Abstract

By the ectopic expression of reprogramming genes OCT, KLF4, SOX2 and MYC (OKSM), somatic cells can be reprogrammed to induced pluripotent stem cells (iPSCs). Human iPSCs are considered a promising cell source to provide an import tool for the basic investigation and the advanced medicine including gene therapy and regenerative medicine. To establish iPSCs, integration-free Sendai virus (SV) vectors have been most widely used do far, but transduction and reprogramming of T cells without stimulation is still very challenging. On the other hand, a great success of chimeric antigen receptor T cell (CAR-T) therapies highlighted the importance of anti-cancer immunity for the cancer treatment. Particularly, many refractory patients with acute lymphoblastic leukemia and B-cell lymphoma were successfully treated with CD19-CAR-T therapies, however, some patients died before receiving the treatment due to long preparation time of CAR-Ts. Therefore, rapid production systems of CAR-Ts are desired, and for this purpose, efficient and safe gene transduction systems to T cells should be developed.

In this study, we developed a new non-integrating measles virus (MV) vector-based delivery system with F deletion to eliminate cell membrane fusion-associated cytotoxicity. MV vectors transduced genes through MV receptors including CD46 and signaling lymphocyte activation molecule (CD150/SLAM). First, we examined transduction efficiencies of MV vectors and SV vectors in hematopoietic cells by using GFP expression vectors (MV-Gs and SV-Gs). Compared to SV-Gs, our MV-Gs allowed more efficient gene transfer into most hematopoietic cell type including T (3-fold) and B cells (7-fold) (Fig. 1). Furthermore, at the same multiplicity of infection (MOI) of viral transduction, MV-Gs induced less apoptosis in T cell subset compared to SV-Gs (Fig. 2) due to the slower kinetics of viral RNA amplification in the transduced cells 24 h ,48 h and 72 h post transduction.

Those results encouraged us to examined if MV vectors are more potent than SV vectors in iPSC generation from unstimulated T cells. To address this question, we developed MV vectors harboring four reprogramming genes (MV-OKSMGs) and compared with SV vectors harboring these genes (SV-OKSMGs). As expected, with the MV-OKSMGs, we could generate high-quality iPSCs with the similar morphology, pluripotency markers, karyotype and differentiation capacity as human embryonic stem cells. Upon the less cytotoxicity, iPSC generation efficiency of MV-OKSMGs was much higher than that of SV-OKSMGs for unstimulated T cells (0.47 ± 0.25% vs 0.008 ± 0.009%).

Considering the safe history of MV vaccine, carrying capabilities of multiple genes, more flexible receptors and higher transduction efficiency for resting T cells, our exclusive MV vector would be a potential gene transfer system for iPSC generation and lymphocyte-based-immunotherapies such as CAR-T therapies.

Disclosures

Liao:neopharma Japan Co. Ltd: Research Funding; TAKARA BIO, INC.: Research Funding; Shinnihonseiyaku Co., Ltd: Research Funding. Soda:Shinnihonseiyaku Co., Ltd: Research Funding; neopharma Japan Co. Ltd: Research Funding; TAKARA BIO, INC.: Research Funding. Sugawara:neopharma Japan Co. Ltd: Research Funding; Shinnihonseiyaku Co., Ltd: Research Funding; TAKARA BIO, INC.: Research Funding. Miura:neopharma Japan Co. Ltd: Research Funding; Shinnihonseiyaku Co., Ltd: Research Funding; TAKARA BIO, INC.: Research Funding. Tahara:TAKARA BIO, INC.: Research Funding. Takishima:neopharma Japan Co. Ltd: Research Funding; TAKARA BIO, INC.: Research Funding; Shinnihonseiyaku Co., Ltd: Research Funding. Hirose:TAKARA BIO, INC.: Research Funding; Shinnihonseiyaku Co., Ltd: Research Funding; neopharma Japan Co. Ltd: Research Funding. Hijikata:Shinnihonseiyaku Co., Ltd: Research Funding; neopharma Japan Co. Ltd: Research Funding; TAKARA BIO, INC.: Research Funding. Miyamoto:Shinnihonseiyaku Co., Ltd: Research Funding; TAKARA BIO, INC.: Research Funding; neopharma Japan Co. Ltd: Research Funding. Takeda:TAKARA BIO, INC.: Research Funding. Tani:neopharma Japan Co. Ltd: Research Funding; Oncolys BioPharma Inc.: Equity Ownership; SymBio Pharmaceuticals Limited: Equity Ownership; TAKARA BIO, INC.: Research Funding; Shinnihonseiyaku Co., Ltd: Research Funding.

Author notes

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Asterisk with author names denotes non-ASH members.