129Xe Hyperpolarized Chemical Exchange Saturation Transfer (HyperCEST) MRI for Tracking Immunotherapy Delivery in the Lungs - PROJECT SUMMARY Osteosarcoma, the most common primary malignant bone tumor in children, begins in the cells that form bones and has the potential to rapidly metastasize if not diagnosed early. The implementation of natural killer cell immunotherapy to treat pediatric osteosarcoma lung metastases is an emerging treatment approach. However, clinicians are currently unable to verify the delivery of immunotherapy to desired target sites in the lungs, which is a critically unmet clinical need. An innovative approach for imaging immune cell delivery in vivo may provide new insight into the journey and destination of administered immunotherapy, which may lead to an increase in immunotherapy treatment-success rates for pediatric osteosarcoma patients with lung metastases. To address this clinical gap, I propose to use “hyperpolarized chemical exchange saturation transfer” (hyperCEST), a novel magnetic resonance lung imaging (MRI) strategy, to track the delivery of administered natural killer cell immunotherapy to the lungs in vivo. While traditional 1H MRI of the lungs suffers severe limitations due to low inherent tissue density, my innovative approach combines emerging, FDA approved and clinically relevant, hyperpolarized 129-Xenon gas and clinically translatable, FDA approved perfluorocarbon nanodroplets as hyperCEST contrast agents for natural killer cell labeling in the lungs. I hypothesize that labeling natural killer immunotherapy cells with perfluorocarbon nanodroplets optimized for 129-Xenon hyperCEST MRI detection will allow for non-invasive visualization of immunotherapy delivery in the lungs. To investigate this hypothesis, I will develop a 129-Xenon pre-scan calibration pulse sequence for a 7T preclinical MRI scanner in order to calibrate the MRI scanner prior to 129-Xenon imaging experiments. I will also develop a series of multi-compartment thermal 129-Xenon gas phantoms to simplify optimization of the conditions for 129-Xenon hyperCEST using perfluorocarbon-labeled natural killer cells (Aim 1). Next, I will optimize a hyperCEST saturation pulse in order to selectively saturate the frequency of dissolved-phase hyperpolarized 129-Xenon in perfluorocarbon-labeled natural killer cells and generate maximum hyperCEST contrast (CNR) in vitro (Aim 2). Finally, in vivo hyperCEST MRI using hyperpolarized 129-Xenon gas will be performed to produce a hyperCEST contrast map of the distribution of perfluorocarbon-labeled NK cells in the lungs of mice. We will validate our findings using Xerra cryo-fluorescence tomography, which will provide the distribution of fluorescent perfluorocarbon-labeled NK cells, which can be correlated with hyperCEST maps (Aim 3). The proposed training offered through this fellowship would further accentuate my existing research strengths, address gaps in needed skills such as MRI physics and pulse programming, provide mentored research experiences, grant me the opportunity to further extend my publication record, and allow me the ability to improve my scientific communication and research presentation skills. Additionally, the Magnetic Resonance Systems Laboratory is the ideal place to perform this research, as I have access to advanced MRI technologies and mentorship from my Sponsors, Drs. Bankson and Sokolov.
