Brain morphological and connectivity changes on MRI after stem cell therapy in a rat stroke model

Abstract

In animal models of stroke, behavioral assessments could be complemented by a variety of neuroimaging studies to correlate them with recovery and better understand mechanisms of improvement after stem cell therapy. We evaluated morphological and connectivity changes after treatment with human mesenchymal stem cells (hMSCs) in a rat stroke model, through quantitative measurement of T2-weighted images and diffusion tensor imaging (DTI). Transient middle cerebral artery occlusion rats randomly received PBS (PBS-only), FBS cultured hMSCs (FBS-hMSCs), or stroke patients’ serum cultured hMSCs (SS-hMSCs). Functional improvement was assessed using a modified neurological severity score (mNSS). Quantitative analyses of T2-weighted ischemic lesion and ventricular volume changes were performed. Brain microstructure/connectivity changes were evaluated in the ischemic recovery area by DTI-derived microstructural indices such as relative fractional anisotropy (rFA), relative axial diffusivity (rAD), and relative radial diffusivity (rRD), and relative fiber density (rFD) analyses. According to mNSS results, the SS-hMSCs group showed the most prominent functional improvement. Infarct lesion volume of the SS-hMSCs group was significantly decreased at 2 weeks when compared to the PBS-only groups, but there were no differences between the FBS-hMSCs and SS-hMSCs groups. Brain atrophy was significantly decreased in the SS-hMSCs group compared to the other groups. In DTI, rFA and rFD values were significantly higher and rRD value was significant lower in the SS-hMSCs group and these microstructure/connectivity changes were correlated with T2-weighted morphological changes. T2-weighted volume alterations (ischemic lesion and brain atrophy), and DTI microstructural indices and rFD changes, were well matched with the results of behavioral assessment. These quantitative MRI measurements could be potential outcome predictors of functional recovery after treatment with stem cells for stroke.

Effect of Neurorepair for Motor Functional Recovery Enhanced by Total Saponins From Trillium tschonoskii Maxim. Treatment in a Rat Model of Focal Ischemia

“…In the present study, DTI images showed that decreased FA values in the sensorimotor cortex and internal capsule of the ischemic hemisphere after ischemia, while TSTT treatment significantly elevated FA value in the corresponding areas. In general, the decreased FA value is possibly attributed to structural breakdown of axons, but enhanced FA represents axonal remodeling after stroke (Son et al, 2021). Data herein indicated that TSTT might facilitate microstructural integrity after ischemic stroke.…”

Development and application of rTMS device to murine model

“…To construct an accurate animal head model, a numerical simulation model of the animal was created by digitizing the animal head structure using 7.0 T MRI 19 . The coil developed by this research team was applied to an animal head model to measure the actual magnetic field value, and the conditions for applying the voltage under the same conditions as those of the clinical study were traced.…”

“…A quadrature birdcage coil (inner diameter, 72 mm) was used for excitation, and an actively decoupled 4-channel phased array surface coil was used to receive the signal. T2-weighted images were acquired from C57BL/6N mice under isoflurane anesthesia (5% for induction, 1.5% for maintenance) using a turbo rapid acquisition with refocusing echoes (Turbo RARE) sequence with the following parameters: repetition time (TR)/echo time (TE) = 3000/60 ms; number of averages = 4; field of view = 30 × 30 mm 2 ; image matrix = 192 × 192; and in-plane resolution = 0.156 × 0.156 × 0.75 mm 3 19 .…”

Advances in differential diagnosis of cerebrovascular diseases in magnetic resonance imaging: a narrative review

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