A Wireless Multi-function Microscope for Lifetime Imaging of the Brain Tumor Vasculome

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ABSTRACTPreclinical and clinical evidence has shown that brain tumors can alter the structure and function of the central nervous system microvasculature (i.e. CNS vasculome) during progression, therapy and the emergence of therapeutic resistance. Brain tumor progression related vasculome remodeling occurs via angiogenesis (i.e. new blood vessel formation). In contrast, non-angiogenic pathways such as ‘co-option’ (i.e. tumor cells hijacking extant blood vessels) and ‘immunomodulation’ (i.e. vascular changes induced by the infiltration of immune cells) are involved in antiangiogenic resistance and immunotherapy evasion, respectively. To elucidate the role of these angiogenic and non- angiogenic pathways on brain tumor progression and therapeutic response necessitates the development of imaging tools that can characterize early to advanced in vivo changes in the CNS vasculome (i.e. over the lifetime of the disease). Therefore, our goal is to build a wireless ‘plug-n-play’ multichannel microscope capable of imaging structural/functional microvascular (~7-10 µm) changes in vivo, over the entire lifetime of a brain tumor. We propose to exploit advances in miniaturized optics, image sensor design and wireless technology to fabricate a miniature, wireless microscope with three channels: fluorescence (FL) to image fluorescent brain tumor cells or dyes; intrinsic optical signals (IOS) to image cerebral blood volume (CBV) and intravascular oxygenation (HbSat); and laser speckle contrast (LSC) to image cerebral blood flow (CBF). Guided by compelling preliminary data, we will pursue the following Specific Aims: (1) Develop a tether-free multichannel microscope with on-chip compressed sensing and wireless transmission; (2) Characterize the in vivo vasculome in angiogenic and co-optive patient-derived (PDX) brain tumor models over their lifetime; and (3) Characterize in vivo changes in the vasculome induced by the immune microenvironment of brain tumors. Under Aim1 we will fabricate a specialized image sensor with compressed sensing for ultra-low power wireless operation. After validation against an equivalent benchtop imaging system, we will image the CNS vasculome in healthy mice without the confounding effects of anesthetics. This will include identifying microvessel type (i.e. artery vs. vein) with FL, quantifying vascular morphology and HbSat with IOS, perfusion with LSC, and mapping ‘microvascular connectivity’ by correlating CBV (or CBF) fluctuations in microvessels. Under Aim2 we will characterize differences in the CNS vasculomes of clinically relevant angiogenic and co-optive patient-derived xenografts, and assess if the former exhibits larger disruptions in microvascular connectivity due to vascular remodeling. Under Aim3, we will characterize in vivo differences in the CNS vasculomes of wild-type and non-immunosuppressed xenografts, to determine if alleviating immunosuppression increases CBV/CBF/HbSat and promotes recruitment of tumor associated macrophages (TAM). We will create a versatile 3D printed plug-n-play wireless microscope that permits neuroimaging in freely behaving animals at any time, for any duration, during any task or physiological recording (e.g. EEG). As this microscope can be customized to any fluorophore, modified for optogenetics or drug delivery, and used for behavioral studies, we believe it will usher in a new era of brain cancer research, with utility in diseases involving the CNS vasculome (e.g. stroke, Alzheimer’s disease).