Perfused Cells, Tissues and Organs by Magnetic Resonance Spectroscopy

Abstract

In this article we review methods for the study of perfused cells, tissues, and organs using magnetic resonance spectroscopy (MRS). Biologically relevant nuclei and the different but often complementary information that they make available are presented. Pulse sequence implementation is discussed in the context of tailoring the desired metabolite information and suppressing unwanted resonances. Metabolites observable with MRS are generally limited to those present in relatively high (millimolar) concentrations. The importance of these metabolites and how flux through metabolic pathways can be observed using isotopic enhancement with 13 C is reviewed. Cell preparation and immobilization methods employing agarose threads, matrigel and alginate beads; and the use of porous and nonporous microcarriers, hollow fibers and bioreactors for perfused cell culture are discussed. Tissue preparation techniques for the study of perfused organs include the Langendorff heart, perfused liver, and lung preparations. Maintaining careful control of the perfusate composition, pH, oxygenation, and temperature all critically affect cell and organ viability as well as the measured levels of cell metabolites. The requisite apparatus for achieving this is reviewed. Perfusion model systems allow the acquisition of real-time kinetic metabolic information by MRS, providing unique insights into the effects of drugs and inhibitors on metabolite levels. They thus provide a valuable intermediate for translational research from cells to animals to humans and back again.

Determination of Intra- and Extracellular Metabolic Adaptations of 3D Cell Cultures upon Challenges in Real-Time by NMR

“…The FIDs were exponentially weighted with a line broadening factor of 20 Hz, Fourier-transformed, manually phased and baseline corrected and calibrated according to the α-ATP signal to −11.30 ppm [ 50 ]. All 31 P chemical shifts were assigned according to literatures references [ 51 , 52 , 53 , 54 , 55 ].…”

Live monitoring of cellular metabolism and mitochondrial respiration in 3D cell culture system using NMR spectroscopy

“…22 Perfused cell and organ model systems for NMR have been developed already in the 1980s and 1990s for the investigation of biochemistry and physiology. [23][24][25][26][27] These perfused cell and organ studies require a perfusion apparatus controlling nutrient delivery, temperature, pH, and gas delivery to keep cells close to natural conditions.…”

“…The vast majority of NMR investigations on living cells in bioreactors have applied 31 P NMR to investigate metabolism or 13 C NMR of labelled (hyperpolarized) substrates, in order to trace metabolic pathways in real time and measure metabolic fluxes. 42,43 Only few studies performed 1 H NMR investigations for small metabolite detection 25,29,30,39,[44][45][46][47][48] and even less longitudinal 1 H NMR metabolomical investigations of living cell cultures in bioreactors under controlled cell culture conditions. Besides assessment of metabolic changes, determination of oxygenation and oxygen consumption is highly valuable as a surrogate marker of aerobic energy production via mitochondrial oxidative phosphorylation.…”