Diffusion-Derived Magnetic Resonance Imaging Measures of Longitudinal Microstructural Remodeling Induced by Marrow Stromal Cell Therapy after Traumatic Brain Injury

Effects of bone marrow mesenchymal stromal cells-derived therapies for experimental traumatic brain injury： A meta-analysis

Background

Bone-marrow-derived mesenchymal stromal (stem) cells [also called MSC(M)] and their extracellular vesicles (EVs) are considered a potentially innovative form of therapy for traumatic brain injury (TBI). Nevertheless, their application to TBI particularly remains preclinical, and the effects of these cells remain unclear and controversial. Therefore, an updated meta-analysis of preclinical studies is necessary to assess the effectiveness of MSC(M) and MSC(M) derived EVs in clinical trials.

Methods

The following databases were searched (to December 2022): PubMed, Web of Science, and Embase. In this study, we measured functional outcomes based on the modified neurological severity score (mNSS), cognitive outcomes based on the Morris water maze (MWM), and histopathological outcomes based on lesion volume. A random effects meta-analysis was conducted to evaluate the effect of mNSS, MWM, and lesion volume.

Results

A total of 2163 unique records were identified from our search, with Fifty-five full-text articles satisfying inclusion criteria. A mean score of 5.75 was assigned to the studies' quality scores, ranging from 4 to 7. MSC(M) and MSC(M) derived EVs had an overall positive effect on the mNSS score and MWM with SMDs -2.57 (95 % CI -3.26; -1.88; p < 0.01) and - 2.98 (95 % CI -4.21; -1.70; p < 0.01), respectively. As well, MSC(M) derived EVs were effective in reducing lesion volume by an SMD of - 0.80 (95 % CI -1.20; -0.40; p < 0.01). It was observed that there was significant variation among the studies, but further analyses could not determine the cause of this heterogeneity.

Conclusions

MSC(M) and MSC(M) derived EVs are promising treatments for TBI in pre-clinical studies, and translation to the clinical domain appears warranted. Besides, large-scale trials in animals and humans are required to support further research due to the limited sample size of MSC(M) derived EVs.

Systematic review and meta-analysis of preclinical studies testing mesenchymal stromal cells for traumatic brain injury

Mesenchymal stromal cells (MSCs) are widely used in preclinical models of traumatic brain injury (TBI). Results are promising in terms of neurological improvement but are hampered by wide variability in treatment responses. We made a systematic review and meta-analysis: (1) to assess the quality of evidence for MSC treatment in TBI rodent models; (2) to determine the effect size of MSCs on sensorimotor function, cognitive function, and anatomical damage; (3) to identify MSC-related and protocol-related variables associated with greater efficacy; (4) to understand whether MSC manipulations boost therapeutic efficacy. The meta-analysis included 80 studies. After TBI, MSCs improved sensorimotor and cognitive deficits and reduced anatomical damage. Stratified meta-analysis on sensorimotor outcome showed similar efficacy for different MSC sources and for syngeneic or xenogenic transplants. Efficacy was greater when MSCs were delivered in the first-week post-injury, and when implanted directly into the lesion cavity. The greatest effect size was for cells embedded in matrices or for MSC-derivatives. MSC therapy is effective in preclinical TBI models, improving sensorimotor, cognitive, and anatomical outcomes, with large effect sizes. These findings support clinical studies in TBI.

A roadmap of brain recovery in a mouse model of concussion: insights from neuroimaging

Concussion or mild traumatic brain injury is the most common form of traumatic brain injury with potentially long-term consequences. Current objective diagnosis and treatment options are limited to clinical assessment, cognitive rest, and symptom management, which raises the real danger of concussed patients being released back into activities where subsequent and cumulative injuries may cause disproportionate damages. This study conducted a cross-sectional multi-modal examination investigation of the temporal changes in behavioural and brain changes in a mouse model of concussion using magnetic resonance imaging. Sham and concussed mice were assessed at day 2, day 7, and day 14 post-sham or injury procedures following a single concussion event for motor deficits, psychological symptoms with open field assessment, T2-weighted structural imaging, diffusion tensor imaging (DTI), neurite orientation density dispersion imaging (NODDI), stimulus-evoked and resting-state functional magnetic resonance imaging (fMRI). Overall, a mismatch in the temporal onsets and durations of the behavioural symptoms and structural/functional changes in the brain was seen. Deficits in behaviour persisted until day 7 post-concussion but recovered at day 14 post-concussion. DTI and NODDI changes were most extensive at day 7 and persisted in some regions at day 14 post-concussion. A persistent increase in connectivity was seen at day 2 and day 14 on rsfMRI. Stimulus-invoked fMRI detected increased cortical activation at day 7 and 14 post-concussion. Our results demonstrate the capabilities of advanced MRI in detecting the effects of a single concussive impact in the brain, and highlight a mismatch in the onset and temporal evolution of behaviour, structure, and function after a concussion. These results have significant translational impact in developing methods for the detection of human concussion and the time course of brain recovery.

The Delayed Neuroprotective Effect of Methylene Blue in Experimental Rat Brain Trauma

After traumatic brain injury (TBI), an increase in dysfunction of the limbs contralateral to injury focus was observed. Using different behavioral tests, we found that a single intravenous injection of methylene blue (MB, 1 mg/kg) 30 min after the injury reduced the impairment of the motor functions of the limbs from 7 to 120 days after TBI. Administration of methylene blue 30 min after the injury and then monthly (six injections in total) was the most effective both in terms of preservation of limb function and duration of therapeutic action. This therapeutic effect was clearly manifested from the seventh day and continued until the end of the experiment-by the 180th day after TBI. MB is known to possess antioxidant properties; it has a protective effect against TBI by promoting autophagy and minimizing lesion volume in the first two weeks after TBI. Studies of the brains on the 180th day after TBI demonstrated that the monthly treatment of animals with MB statistically significantly prevented an increase in the density of microglial cells in the ipsilateral hemisphere and a decrease in the thickness of the corpus callosum in the contralateral hemisphere in comparison with untreated animals. However, on the 180th day after TBI, the magnetic resonance imaging scan of the animal brains did not show a significant reduction in the volume of the lesion in MB-treated animals. These findings are important for understanding the development of the long-term effects of TBI and expand the required therapeutic window for targeted neuroprotective interventions.

The single intravenous administration of methylene blue after traumatic brain injury diminishes neurological deficit, blood-brain barrier disruption and decrease in the expression of S100 protein in rats

The protective effect of methylene blue (MB) was investigated on the model of focal one-sided traumatic brain injury (TBI) of the sensorimotor cortex region from 1 to 7 days after the injury. TBI caused a reliable disruption of the functions of the limbs contralateral to injury focus, an increase in the expression of S100 protein and blood-brain barrier (BBB) permeability in the ipsilateral hemisphere. The single intravenous injection of MB (1 mg/kg body weight) 30 min after TBI significantly reduced the limb function impairment as well as a TBI-induced increase in the expression of inflammatory marker S100 protein, and BBB permeability. When modeling inflammation in vitro, MB was found to protect cultured neurons from the toxic effects of lipopolysaccharide. In conclusion, the preservation of blood-brain barrier and a decrease in the expression of S100 protein may be an important mechanism by means of which MB improves neurological outcome. Our data demonstrate that MB can be a very promising pharmacological compound with neuroprotective properties for TBI treatment.

Diffuse white matter response in trauma-injured brain to bone marrow stromal cell treatment detected by diffusional kurtosis imaging

Diffuse white matter (WM) response to traumatic brain injury (TBI) and transplantation of human bone marrow stromal cells (hMSCs) after the injury were non-invasively and dynamically investigated. Male Wistar rats (300-350 g) subjected to TBI were intravenously injected with 1 ml of saline (n = 10) or with hMSCs in suspension (∼3 × 106 hMSCs, n = 10) 1-week post-TBI. MRI measurements of T2-weighted imaging and diffusional kurtosis imaging (DKI) were acquired on all animals at multiple time points up to 3-months post-injury. Functional outcome was assessed using the Morris water maze test. DKI-derived metrics of fractional anisotropy (FA), axonal water fraction (AWF) and radial kurtosis (RK) longitudinally reveal an evolving pattern of structural alteration post-TBI occurring in the brain region remote from primary impact site. The progressive structural change is characterized by gradual disruption of WM integrity at an early stage (weeks post-TBI), followed by spontaneous recovery at a later stage (months post-TBI). Transplantation of hMSCs post-TBI promotes this structural plasticity as indicated by significantly increased FA and AWF in conjunction with substantially elevated RK at the later stage. Our long-term imaging data demonstrate that hMSC therapy leads to modified temporal profiles of these metrics, inducing an earlier presence of enhanced structural remodeling, which may contribute to improved functional recovery.

The delayed protective effect of GK-2, а dipeptide mimetic of Nerve Growth Factor, in a model of rat traumatic brain injury

The delayed protective effect of GK-2, a dipeptide mimetic of Nerve Growth Factor, was investigated on the model of focal one-sided traumatic brain injury (TBI) of the sensorimotor cortex region on the 180th day after the injury. TBI caused a reliably disruption of the functions of the limbs contralateral to injury focus. The intraperitoneal administration of GK-2 (1 mg/kg) from 1st to 4th and from 7th to 10th days after TBI reduced the impairment of the motor functions of the limbs. This therapeutic effect significant manifested itself from the 7th day and continued until the end of the experiment - on the 180th day after TBI. Morphological studies of the animal brains on the 180th day after TBI demonstrated a decrease in the number of neurons in the V layer of the cerebral cortex and a decrease in the thickness of the corpus callosum. The treatment of animals with GK-2 after TBI statistically significant prevented a decrease in the density of neurons in the ipsilateral hemisphere and a decrease in the thickness of the corpus callosum in the contralateral hemisphere in comparison with untreated animals. Additionally, we showed in vitro that GK-2 exhibits neuroprotective properties under oxidative stress in primary hippocampal cultures. Our results demonstrate that the use of GK-2 at the early stages of development of traumatic brain damage can prevent such delayed damage as neuronal and axonal degeneration as well as reduce TBI-related disruptions of brain functions.

Chronic global analysis of vascular permeability and cerebral blood flow after bone marrow stromal cell treatment of traumatic brain injury in the rat: A long-term MRI study

Vascular permeability and hemodynamic alteration in response to the transplantation of human bone marrow stromal cells (hMSCs) after traumatic brain injury (TBI) were longitudinally investigated in non directly injured and normal-appearing cerebral tissue using magnetic resonance imaging (MRI). Male Wistar rats (300-350g, n=30) subjected to controlled cortical impact TBI were intravenously injected with 1ml of saline (at 6-h or 1-week post-injury, n=5/group) or with hMSCs in suspension (∼3×10⁶ hMSCs, at 6-h or 1-week post-injury, n=10/group). MRI measurements of T2-weighted imaging, cerebral blood flow (CBF) and blood-to-brain transfer constant (Ki) of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA), and neurological behavioral estimates were performed on all animals at multiple time points up to 3-months post-injury. Our long-term imaging data show that blood-brain barrier (BBB) breakdown and hemodynamic disruption after TBI, as revealed by Ki and CBF, respectively, affect both hemispheres of the brain in a diffuse manner. Our data reveal a sensitive vascular permeability and hemodynamic reaction in response to the time-dependent transplantation of hMSCs. A more rapid reduction of Ki following cell treatment is associated with a higher level of CBF in the injured brain, and acute (6h) cell administration leads to enhanced therapeutic effects on both the recovery of vascular integrity and stabilization of cerebral perfusion compared to delayed (1w) cell engraftment. Our results indicate that cell-enhanced BBB reconstitution plays an important role in underlying the restoration of CBF in the injured brain, which in turn, contributes to the improvement of functional outcome.