Objective To determine whether the transforminggrowth factor β1 (TGF-β1) is a key regulatory molecule required for an increase or a balance of extracellular matrix (ECM) and DNA synthesis in the goat passaged nucleus pulposus (NP) cells. Methods The NP cells isolated from the goat intervertebral discs were cultured in vitro for a serial of passages and transfected with the replicationincompetent adenoviral vectors carrying the human TGF-β1 (hTGF-β1) or lacZ genes. Then, they were cultured in monolayer or alginate bead 3dimensional (3-D) systems for 10 days.The changes in the production and the molecular components of ECM that occurredin the NP cells transfected with Ad/hTGF-β1 or the controls were evaluated by Westernblot and absorbance of glycosaminoglycan (GAG)-Alcian Blue complexes. Differences of DNA synthesis in the variant cells and culture systems were assessed by fluorometric analysis of the DNA content. ResultsA quantitation in the variant culture systems indicated that in monolayers the NP cells at Passage 3 transfected with Ad/hTGF-β1 had a much higher cell viability and more DNA synthesis(P＜0.05); however, in the alginate 3-D culture system, the NP cells transfected with Ad/hTGF-β1 did not have any significant difference from the controls(P＞0.05). The Western blotting analysis ofthe protein sample isolated from the variant cells for TGF-β1, type Ⅱ collagen, and Aggrecan expression indicated that in the monolayers and alginate 3-D culture systems the NP cells at Passage 3 transfected with Ad/hTGF-β1 revealed much higher protein levels than the controls(P＜0.05)； whereas the type Ⅰcollagen content was much lower than the controls (P＜0.05), but a significatly increased ratio of type Ⅱ/type Ⅰ collagen was found in both of the cell culture systems(P＜0.05). The GAG quantification also showed a positive result in both the cell culture systems and the NP cells at Passage 3 transfected with Ad/hTGF-β1 had a much higher GAG content than the controls(P＜0.05). Conclusion To a greaterextent, hTGF-β1 can play a key role in maintaining the phenotype of the NP cells and can still have an effect of the phenotypic modulation after a serial of the cell passages. The NP cells that are genetically manipulated to express hTGF-β1 have a promising effect on the restoration of the intervertebral disc defects. The NP cells transfected with Ad/hTGF-β1 cultured in the 3-D alginate bead systems can show a nearly native phenotype.
Objective To study the adenovirus-mediated human bone morphogenetic protein-2 gene （Ad-hBMP-2）transferred to the intervertebral disc cells of the New Zealand rabbit in vitro. Methods The cells of New Zealand white rabbitswere isolated from their lumbar discs. The cells were grown in the monolayer and treated with an adenovirus encoding the LacZ gene (Ad-LacZ) and Ad-hBMP-2 (50,100, 150 MOI,multiplicity of infection) in the Dulbecco’s Modified Eagle Medium and the Ham’s F-12 Medium in vitro. Three days after the Ad-hBMP-2 treatment,the expression of hBMP-2 in the cells that had been infected by different dosesof MOI was determined by immunofluorescence and the Western blot analysis, and the expression was determined in the cells with the Ad-LacZ treatment in a dose of 150 MOI. Six days after the Ad-hBMP-2 treatment, mRNA was extracted for the reverse transcription polymerase chain reaction (RT-PCR) and the difference was detected between the control group and the culture group that was treated withAd-hBMP-2 in doses of 50, 100 and 150 MOI so that the expressions of aggrecan and collagen ⅡmRNA could be observed. Results The expression of hBMP-2 in the cells was gradually increased after the transfection in an increasing dose, which was observed by immunofluorescence and the Western blot analysis. At 6 days the aggrecan and collagen type Ⅱ mRNA expressions were up-regulated by Ad-hBMP-2 after the transfection at an increasing viral concentration in the dosedependent manner. Conclusion The results show that Ad-hBMP-2 can transfect the rabbit intervertebral disc cells in vitro with a high efficiency rate and the expression of hBMP-2 after theinfection is dose-dependent in the manner. AdhBMP-2 after transfection can up-regulate the expression of aggrecan and collagen Ⅱ mRNA at an increasing viral concentration.
Objective To observe effects of the direct impaction onthe cell survival and the bone formation of the tissue engineered bone modified by the adenovirus mediated human bone morphogenetic protein 2 (Adv-hBMP2) gene and to verify the feasibility of the impacted grafting with it. Methods The marrow stromal cells (MSCs) were separated from the canine bone marrow and were cultured. MSCs were transfected with the Adv-hBMP2 gene and combined with the freeze-dried cancellous bone (FDB) to form the tissue engineered bone. Four days after the combination, the tissue engineered bone was impacted in a simulated impactor in vitro and implanted in the mouse. The cell survivals were evaluated with SEM 1 and 4 days after the combination, immediately after the impaction, and 1 and 4 days after the impaction, respectively. The bone formation and the allograft absorption were histologically evaluated respectively. Results There were multiple layers of the cells and much collagen on FDB before the impaction. Immediately after the impaction, most of the cells on the direct contact area disappearedand there was much debris on the section. Some of the cells died and separatedfrom the surface of FDB at 1 day, the number of the cells decreased but the collagen increased on the surface at 4 days. Histologically, only the fibrous tissue was found in FDB without the cells, the bone formation on FDB was even in distribution and mass in appearance before the impaction, but declined and was mainly on the periphery after the impaction in the AdvhBMP2 modified tissue-engineered bone. Conclusion The simulated impaction can decrease the cells survival and the bone formation of the AdvhBMP-2 modified tissue-engineered bone. The survival cells still function well.It is feasible to use the tissue engineered bone in the impaction graft.
Objective To evaluate the host immune reaction against adenovirus mediated human bone morphogenetic protein 2 (Adv-hBMP-2) gene therapy in repairof tibial defects. Methods Twelve goats were made 2.1 cm segmental defects in he tibial diaphysis and divided into 2 groups. AdvhBMP2 transfected marrow mesenchymal stem cells(MSCs) and untransfected MSCs were implanted into the defect sites of transfected group(n=7) and untransfected group (n=5), respectively. The defect repair was observed by X-ray films after 4, 8, 16 and 24 weeks of transplantation and cellular and humoral immune reactions to adenovirus were assayed before implantation and after implantation. Results More bony callus was found in the bone defects of transfected group. The healing rates were 6/7 in transfected group and 2/5 in untransfected group, respectively at 24 weeks after implantation. The mixed culture of lymphocytes and MSCs showed that the lymphocytes stimulation indexes (SI) increased 14 days after implantation, and there was significant difference between the transfected group (4.213±1.278) and the untransfected group(－0.310±0.147，Plt;0.05); SI decreased after 28 days, but there was no significant difference between the transfected group (2.544±0.957) and the untransfected group (3.104±0.644，Pgt;0.05). After 14, 28, 49, and 120 days of treatment, the titer values of neutralizing antibody against Adv-hBMP-2 (log0.1) were 2.359±0226, 2.297±0.200, 2.214±0.215 and 2.297±0.210 in transfected group, and -0.175±0.335, -0.419±0.171, 0±0.171 and 0.874±0.524 in untransfected group, being significant differences betweentwo groups(Plt;0.05). Conclusion Adenovirus mediated BMP-2gene therapy can cause cellular and humoral immune reactions against adenovirus, which can eliminate the influence of adenoviral genes and proteins within a certain period.
Objective To review the current concepts of gene therapy approachesmediated by adenovirus vectors for bone trauma and bone disease. Methods The recent literature concerned gene therapy mediated by adenovirus vectors was reviewed, which provides new insights into the treatments of bone trauma and bone disease. Results Adenovirus vectors was efficient, achieved high expression after transduction, and could transfer genes to both replicating and nonreplicating cells, such as osteoblasts, osteoclasts, fibroblasts, chondrocytes, bone marrow stromal cells, etc. Gene therapy mediated by adenovirus vectors achieved affirmative results in enhancing bone union and in curing bone diseases, such as osteoporosis and rheumatoid arthritis. Conclusion Gene therapy mediatedby adenovirus offers an exciting avenue for treatment of bone trauma and bone diseases.
ObjectiveTo construct recombinant adenovirus expressing nerve growth factor (NGF) and myelin associated glycoprotein (MAG) (Ad-NGF-MAG) and to investigate its effect on repair and regeneration of sciatic nerve injury in rats. MethodsNGF and MAG gene sequences were cloned into shuttle plasmid pCA13 of adenovirus type 5. After packed in HEK293 cells, the recombinant Ad-NGF-MAG underwent sequence and identification. Thirty-two male Sprague Dawley rats were randomly divided into 4 groups (n=8): control group (normal control), adenovirus vector group (Ad group), Ad-NGF group, and Ad-NGF-MAG group. The sciatic nerve injury model was established by transection of the right sciatic nerve; then, the empty adenovirus vector, Ad-NGF, and Ad-NGF-MAG were injected into the gastrocnemius muscle of the affected limb at a dose of 1×108 PFU every other day for 3 times in Ad group, AdNGF group, and Ad-NGF-MAG group, respectively. The right sciatic nerve was exposed only, and then the incision was closed in the control group. The sciatic nerve function index (SFI) was measured, and neuro-electrophysiology was observed; mRNA and protein expressions of NGF and MAG were detected by RT-PCR and Western blot; and histological examination was performed at 31 days after operation. ResultsRecombinant adenovirus vectors of Ad-NGF and Ad-NGF-MAG were constructed successfully. All rats survived and incision healed by first intension. The SFI, nerve conduction velocity, evoked potential amplitude, and latent period of Ad-NGF-MAG group were significantly better than those of Ad group and Ad-NGF group (P < 0.05). MAG mRNA and protein expressions of Ad-NGF-MAG group were the highest in all the groups (P < 0.05). The expressions of NGF mRNA and protein increased in Ad-NGF group and AdNGF-MAG group when compared with control group and Ad group (P < 0.05). Histological examination showed that the nerve had good continuity in control group; nerve fibers disarranged in Ad group; neurons connections formed in some nerve fibers of Ad-NGF group, but nerve fibers arrange disorderly; and the growth of the nerve were ordered and wellstructured in Ad-NGF-MAG group. ConclusionAd-NGF-MAG can effectively promote the growth of the nerve and inhibit the form of abnormal branches, facilitating the repair of sciatic nerve injury in rats.
Objective To construct AWP1 (associated with protein kinase C related kinase 1) recombinant adenovirus as the tool of transferring the gene and investigate its expression and localization in human vascular endothelial cell ECV304. Methods Cloned AWP1 cDNA was inserted into the multiply clone sites (MCS) of plasmid pcDNA3 for adding flag tag, and the flag-AWP1 gene was subcloned into shuttle vector pAdTrack-CMV. After identified with restrictional enzymes, plasmid pAdTrack-flag-AWP1 was linearized by digestion with restriction endonuclease PmeⅠ, and subsequently cotransformed into E.coli BJ5183 cells with adenoviral backbone plasmid pAdEasy-1 to make homologous recombination. After linearized by PacⅠ, the homologous recombinant adenovirus plasmid transfected into 293 cells with Lipofectamine to pack recombinant adenovirus. After PCR assay of recombinant adenovirus granules, recombinant adenoviruses infected 293 cells repeatedly for obtaining the high-level adenoviruses solution. And then, the recombinant adenoviruses infected human ECV304 cells for observing the expression and localization of AWP1 under laser scanning confocal microscope (LSCM). Results PCR assay showed that recombinant adenovirus Ad-flag-AWP1 was obtained successfully; and ECV304 cells were infected high-efficiently by the homologous recombinant virus. Then, it was observed that flag-AWP1 protein expressed in ECV304 cells and distributed in the leading edges of the cell membrane. Conclusion The vectors of flag-AWP1 recombinant adenovirus are constructed, and the localization of AWP1 protein in ECV304 cells might show that AWP1 may be a potential role on the cell signal transduction.
Objective To construct a recombinant adenovirus vector pAdxsi-GFP-NELL1 that co-expressing green fluorescent protein (GFP) and homo sapiens NEL-l ike 1 (NELL1) protein (a protein bly expressed in neural tissue encoding epidermal growth factor l ike domain), to observe its expression by transfecting the recombinant adenovirus into rat bone marrow mesenchymal stem cells (BMSCs) so as to lay a foundation for further study on osteogenesis of NELL1 protein. Methods From pcDNA3.1-NELL1, NELL1 gene sequence was obtained, then NELL1 gene was subcloned into pShuttle-GFP-CMV (-)TEMP vector which was subsequently digested with enzyme and insterted into pAdxsi vector to package the recombinant adenovirus vector (pAdxsi-GFP-NELL1). After verified by enzyme cutting and gel electrophoresis, pAdxsi-GFPNELL1 was ampl ified in HEK293 cells and purified by CsCl2 gradient purification, titrated using 50% tissue culture infective dose (TCID50) assay. The rat BMSCs were cultured and identified by flow cytometry and directional induction, then were infected with adenoviruses (pAdxsi-GFP-NELL1 and pAdxsi-GFP). NELL1 expression was verified by RT-PCR and immunofluorescence; GFP gene expression was verified by the intensity of green fluorescence under fluorescence microscope. Cell counting kit-8 (CCK-8) was used for investigate the influence of vectors on the prol iferation of rat BMSCs. Results Recombinant adenoviral vector pAdxsi-GFP-NELL1, which encodes a fusion protein of human NELL1, was successfully constructed and ampl ified with titer of 1 × 1011 pfu/mL. The primary BMSCs were cultured and identified by flow cytometric analysis, osteogenic and adipogenic induction, then were used for adenoviral transfection efficiency and cell toxicity tests. An multipl icity of infection of 200 pfu/cell produced optimal effects in transfer efficiency without excessive cell death in vitro. Three days after transfection with 200 pfu/cell pAdxsi-GFP-NELL1 or pAdxsi-GFP, over 60% BMSCs showed green fluorescent by fluorescence microscopy. Imunofluorescence with NELL1 antibody also revealed high level expression of human NELL1 protein in red fluorescent in these GFP expressing cells. RT-PCR analysis confirmed that the exogenous expression of NELL1 upon transfection with pAdxsi-GFPNELL1 at 200 pfu/cell, whereas NELL1 remained undetectable in Ad-GFP-transfected rat BMSCs. The prol iferative property of primary rat BMSCs after adenoviral NELL1 transfection was assayed by CCK-8 in growth medium. Growth curve demonstratedno significant difference among BMSCs transfected with pAdxsi-GFP-NELL1, pAdxsi-GFP, and no treatment control at 7 days (P gt; 0.05). Conclusion Recombinant adenovirus vector pAdxsi-GFP-NELL1 can steady expressing both GFP and NELL1 protein after being transfected into rat BMSCs. It provides a useful tool to trace the expression of NELL1 and investigate its function in vitro and in vivo.
Objective To explore the effects of bone marrow mesenchymal stem cells (BMSCs) transfected with adenovirus hepatocyte growth factor (Ad-HGF) on wound repair in diabetic rats. Methods BMSCs from male Wistar rats were isolated by density gradient centrifugation, cultured, and transfected with Ad-HGF. The multi pl icity of infection was 100. Diabetic models were establ ished in 20 female Wistar rats by diets in high fat and sugar plus intraperitoneal injection ofstreptozotocin (30 mg/kg). Then 2 full-thickness skin wounds (approximately 1.5 cm in diameter) were made on the dorsum. The rats were randomly divided into 4 groups (n=5 rats). After wounding, the 0.3 mL suspensions of BMSCs (group A), Ad- HGF (group B), BMSCs transfected with Ad-HGF (group C), and PBS (group D) were injected directly into the derma of wounds. The transverse diameter and longitudinal diameter of wound were measured at 21 days after treatment. At 7 days and 28 days after treatment, HE staining was performed to evaluate wound heal ing. The contents of hydroxyprol ine and advanced glycosylation end products (AGEs) in the wounds were measured by enzyme l inked immunosorbent assay and fluorospectrophotometer, respectively, at 3, 7, 14, and 28 days after treatment. Results At 21 days after treatment, the wounds almost healed in group C, and the transverse diameter and longitudinal diameter were 0 and (0.110 ± 0.024) cm, respectively. But the wounds healed partially in groups A, B, and D, and the transverse diameter and longitudinal diameter were (0.470 ± 0.051) cm and (0.590 ± 0.041) cm, (0.390 ± 0.042) cm and (0.480 ± 0.032) cm, and (0.700 ± 0.068) cm and (0.820 ± 0.068) cm, respectively. There were significant differences in wound heal ing between group C and groups A, B, and D (P lt; 0.05). The wound heal ing time of group C [(20.5 ± 1.9) days] was significantly shorter (P lt; 0.05) than those of groups A, B, and D [(28.3 ± 1.9), (25.9 ± 2.3), and (36.6 ± 5.1) days]. At 7 days, the HE staining showed that evident epidermis transportation, collagen formation, and leukocytes infiltration were observed in group C. At 28 days, the HE staining showed that the epidermis in group C was significantly thinner and more regular than those in other groups, and the decreased collagen and many small vessels were observed in group C. The content of hydroxyprol ine in group C was higher than those in groups A, B, and D at 7 days and 14 days (P lt; 0.05). The contents of AGEs in group C was lower than those in groups A, B, and D at 14 days and 28 days (P lt; 0.05). Conclusion Transplantation of BMSCs transfected with Ad-HGF can accelerate the wounds repair in diabetic rats.