Genetically re-engineered K562cells significantly expand and functionally activate cord blood natural killer cells: Potential for adoptive cellular immunotherapy.

Abstract

Natural killer (NK) cells play a significant role in reducing relapse in patients with hematological malignancies after allogeneic stem cell transplantation, but NK cell number and naturally occurring inhibitory signals limit their capability. Interleukin-15 (IL-15) and 4-1BBL are important modulators of NK expansion and functional activation. To overcome these limitations, cord blood mononuclear cells (CB MNCs) were exvivo expanded for 7days with genetically modified K562-mbIL15-41BBL (MODK562) or wild-type K562 (WTK562). NK cell expansion; expression of lysosome-associated membrane protein-1 (LAMP-1), granzyme B, and perforin; and invitro and invivo cytotoxicity against B-cell non-Hodgkin lymphoma (B-NHL) were evaluated. Invivo tumor growth in B-NHL-xenografted nonobese diabetic severe combined immune deficient (NOD-scid) gamma (NSG) mice was monitored by tumor volume, cell number, and survival. CB MNCs cultured with MODK562 compared with WTK562 demonstrated significantly increased NK expansion (thirty-fivefold, p<0.05); LAMP-1 (p<0.05), granzyme B, and perforin expression (p<0.001); and invitro cytotoxicity against B-NHL (p<0.01). Xenografted mice treated with MODK562 CB experienced significantly decreased B-NHL tumor volume (p=0.0086) and B-NHL cell numbers (p<0.01) at 5weeks and significantly increased survival (p<0.001) at 10weeks compared with WTK562. In summary, MODK562 significantly enhanced CB NK expansion and cytotoxicity, enhanced survival in a human Burkitt's lymphoma xenograft NSG model, and could be used in the future as adoptive cellular immunotherapy after umbilical CB transplantation. Future directions include expanding anti-CD20 chimeric receptor-modified CB NK cells to enhance B-NHL targeting invitro and invivo.