Metabolic Studies of Tumor Cells Using [1‐¹³C] Pyruvate Hyperpolarized by Means of PHIP‐Side Arm Hydrogenation

Abstract

The kinetics of metabolic processes can be assessed, in real time by means of MR hyperpolarized (HP) metabolites. [1‐13C]pyruvate, hyperpolarized by means of d‐DNP, is, by far, the substrate most widely applied to the investigation of several pathologies characterized by deregulated glycolytic metabolic networks, including cancer. Hyperpolarization of [1‐13C]pyruvate by means of the cost effective, fast and easy to handle PHIP‐SAH (para‐hydrogen induced polarization‐side arm hydrogenation) method opens‐up a pathway for the application of HP metabolites to a wide range of cancer‐related studies. Herein, we report the first application of PHIP‐SAH hyperpolarized [1‐13C]pyruvate in the investigation of upregulated glycolysis in two murine breast cancer cell lines (168FARN and 4T1). The results obtained using HP pyruvate have been validated with a conventional biochemical assay and are coherent with previously‐reported lactate dehydrogenase activity measured in those cells.

Multiple Quantum Coherences Hyperpolarized at Ultra‐Low Fields

“…When the magnetic field was reduced to the observation field, B 0 , two 90 0 1 H- 19 F excitation pulses with the phases f 1 and f 2 and a variable interpulse interval, t 1 , were xcitation pulse at B 0 = 91 μT, the SABRE signal is acquired. When the magnetic field was reduced to the observation field, B 0 , two 90 0 1 H- 19 F excitation pulses with the phases f 1 and f 2 and a variable interpulse interval, t 1 , were xcitation pulse at B 0 = 91 μT, the SABRE signal is acquired.…”

“…The ULF COSY sequence starts with a prepolarization phase at the magnetic field strength B p for the period of t Bp by means of SABRE. When the magnetic field was reduced to the observation field, B 0 , two 90 0 1 H- 19 F excitation pulses with the phases f 1 and f 2 and a variable interpulse interval, t 1 , were xcitation pulse at B 0 = 91 μT, the SABRE signal is acquired. Simulated 1 Hspectra of hyperpolarized 3FPy substrate (purple), H 2 (orange) and IrHH-3FPy complex (red).…”

“…Such frequencies can be easily obtained using the product operator formalism (SI, Section 7). [62] Four uncoupled undistinguishable 1 H spins and one 19 F spin in maximum have 26 different sorts of quantum coherences with different frequencies due to the Zeeman interaction (Table S5); a total number of coherences of 5 spin-1 = 2 system is 2 4 (2 5 -1) = 496. Although J-coupling constants make the system more complex, at ULFs of 91 μT, the Zeeman interaction is still the leading term which defines the frequencies of quantum coherences and J-coupling only adds multiplicity to the peaks ( Figure 2).…”

“…During the past decades, various hyperpolarization techniques have been developed [1][2][3][4][5][6][7][8][9][10][11][12][13][14] to boost the magnetic resonance (MR) signal in order to bring new applications to industry [15][16][17] and life-sciences. [18][19][20][21][22][23][24][25] One of these methods is signal amplification by reversible exchange (SABRE), [26][27][28][29][30][31][32][33][34][35][36] where parahydrogen (pH 2 ) is used to polarize dissolved molecules by their mutual exchange with a transient complex. SABRE is unique in providing continuous hyperpolarization in the liquid state with high-throughput [26,37] and is relatively cost-efficient.…”

“…H, one19 F for 3FPy or three 1 H, one 19 F for EFNA; 2. Additions of two singlet-state hydride protons (pH 2 ) to the system forming the polarized Ir-complex: IrHH-3FPy or IrHH-Scheme 2.…”