Gene therapy for hemophilia B mediated by recombinant adeno-associated viral vector with hFIXR338A, a high catalytic activity mutation of human coagulation factor IX

A mutant human factor IX with arginine at 338 residual changed to alanine (hFIXR338A) by site-directed mutagenesis was introduced into AAV vectors, and a recombinant adeno-associ- ated viral vector containing hFIXR338A, prepared by rHSV/AAV hybrid helper virus system, was directly introduced to the hind leg muscle of factor IX knock out mice. The expression and the biological activity of human factor IX mutant, hFIXR338A, and the immune response against it in the treated mice were assayed and detected. The results showed that (i) the high-level expression of human factor IX mutant protein, hFIXR338A, has been detected in rAAV-hFIXR338A treated hemophilia B mice and lasted more than 15 weeks; (ii) the clotting activity of hFIXR338A in plasma is 34.2%± 5.23%, which is remarkably higher than that of (14.27% ± 3.4%) of wild type hFIX treated mice in the activated partial thromboplastin assay; (iii) immune response against factor IX R338A was absent, with no factor IX mutant protein (hFIXR338A) inhibitors development in the treated mice; and (iv) no local or systemic side-effects and toxicity associated with the gene transfer were found. It demonstrated the potential use of treating hemophilia B by recombinant adeno-associated viral vectors with mutant hFIXR338A gene, an alternative strategy for hemophilia B gene therapy to wild-type human factor IX.     

A study of gene transfer and expression of human clotting factor IX in hemophilia B mice mediated by mini-adenoviral vector

Vector Gti'IX containing human clotting factor IX cDNA with intron 1 (hFIX mini-gene or Fi'IX) driven by CMV promoter was constructed based on the mini-adenoviral vector GT2073 (mini-Ad vector) with all viral protein coding sequences deleted. Mini-Ad packaging cell 293Cre4 was first transduced with Gti'IX, and then was transfected with helper-adenovirus AdLC8, thus mini-Ad virions AdGTi'IX were obtained. At the same time, previous normal adenoviral vector pAdSPi'IX containing viral genome and hFIX mini-gene was constructed, and then previous adenovirus (pre-Ad) AdSPi'IX was obtained as control. The ratio of helper-adenovirus among purified virons AdGTi'IX was less than 0.8%. 3T3 cells were transfected with AdGTi'IX and AdSPi'IX at a MOI of 50 per cell and ELISA result showed that transient expression level in vitro was 1.4±0.2 μg /106@24 h and 1.6±0.3 μg/106@24 h respectively. Each hemophilia B (FIX knock-out) mouse received celiac injection of 1×1010pfu AdGTi'IX or AdSPi'IX. The highest expression level of hFIX in mouse plasma was 590 ng/mL and 690 ng/mL respectively, and the expression time lasted for 16 weeks and 9 weeks respectively. The bleeding time reduced from over 30 min to 7.5 min, and 5-min blood lost reduced from 430 μL to 60 μL. The results of anti-Ad IgG assays indicated that immune response triggered by AdGTi'IX was obviously weaker than that triggered by AdSPi'IX. These results indicated that, compared with previous adenovirus (pre-Ad), the mini-Ad vector system prolonged the expression time of hFIX and reduced immune response, thus offering a promising result for further pre-clinical study.     

A study of gene transfer and expression of human clotting factor IX in Hemophilia B mice mediated by mini-adenoviral vector

Hemophilia B is an X-linked disorder caused by the deficiency of clotting factor IX (FIX) activity. Compared with conventional treatment, gene therapy offers an attractive approach by which the goal of prophylactic hemostasis may be achieved without extreme costs, infectious and thrombotic risks. It is the key for?successful somatic gene therapy to effectively and safely ex-press target gene in cell, animal or human as well mediated by appropriate vectors. Adenoviral vectors are currently a…     

Sustained and therapeutic levels of human factor IX in hemophilia B mice implanted with microcapsules: key role of encapsulated cells

BACKGROUND: A gene therapy delivery system based on microcapsules enclosing recombinant cells engineered to secrete a therapeutic protein was explored in this study. In order to prevent immune rejection of the delivered cells, they were enclosed in non-antigenic biocompatible alginate microcapsules prior to being implanted intraperitoneally into mice. We have shown that encapsulated C2C12 myoblasts can temporarily deliver therapeutic levels of factor IX (FIX) in mice, but the C2C12 myoblasts elicited an immune response to FIX. In this study we report the use of mouse fetal G8 myoblasts secreting hFIX in hemophilia mice. METHODS: Mouse G8 myoblasts were transduced with MFG-FIX vector. A pool of recombinant G8 myoblasts secreting approximately 1500 ng hFIX/10(6) cells/24 h in vitro were enclosed in biocompatible alginate microcapsules and implanted intraperitoneally into immunocompetent C57BL/6 and hemophilic mice. RESULTS: Circulating levels of hFIX in treated mice reached approximately 400 ng/ml for at least 120 days (end of experiment). Interestingly, mice treated with encapsulated G8 myoblasts did not develop anti-hFIX antibodies. Activated partial thromboplastin time (APTT) of plasmas obtained from treated hemophilic mice was reduced from 107 to 82 sec on day 60 post-treatment, and whole blood clotting time (WBCT) was also corrected from 7-9 min before treatment to 3-5 min following microcapsule implantation. Further, mice were protected against bleeding following major trauma. Thus, the FIX delivery in vivo was biologically active. CONCLUSIONS: Our findings suggest that the type of cells encapsulated play a key role in the generation of immune responses against the transgene. Further, a judicious selection of encapsulated cells is critical for achieving sustained gene expression. Our findings support the feasibility of encapsulated G8 myoblasts as a gene therapy approach for hemophilia B.     

Gene therapy for pathological scar with hepatocyte growth factor mediated by recombinant adenovirus vector

Pathologic scar, characterized by excessive dermal fibrosis and scarring, is a common im-portant clinical sequela after wound healing. It often appears during wound healing after deep burn, surgical cutting and other injured skin. Accumulation of extracellular matrix (ECM) proteins is a manifestation of increased collagen synthesis and/or reduced matrix degradation, resulting in excessive scarring with a deformed appearance and dysfunction[1]. To date, treatment modalities to scar include sur…     

Gene therapy for pathological scar with hepatocyte growth factor mediated by recombinant adenovirus vector

A complementary DNA (cDNA) encoding human hepatocyte growth factor was introduced into a replication-defective type 5 adenovirus (lacking E1, E3 domains) vector by homologous recombination of intracellular plasmid DNA, thus a recombinant vector containing HGF (Ad-HGF) was obtained. Ad-HGF and Ad-GFP (adenovirus vector carrying green fluorescence protein gene) were expanded in 293 cells and purified by cesium chloride gradient centrifugation for large-scale preparation, then were infected to the primarily cultured scar fibroblast of rabbit ear to observe the transfer efficiency and expression level of HGF in vitro. To evaluate the effect of Ad-HGF on established scar Ad-HGF solution was injected into excessively formed scar, which bears some clinical and histologic similarities to human hypertrophic scars. The results showed that: (i) the transfer efficiency was 36.8% ±14.1% on day 3 in primarily cultured scar fibroblasts treated with Ad-GFP and lasted more than 20 d; (ii) high-level expression of HGF protein was detected by means of ELISA in supernatant of scar fibroblasts treated with Ad-HGF, the amount of expression was 76 ng/4.0 x 10⁵ cells on day 3; (iii) on day 32 after a single intradermal injection of Ad-HGF at different doses (8.6 x 10⁹ pfu, 8.6 x 10⁸ pfu, 8.6 x 10⁷ pfu, 8.6 x 10⁶ pfu) per scar, most of the scars in the former two dose groups were dramatically flattened, some were even similar to that of the normal skin. The value of Hl (hypertrophie index) showed that there was a therapeutic effect of Ad-HGF on scars at the dose of 10⁹ pfu and 10⁸ pfu. Whereas no therapeutic effects were seen at lower dose (10⁷ pfu and 10⁶ pfu of Ad-HGF) groups. In addition, clusters of hair were observed to different extent on healed wound treated with Ad-HGF. Histopathologic examination revealed that in most healed wounds of Ad-HGF treated group, the dermal layer was thinner, the amount of fibrous tissue was much fewer, and hair follicles growth and sebaceous glands were observed. In Sirius red-stained sections the amount of type I collagen in the Ad-HGF-treated scars was diminished markedly, compared to that in Ad-GFP group, in which a huge amount of type I collagen was still observed; (iv) immune response against HGF was absent. Antibody against HGF was not detectable by ELISA in serum from rabbit treated with Ad-HGF; (v) no local or systemic side-effects and toxicity associated with the gene transfer were found. These results demonstrated the potential use of treating pathologic scar by Ad-HGF, an alterative strategy of gene therapy for scar in clinical practice.     

Skeletal muscle-specific expression of human blood coagulation factor Ⅸ rescues factor Ⅸ deficiency mouse by AAV-mediated gene transfer

The efficacy of recombinant adeno-associated virus (AAV) vector to deliver and express human blood clotting factor DC (hFIX) gene in skeletal muscle of coagulation factor IX deficiency mouse strain (FactorIX-knockout) is e-valuated. The muscle creatine kinase enhancer (MCK) and βactin promoter ((3A) were used to drive the hFIX minigene (hFIXml), which was flanked by AAV inverted terminal repeats (ITRs). Following intramuscular injection of high liter (2.5 x 1011 vector genomes/mL) of AAV, increased hFIX expression (256 ng/mL of plasma) was achieved. The time course of hFIX expression demonstrated that the expression level gradually increased over a period of two weeks before anti-hFIX antibodies developed in mouse circulating plasma. Those results provided a promising evidence that rAAV-me-diated gene transfer and skeletal muscle-specific expression of hFIX is a feasible strategy for treating patients for hemophilia B.     

基于凝血因子IX基因剔除小鼠建立血友病乙转基因动物模型

为在凝血基因IX基因剔除小鼠基础上建立基因组中整合有含特定点突变的人凝血因子IX基因表达载体原转基因小鼠家系,为血友病乙的研究提供更接近临床实际的动物模型。利用体外定点突变技术,构建含有特定点突变的人凝因IX基因表达载体,该载体包括由人凝血因子IX编码区及第一内含子构成的人凝血因子IX基因（hFIXml）、4个拷贝的MCK增强子（MCKe）、鸡β－肌动蛋白启动子（bA）及PolyA,命名为pMe4bAIXml质粒。将其线性化后,用显微注射法注射入817只凝血因子IX基因剔除小鼠受精卵雄原核,再将它们分别回输45只假孕受体母鼠的输卵管中,共产仔69只,存活63只。采用PCR与基因组Southern杂交筛选法鉴定小鼠,证实6只小鼠基因组中整合有含特定点突变的pMe4bAIXml质粒,并对1只小鼠的PCR产物进行测序,证实转基因结构特征符合设计要求。     

Inhibition of corneal neovascularization with endostatin delivered by adeno-associated viral (AAV) vector in a mouse corneal injury model

The use of a recombinant adeno-associated viral (rAAV) vector carrying endostatin gene as an anti-angiogenesis strategy to treat corneal neovascularization in a mouse model was evaluated. Subconjunctival injection of recombinant endostatin-AAV was used to examine the inhibition of corneal neovascularization induced by silver nitrate cauterization in mice. The results showed that gene expression in corneal tissue was observed as early as 4 days after gene transfer and stably lasted for over 8 months with minimal immune reaction. Subconjunctival injection of a high-titer rAAV-endostatin successfully inhibited neovascularization. Immunohistchemistry staining of CD 31 and endostatin showed that the treatment significantly inhibits angiogenesis in cornea. We concluded that the rAAV was capable of directly delivering genes to the ocular surface epithelium by way of subconjunctival injection and was able to deliver sustained, high levels of gene expression in vivo to inhibit angiogenesis.