Failure of intravenous or intracardiac delivery of mesenchymal stromal cells to improve outcomes after focal traumatic brain injury in the female rat

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.

A Prosperous Application of Hydrogels With Extracellular Vesicles Release for Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of disability worldwide, becoming a heavy burden to the family and society. However, the complexity of the brain and the existence of blood-brain barrier (BBB) do limit most therapeutics effects through simple intravascular injection. Hence, an effective therapy promoting neurological recovery is urgently required. Although limited spontaneous recovery of function post-TBI does occur, increasing evidence indicates that exosomes derived from stem cells promote these endogenous processes. The advantages of hydrogels for transporting drugs and stem cells to target injured sites have been discussed in multitudinous studies. Therefore, the combined employment of hydrogels and exosomes for TBI is worthy of further study. Herein, we review current research associated with the application of hydrogels and exosomes for TBI. We also discuss the possibilities and advantages of exosomes and hydrogels co-therapies after TBI.

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.

Combined bioscaffold with stem cells and exosomes can improve traumatic brain injury

The intricacy of the brain, along with the existence of blood brain barrier (BBB) does complicate the delivery of effective therapeutics through simple intravascular injection. Hence, an effective delivery mechanism of therapeutics in the event of either traumatic brain injury (TBI) or other brain injuries is needed. Stem cells can promote regeneration and repair injury. The usage of biomaterials and exosomes in transporting stem cells to target lesion sites has been suggested as a potential option. The combination of biomaterials with modified exosomes can help in transporting stem cells to injury sites, whiles also increasing their survival and promoting effective treatment. Herein, we review the current researches pertinent to biological scaffolds and exosomes in repairing TBI and present the current progress and new direction in the clinical setting. We begin with the role of bioscaffold in treating neuronal conditions, the effect of exosomes in injury, and conclude with the improvement of TBI via the employment of combined exosomes, bioscaffold and stem cells.

Neurorepair and Regeneration of the Brain: A Decade of Bioscaffolds and Engineered Microtissue

Repairing the human brain remains a challenge, despite the advances in the knowledge of inflammatory response to injuries and the discovery of adult neurogenesis. After brain injury, the hostile microenvironment and the lack of structural support for neural cell repopulation, anchoring, and synapse formation reduce successful repair chances. In the past decade, we witnessed the rise of studies regarding bioscaffolds’ use as support for neuro repair. A variety of natural and synthetic materials is available and have been used to replace damaged tissue. Bioscaffolds can assume different shapes and may or may not carry a diversity of content, such as stem cells, growth factors, exosomes, and si/miRNA that promote specific therapeutic effects and stimulate brain repair. The use of these external bioscaffolds and the creation of cell platforms provide the basis for tissue engineering. More recently, researchers were able to engineer brain organoids, neural networks, and even 3D printed neural tissue. The challenge in neural tissue engineering remains in the fabrication of scaffolds with precisely controlled topography and biochemical cues capable of directing and controlling neuronal cell fate. The purpose of this review is to highlight the existing research in the growing field of bioscaffolds’ development and neural tissue engineering. Moreover, this review also draws attention to emerging possibilities and prospects in this field.

Overexpression of anti-fibrotic factors ameliorates anti-fibrotic properties of Wharton's jelly derived mesenchymal stem cells under oxidative damage

Transplantation with Wharton's jelly derived mesenchymal stem cells (WJ-MSCs) showed great benefits for restoring myocardial function. However, the outcome of WJ-MSCs transplantation was unsuccessful due to multiple factors including oxidative damage. The presence of oxidative stress due to myocardium injury influences fibrous tissue formation, which causes disability of cardiac muscle. Hepatocyte growth factor (HGF), insulin-like growth factor (IGF1), and sonic hedgehog (SHH) are well-known master regulators in anti-fibrosis when secreted by WJ-MSCs. They showed a beneficial role in the recovery of cardiac fibrosis after WJ-MSCs transplantation. This study hypothesizes whether the reduction of the anti-fibrosis property in WJ-MSCs from oxidative damage can be recovered by overexpression of the HGF, IGF1, or SHH gene. Overexpression was attained by transfection of WJ-MSCs with pCMV3-HGF, pCMV3-IGF1, or pCMV3-SHH followed by H2O2 exposure and co-culturing with cardiac fibroblasts. Myofibroblast specific markers comprised of alpha-smooth muscle actin (α-SMA) and collagen type 1 (COL1) were evaluated. The WJ-MSCs treated with H2O2 influenced the expression of myofibroblastic markers, whereas the overexpression of HGF, IGF1 or SHH reduced myofibroblastic formation. These results indicate that the oxidative stress impaired anti-fibrotic property of WJ-MSCs, leads to an increase of myofibroblasts. Overexpression of anti-fibrotic genes restored the endogenous HGF, IGF1, and SHH alleviating improvement of cardiac function.

Myths, reality and future of mesenchymal stem cell therapy

Mesenchymal stem cell (MSC) therapy represents an alternative approach for tissue regeneration and inflammation control. In spite of a huge amount of preclinical data that has been accumulated on the therapeutic properties of MSCs, there are many conflicting results, possibly due to differences in the properties of MSCs obtained from different sources or underestimated mechanisms of MSC in vivo behavior. This review consolidates the in vivo effects of MSC therapy, discusses the fate of MSCs after intravascular and local delivery and proposes possible trends in MSC therapy.

Rotary jet-spun porous microfibers as scaffolds for stem cells delivery to central nervous system injury

Stem cell transplantation is a promising strategy to treat brain injuries. However, cell-based therapies are limited because poor local cell engraftment. Here, we present a polylactic acid (PLA) scaffold to support mesenchymal stem cells (MSCs) delivery in stroke. We isolated bone marrow MSCs from adult C57/Bl6 mice, cultured them on PLA polymeric rough microfibrous (PRM) scaffolds obtained by rotary jet spinning, and transplanted over the brains of adult C57/Bl6 mice, carrying thermocoagulation-induced cortical stroke. No inflammatory response to PRM was found. MSCs transplantation significantly reduced the area of the lesion and PRM delivery increased MSCs retention at the injury site. In addition, PRM upregulated α6-integrin and CXCL12 production, which may be the cause for greater cell retention at the lesion site and may provide additional benefit to MSCs transplantation procedures. We conclude that PRM scaffolds offer a promising new system to deliver stem cells to injured areas of the brain.

Controlled Cortical Impact in the Rat

Traumatic brain injury (TBI) is a major cause of death and disability world-wide. Following initial injury, TBI patients can face long-term disability in the form of cognitive, physical, and psychological deficits, depending on the severity and location of injury. This results in an economic burden in the United States estimated to be $60 billion due to health-care costs and loss of productivity. TBI is a significant area of active research interest for both military and civilian medicine. Numerous pre-clinical animal models of TBI are used to characterize the anatomical and physiological pathways involved and to evaluate therapeutic interventions. Due to its flexibility and scalability, controlled cortical impact (CCI) is one of the most commonly used preclinical TBI models. This unit provides a basic CCI protocol performed in the rat. © 2017 by John Wiley & Sons, Inc.

Treatment of Severe Adult Traumatic Brain Injury Using Bone Marrow Mononuclear Cells

Preclinical studies using bone marrow derived cells to treat traumatic brain injury have demonstrated efficacy in terms of blood-brain barrier preservation, neurogenesis, and functional outcomes. Phase 1 clinical trials using bone marrow mononuclear cells infused intravenously in children with severe traumatic brain injury demonstrated safety and potentially a central nervous system structural preservation treatment effect. This study sought to confirm the safety, logistic feasibility, and potential treatment effect size of structural preservation/inflammatory biomarker mitigation in adults to guide Phase 2 clinical trial design. Adults with severe traumatic brain injury (Glasgow Coma Scale 5-8) and without signs of irreversible brain injury were evaluated for entry into the trial. A dose escalation format was performed in 25 patients: 5 controls, followed 5 patients in each dosing cohort (6, 9, 12 ×106 cells/kg body weight), then 5 more controls. Bone marrow harvest, cell processing to isolate the mononuclear fraction, and re-infusion occurred within 48 hours after injury. Patients were monitored for harvest-related hemodynamic changes, infusional toxicity, and adverse events. Outcome measures included magnetic resonance imaging-based measurements of supratentorial and corpus callosal volumes as well as diffusion tensor imaging-based measurements of fractional anisotropy and mean diffusivity of the corpus callosum and the corticospinal tract at the level of the brainstem at 1 month and 6 months postinjury. Functional and neurocognitive outcomes were measured and correlated with imaging data. Inflammatory cytokine arrays were measured in the plasma pretreatment, posttreatment, and at 1 and 6 month follow-up. There were no serious adverse events. There was a mild pulmonary toxicity of the highest dose that was not clinically significant. Despite the treatment group having greater injury severity, there was structural preservation of critical regions of interest that correlated with functional outcomes. Key inflammatory cytokines were downregulated. Treatment of severe, adult traumatic brain injury using an intravenously delivered autologous bone marrow mononuclear cell infusion is safe and logistically feasible. There appears to be a treatment signal as evidenced by central nervous system structural preservation, consistent with previous pediatric trial data. Inflammatory biomarkers are downregulated after cell infusion. Stem Cells 2016 Video Highlight: https://youtu.be/UiCCPIe-IaQ Stem Cells 2017;35:1065-1079.

Preclinical progenitor cell therapy in traumatic brain injury: a meta-analysis

BACKGROUND

No treatment is available to reverse injury associated with traumatic brain injury (TBI). Progenitor cell therapies show promise in both preclinical and clinical studies. We conducted a meta-analysis of preclinical studies using progenitor cells to treat TBI.

METHODS

EMBASE, MEDLINE, Cochrane Review, Biosis, and Google Scholar were searched for articles using prespecified search strategies. Studies meeting inclusion criteria underwent data extraction. Analysis was performed using Review Manager 5.3 according to a fixed-effects model, and all studies underwent quality scoring.

RESULTS

Of 430 abstracts identified, 38 met inclusion criteria and underwent analysis. Average quality score was 4.32 of 8 possible points. No study achieved a perfect score. Lesion volume (LV) and neurologic severity score (NSS) outcomes favored cell treatment with standard mean difference (SMD) of 0.86 (95% CI: 0.64-1.09) and 1.36 (95% CI: 1.11-1.60), respectively. Rotarod and Morris water maze outcomes also favored treatment with improvements in SMD of 0.34 (95% CI: 0.02-0.65) and 0.46 (95% CI: 0.17-74), respectively. Although LV and NSS were robust to publication bias assessments, rotarod and Morris water maze tests were not. Heterogeneity (I²) ranged from 74%-85% among the analyses, indicating a high amount of heterogeneity among studies. Precision as a function of quality score showed a statistically significant increase in the size of the confidence interval as quality improved.

CONCLUSIONS

Our meta-analysis study reveals an overall positive effect of progenitor cell therapies on LV and NSS with a trend toward improved motor function and spatial learning in different TBI animal models.

T-cell factor (TCF/LEF1) binding elements (TBEs) of FasL (Fas ligand or CD95 ligand) bind and cluster Fas (CD95) and form complexes with the TCF-4 and b-catenin transcription factors in vitro and in vivo which result in triggering cell death and/or cell activation

T-cell factor 4 (TCF4) is an important transcription factor of the Wnt signaling system. β-catenin, an upstream protein of TCF4, accumulates in the cytoplasm, then translocates to the nucleus to activate the β-catenin/T-cell factor/lymphoid enhancer factor (TCF/LEF) transcriptional machinery and regulates target genes. Previous studies showed that TCF4 was involved in cell proliferation and apoptosis. However, its expression and function in central nervous system injury are unclear. We performed a traumatic brain injury (TBI) model in adult rats. The expression of TCF4 in the brain cortex detected by Western blot increased after TBI. Double immunofluorescence staining revealed that TCF4 was expressed by neurons and microglia. In addition, co-localization of TCF4 with active caspase-3 or proliferating cell nuclear antigen was observed in neurons and microglia, respectively, suggesting that TCF4 might participate in neuronal apoptosis and microglial proliferation after TBI. To further investigate the functions of TCF4, PC12 and HAPI cells were employed to establish a neuronal apoptosis and microglial proliferation model in vitro, respectively. Knocking down TCF4 with siRNA proved the pro-apoptotic and pro-proliferation effect of TCF4 in PC12 and HAPI cells, respectively. Taken together, TCF4 might promote neuronal apoptosis and microglial proliferation after TBI.

Radiological-pathological correlation of diffusion tensor and magnetization transfer imaging in a closed head traumatic brain injury model

OBJECTIVE

Metrics of diffusion tensor imaging (DTI) and magnetization transfer imaging (MTI) can detect diffuse axonal injury in traumatic brain injury (TBI). The relationship between the changes in these imaging measures and the underlying pathologies is still relatively unknown. This study investigated the radiological-pathological correlation between these imaging techniques and immunohistochemistry using a closed head rat model of TBI.

METHODS

TBI was performed on female rats followed longitudinally by magnetic resonance imaging (MRI) out to 30 days postinjury, with a subset of animals selected for histopathological analyses. A MRI-based finite element analysis was generated to characterize the pattern of the mechanical insult and estimate the extent of brain injury to direct the pathological correlation with imaging findings.

RESULTS

DTI axial diffusivity and fractional anisotropy (FA) were sensitive to axonal integrity, whereas radial diffusivity showed significant correlation to the myelin compactness. FA was correlated with astrogliosis in the gray matter, whereas mean diffusivity was correlated with increased cellularity. Secondary inflammatory responses also partly affected the changes of these DTI metrics. The magnetization transfer ratio (MTR) at 3.5ppm demonstrated a strong correlation with both axon and myelin integrity. Decrease in MTR at 20ppm correlated with the extent of astrogliosis in both gray and white matter.

INTERPRETATION

Although conventional T2-weighted MRI did not detect abnormalities following TBI, DTI and MTI afforded complementary insight into the underlying pathologies reflecting varying injury states over time, and thus may substitute for histology to reveal diffusive axonal injury pathologies in vivo. This correlation of MRI and histology furthers understanding of the microscopic pathology underlying DTI and MTI changes in TBI. Ann Neurol 2016;79:907-920.