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Keywords:
Transplantation, Image verification, Grafts, Surgery, Contrast agent-other, MR, Experimental, Molecular imaging, CNS, Animal (veterinary) studies
Authors:
D. Namestnikova, I. L. Gubskiy, L. Gubsky, I. Kholodenko, K. Yarygin, K. Sukhinich, I. Vakhrushev, V. Pogoreltsev, M. Abakumov; Moscow/RU
DOI:
10.1594/ecr2015/C-2308
Aims and objectives
Stem cells transplantation for regenerative medicine has shown promising therapeutic results in various injury animal models and even in humans during first clinical trials [1].
Currently several clinical trials are being conducted worldwide,
showing the effectiveness of stem cells therapy in the treatment of such pathological conditions as ischemic stroke [1,2] spinal cord injury [3],
myocardial infarction [4] and disorders of the skeletal system [5].
Multiple studies have demonstrated that transplanted stem cells are capable of homing and engrafting into areas of tissue injury [6],
may have positive paracrine effects [7] and even could stimulate endogenous neurogenesis [8].
Despite the large number of studies,
the mechanism of therapeutic effects,
optimal route of administration,
migration and fate of transplanted stem cells has not been fully understood yet [1].
For further development of stem cell therapy a crucial role plays in vivo visualization of transplanted cells [9].
Magnetic resonance imaging provides serial high-resolution detection of organs and tissues of living animal and humans,
and therefore has been widely used for in vivo tracking of labeled stem cells [10].
Stem cells commonly labeled with superparamagnetic iron oxide micro- and nanoparticles (SPIO).
SPIO-labeled cells can be detected with MRI on T2-WI and T2*-WI as a hypointense areas (as ferromagnetic particles cause a reduction in signal intensity in areas of their accumulation due to high sensitivity of T2*- effect to the heterogeneity of the local magnetic fields).
Recently available in laboratory and clinical practice susceptibility weighted MR-imaging is an image sequence,
proposed by Haacke et al.
[12],
and is extremely sensitive to susceptibility changes and can be used for detecting SPIO-labeled cells.
SWI is a three-dimensional (3D) gradient echo sequence with t2*-weighting and combination of magnitude and phase data after high pass filtering.
SWI is more sensitive to field inhomogeneities,
than sequences based on just gradient echo,
and hence is more sensitive to iron oxide labelled cells and can improve their traceability [13,
14].
Except iron accumulation SWI allows good visualization of veins and hemorrhage.
In our study using MRI we evaluate distribution and migration of SPIO-labeled human mesenchymal stem cells (hMSCs) in intact rat brain and compare T2-WI,
T2*-WI and SWI for in vivo and in vitro stem cells detection.