Establishment of a New Cryopreservation Solution for Chimeric Antigen Receptor T Cells.

Preservation and transportation are essential for the clinical application of chimeric antigen receptor T (CAR-T) cells. This study aimed to optimize a cryopreservation solution for CAR-T cells and evaluate the antitumor efficiency of CAR-T cells using this optimized solution in vitro and in vivo. First, the stability of the cryopreservation solution for CAR-T infusion was detected by the L27 (37) orthogonal experiment. Subsequently, osmolality and pH were analyzed for the preservation reagent. Additionally, apoptosis and CAR expression of CAR-T cells were measured by flow cytometry, and the cytotoxicity was determined by calcein-AM staining. The results showed that cryopreservation solutions used in this study demonstrated high chemical stability, which induced only 2% CAR-T cells apoptosis in optimal solutions, which were slightly lower than other commercial solutions. Moreover, the CAR expression was not significantly affected by preservation with these solutions. There were no significant differences in the cytotoxicity between fresh and thawed CAR-T cells cryopreserved in the cryopreservation solutions in vivo and in vitro. This study developed a new cryopreservation solution for CAR-T cells, and it was safe and also had negligible effects on the CAR-T cells antitumor activity.

Establishing functional lentiviral vector production in a stirred bioreactor for CAR-T cell therapy.

As gene delivery tools, lentiviral vectors (LV) have broad applications in chimeric antigen receptor therapy (CAR-T). Large-scale production of functional LV is limited by the adherent, serum-dependent nature of HEK293T cells used in the manufacturing. HEK293T adherent cells were adapted to suspension cells in a serum-free medium to establish large-scale processes for functional LV production in a stirred bioreactor without micro-carriers. The results showed that 293 T suspension was successfully cultivated in F media (293 CD05 medium and SMM293-TII with 1:1 volume ratio), and the cells retained the capacity for LV production. After cultivation in a 5.5 L bioreactor for 4 days, the cells produced 1.5 ± 0.3 × 107 TU/mL raw LV, and the lentiviral transduction efficiency was 48.6 ± 2.8% in T Cells. The yield of LV equaled to the previous shake flask. The critical process steps were completed to enable a large-scale LV production process. Besides, a cryopreservation solution was developed to reduce protein involvement, avoid cell grafting and reduce process cost. The process is cost-effective and easy to scale up production, which is expected to be highly competitive.

Killing effect of NK92 cells modified with CD33-CAR on CD33+ acute myeloid leukemia cells / 中国肿瘤生物治疗杂志

@#[Abstract] Objective: To construct CD33-CAR modified NK92 cells based on CD33-scFv sequence, and to explore its killing effect on CD33+ AML (acute myeloid leukemia) cells. Methods: DNA fragment encoding CD33-CAR was synthesized by gene synthesis and molecular cloning technology and then cloned into lentiviral vector. Lentivirus were packaged and used to transfect NK92 cells. The transfection efficiency was detected by flow cytometry, and puromycin was used to screen NK92 cells stably expressing CD33-CAR (CD33-CAR-NK92). Killing effect of CD33-CAR-NK92 cells on AML cells in vitro was examined with calcein-AM release assays. IFN-γ secretions of NK92 cells and CD33-CAR-NK92 cells were measured by ELISA. Results: The pCDH-CD33-CAR lentiviral vector was successfully constructed. After lentiviral transfection, about 18.7% of NK92 cells express CD33-CAR (referred as CD33-CARNK92 cells). The percentage of CD33-CAR+ NK92 cells was about 86.3% after puromycin selection. In contrast to unmodified NK92 cells, significantly higher cytotoxic effect against CD33+ MOLM-13 cells was found in CD33-CAR-NK92 cells (P<0.01); however, there was no significant difference in cytotoxicity against CD33- JURKAT cells between NK92 cells and CD33-CAR-NK92 cells (P> 0.05). After co-culture at an effect-target ratio of 2∶1 for 6 hours, the level of IFN-γ secreted by the CD33-CAR modified NK92 cells was significantly higher than that of the unmodified ([190.97±11.52] vs [88.41±2.75]pg/ml, P<0.01). Conclusion: The CD33-CARNK92 cells could specifically recognize CD33 antigen and kill CD33+ AML cells in comparison with the unmodified NK92 cells, which provides experimental basis for clinical transformation of CD33-CAR-NK92 cells in treatingAML.