Objective To investigate the stable, high effective and low toxicity gene transfer vectors’ basics in research and clinical application.Methods Current status of hepatocytedirected gene transfer vectors were reviewed by history document and contemporary experimental advances analysis.Results Viral and nonviral vector systems could both transduce target genes to liver effectively with various transduction rates based on their corresponding biological characteristics.Conclusion Hepatocyte is the effective target for gene therapy of liverrelated genetic, neoplastic and infectious diseases, although the security needs to be further evaluated.
Abstract: Objective To assess the feasibility of transferring major histocompatibility complex (MHC) gene into the thymus to mitigate xenograft rejection. Methods By molecular cloning technique, we extracted and proliferated the-H-2K d gene from donor mice (MHC class Ⅰ gene of Balb/c mice) and constructed the expression vector plasmid of pCI-H-2K d. Twenty SD rats were selected as receptors, and by using random number table, they were divided into the experimental group and the control group with equal number of rats in each group. By ultrasoundguided puncture and lipofection method, the pCI-H-2Kd was injected into thymus of SD rats in the experimental group and meanwhile, empty vector plasmid of pCIneo was injected into thymus of SD rats in the control group. Subsequently, we transplanted the donor mice myocardium xenografts into the receptor rats, and observed the xenograft rejection in both the two groups. Results The survival time of the xenotransplanted myocardium in the experimental group was significantly longer than that in the control group (14.61±2.98 d vs. 6.40±1.58 d, t=-7.619,Plt;0.05). Microtome section of transplanted myocardium in the control group showed a relatively large amount of lymphocyte infiltration and necrosis occurred to most part of the transplanted myocardium, while microtome section of experiment group showed no lymphocyte infiltration and most of the cells of the transplanted myocardium were still alive. After mixed lymphocyte culture, the reaction of receptors to donor cells in the experiment group was obviously lower than that in the control group (t=4.758, P=0.000).After the count by flow cytometer, the xenoMHC molecules were expressed in the receptors’ thymus with a transfection efficiency of 60.7%. Conclusion Our findings suggest that xenograft rejection can be mitigated substantially by donor’s MHC gene transferring into receptor’s thymus. This may provide theoretical and experimental evidence for inducing xenotransplantation tolerance.
Objective To study efficiency and security of the recombinant adenoviralmediated gene transfer to the donor heart during the heart transplantation. Methods A total of 140 healthy male Wistar rats,aged 10 weeks, weighing 200250 g, were equally divided into the donor group and the recipient group, and then 70 rats in the recipient group were randomly andequally divided into 2 subgroups: the gene transfer group and the control group. The rat model of heterotopic heart transplantation(Abdomen)was developed, the donor hearts were removed and their coronary arteries were perfused with 800 μlof the recombinant adenoviral vectors encoding the β-galactosidase gene（Ad-LacZ）. The grafts were stored in the 4℃ cold saline solution for 30 minutes, and then the syngeneic transplant was performed. In the control group, saline of tales doses was perfused. The donor hearts were harvested at 3, 5, 7, 14, and 28days (n=7)after transplantation, and the β-galactosidase activity was assessed by the X-gal staining. At 28 days the major organs of the recipients were tested by the histopathological analysis and the polymerase chain reaction of the adenoviral E1A sequences. Results The successful gene transfer of the βgalactosidase gene was demonstrated in the adenovirus-perfused hearts, with no staining in the control group. The gene expression reached a peak level at 3, 5 and 7 days, and the averaged numbers of the total βgalactosidase positive staining cells per slice were 66.4±23.1, 91.3±32.4 and 68.7±22.7, respectively, with no significant difference between the groups (Pgt;0.05). At 14 days the gene expression gradually declined (32.1±13.9), and the significant difference was found when compared with that at 3, 5 and 7 days (Plt;0.05). At 28 days the cells positive for β-galactosidase were sparse (3.9±3.4), and the gene transfer was significantly less efficient compared with that at 3, 5, 7 and 14 days (Plt;0.05). The major organs of the recipients were not affected seriously at 28 days. No virus spread to other organs in this experimental protocol. Conclusion The ex vivo adenoviralmediated gene transfer intracoronarily to the donor heart during the heart transplantation is feasible and safe.
Objective Targeted adenoviral gene delivery from peripheral nerves was used to integrally analyse the characterization and time course of LacZ gene (AdLacZ) retrograde transfer to spinal cord and transgene product anterograde labeling ofperipheral nerve. Methods Recombinant replication-defective adenovirus containing AdLacZ was administrated to the cut proximal stumps of median and tibial nerves in Wister rats. Then the transected nerve was repaired with 10-0 nylon sutures. At different time point postinfection the spinal cords of C5 to T1 attached with DRGs and brachial plexuses, or L2 to L6 attached with DRGs and lumbosacralplexuses were removed. The removed spinal cord and DRGs were cut into 50 μm serialcoronal sections and processed for X-gal staining and immunohistochemical staining. The whole specimens of brachial or lumbosacral plexuses attaching with theirperipheral nerves were processed for X-gal staining. The number of X-gal stained neurons was counted and the initial detected time of retrograde labeling, peaktime and persisting period of gene expression in DRG sensory neurons, spinal cord motor neurons and peripheral nerves were studied. Results The gene transfer was specifically targeted to the particular segments of spinal cord andDRGs, and transgene expression was strictly unilaterally corresponding to the infected nerves. Within the same nerve models, the initial detected time of gene expression was earliest in DRG neurons, then in the motor neurons and latest in peripheral nerves. The persisting duration of β-gal staining was shortest in motor neurons, then in sensory neurons and longest in peripheral nerves. The initial detected time of β-gal staining in median nerve models was earlier in mediannerve models compared with that in the tibial nerve models. Although the initial detected time and the beginning of peak duration of β-gal staining were not same, the decreasing time of β-gal staining in motor and sensory neurons of thetwo nerve models were started at about the same day 8 post-infection. The labeled neurons were more in tibial nerve-models than that in median nerve models. Within the same models, the labeled sensory neurons of DRGs were morethan labeled motor neurons of ventral horn. The β-gal staining was tenser in median nerves than that in tibial nerves. However the persisting time of β-gal staining was longer in tibial nerve models. Conclusion The b gene expression in neurons and PNS renders this system particularly attractive for neuroanatomical tracing studies. Furthermore this gene delivery method allowing specific targeting of motor and sensory neurons without damaging the spinal cord might offer potentialities for the gene therapy of peripheral nerve injury.
Objective To study the effect of adenovirus bone morphogenetic protein 2 gene(Ad-BMP-2) transfer inducing mesenchymal stem cells (MSCs) compounded with fibrin gel on repair of rabbit cartilage defect. Methods ①BMP-2 and collagen type Ⅱ in MSCs transferred by Ad-BMP-2 were examined by RT-PCR, aniline dyeing and immunohistochemical analysis in vitro. ②MSCs were cultured in fibrin gel for 9 days, and were examined with electron microscope. ③Fortytwo rabbits suffering from cartilage defect were divided into 3 groups:the defects were treated with Ad-BMP-2 transfer inducing MSCs compounded with fibrin in group A, with MSCs compounded with fibringel in group B and with no implants in group C as control. HE and aniline dyeing, immunohistochemical analysis and biomechanics study were carried out in the 4th, 8thand 12th weeks. Results ①The positive results were observed for BMP-2 and collagen type Ⅱ with RT-PCR on the 3rd day and 5th day respectively, being statisticallysignificant difference when compared with control group(P＜0.05). ②Ad-BMP-2 transfer inducing MSCs cultured in fibrin gel were positively stained by aniline dyeing and immunohistochemstry. ③The therapy effect of group A was better than that of the other two groups in histology, biochemistry and biomechanics, and the biomechanic and histological features of repaired cartilage were similar to those of the natural cartilage. Conclusion Ad-BMP-2 can induce the expressionof collagen type Ⅱ and mucopolysaccharide in MSCs by secreting BMP-2, and can reconstruct articular cartilage defects better when compounded with fibrin gel.
OBJECTIVE To probe the possibility of direct transfer of exogenous gene into peripheral nerve and its following expression in vivo. METHODS The PCMV beta plasmid containing cytomegalovirus (CMV) promoter and Escherichia Coli (E. Coli), beta-Galactosidease (beta-Gal) structural gene (lacZ gene) was constructed and injected into the rabbit sciatic nerve. The control group was injected PBS solution. The injected nerves were sampled and tested by beta-Gal enzyme activity assay of the 5-bromo-4-chloro-3-indolyl-beta-D-galactoside and beta-Gal histochemical stain. RESULTS In the control group, no beta-Gal enzyme activity was detected in the different stages after operation, and beta-Gal histochemical stains showed positive. In the experimental group, enzyme activity could be detected from 2 days to 30 days after operation, and the histochemical stains showed negative. CONCLUSION The exogenous gene can be transferred into peripheral nerve and expressed with bioactivity, thus the gene therapy to accelerate the recovery of nerve is practical.
Objective To observe the inhibition of LipofectamineTM2000 (LF2000)mediated pSUPER recombinant plasmid expressing small interference RNA targeting hypoxia-induced factor (HIF)-1alpha;(pSUPERsiHIF-1alpha;) on retinal neovascularization in mice. Methods pSUPERsiHIF-1alpha; recombinant plasmid was created. Forty-eight (seven-day-old) C57BL/6J mice were randomly divided into a normal group, the control group, empty vector group and gene therapy group with 12 mice in each group. Mice in the normal group were kept in normal room air, while the other three groups retinal neovascularization was induced by hypoxia. The mice in control group were not treated. The mice in the vector group received intravitreous injection of pSUPER and LF2000 (1 mu;l), and the gene therapy group received pSUPERsiHIF-1alpha; and LF2000 (1 mu;l)one day before being returned to normal room air．Fluorescent angiography was used to assess the vascular pattern. The proliferative neovascular response was quantified by counting the nuclei of new vessels extending from the retina into the vitreous in cross-sections．HIF-lalpha;and vascular endothelial growth factor (VEGF) levels in retinas were measured by immune histochemical staining method and reverse transeriptase-polymerase chain reaction (RT-PCR). Results Fluorescent angiography showed radial branching pattern vessels in the normal group and distorted large vessels, obstructed capillaries, many neovascular tuffs, fluorescence leakage in the peripheral retina in the control group and vector group. The gene therapy group demonstrated a significant reduction in neovascular tufts and fluorescence leakage compared with the control group and the vector group. The number of vascular cell nuclei extending breaking through the internal limiting membrane(ILM) of control group and vector group increased significantly compared with normal group (F=5850.016,P＜0.05), while obviously decreasing in the gene therapy group compared with control group (F=3012.469,P＜0.05). Immunohistochemical staining showed the expression of HIF-1alpha; protein in nucleus and VEGF protein in cytoplasm. The expression of HIF-1alpha; protein in retina was negative, while VEGF protein was weakly positive in normal group. The expression of HIF-1alpha; and VEGF protein were both positive in control group and vector group, while weakly positive in gene therapy group. The Results of RT-PCR showed that the expression of HIF-1alpha; mRNA in retina was increased significantly in control group and vector group as compared with normal group (F=3102.326,P＜0.05), while decreasing significantly in gene therapy group as compared with control group (F=3336.425,P＜0.05). Conclusion Retinal neovascularization in the mice is significantly inhibited by intravitreal injection of LF2000-mediated recombinant plasmid pSUPERsiHIF-1alpha;.
Objective To investigate the inhibitory effects of 15-lipoxygenase-1 (15-LOX-1) gene transfer on oxygen-induced retinal neovascularization in mice. Methods Ninety-six 7-day-old C57BL/6J mice were randomly divided into normal control group, oxygeninduced retinopathy (OIR) model group, gene treated group and empty vector group. The mice with their mothers were kept in (75plusmn;2) % 02 environment for 5 days and then returned to normoxia for 5 days to establish the OIR model. At postnatal day 12, the gene treated group received intravitreous injection of recombinant adenovirus (Ad) vector containing both enhanced green fluorescent protein (EGFP) and mouse 15-LOX-1 genes (Ad-15-LOX-1-EGFP) at 1 l, while the empty vector group received the same volume of recombinant Ad vector containing EGFP (Ad-EGFP). The expression of EGFP was observed on flat-mounted retina by fluorescence microscopy 2 days after intravitreous injection of Ad-15-LOX-1-EGFP. At postnatal day 17, the efficacy of 15-LOX-1 gene transfer on retinal tissue was detected by immunofluorescence staining, real-time polymerase chain reaction and Western blot. The changes of retinal vessels, relative retinal non-perfusion and neovascularization areas were evaluated by fluorescein isothiocyanate-dextran fluorescein angiography on flatmounted retina. The number of endothelium cell nuclei breaking through the inner limiting membrane (ILM) was counted on hematoxylin and eosin-stained retinal section. Results Two days after intravitreous injection of Ad-15-LOX-1-EGFP, the expression of EGFP had been seen by fluorescence microscopy on Flat-mounted retina. Immunofluorescence staining of retinal section revealed that 15-LOX-1 expression was primarily in the outer plexiform layer, inner nuclear layer and ganglion cell layer of retina. The 15-LOX-1 protein and mRNA expression levels were higher in gene treated group than those in OIR model group and empty vector group (tprotein=22.74 and 24.13 respectively.tmRNA=12.51 and 13.40 respectively; P＜0.01). The relative retinal non-perfusion and neovascularization areas were significantly smaller in gene treated group than those in OIR model group and empty vector group (tnon-perfusion=16.22 and 14.31 respectively.tneovascularization=9.97 and 9.07 respectively; P＜0.01), and the number of endothelium cell nuclei breaking through the ILM in gene treated group was obviously lower than the other two groups (t=14.25 and 11.62 respectively，P＜0.01). Conclusion 15-LOX-1 gene transfer can decrease the oxygen-induced retinal non-perfusion areas and inhibit the retinal neovascularization in mice.
Objective To construct small hairpin RNA (shRNA) expression plasmid targeting rat opticin gene.Methods Four pairs of opticin oligonucleotides were synthesized and inserted into the plasmid vector, resulting into four plasmids: shRNA-1, shRNA-2, shRNA-3 and shRNA-4. Then the four constructed shRNA expression vectors and empty vector were transfected into rat ciliary non-pigment epithelium (NPE) cells by lipofectmaine 2000. Nontransfected NPE cells were set as control group.The expression of opticin mRNA and protein were measured by Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot respectively.Results The opticin mRNA expression of the shRNA-1,shRNA-2,shRNA-3,shRNA-4 group were decreased compared with the control group (F=10.239，P＝0.000)；the inhibitory rate were 85.7%，62.87%，54.87% and 48.77% respectively.The opticin protein expression of the shRNA-1,shRNA-2,shRNA-3,shRNA-4 group were also decreased compared with the control group (F=17.870，P=0.000)；the inhibitory rate were 78.7%，34.6%，31.1% and 16.8% respectively.Conclusions The shRNA-1 expression plasmid has most potent inhibitory effect on opticin expression in rat ciliary NPE cells.
Objective To investigate the enhancing effect of ultrasound microbubbles on transfection of recombinant adenoassociated virus (rAAV) mediated green fluorecent protein (EGFP) gene into retinal ganglion cells (RGC) in vivo.Methods A total of 40 adult Sprague-Dawley (SD) rats were divided into four groups randomly (group A,B,C,D) with 10 rats in each. Group A was the normal control, in which the rats underwent intravitreal injection with 5 mu;l phosphate buffered solution. The rats in group B underwent intravitreal injection with 5 mu;l recombinant adenoassociated virus encoding EGFP gene (rAAV2-EGFP). The rats in group C underwent ultrasound irradiation on eyes right after intravitreal injection with 5 mu;l rAAV2-EGFP; The ultrasound irradiation was performed on the rats in group D right after intravitreal injection with the mixture solution of microbubbles and rAAV2-EGFP ultrasound. After 21 days, RGC were labeled retogradely with fluogold. Seven days after labeling, the retinal flatmounts and frozen sections were made from five rats in each group. Expression of EGFP reporter gene was observed by laser scanning confocal microscope and evaluated via average optical intensity (AOD) and RGC transfection rate. Labeled RGC were counted to evaluate the adverse effects.Results Green fluorescence can be observed exactly in labeled RGC in B，C，and D groups. The AOD and transfection rate in group D was （95.02plusmn;7.25）% and（20.10plusmn;0.74）% , respectively; which were higher than those in group B and C (F=25.970，25.799；P＜0.01). The difference of the number of RGC among the four groups was not significant(F=0.877,P＞0.05). Conclusion Under the condition of low frequency and with certain energy, ultrasoundmediated microbubble destruction can effectively and safely enhance rAAV delivery to RGC in rats.