Microfluidic tumor-on-a-chip model to evaluate the role of tumor environmental stress on NK cell exhaustion

Abstract

Solid tumors generate a suppressive environment that imposes an overwhelming burden on the immune system. Nutrient depletion, waste product accumulation, hypoxia, and pH acidification severely compromise the capacity of effector immune cells such as T and natural killer (NK) cells to destroy cancer cells. However, the specific molecular mechanisms driving immune suppression, as well as the capacity of immune cells to adapt to the suppressive environment, are not completely understood. Thus, here, we used an in vitro microfluidic tumor-on-a-chip platform to evaluate how NK cells respond to the tumor-induced suppressive environment. The results demonstrated that the suppressive environment created by the tumor gradually eroded NK cell cytotoxic capacity, leading to compromised NK cell surveillance and tumor tolerance. Further, NK cell exhaustion persisted for an extended period of time after removing NK cells from the microfluidic platform. Last, the addition of checkpoint inhibitors and immunomodulatory agents alleviated NK cell exhaustion.

Microfluidic technologies for immunotherapy studies on solid tumours

“…More recently, the same group adapted the microfluidic set-up to investigate NK exhaustion due to tumour environmental stresses reproduced on-a-chip. 59 The device design allowed to control nutrient and pH gradients across 3D tumour models, as well as inducing cell proliferation and necrosis. Gene expression analysis showed greater exhaustion of the NK cells cultured in devices in comparison to those in well plates.…”

Engineering microenvironments for manufacturing therapeutic cells

“…The migration of NK.92 NK cells in RGD-modified and MMP-degradable PEG gels was shown to be impaired in the presence of H1299 cancer lines that secreted anti-inflammatory TGF-β. 58 A more complex tumor on a chip model was developed that co-cultured NK.92 cells with MCF7 breast cancer cells in the presence of a endothelial cell-lined lumen; the cancer cells provided an immunosuppressive environment to the NK cells that diminished their cytotoxicity and resulted in their exhaustion, even after removal from the device 59 (Figure 4(a)).…”

Integrating Subclonal Response Heterogeneity to Define Cancer Organoid Therapeutic Sensitivity

“…The cell cytoplasm was defined as the cell borders minus the nucleus. Values for NAD(P)H lifetime variables (𝜏𝜏 𝑚𝑚 , 𝜏𝜏 1 , 𝜏𝜏 2 , 𝛼𝛼 1 , 𝛼𝛼 2 ), FAD lifetime variables, NAD(P)H intensity, and FAD intensity were averaged for all pixels within the cytoplasm of each cell, as described previously 14,55,56 .…”

“…Fluorescence intensity measurements are influenced by laser power, detector gain, light scattering, and the concentration of the fluorophore; however, fluorescence lifetimes are independent of these experimental factors 57,59 . Although the FLIRR is a useful measurement of cellular metabolism, it is not a substitute for the optical redox ratio and instead represents an additional variable to compare metabolic endpoints 55 . Hierarchical cluster analysis of OMI parameters was completed using group average cluster methods defined using Euclidean distant type (OriginPro 2020).…”