Natural killer cells differentiated in vitro from cord blood CD34(+) cells are more advantageous for use as an immunotherapy than peripheral blood and cord blood natural killer cells

BACKGROUND AIMS: Natural killer (NK) cells have the potential to become a successful immunotherapy as they can target malignant cells without being direct effectors of graft-versus-host disease. Our group has previously shown that large numbers of functional NK cells can be differentiated in vitro from umbilical cord blood (CB) CD34(+) cells. To produce a clinically relevant and effective immunotherapy, we hypothesized that it is essential that the NK cells are able to proliferate and persist in vivo while maintaining an optimal activation status and killing capacity. METHODS: We evaluated the proliferation capacity, telomere length and terminal differentiation markers expressed by NK cells differentiated in vitro. We also determined how their cytotoxicity compared with peripheral blood (PB) NK cells and CBNK cells when targeting patient acute myeloid leukemia (AML) blasts and solid tumor cell lines. RESULTS: We found that the differentiated NK cells could respond to interleukin-2 and proliferate in vitro. Telomere length was significantly increased, whereas CD57 expression was significantly reduced compared with PBNK cells. The cytotoxicity of the differentiated NK cells was equivalent to that of the PBNK and CBNK cell controls, and priming consistently led to higher levels of killing of patient leukemic blasts and solid tumor cell lines in vitro. Interestingly, this activation step was not required to observe killing of patient AML blasts in vivo. CONCLUSION: We are able to generate NK cells from CBCD34(+) cells in high numbers, allowing for multiple infusions of highly cytotoxic NK cells that have potential to further proliferate in vivo, making them a desirable product for application as an immunotherapy in the clinic

Regulatory T cells inhibit CD34+ cell differentiation into NK cells by blocking their proliferation

Graft versus Host Disease (GvHD) remains one of the main complications after hematopoietic stem cell transplantation (HSCT). Due to their ability to suppress effector cells, regulatory T cells (Tregs) have been proposed as a cellular therapy to prevent GvHD, however they also inhibit the functions of natural killer (NK) cells, key effectors of the Graft versus Leukemia effect. In this study, we have explored whether a Tregs therapy will also impact on NK cell differentiation. Using an in vitro model of hematopoietic stem cell (HSC) differentiation into NK cells, we found that activated Tregs led to a 90% reduction in NK cell numbers when added at the time of commitment to the NK cell lineage. This effect was contact dependent and was reversible upon Tregs depletion. The few NK cells that developed in these cultures were mature and exhibited normal functions. Furthermore, adoptive transfer of activated Tregs in rag(-/-) γc(-/-) mice abrogated HSC differentiation into NK cells thus confirming our in vitro findings. Collectively, these results demonstrate for the first time that activated Tregs can inhibit NK cell differentiation from HSC under specific conditions

Operating an Unmanned Aerial System from a Moving Platform

While the Spatial Disorientation (SD) has long been recognized as an important causal factor in aviation incidents and accidents, it is only beginning to be recognized as a factor in Uninhabited Aerial Systems (UASs). Self, Ercoline, Olson and Tvaryanas (2006) predicted SD to be most likely for a manually controlled UAV when operated from a mobile platform. As a first step towards better understanding the effects of control platform motion on manual UAV control Olson, DeLauer and Fale (2006) had 10 rated Air Force pilots fly a simulated UAV task (MS Flight Simulator) from a motion capable control platform (aircraft simulator). Participants performed two basic flight tasks – a vertical task (climb/descent) and a horizontal (turning task). The control platform motion was varied to provide either congruent, neutral, or conflicting motion cues. Congruent and incongruent motion cures were defined as motion in the same axis and either same/different direction as the primary task (i.e., simulator turned left/right and task was a constant left hand turn). Neutral motion was defined as motion in a different axis of motion relative to the primary task (i.e., simulator motion was climb/descent and task was a constant bank turn). There were three levels of visual and vestibular control platform motion cues (no motion/visual cues, motion with no outside visual display, motion with outside visual). The results indicate that there was little effect of control platform motion on roll axis performance, i.e., bank and heading error. However, pitch axis deviations (altitude and vertical velocity) showed an effect of both control platform motion and motion type. Presence of both visual and motion cues resulted in greater pitch deviations than motion only or baseline (no motion/no visual cue) conditions and the presence of motion in the off-axis of motion resulted in the greatest error. These results suggest that platform motion may interfere with an operator’s ability to manually control a UAV from a moving platform (a possible precursor to SD). The current study replicates the simulator study using an aircraft (C-172) as the control platform. This will allow for a more complete examination of platform motion cues since simulators cannot adequately simulate sustained motion. This study also adds a landing task to examine glide path and azimuth error. Data collection is not yet complete, however initial results indicate that, as in the previous simulator study, control platform motion resulted in greatest interference in the vertical axis and the presence of both motion and visual cues resulted in the greatest control interference. These results have implications for planned UAV operations from both fighter and transport aircraft