Enhanced Bone Marrow Homing Of Natural Killer Cells By mRNA Transfection With Gain-Of-Function CXCR4

Authors

• ER Levy
• RN Reger
• MC Carlsten*
• RW Childs*

Abstract

Natural killer (NK) cells have proven to be powerful effectors against hematological tumor targets in pre-clinical studies. However, the therapeutic potential of intravenously (IV) transferred NK cells has thus far been limited, perhaps in part the consequence of their suboptimal bone marrow (BM) homing capacity. As most hematological neoplasms arise and reside in BM compartments, developing an NK cell product that can reach those targets may lead to improved clinical responses in patients who receive adoptive NK cell-based immunotherapy for homological cancers. Hematopoietic stem cells (HSCs) are known to engraft in BM compartments via CXCR4/SDF-1a signaling, thus we explored the potential of NK cells genetically engineered to express a naturally occurring, gain-of-function, CXCR4 (CXCR4-R334X) receptor to enhance cell capacity for BM homing. Ex vivo expanded human NK cells were transfected with mRNA coding for the wild-type CXCR4 receptor (CXCR4-WT) and CXCR4-R334X. NK cell chemotaxis toward increasing concentrations of SDF-1 alpha was assessed in vitro (n=10 donors). Next, immunocompromised mice either received 1e7 unmodified control NK cells, 1e7 CXCR4-R334X NK cells, or 1e7 AMD3100-mobilized CD34+ HSCs as a BM homing control (n=9-10 animals per group). Blood, BM, liver, lung, and spleen were harvested 24 hours post IV infusion Transfection of CXCR4 mRNAs into NK cells consistently leads to an increase of surface CXCR4 with no significant impact on cell viability. CXCR4-R334X NK cells had significantly greater chemotaxis toward SDF-1 alpha compared to CXCR4-WT and control NK cells. Overall, surface CXCR4 expression positively correlated with NK cell migration, in vitro (p

Scientific Focus Area: Immunology

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