Magnetic Resonance Microscopy (MRM) of Single Mammalian Myofibers and Myonuclei

Abstract

Recently, the first magnetic resonance microscopy (MRM) images at the cellular level in isolated mammalian brain tissues were obtained using microsurface coils. These methods can elucidate the cellular origins of MR signals and describe how these signals change over the course of disease progression and therapy. In this work, we explore the capability of these microimaging techniques to visualize mouse muscle fibers and their nuclei. Isolated myofibers expressing lacZ were imaged with and without a stain for β-galactosidase activity (S-Gal + ferric ammonium citrate) that produces both optical and MR contrast. We found that MRM can be used to image single myofibers with 6-μm resolution. The ability to image single myofibers will serve as a valuable tool to study MR properties attributed to healthy and myopathic cells. The ability to image nuclei tagged with MR/Optical gene markers may also find wide use in cell lineage MRI studies.

Systematic Analysis of the Improvements in Magnetic Resonance Microscopy with Ferroelectric Composite Ceramics

“…Aligned with the development of ultrahigh static magnetic fields ( B 0 ), MRM is an important tool for visualizing tiny structural details and studying functional behavior of living samples . State‐of‐the‐art magnets with B 0 from 14 to 21 T enable micrometer resolution, which allows magnetic resonance imaging and spectroscopy of small specimens as single cells, single neurons, and myofibers, and even functional investigation of such samples …”

“…The former provides the highest SNR in direct proximity to the coil's surface and is therefore ideally suited for imaging very thin samples such as histological sections. The coil size can be reduced to reach high local resolution, as in so‐called microcoils . Volumetric probes are the second type of probes used to study the entire sample volume.…”

Ex vivo MR microscopy of a human brain with multiple sclerosis: Visualizing individual cells in tissue using intrinsic iron

“…MRM has been performed using intrinsic contrast at high fields and specialized hardware at even higher resolutions (as high as 5 μm ( Filippi and Rocca, 2011 )), enabling visualization of individual isolated cells, such as neurons, and identification of subcellular structures, such as nuclei. ( Aguayo et al, 1986 ; Schoeniger et al, 1994 ; Bowtell et al, 1995 ; Lee et al, 2015 ; Lee et al, 2017 ) Other studies have looked at the microenvironment of cells in tissue such as rat spinal cord. ( Flint et al, 2009 ) The MRM contrast reported herein originated largely from differences in concentration of iron, myelin, and collagen.…”

Across the spectrum: integrating multidimensional metal analytics forin situmetallomic imaging

“…Typical resolutions for in vivo MRI fall around 1 mm 3 , however advances in both molecular and cellular MR imaging (MR-microscopy (MRM)) now allow for longitudinal monitoring of subcellular events whilst providing highly resolved anatomical contexts with spatial resolutions in the sub 100 μm range. MRM has been used to reveal characteristic pathologic features of both benign and malignant breast and lymph tissue,9 and as an in vitro tool to study myonuclei of individual muscle fibres down to 6 μm planar spatial resolution 10. Particularly relevant for metallomics, MRI chemical probes have also been synthesised for specific investigations of biologically important metal ions, such as potassium, magnesium, copper( i ), copper( ii ), zinc, calcium and even toxic metals such as lead and cadmium 11.…”