In-vitro NMR Studies of Prostate Tumor Cell Metabolism by Means of Hyperpolarized [1-13C]Pyruvate Obtained Using the PHIP-SAH Method

Abstract

Nuclear Magnetic Resonance allows the non-invasive detection and quantitation of metabolites to be carried out in cells and tissues. This means that that metabolic changes can be revealed without the need for sample processing and the destruction of the biological matrix. The main limitation to the application of this method to biological studies is its intrinsic low sensitivity. The introduction of hyperpolarization techniques and, in particular, of dissolution-Dynamic Nuclear Polarization (d-DNP) and ParaHydrogen Induced Polarization (PHIP) is a significant breakthrough for the field as the MR signals of molecules and, most importantly, metabolites, can be increased by some orders of magnitude. Hyperpolarized pyruvate is the metabolite that has been most widely used for the investigation of metabolic alterations in cancer and other diseases. Although d-DNP is currently the gold-standard hyperpolarization method, its high costs and intrinsically slow hyperpolarization procedure are a hurdle to the application of this tool. However, PHIP is cost effective and fast and hyperpolarized pyruvate can be obtained using the so-called Side Arm Hydrogenation approach (PHIP-SAH). The potential toxicity of a solution of the hyperpolarized metabolite that is obtained in this way is presented herein. HP pyruvate has then been used for metabolic studies on different prostate cancer cells lines (DU145, PC3, and LnCap). The results obtained using the HP metabolite have been compared with those from conventional biochemical assays.

Pd-based bimetallic catalysts for parahydrogen-induced polarization in heterogeneous hydrogenations

“…Furthermore, hydrogenation of symmetric gaseous substrates is a potential route to the enrichment of their NSIMs, as successfully demonstrated earlier for ethylene in a heterogeneous hydrogenation of acetylene with parahydrogen (Zhivonitko et al, 2013). This development is rather significant -while there are several known methods for enrichment or separation of NSIMs of polyatomic molecules (Chapovsky and Hermans, 1999;Kilaj et al, 2018;Krüger et al, 2018), to date none of them is able to produce sufficient quantities of an enriched polyatomic gas for NMR signal enhancement applications, including the reported production of the singlet spin state of 15 N 2 by SABRE in solution (Bae et al, 2018). Thus, the work of Zhivonitko et al (2013) so far remains the only demonstration of NMR signal enhancement derived from a NSIM-enriched polyatomic gas.…”

“…In particular, in vivo applications certainly require catalyst-free hyperpolarized fluids. Removal of potentially toxic transition-metal complexes utilized in the homogeneous implementations of PHIP and SABRE, while possible (Cavallari et al, 2020;Kidd et al, 2018;Knecht et al, 2021), still remains one of the primary challenges to be solved. In this respect, solid heterogeneous catalysts can be filtered out much faster; thus, higher polarization levels can be available upon injection.…”

“…This, however, does not exhaust the list of activities that would benefit from the facile production/enrichment of NSIMs of polyatomic molecules. In modern science, of significant interest are the properties of NSIMs, including their interconversion processes (Chapovsky and Hermans, 1999) and NSIM behavior upon phase transitions (Curl et al, 1966;Hama et al, 2018); the NSIM-related selection rules in molecular spectroscopy (Kanamori et al, 2017;Ozier et al, 1970) and upon chemical transformations (Hu et al, 2020;Kilaj et al, 2018;Oka, 2004); NSIMs in astrophysics and astrochemistry research (Hama and Watanabe, 2013;Hily-Blant et al, 2018;Shinnaka et al, 2016;Tielens, 2013); and more.…”

Rapid hyperpolarization and purification of the metabolite fumarate in aqueous solution

“…Signal enhancements on the order of 10 5 can be achieved for solution-state samples using hyperpolarization techniques such as dissolution dynamic nuclear polarization (dDNP) ( 1 , 2 ) or parahydrogen-induced polarization (PHIP) ( 3 – 5 ). This allows the injection of hyperpolarized probe molecules in vivo, and subsequent imaging of metabolism ( 6 – 10 ). One such example is the imaging of hyperpolarized fumarate, which is converted to malate in one step of the Krebs cycle, and acts as a sensitive probe of cell necrosis ( 11 – 18 ).…”

Rapid Hyperpolarization and Purification of the Metabolite Fumarate in Aqueous Solution

“…Signal enhancements in the order of 10 5 can be achieved for solution-state samples using hyperpolarization techniques such as dissolution dynamic nuclear polarization (dDNP) 1,2 or parahydrogen-induced polarization (PHIP) [3][4][5] . This allows the injection of hyperpolarized probe molecules in vivo, and subsequent imaging of metabolism [6][7][8][9][10] . One such example is the imaging of hyperpolarized fumarate, which is converted to malate in one step of the Krebs cycle, and acts as a sensitive probe of cell necrosis [11][12][13][14][15][16][17][18] .…”