Evaluating Expansion Protocols for Generating Cord Blood Derived Natural Killer Cell Therapies

Certain malignancies of the brain in children are still associated with high mortalities and poor prognosis. There are also indications that incidence may be steadily increasing.[1] Current therapies are limited, and also expose the child’s developing body to toxicity. There is thus a clear need for a novel therapy, and we propose to use immunotherapy based on natural killer cells as an alternative.Natural killer cells are among the most critical cellular components of the innate immune response. As members of the innate compartment, they do not need to have encountered the their target before they can kill them. Their ability to differentiate diseased cells from healthy cells, their ability to kill cells without need for MHC matching, and their ability to secrete cytokines that can recruit other immune cells make them attractive cell substrates for adoptive immunotherapy for difficult to treat cancers like pediatric brain tumors.One major focus in the immune therapy field is developing off the shelf treatments. Cells that are banked will allow immediately accessible therapies, as opposed to those requiring manufacture upon patient identification. In this sense, natural killer cells derived from umbilical cord blood as a cell source may be advantageous. There are currently numerous established cord blood banks globally, which can serve as a source of these cells.Therefore, we chose to develop cord blood derived NK cell therapies. To provide the most optimal cell product, we looked into comparing different methods of expanding these cells ex vivo. We also compared their expansion with cells derived from peripheral blood as a reference. We characterized phenotype and function of expanded cells by measuring cell proliferation by trypan blue exclusion, and expression of markers by flow cytometryOur preliminary results show that optimal expansion was seen in cells grown in in the presence of low dose IL2. We show purity of NK cells cultured with IL2+IL15 and IL2+IL15+IL7 using flow cytometry. We are currently looking at other cytokine combinations, culture media, and feeder cell ratios. [1] Patel S, Bhatnagar A, Wear C, Osiro S, Gabriel A, Kimball D, John A, Fields PJ, Tubbs RS, Loukas M. Are pediatric brain tumors on the rise in the USA? Significant incidence and survival findings from the SEER database analysis. Childs Nerv Syst 2014;30:147–154.