposed model encompasses the generation and administration of recombinant HIV-1 particles whose genomes having pro-apoptotic gene,tBid,will activate apoptotic cell death pathways after infecting only the latent cells,thereby removing latent HIV host cells from patients’bodies.

Peroxisome proliferator-activated receptor gamma inhibits hepatic fibrosis in rats

BACKGROUND:Hepatic fibrosis is a necessary step in the development of hepatic cirrhosis.In this study we used lentiviral vector-mediated transfection technology to evaluate the effect of peroxisome proliferator-activated receptor gamma(PPAR-γ) on rat hepatic fibrosis. METHODS:Hepatic fibrosis in rats was induced by CCl4 for 2 weeks(early fibrosis)and 8 weeks(sustained fibrosis).The rats were randomly divided into four groups:normal control, fibrosis,blank vector,and PPAR-γ.They were infected with the recombinant lentiviral expression vector carrying the rat PPAR-γgene by portal vein injection.The liver of the rats was examined histologically and hydroxyproline was assessed.In vitro primary hepatic stellate cells(HSCs)were infected with the recombinant lentiviral expression vector carrying the rat PPAR-γgene.The status of HSC proliferation was measured by the MTT assay.The protein levels of PPAR-γ,α-smooth muscle actin(α-SMA)and type I collagen expression were evaluated by the Western blotting method. RESULTS:In vitro studies revealed that expression of PPAR-γ inhibited expression ofα-SMA and type I collagen in activated HSCs(P<0.01)as well as HSC proliferation(P<0.01).In vivo experiments indicated that in the early hepatic fibrosis group,the hydroxyproline content and the level of collagen I protein in the liver in the PPAR-γtransfected group were not significantly different compared to the hepatic fibrosis group and the blank vector group;whereas the expressions of PPAR-γ andα-SMA were different compared to the hepatic fibrosis group(P<0.01).In the sustained hepatic fibrosis group,there were significant differences in the hydroxyproline content and the expression of PPAR-γ,α-SMA,and type I collagen between each group.CONCLUSION:PPAR-γcan inhibit HSC proliferation and hepatic fibrosis,and suppressα-SMA and type I collagen expression.

miRNA-155 Modulates the Malignant Biological Characteristics of NK/T-Cell Lymphoma Cells by Targeting FOXO3a Gene

This study investigated the effects of miRNA-155 on malignant biological characteristics of NK/T-cell lymphoma cell lines and the possible mechanism. The expression of miRNA-155 was detected in lymphoma cell lines from different sources （SNK-6, YTS, Jurkat and DOHH2） by real-time PCR. Lentiviral vectors （pLL3.7） that could overexpress or downexpress miRNA-155 were constructed. Recombinant lentiviral particles were prepared and purified, and their titers determined. The expression of miRNA-155 in the infected SNK-6 cells and the cell proliferation were detected by PCR and CCK-8, respectively. Flow cytometry was used to determine the apoptosis of infected SNK-6 cells. The target of miRNA155 was predicted from Targetscan website. The effect of miRNA155 on FOXO3a expression was examined by Western blotting. The results showed that among the human NK/T-cell lymphoma cell lines SNK-6, YTS, Jurkat and DOHH2, the expression of miRNA-155 was highest in SNK-6. The infection efficiency of the recombinant lentivirns in SNK-6 was more than 70% at multiplicity of infection （MOI） of 100. The expression of miRNA-155 was significantly increased in SNK-6 cells infected by lentivirus vectors with high expression of miRNA-155 （4 times higher than the control group）, and profoundly decreased in those infected with lentivirnses with low expression of miRNA-155. The proliferation of letivirns-infected SNK-6 cells was decreased as the expression of miRNA-155 reduced. The apoptosis rate was increased with the reduction in the expression of miRNA-155. FOXO3a was found to be a possible target of miRNA155, as suggested by Targetscan website. Western blotting showed that the expression of FOXO3a was significantly elevated in SNK-6 cells with miRNA-155 inhibition. It was concluded that reduction in miRNA-155 expression can inhibit the proliferation of SNK-6 lymphoma cells and promote their apoptosis, which may be associated with regulation of FOXO3a gene.

Protective effects of ciliary neurotrophic factor on the retinal ganglion cells by injure of hydrogen peroxide

AIM： To explore the effect of ciliary neurotrophic factor （CNTF） on retinal ganglion cell （RGC）-5 induced by hydrogen peroxide （H2O2）. METHODS： After cell adherence, RGC-5 culture medium was changed to contain different concentrations of H2O2 from 50 to 150 μmol/L at four time points （0.5, 1, 1.5 and 2h） to select the concentration and time point for H2O2 induced model. Two different ways of interventions for injured RGC-5 cells respectively were CNTF as an addition in the culture medium or recombinant lentiviral plasmid carrying CNTF gene transfecting bone mesenchymal stem cells （BMSCs） for co-culture with RGC-5. RESULTS： Compared to the control group, H2O2 led to RGC-5 death closely associated with concentrations and action time of H2O2 and we chose 125 μmol/L and 2h to establish the H2O2-induced model. While CNTF inhibited the loss of RGC-5 cells obviously with a dose-dependent survival rate. Nevertheless two administration routes had different survival rate yet higher rate in recombinant lentiviral plasmid group but there were no statistically significant differences. CONCLUSION： Both the two administration routes of CNTF have effects on RGC-5 cells induced by H2O2. If their own advantages were combined, there may be a better administration route.

Effects of Over-expression of ANXA10 Gene on Proliferation and Apoptosis of Hepatocellular Carcinoma Cell Line HepG2

The effects of over-expression of ANXA10 gene on proliferation and apoptosis of hepatocellular carcinoma cell line HepG2 were elucidated.The human ANXA10 gene was subcloned into the lentiviral vector,PGC-FU,to generate the lentiviral expression vector,PGC-FU-ANXA10.The corrected ANXA10 was confirmed by endoenzyme digestion,and sequencing.Recombinant lentiviruses were produced by 293T cells following the co-transfection of PGC-FU-ANXA10 with the packaging plasmids pHelper1.0 and pHelper2.0.The resulting recombinant lentiviruses carrying ANXA10 were then used to infect human embryonic kidney epithelial cells,and lentiviral particles were produced.The ANXA10 expression in 293T cells was detected by using fluorescent microscope and Western blotting.HepG2 cells were infected,and divided into PGC-Fu-ANXA10 group,PGC-Fu group and HepG2 cell group.The changes of ANXA10 mRNA and protein expression were detected by using RT-PCR and Western blotting respectively.Flow cytometry and MTT assay were performed to examine the changes in cell apoptosis and proliferation respectively.The recombinant PGC-FU-ANXA10 vector was successfully constructed,the ANXA10 protein was detected by using Western blotting,and virus titer was 2×108 TU/mL.The recombinant lentiviruses were effectively infected into HepG2 cells in vitro and the infection efficiency was 70%.At 72 h after infection,the ANXA10 mRNA and protein expression levels in PGC-Fu-ANXA10 group were significantly higher than in PGC-Fu group and HepG2 cell group (P<0.05);the in vitro growth inhibition rate of HepG2 cells in PGC-Fu-ANXA10 group was 24.65%,significantly higher than that in PGC-Fu group and HepG2 cell group (P<0.05),but there was no significant difference between PGC-Fu group and HepG2 cell group;the apoptosis rate in PGC-Fu-ANXA10 group,PGC-Fu group and HepG2 cell group was (51.92±1.41)%,(19.00±1.12)% and (3.59±0.89)% respectively.The apoptosis rate in PGC-Fu-ANXA10 group was significantly higher than in PGC-Fu group and HepG2 cell group (P<0.05).The recombinant lentiviruses PGC-FU-ANXA10 were constructed successfully and infected into HepG2 cells.The overexpression of ANXA10 gene can significantly inhibit proliferation and promote apoptosis of HepG2 cells in vitro.

Tetracysteine as a Reporter for Gene Therapy

Objective To study the feasibility of using tetracysteine （TC） reporter in gene therapy. Methods Effects of TC reporter and conventional reporter genes encoding green fluorescence protein （GFP） and luciferase （Luc） on expression and function of the therapeutic gene MGMT^P140K were compared. Cytotoxicity and drug resistance were studied by Western blot. TC reporter used in therapy was analyzed by flow cytometry （FCM）. Results The TC reporter had no toxicity to cells and neither affected the expression or activity of therapeutic gene as compared to GFP and Luc. TC could be used in blood sample detection. Conclusion TC is a new kind of reporter gene for lentiviral vector in future gene therapy.

Expression of human adrenomedullin gene in gastric adenocarcinoma and construction and identification of adrenomedullin overexpression vector and adrenomedullin-shRNA vector

Background:To explore the expression of adrenomedullin in gastric adenocarcinoma tissues,and to construct a eukaryotic expression vector that effectively overexpresses adrenomedullin gene and a short hairpin RNA eukaryotic expression vector that effectively inhibits adrenomedullin gene.This study lays the foundation for exploring the impact of adrenomedullin on solid tumors.Methods:A total of 60 samples of gastric adenocarcinoma tissues and adjacent tissues were collected.Immunohistochemical staining was used to verify the expression of adrenomedullin in gastric adenocarcinoma and the adjacent tissues.According to the adrenomedullin gene sequence in the National Center for Biotechnology Information and the design principle of the small interfering RNA target sequence,design and construct three specific short hairpin RNA expression vectors targeting the adrenomedullin gene mRNA and one homology using the lentiviral vector KLPO.1.The negative control vector,RT-PCR and Western blotting methods were used to detect the expression of the adrenomedullin gene,and the expression vector with the best inhibitory effect was selected.The eukaryotic expression vector pcDNA3 was used to construct an overexpression vector containing the full length of the adrenomedullin cDNA.RT-PCR and Western blotting methods were used to detect the expression of the adrenomedullin gene.Results:The PLKO.1-adrenomedullin with the best inhibitory effect and the human adrenomedullin gene overexpression vector pcDNA-adrenomedullin were successfully constructed and screened.Conclusion:Adrenomedullin is highly expressed in gastric cancer,and effectively inhibiting the expression of adrenomedullin in gastric cancer may have certain value in the treatment of gastric cancer.

CO-TRANSFECTION OF RAT BONE MARROW MESENCHYMAL STEM CELLS WITH HUMAN BMP2 AND VEGF165 GENES

Objective To explore the feasibility and efficacy of lentivirus-mediated co-transfection of rat bone marrow mesenchymal stem cells （MSCs） with human vascular endothelial growth factor 165 （hVEGFI65） gene and human bone morphogenetic protein 2 （hBMP2） gene. Methods The hVEGF165 and hBMP2 cDNAs were obtained from human osteosarcoma cell line MG63 and cloned into lentiviral expression vectors designed to co-express the copepod green fluorescent protein （copGFP）. The expression lentivector and packaging Plasmid Mix were co-transferred to 293TN cells, which produced the lentivirus carrying hVEGF165 （Lv-VEGF） or hBMP2 （ Lv-BMP） , respectively. MSCs of Wistar rats were co-transfected with Lv-BMP and Lv-VEGF （BMP ＋ VEGF group）, or each alone （BMP group and VEGF group）, or with no virus （ Control group）. The mRNA and protein expressions of hVEGF165 and hBMP2 genes in each group were detected by real-time PCR and enzyme linked immunosorbent assay （ELISA）. Results Lentiviral expression vectors carrying hVEGF165 or hBMP2 were correctly constructed and confirmed by restriction endonucleses analysis and DNA sequencing analysis. A transfer efficiency up to 90% was archieved in all the transfected groups detected by the fraction of fluorescent cells using fluorescent microscopy. From the results generated by real-time PCR and ELISA, VEGF165 and BMP2 genes were co-expressed in BMP ＋ VEGF group. No significant difference of BMP2 expression was detected between BMP ＋ VEGF and BMP groups （ P 〉 0. 05）. Similarly, there was no significant difference of VEGF165 expression between BMP ＋ VEGF and VEGF groups （ P 〉 0. 05）. Conclusion VEGF165 and BMP2 genes were successfully co-expressed in MSCs by lentivirus-mediated co-transfection, which provided a further foundation for the combined gene therapy of bone regeneration.

Production of Transgenic Korean Native Cattle Expressing Enhanced Green Fluorescent Protein Using a FIV-Based Lentiviral Vector Injected into MII Oocytes

The potential benefits of generating and using transgenic cattle range from improvements in agriculture to the production of large quantities of pharmaceutically relevant proteins. Previous studies have attempted to produce transgenic cattle and other livestock by pronuclear injection and somatic cell nuclear transfer, but these approaches have been largely ineffective; however, a third approach, lentivirus-mediated transgenesis, has successfully produced transgenic livestock. In this study, we generated transgenic （TG） Korean native cattle using perivitelline space injection of viral vectors, which expressed enhanced green fluorescent protein （EGFP） systemically. Two different types of lentiviral vectors derived from feline immunodeficiency virus （FIV） and human immunodeficiency virus （HIV） carrying EGFP were injected into the perivitelline space of MII oocytes. EGFP expression at 8-cell stage was significantly higher in the FIV group compared to the HIV group （47.5% ± 2.2% v.s. 22.9% 4± 2.9%）. Eight-cell embryos that expressed EGFP were cultured into blastocysts and then transferred into 40 heifers. Ten heifers were successfully impregnated and delivered 10 healthy calves. All of these calves expressed EGFP as detected by in vivo imaging, PCR and Southern blotting. In addition, we established an EGFP-expressing cell line from TG calves, which was followed by nuclear transfer （NT）. Recloned 8-cell embryos also expressed EGFP, and there were no differences in the rates of fusion, cleavage and development between cells derived from TG and non-TG calves, which were subsequently used for NT. These results illustrate that FIV-based lentiviruses are useful for the production of TG cattle. Moreover, our established EGFP cell line can be used for additional studies that involve induced pluripotent stem cells.

Differential Effects of Strategies to Improve the Transduction Efficiency of Lentiviral Vector that Conveys an Anti-HIV Protein,Nullbasic,in Human T Cells

Nullbasic is a mutant form of HIV-1 Tat that has strong ability to protect cells from HIV-1 replication by inhibiting three different steps of viral replication: reverse transcription, Rev export of viral m RNA from the nucleus to the cytoplasm and transcription of viral m RNA by RNA polymerase II. We previously showed that Nullbasic inhibits transduction of human cells including T cells by HIV-1-based lentiviral vectors. Here we investigated whether the Nullbasic antagonists huTat2(a Tat targeting intrabody), HIV-1 Tat or Rev proteins or cellular DDX1 protein could improve transduction by a HIV-1 lentiviral vector conveying Nullbasic-Zs Green1 to human T cells. We show that overexpression of huTat2, Tat-FLAG and DDX1-HA in virus-like particle(VLP) producer cells significantly improved transduction efficiency of VLPs that convey Nullbasic in Jurkat cells. Specifically, co-expression of Tat-FLAG and DDX1-HA in the VLP producer cell improved transduction efficiency better than if used individually. Transduction efficiencies could be further improved by including a spinoculation step. However, the same optimised protocol and using the same VLPs failed to transduce primary human CD4^+T cells. The results imply that the effects of Nullbasic on VLPs on early HIV-1 replication are robust in human CD4^+T cells. Given this significant block to lentiviral vector transduction by Nullbasic in primary CD4^+T cells, our data indicate that gammaretroviral, but not lentiviral, vectors are suitable for delivering Nullbasic to primary human T cells.

Gene Transfer to Dendritic Cells Induced a Protective Immunity against Melanoma

Lentiviral vectors have shown promises for efficient gene transfer to dividing as well as nondividing cells. In this study, we explored lentiviral vector-mediated, the entire mTRP-2 gene transfer and expression in dendritic cells （DCs）. Adoptive transfer of DCs-expressing mTRP-2 （DC-HR＇CmT2） into C57BL/6 mouse was also assessed. Dendritic cells were harvested from bone marrow and functional DCs were proved by allogeneic mixed lymphocyte reaction. Lentiviral vectors were produced by transient transfection of 293T cells. Transduction of DCs was proved by marker gene expression and PCR and RT-PCR amplification. Implantation of the transduced DCs, depletion of immune cells as well as the survival of the mice after tumour challenge were investigated. High efficiency of gene transfer into mature DCs was achieved. The high level expression of the functional antigen （TRP-2） and induction of protective immunity by adoptive transfer of TRP-2 gene modified DCs were demonstrated. In vivo study showed a complete protection of mice from further melanoma cell challenge. In comparison, only 83% of mice survived when mTRP-2 peptide-pulsed DCs were administered, suggesting the generation of specific protection. Together, these results demonstrated the usefulness of this gene transfer to DC approach for immunotherapy of cancer and indicated that using tumour associated antigens （TAAs） for gene transfer may be potentially beneficial for the therapy of melanoma.

Lentivector-mediated RNAi efficiently downregulatesexpression of murine cdk4 gene in vitro

In order to explore the role of cyclin-dependent kinase 4(cdk4)in neurodegenerative diseases,lentiviral-delivered RNA interference(RNAi)was used to silence the expression of the murine cdk4 gene in vitro.Three cdk4-shRNAs of mouse and a negative sequence were designed.After synthesis and annealing,double strand oligonucleo-tides were cloned into a linearized pSIH1-H1-copGFP shRNA vector.It was confirmed by polymerase chain reaction(PCR)and sequencing that three pairs of cdk4-shRNAs and a negative shRNA were correctly inserted into the pSIH1-H1-copGFP vector.The above recombi-nants were transfected by lipofectamine into BV-2 cells.The gene silencing efficacy rates of the 3 targets were compared by Western blotting.The cdk4-siRNA2 was the most effective in silencing cdk4.The optimized pSIH1-cdk4-siRNA2 and pSIH-negative-siRNA were co-transfected into 293T cells with the lentiviral packaging plasmids respectively.The culture supernatant was har-vested and condensed at the 24th and 48th h after transfection.Interference efficiency of the lentivirus expressing cdk4-siRNA was determined by reverse transcriptase-PCR(RT-PCR)and Western blotting in BV-2 cells.Lentivector-mediated RNAi could efficiently down-regulate the expression of the murine cdk4 gene in vitro,which provides a potential tool for studying and treating cdk4-related diseases.