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@#[Abstract] Objective: To develop a new type of CD7 chimeric antigen receptor modified T cell (CD7-CAR-T) for the treatment of CD7 positive acute myeloid leukemia (AML), and to observe its killing effect on CD7 positive AML cells. Methods: The CD7-CAR lentiviral vector was constructed based on the CD7 Nanobody sequence and costimulatory domain sequence of CD28 and 4-1BB. The lentiviral particles were packaged and used to co-transfect human T cells with protein expression blocker (PEBL), so as to prepare CD7- CAR-T cells. Real time cellular analysis (RTCA) was used to monitor the cytotoxicity of CD7-CAR-T cells on CD7 overexpressed 293T cells. Flow cytometry assay was used to detect the effect of CD7-CAR-T cells on proliferation and cytokine secretion of AML cells with high, medium and low CD7 expressions (KG-1, HEL and Kasumi-1 cells, respectively). Results: CD7-CAR-T cell was successfully constructed and its surface expression of CD7 was successfully blocked. Compared with T cells, CD7-CAR-T cells could significantly inhibit the proliferation of CD7-293T cells and promote the release of TNF, Granzyme B and INF-γ; in addition, CD7-CAR-T cells also significantly promoted the apoptosis (t=147.1, P<0.01; t=23.57, P<0.01) and cytokine release (P<0.05 or P<0.01) in CD7 positive KG-1 and HEL cells, but had little effect on Kasumi-1 cells that only expressed minimal CD7 antigen (t=0.7058, P>0.05). Conclusion: CD7-CAR-T cells can specifically kill CD7-positive AML cells in vitro.
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@# Objective: To investigate the expression and clinical significance of PD-1 molecule in tumor cells (T-ALL cells) derived from the patient with T-cell acute lymphoblastic leukemia (T-ALL). Methods: T-ALL cells from one patient and PBMCs from four healthy volunteers provided by the Department of Hematology in Jiangsu Provincial Hospital of Traditional Chinese Medicine in December 2015, and human 293T/PD-1 cells provided by Persongen Bio Therapeutics (Suzhou) Co., Ltd. were used for this study. The mouse T-ALL xenograft model was constructed by injecting T-ALL cells into tail vein of B-NDG mice, and flow cytometry was used to verify whether the cells obtained from the spleen of transplanted mice were mainly consisted of T-ALL cells. Flow cytometry was used to study the protein expression of PD-1 in T-ALL cells, and RT-PCR was applied to further verify the mRNA expression of PD-1 in T-ALL cells. The PD-1 gene in T-ALL cells was sequenced by SNP genotyping to detect whether the DNA sequence of PD-1 gene changed. PD-1 inhibitor was used in vitro to study their effects on proliferation, apoptosis, and the mRNA expression levels of related factors in T-ALL cells. Results: The mouse T-ALL xenograft model was successfully constructed and verified by flow cytometry as T-ALL. PD-1 was highly expressed at both mRNA and protein levels in T-ALL cells (all P<0.01). A C-to-T mutation was detected in the fifth exon of the PD-1 gene. PD-1 inhibitor had no significant effect on proliferation and apoptosis of T-ALL cells in vitro; PD-1 inhibitor up-regulated the mRNA expression of tumor-suppressor protein IGFBP3 and decreased the mRNA expression of oncoprotein SULT1A3 (all P<0.01). Conclusion: PD-1 is highly expressed in T-ALL cells, and PD-1 could be used as a target for clinical diagnosis and treatment for T-ALL.
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@#[Abstract] Objective：To investigate whether the proliferation and cytotoxicity of NK-92MI cells can be improved by IL-7 and IL-21 genes modification, and determine the effects of this genetically modified NK-92MI cells on T cells from normal human peripheral blood. Methods：IL-7 and IL-21 gene fragments were constructed into electroporation vector by genetic engineering method, and NK92MI/IL-21 and NK-92MI/IL-7&21 cells were constructed by electroporation transfection. The in vitro proliferation and cytotoxicity of NK-92MI, NK-92MI/IL-21 and NK-92MI/IL-7&21 cells were measured by cell count and flow cytometry assays. Then, normal human PBMCs were co-cultured with NK-92MI, NK-92MI/IL-21 and NK-92MI/IL-7&21 cells in vitro respectively, and the phenotype change of T cells was measured by flow cytometry. In addition, the cytotoxicity between the activated T cells and three NK-92MI cell lines (NK-92MI, NK-92MI/IL-21 and NK-92MI/IL-7&21 cells) as well as the cytotoxicity of the three NK-92MI cells on tumor cells after co-incubation with activated T cells were detected. Results: NK-92MI/IL-21 cell line (highly expressing IL-21) and NK-92MI/IL-7&21 cell line (highly expressing both IL-7 and IL-21) were successfully constructed. The toxicity of NK-92MI, NK-92MI/IL-21 and NK92MI/IL-7&21 cells on Jurkat and K562 cells showed no difference, while the proliferation of NK-92MI/IL-21 and NK-92MI/IL-7&21 cells was increased compared with NK-92MI cells. Furthermore, NK-92MI/IL-21 and NK-92MI/IL-7&21 cells promoted the activation of T cells to a certain degree, and the activated T cells showed merely no cytotoxicity on NK-92MI, NK-92MI/IL-21 and NK-92MI/IL7&21 cells; Meanwhile, the activated T cells did not affect the cytotoxicity of the three NK cells (NK-92MI, NK-92MI/IL-21, and NK92MI/IL-7&21 cells) on K562 cells under their co-existence. Conclusion: The in vitro proliferation of NK-92MI/IL-21 and NK-92MI/ IL-7&21 cells were enhanced after gene modification, which could also stimulate and promote the activation of T cells from peripheral blood. The cytotoxicity assay showed that the activated T cells had no cytotoxicity on NK-92MI, NK-92MI/IL-21, and NK-92MI/IL-7& 21 cells. Meanwhile, the presence of the activated T cells did not affect the cytotoxicity of NK-92MI cells.
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@#[Abstract] Objective: To investigate the in vitro cytotoxicity of the chimeric antigen receptor-modified T cells and NK-92MI cells (CAR-NK-92MI cells) and CAR-CD19-T cells against mantle cell lymphoma (MCL). Methods: CAR-T cell technology, successfully obtained in clinical trial of B-lineage acute lymphoblastic leukemia (B-ALL) treatment, was used in this study. In the case of high expression of CD19 antigen in MCL, CAR- CD19-T cells and CAR- CD19-NK-92MI cells targeting CD19 antigen were generated, respectively. Then, their cytotoxicity against MCL cell lines was detected by LDH release assay and the results were verified by flow cytometry. Results: Compared with control group, both CAR-NK-92MI and CAR-CD19-T cells exhibited prominent killing effect against MCLcells（all P<0.01）; in addition, the two CAR cells exhibited high cytotoxicity against K562-CD19 cells but not on K562 cells（all P <0.01）. The death rate of MCL cells from CAR-NK-92MI group was 30%-40% more than that of control group, and the death rate of MCL from CAR-CD19-T group was 40%-50% more than that of control group. Conclusion: Both CAR-NK-92MI and CAR-CD19-T cells exhibited potent cytotoxicity against MCLcells in vitro.