Human brain tumor cell culture characterization after immunostimulatory gene transfer

OBJECTIVE: Immunogene therapy is a novel cancer treatment strategy based on vaccination with irradiated autologous tumor cells transduced with immunostimulatory genes. To characterize such cells before clinical applications, we studied a human glioma cell line (D54 MG) and early passage human glioma (Ed147.BT, Ed149.BT) and melanoma (Ed141.MEL) cultures after immunostimulatory gene transfer. METHODS: Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-12 (IL-12), and B7-2 genes were retrovirally transferred to tumor cells. Gene expression before and after irradiation (200 Gy) was assessed by enzyme-linked immunosorbent assay (GM-CSF, IL-12) and flow cytometry (B7-2). Viability and clonogenicity were determined via trypan blue staining before and after irradiation. Growth rates were determined by serial cell counts. RESULTS: GM-CSF expression was high in GM-CSF-transduced (10.36-162.10 ng/10(6) cells/d preirradiation and 10.22-122.02 ng/10(6) cells/d postirradiation) but lower in B7-2/GM-CSF-transduced cultures (1.41-2.90 ng/10(6) cells/d preirradiation, 1.96-5.02 ng/10(6) cells/d postirradiation). IL-12 expression also was lower (1.30-2.10 ng/10(6) cells/d preirradiation, 0.47-1.70 ng/10(6) cells/d postirradiation). B7-2 expression was high (one- to two-logarithm increase in fluorescence) and unaffected by radiation. Postirradiation viability was initially high (94.20 +/- 8.46%, Day 1) but decreased rapidly (28.13 +/- 4.64%, Day 10). No cultures demonstrated evidence of clonogenicity (i.e., cell division) after 200-Gy irradiation. Growth rates were similar in wild-type and gene-transduced Ed141.MEL, Ed147.BT, and Ed149.BT. However, D54MG-IL-12 growth was slower than that of wild-type D54MG. CONCLUSION: GM-CSF, IL-12, and B7-2 genes can be transferred to human glioma and melanoma cell cultures efficiently by use of our retroviral vectors. Irradiation (200 Gy) does not significantly alter therapeutic gene expression. Irradiated cells remain viable for several days but cannot undergo further cell division. Early passage culture growth rates are not altered by therapeutic gene expression but are decreased by IL-12 in an immortalized cell line (D54MG). These results suggest that it is feasible to create vaccines with irradiated, autologous, genetically modified brain tumor cells.     

Glucagon-like polypeptides in canine brain.

Glucagon-like material has been detected by radioimmunoassay in several areas of the canine brain. High concentrations of glucagon-like immunoreactivity (GLI), measured with antibodies directed against the N-terminal region of glucagon, have been found in the hypothalamus, amygdala, and mesencephalon, but a high concentration of immunoreactive glucagon (IRG), measured with antibodies directed against the C-terminal region of glucagon, has been found only in the hypothalamus. The predominant molecular forms of GLI isolated from brain extracts by affinity chromatography are the same as those isolated from gut extracts. The predominant form of IRG in brain extracts is of the same (approximate) molecular weight as pancreatic glucagon.     

Limited efficacy of gene transfer in herpes simplex virus-thymidine kinase/ganciclovir gene therapy for brain tumors

OBJECT: Low efficacy of gene transfer, transient gene expression, and toxicity of viral vectors are the major hurdles in successful anticancer gene therapy. The authors conducted in vitro (U87MG cell line) and in vivo (xenograft, tumor-bearing rodent model) studies to address the stability of transduction by using the adenoassociated virus serotype-2 (AAV2)-thymidine kinase (TK) vector over time. METHODS: Standard methods for cell growth and a ganciclovir (GCV) cytotoxicity assay were applied. The AAV2-TK was infused into implanted tumors in athymic rats via convection-enhanced delivery (CED). Thymidine kinase expression was evaluated through immunohistochemical analysis, and the distribution volumes of the transduced tumors were calculated. Twenty-four hours following the viral infusions, animals were treated with GCV (50 mg/kg intraperitoneally every day for 10 days; six rats) or phosphate-buffered saline (six rats). A rapid decrease in TK expression over time was observed both in vitro and in vivo. A large volume of the tumor (up to 39%) was transduced with AAV2-TK following CED. Administration of GCV resulted in limited therapeutic effects (survival of 25.8 compared with 21.3 days). CONCLUSIONS: Rapid elimination of TK expression from dividing tumor cells and focal transduction of the brain tumor were most likely responsible for the limited bystander effect in this approach. Immediate administration of GCV is crucial to assure maximal efficacy in the elimination of cancer cells. In addition, the complete or diffused transduction of a brain tumor with TK may be required for its total eradication.     

Microsurgical transfer of the greater omentum in the treatment of canine obstructive lymphoedema

In 13 dogs, experimental obstructive lymphoedema of the lower limb was created by combined radiotherapy and radical groin dissection. Six months later, when the degree of lymphoedema was stable, the lymphatic obstruction was bridged by microvascular insertion of a free omental graft. Six months after grafting, circumferential measurements indicated a statistically significant 38% reduction in the magnitude of lymphoedema. Biopsies showed the omental grafts were alive but contained much fibrous tissue. Lymphatic vessels were identified in 10 of 11 biopsies but connections between these lymphatics and lymphatics proximal to the graft could not be demonstrated by either lymphangiography or dye-injection techniques. The findings indicate that experimental obstructive lymphoedema in the dog can be reduced significantly by insertion of a vascularised omental graft. However, it could not be established that improvement was due to union of graft lymphatics with those of the lymphoedematous limb, although this union may have consisted of lymphatics too small to be demonstrated.     

Lymph node transfer for the treatment of obstructive lymphoedema in the canine model

The efficacy of transferring vascularised lymph nodes into lymphoedematous limbs was investigated. Stable below-knee lymphoedema was established in one hind limb of 10 dogs. The superficial inguinal lymph node and perinodal tissue from the normal hind limb was moved to the popliteal region of the lymphoedematous leg as a free vascularised transfer. In five dogs lymphaticolymphatic anastomoses between lymphatics of the node and proximal recipient site lymphatics were also performed. Circumferential measurements of the foot, ankle and midleg were obtained preoperatively and postoperatively at 3 and 6 months. These measurements showed postoperative reduction of the lymphoedematous legs compared to controls, with no added benefit from lymphaticolymphatic anastomoses. Technetium 99 scans and lymphangiography demonstrated re-establishment of lymphatic continuity in all recipient legs at 3 and 6 months post-transfer. Histological examination at 3 and 6 months revealed normal architecture in 9 of 10 nodes, although areas of lymphocyte depletion were common. Vascularised lymph node transfer to a lymphoedematous leg re-established lymphatic continuity and resulted in partial reduction of limb size. The addition of lymphaticolymphatic anastomosis to vascularized node transfer is neither necessary nor beneficial.     

High-level expression of recombinant human tPA in cultivated canine endothelial cells under varying conditions of retroviral gene transfer.

Successful genetic transduction of endothelial cells (EC) provides a theoretic means of increasing luminal secretion of tissue-type plasminogen activator (tPA) and lessening arterial and venous thrombotic processes. To identify the duration and number of retroviral exposures for an optimal tPA expression, enzymatically derived adult canine jugular venous EC were subjected to different exposure regimens using an amphotropic murine retroviral vector, MFG, containing the human tPA gene. Human tPA antigen secretion and its functional activity were determined at 2 days (subconfluent cells) and 14 days (confluent cells) after retroviral exposure. High-level secretion of human tPA was detected among transduced EC in all experimental groups. No secretion of human tPA occurred in control EC exposed to media alone. At 2 days after transduction, no significant differences in tPA secretion rates occurred among the different exposure regimens. At 14 days, the 12-hour X two-exposure group exhibited higher tPA secretion rates than all other exposure regimens (analysis of variance, p < 0.05). All exposure groups at 14 days exhibited significantly higher tPA secretion compared with those at 2 days (analysis of variance, p < 0.05). The presence of retroviral sequences in the genome of transduced EC was confirmed by Southern blot analysis. At 14 days, increased EC numbers were observed in vector-exposed wells compared with controls. Human tPA functional activity paralleled tPA antigen secretion. Genetically modified canine EC are capable of high levels of constitutive expression of human tPA after relatively short exposures to a retroviral vector containing the reporter gene. Increased cell number of tPA-transduced EC in culture suggests that tPA also may have other biologically important effects. These results support the efficacy of MFG-tPA gene transfer as a means of genetically modifying EC fibrinolytic activity and establishes the potential of this technology in vivo.     

Vascularized autogenous canine coccygeal bone transfer.

Based on cadaver studies in dogs, the 8th, 9th, or 10th canine coccygeal vertebra with overlying skin was designed for free vascularized bone transfer. In six dogs the coccygeal osteocutaneous flap was transferred to fill a defect of the tibia, anastomosing the median caudal artery and one of the two caudal veins to the tibial vessels. The overlying skin provided a reliable monitoring system for the transferred tissue. The behavior of the vascularized coccygeal vertebrae was then evaluated with radiographic and histologic examination and compared with control vertebrae transferred without reconnection of the blood vessels. The results revealed that the canine coccygeal bone graft is a reliable vascularized osteocutaneous flap, which can be applied either in clinical veterinary surgery or in orthopedic microsurgical research.     

Efficacy and safety of the Nd:YAG laser in canine partial nephrectomy

Partial nephrectomy using 100 watts of focused Neodymium: Yttrium Aluminum Garnet (Nd:YAG) laser power was evaluated to determine its hemostatic capabilities, safety, and effect on renal function and histology. Six adult female dogs ranging from 22 to 33 lbs. underwent nephrectomy and contralateral partial nephrectomy using the laser. Closure of the collecting system and drains were not used to determine if the laser could seal the collecting system. There was no blood loss with this technique. Four of the 6 dogs had no postoperative complications but two had urinary extravasation which led to death in one dog and required drainage in another. One month postoperative serum creatinine levels were 66 per cent higher than pre-operative values. Intravenous urograms revealed no evidence of dilation of the collecting system nor contrast extravasation. The depth of necrosis ranged from 4 mm. in the cortex to 7 mm. in the medulla. The data indicate that Nd:YAG laser partial nephrectomy is effective, and provides complete hemostasis, manageable urinary extravasation and acceptable impairment of renal function.     

严重烧伤犬早期脑水肿模型的建立

目的　建立一种严重烧伤早期犬的脑水肿模型。　方法　采用凝固汽油体表烧伤制成 5 0 %TBSAⅢ度烧伤犬模型。随机将实验组分为单纯烧伤组 ,乳酸钠液组和葡萄糖液组 ,于伤后 6、12、18、2 4h各时相点观察大体形态及镜下 (光镜 ,电镜 )组织变化 ,计算脑含水量 ,用99锝一半双胱乙酯 (99TCm-ECD)观察血脑屏障的变化。　结果　伤后 6h犬脑即出现早期脑水肿的组织学改变 ,部分毛细血管内皮及血管周围星形细胞肿胀 ,毛细血管内皮细胞、神经细胞及轴突不同程度的缺血坏死。随着伤后时间的延长 ,这种改变逐渐明显。实验各组伤后 6h脑含水量与对照组比较即有增加 ,而以葡萄糖液组伤后 2 4h增高最为显著 (P <0 .0 1)。脑核素显像显示单纯烧伤组及葡萄糖液组伤后 6h开始即出现逐渐明显的脑组织核素浓集。　结论　严重烧伤早期犬脑水肿模型的建立 ,为临床对严重烧伤后脑水肿的防治研究提供了形态学基础 ,是一种具有较好稳定性和可重复性的脑水肿动物模型     

多聚乙烯亚胺介导IL-12基因增强裸鼠抗骨肉瘤免疫

目的 :观察以多聚乙烯亚胺 (polyethylenimine ,PEI)为载体 ,体内转染小鼠白细胞介素 12 (inter leukin 12 ,mIL 12 )基因 ,治疗裸鼠骨肉瘤模型的疗效。方法 :以PEI为载体 ,体外转染mIL 12基因入人骨肉瘤细胞 ,并观察此基因表达情况。建立裸鼠骨肉瘤动物模型 ,将PEI包裹mIL 12基因直接注入肿瘤局部 ,检测此基因的蛋白表达情况和小鼠脾脏自然杀伤细胞 (NK)活性。结果 :在PEI/DNA治疗组小鼠的肿瘤局部 ,mIL 12蛋白水平明显升高 ,小鼠脾NK细胞活性增强。结论 :PEI可以成功的将mIL 12基因导入裸鼠骨肉瘤模型 ,mIL 12基因治疗可提高机体的抗肿瘤免疫应答     

Immune transfer studies in canine allogeneic marrow graft donor-recipient pairs

Transfer of immunity occurring with bone marrow grafting was studied using the dog as a preclinical model. Allogeneic bone marrow transplantation (BMT) was performed between DLA-identical beagle litter-mates. The donors were immunized with tetanus toxoid (TT) or sheep red blood cells (SRBC), and their humoral response was monitored by hemagglutination. The recipients of bone marrow from TT-immunized donors showed a marked increase of antibody titer one week posttransplantation, while in the recipients of marrow from SRBC immunized donors the antibody titers were considerably lower. Within the following 60 days the antibody titers in both groups diminished gradually to pregrafting levels. Control experiments in which cell-free plasma from donors immunized with TT and SRBC respectively was transfused indicated that the initial rise of specific antibody titers after marrow grafting is likely to be due to a passive transfer of humoral immunity. A single challenge of these marrow graft recipients with the respective antigen 15-18 weeks posttransplantation led to a secondary type of humoral immune response. In addition, it could be demonstrated that transfer of memory against TT or SRBC was independent from the actual antibody titer and the time of vaccination of the donor. One dog was immunized with TT after serving as marrow donor. When the donor had shown an antibody response, a peripheral blood leukocytes (PBL) transfusion was given to his chimera. Subsequent challenge of the latter resulted in a secondary type of specific antibody response. This indicates that specific cellular-bound immunological memory can be transferred after BMT from the donor to his allogeneic bone marrow chimera by transfusion of peripheral blood leukocytes. The data presented may be of importance in clinical BMT to protect patients during the phase of reduced immune reactivity by transfer of memory cells from histocompatible immunized donors.     

Myoblast-mediated gene transfer to the joint

Several genetic and acquired pathologic conditions of the musculoskeletal system, such as arthritis and damage to ligament, cartilage, and meniscus, may be amenable to gene therapy. Even though ex vivo gene transfer with synovial cells has been shown to deliver genes encoding for anti-arthritic proteins into the rabbit knee joint, its success has been limited by a transient transgene expression, In this study, data were investigated regarding the use of muscle cells as an alternative gene-delivery vehicle to the joint in newborn rabbit and adult severe combined immunodeficiency mice. We demonstrated that myoblasts were transduced more efficiently than synovial cells with use of the same adenoviral preparation in vitro. After intra-articular injection, the engineered muscle cells adhered to several structures in the joint, including the ligament, capsule, and synovium. In addition, myoblasts fused to form many post-mitotic myotubes and myofibers at different locations of the joint of the newborn rabbit 5 days after the injection. In the knee of the adult mouse, myoblasts fused and expressed the reporter gene for at least 35 days after the injection. The presence of post-mitotic myofibers in the knee joint raises the possibility of long-term expression of the secreted protein. Currently, numerous tissues in the joint (ligament, meniscus, and cartilage) have poor intrinsic healing capacity and frequently need surgical corrections. A stable gene-delivery vehicle to the joint producing proteins that ameliorate these different musculoskeletal conditions may change the clinical implications of these pathologies.     

Adenoviral gene transfer in the peripheral nervous system

Background Viral vectors have gained widespread use as vehicles for somatic gene transfer, and the targeted expression of foreign proteins by these vectors offers advantages over the systemic administration of the drugs in some therapeutic situations. Selective virus-mediated gene transfer to the peripheral nervous system (PNS), however, remains to be established. There are no data showing efficiency of protein transduction in the PNS, which consists of a variety of cell types, many of which are postmitotic. Methods We prepared the first-generation replication-deficient recombinant adenovirus vectors engineered to express LacZ. Eight-week-old Wister rats were used in this study. Adenovirus vector (5 μl) containing the LacZ gene (5 × 10⁸ pfu) was injected into rat sciatic nerves or the dorsal root ganglia at the level of L5. The sciatic nerves, the dorsal root ganglia, and the spinal cords were obtained 7, 14, 21, and 28 days after injection. Expression of LacZ was assessed by X-gal histochemistry and β-gal immunohistochemistry. Results Following injection of the adenovirus carrying the LacZ gene into the sciatic nerve, LacZ expression was seen mainly in the Schwann cells and the small neurons in the dorsal root ganglion. In contrast, expression was observed in the primary nerve terminals of the spinal dorsal horn and the small to large dorsal root ganglion neurons and the Schwann cells after injection of the vectors into the L5 dorsal root ganglion. There were no side effects in rats with injection in the dorsal root ganglia or the sciatic nerve. Conclusions The present study shows efficient protein transduction by adenovirus vectors in the PNS. It is noted that injection of the virus into the dorsal root ganglia leads to extensive expression of LacZ in the spinal cord, the dorsal root ganglia, and the sciatic nerves.     

转基因治疗脊髓损伤的研究进展

脊髓损伤(SCI)一直是困扰医学界的一大难题。近年来神经干细胞(NSCs)的培养成功为破解这一难题带来了希望。然而,NSCs移植后在中枢神经系统只有很少一部分能存活和分化为神经元[1]。而且分化为神经元的细胞通常不能形成轴突而成为有功能的神经元[2]。自Blaese等1990年首次对腺苷脱胺酶(ADA)缺乏严重联合免疫缺陷症患者成功地进行基因治疗以来,基因治疗已成为当前生物医学中进展最快的学科之一,为解决许多医学难题带来了曙光。近年来这一技术也应用于SCI修复的研究。其结果令人振奋。现就SCI后转基因治疗研究现状作一综述。1载体及受…     

Reevaluation of an experimental streptococcal canine brain abscess model

An experimental cerebral abscess model in which alpha-hemolytic Streptococci were inoculated into the brain parenchyma of dogs was evaluated for assessment of antimicrobial therapy. Intracerebral ring-enhancing lesions were visualized by computerized tomography, but they resolved after time without therapeutic intervention. Histopathological study demonstrated evolution of the lesions into sterile granulomas. Quantitative cultures were performed and uniformly became sterile in the early cerebritis stage, approximately 3 days after bacterial inoculation. Therefore, this brain abscess model should not be utilized for the evaluation of new antimicrobial treatment regimens. Rather, other models which document persistent viable organisms within cerebral abscesses need to be developed.