ABSTRACT
@#[摘 要] 目的：制备双特异性CAR-T（bsCAR-T）细胞，观察其对表达表皮生长因子Ⅲ型突变阳性（EGFRvⅢ+，简称vⅢ+）和CD133+胶质瘤干细胞的靶向杀伤作用。方法：基于前期研制的vⅢ/CD133双特异性微抗体和二代CAR构建的双特异性CAR（bsCAR），制备慢病毒载体转染人外周血T细胞，FCM和WB法检测bsCAR转染效率和表达水平。bsCAR-T细胞和vⅢ+/CD133+ U87胶质瘤干细胞共培养，乳酸脱氢酶（LDH）释放实验、IFN-γ分泌实验检测其特异性杀伤作用和对IFN-γ分泌的促进作用。制备裸鼠vⅢ+/CD133+ U87干细胞移植瘤模型检测bsCAR-T细胞对移植瘤生长的抑制作用。结果：vⅢscFv和CD133scFv通过重叠PCR无缝连接入二代CAR表达框（S-vⅢscFv/CD133scFv-Hinge-TM-CD137-CD3z）中，然后克隆入pCDH-MSCV-MCS-EF1-copGFP载体的EcoRⅠ和BamHⅠ位点（pbsCAR）。3种质粒（pVSV-G、pCMV-dR8.9和pbsCAR）共转染HEK293T细胞制备慢病毒载体，转染外周血T细胞，FCM检测bsCAR表达率为71.1%，WB法结果显示bsCAR表达正确。bsCAR-T细胞和vⅢ+/CD133+ U87干细胞共培养检测结果显示，bsCAR-T细胞对胶质瘤干细胞具有特异性杀伤作用，与效靶比呈正比；IFN-γ分泌量为（2 350.6±92） pg·mL-1，明显高于对照组（P<0.01）。裸鼠移植瘤动物模型显示，bsCAR-T细胞在体内具有明显的移植瘤抑制作用（P<0.01）。结论： bsCAR-T细胞能够特异性靶向杀伤vⅢ+/CD133+胶质瘤干细胞，实验结果为促进实体瘤的细胞免疫治疗提供了实验依据。
ABSTRACT
@#Objective: To explore the gene transduction method of chimeric antigen receptor (CAR) mediated by novel cationic polymer nanocarrier mPEG-P (Asp-AED-g-HFB) (PAEF) and PigyBac transposon system to modify natural killer (NK) cells, providing a new strategy for immunotherapy of cancer cells. Methods: PAEF/DNA (transposase+transposon) complex were prepared. The particle size distribution and surface potential of PAEF/DNA complexes were measured with Nano-ZSE Dynamic Light Scattering System (Malvern Instruments). The DNA encapsulation rate, release and stability of PAEF were evaluated by DNA gel electrophoresis, and then by combiningwithparticlesizeandsurfacepotentialtodeterminethepreferentialN/PratiotoenterNKcells.Thecell cytotoxicity of PAEF/DNA complexes under different N/P ratios was analyzed by CCK-8 cytotoxicity test. Transduction efficiency of NK cells was evaluated by Fluorescence microscopy and Flow cytometry, and the feasibility of PAEF gene transfection vectors was assessed. Results: PAEF could encapsulate DNA to form nano-complexes with the diameter of 100-150 nm, which was suitable to mediate DNA entering into cells. PAEF could completely encapsulate DNA with N/P ratio of 20. In the presence of reducing agent dithiothreitol (DTT), PAEF had a good ability to release DNA. NK-92 cells transfected with PAEF/DNA complex, which was formed at the N/P ratio of 80, attained a significantly higher cell viability than cells of lipofectamine transfection group [(72.50±3.9)% vs (64.03±1.8)%, P<0.05]; Fluorescence microscopic observation showed more fluorescence and higher fluorescence intensity in cells of PAEF/DNA group; Flow cytometry showed the highest transfection efficiency of 83.4%. Conclusions: Nanocarrier PAEF can encapsulate DNA well by electrostatic adsorption, and has good biocompatibility and high efficiency for gene transduction. It provides a good experimental basis for adoptive immunotherapy.
ABSTRACT
@#[Abstract] Objective:To prepare the third generation CAR-T cells targeting EGFRvⅢ (EGFRvⅢCAR-T) and to detect its specific killing effect against EGFRvⅢ+ U87 cells in vitro and in vivo. Methods: Human CD3+ T cells were transfected with lentiviral EGFRv Ⅲ/3CAR, which was generated by calcium phosphate co-precipitation of three plasmids. The expression of EGFRvⅢ/3CAR in T cells was detected by Western blotting and flow cytometry. In vitro killing effect of EGFRvⅢ/3CAR-T cells on EGFRvⅢ+ U87 cells was detected by 51Cr release assay. The secretion of cytokine IFN-γ of EGFRvⅢ/3CAR-T cells was detected by ELISA. Nude mouse xenograft model was constructed to detect the in vivo cytotoxicity of EGFRvⅢ/3CAR-T cells on xenograft tumor. Results: The EGFRvⅢ/3CAR lentivirus was successfully packaged with an average titer of 5×106 TU/ml. Western blotting showed that a protein band of approximate 58 000 molecular weight was observed in EGFRvⅢ/3CAR-T cells but absent in untransfected T cells. Flow cytometry indicated the average transduction efficiency of EGFRvⅢ/3CAR was 52.3%. 51Cr release assay showed that the specific killing effect of EGFRvⅢ/ 3CAR-T cells was positively correlated with E/T ratio (E∶T=4∶1, 8∶1, 16∶1, 32∶1). ELISA showed that cytokine IFN-γ secretion was (1 836±148.2) pg/ml, which was significantly different from that of NTT and GFP+ T cells (P<0.01). The specific killing activity of EGFRvⅢ/3CAR-T cells and IFN-γ secretion were both dependent on the expression level of EGFRvⅢ in U87 cells. The tumor growth monitoring results showed that the tumor volume of EGFRvⅢ/3CAR-T cell group was significantly different from that of GFP+ T cell group and PBS group around 3 weeks after injection (P<0.01). Conclusion: EGFRvⅢ/3CAR-T cells demonstrated specific antitumor effectagainstEGFRvⅢ+U87cellsbothinvitro and in vivo, providing basis for immunotherapyofgliomainfuture clinical use.
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@#[Abstract] Glioblastoma multiforme（GBM）is a malignant tumor of central nervous system with high incidence, aggressive and poor prognosis. Since temozolomide was approved by FDAin 2005, there is no new curative strategy with obvious improvement in therapeutic effect. With the developments in molecular biology, tumor immunology and immunotherapy technology, the discovery of new molecular targets, breakthrough in central immunization exemption theory, and advance in gene transduction and cell technology, GBM immunotherapy ushered in a new breakthrough in immunotherapy. Cellular immunotherapy, presented by chimeric antigen receptor-modified T cell (CAR-T) therapy, has exhibiteditsprominentapplicationprospectinGBMinvitro experimentstargetingEGFRvIII, IL-13Rα2, HER2, erythropoietin-producing hepatocellular carcinomaA2 (EphA2), animal models and early clinical trials. However, the GBM molecular heterogeneity, immunosuppressive microenvironment and blood-brain barrier have presented challenge for CAR-T going into the first-line clinical treatment. Researchers are now exploring key antigens of oncogenic phenotype, designing optimal combination of target antigens to prevent the immune escape, improving CAR-T passing through blood-brain barrier and invading tumor tissue, finding the best route for cell deliver, and optimizing evaluation system for central nervous system (CNS) immunotherapy. It is believed that the breakthrough of CAR-T cell immunotherapy will finally help GBM patients pursuing a beautiful life.
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@#[Abstract] Objective： ： To explore the impact of γ-chain (γc) family cytokines (IL-2, IL-7, IL-15, IL-21) on T cell phenotypes in ex vivo culture to provide experimental evidence for ex vivo cell preparation in adoptive immunotherapy. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from peripheral blood of healthy volunteers; nylon column sorting, CD3+ magnetic beads sorting, CD3- magnetic beads sorting and natural sedimentation were used to sort T cells from PBMCs. The purity, recovery rate and viability of T cells sorted by the above methods were compared. The CD3/CD28 magnetic beads-activated CD3+T cells were cultured inAIMV medium with IL-2 or mixed cytokines (IL-7, IL-15, IL-21). The expansion fold and phenotypes of T cells in ex vivo culture were detected by flow cytometry. Results： ： The purity of T cells sorted by CD3- magnetic beads sorting was significantly higher than that sorted by nylon column, CD3+ magnetic beads sorting and natural sedimentation ([94.06±1.07]% vs [86.74±1.06]%, [89.61±1.40]%, [88.48 ± 1.86]%, P<0.05); The recovery rate of T cells sorted by natural sedimentation was significantly higher than that by other three methods ([60.29±1.53]% vs [45.03±2.79]%, [20.15±3.41]%, [42.98±2.82]%, P<0.05). Comprehensively, the natural sedimentation method is the best option. The ex vivo expansion fold of T cells in IL-2 group was significantly higher than that in mixed group ([262.6±143.2] times vs [73.0±25.8] times, P<0.05). The proportions of early memory T cells, Tscm+Tscm-like and Tcmin the mixed group were significantly higher than those in the IL-2 group ([55.6±1.82]% vs [39.6±1.52]%, [16.6±1.82]% vs [9.8±1.30]%, [39.0±1.58]% vs [29.2±1.79]%; all P < 0.05). Conclusion： ： Natural sedimentation sorting has advantages of low cost, high recovery and purity. Mixed cytokines of IL-7, IL-15 and IL-21 are beneficial for production of early memory T cells. This study provides an experimental data of ex vivo T cell preparation for cancer adoptive immunotherapy.
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@#[Abstract] EGFRvIII (epidermal growth factor receptor variant Ⅲ) is the most common mutant of epidermal growth factor receptor, which expresses in over 30% glioblastoma multiforme (GBM). EGFRvIII results from deletion of exon 2-7, leading to its constitutive activation, which is closely related to tumorigenesis, development and poor prognosis of GBM. The unique glycine site on EGFRvIII provides ideal molecular target for immunotherapy, which possess great potential value of killing GBM cell, inhibiting progress and invasion. Encouraging progress has been achieved in peptide/DC vaccine, therapeutic antibody, small molecular inhibitor and adoptive immunotherapy experimentally and clinically. The characteristics of EGFRvIII and the development in its oriented immunotherapy were summarized in this review.