{
  "abstract": "Background Natural killer (NK) cells are cytotoxic cells with capacity to destroy tumor cells, making them a promising cell source for cancer immunotherapy. However, solid tumors generate a unique microenvironment characterized by hypoxia, nutrient depletion, and accumulation of immunosuppressive metabolites like lactic acid or adenosine. Consequently, the tumor microenvironment gradually erodes the anti-tumor capacity of NK cells as they penetrate in the deepest regions of the tumor for prolonged periods of time. Despite the importance of the tumor microenvironment, we still lack robust models to monitor and manipulate the tumor microenvironment in real-time. Therefore, we have developed an in vitro microphysiological system (named ORACLE) to generate anatomically inspired tissue hydrogels that co-culture tumor, stromal, and immune cells in a 3D environment supported by a perfusable vasculature. We used this technology to monitor how NK cells evolve over time inside a model of melanoma brain metastasis.Methods The microdevice was manufactured in polystyrene using CNC micromilling. M21 melanoma cells were cultured inside the platform surrounded by normal astrocytes to mimic a melanoma lesion surrounded by stroma. Microvascular endothelial cells were used to generate perfusable blood vessels in the platform that allowed us to perfuse NK-92 cells, primary NK cells, or memory-like NK cells. We used live-cell microscopy to monitor NK cell migration into the tumor and cytotoxicity against tumor cells. We used ELISA based assays to spatially resolve molecular and metabolic signaling across the platform in a non-destructive mannerResults Non-destructive spatial profiling showed that tumor cells rapidly created a unique environment characterized by low glucose levels and high concentration of lactic acid that disrupted the surrounding astrocyte stroma ( figure 1). Microscopy analysis showed NK cells were able to destroy tumor cells, with memory-like NK cells showing the highest cytotoxic capacity. However, we observed that accumulation of immunosuppressive metabolites like lactic acid and adenosine led to NK cell mitochondrial disruption, decreased NK cell migration, viability, and killing potential. Using this approach we are unraveling the temporal dynamics that drive NK cell exhaustion and impairment in the tumor microenvironment.Conclusions Microphysiological systems enable manipulation of the biochemical milieu to study how immune cells spatially and temporally respond to molecular and metabolic perturbations in the tumor microenvironment.Abstract 757 Figure 1A) Microfluidic device to generate spatially defined cultures. B-C) Nutrients, immune cells, and drugs are perfused through a blood vessel surrogate. D) Non-destructive spatial profiling in the microfluidic device",
  "authors": [
    {
      "affiliations": [
        "University of Wisconsin-Madison, Madison, WI, USA"
      ],
      "name": "Jose Ayuso"
    },
    {
      "affiliations": [
        "University of Wisconsin-Madison, Madison, WI, USA"
      ],
      "name": "Seth Zima"
    },
    {
      "affiliations": [
        "University of Wisconsin-Madison, Madison, WI, USA"
      ],
      "name": "Rithvik Turaga"
    },
    {
      "affiliations": [
        "University of Wisconsin-Madison, Madison, WI, USA"
      ],
      "name": "Catherine Reed-McBain"
    }
  ],
  "title": "757 Microphysiological systems to explore the temporal and spatial evolution of natural killer cells in the tumor microenvironment",
  "uid": "a010326a-e355-5abb-8123-0a49a77e03b3"
}