Immunosuppression does not affect human bone marrow mesenchymal stromal cell efficacy after transplantation in traumatized mice brain

Mapping small metabolite changes after traumatic brain injury using AP-MALDI MSI

Traumatic brain injury (TBI) is an alteration of brain function caused by a sudden transmission of an external force to the head. The biomechanical impact induces acute and chronic metabolic changes that highly contribute to injury evolution and outcome. TBI heterogeneity calls for approaches allowing the mapping of regional molecular and metabolic changes underpinning disease progression, with mass spectrometry imaging (MSI) as an efficient tool to study the spatial distribution of small metabolites. In this study, we applied an innovative targeted atmospheric pressure-MALDI mass spectrometry imaging (AP-MALDI MSI) approach, starting from an extensive list of metabolites, representative of different metabolic pathways, individually validated on the tissue under analysis with original standards using 2,5-dihydroxybenzoic acid (DHB), to characterize the impact of TBI on regional changes to small metabolites in the brain. Brains from sham and TBI mice obtained 21 days post-injury were analyzed to examine the spatial metabolic profile of small metabolites belonging to different metabolic pathways. By a whole brain analysis, we identified four metabolites (alanine, lysine, histidine, and inosine) with higher abundance in TBI than sham mice. Within the TBI group, lysine, histidine, and inosine were higher in the hemisphere ipsilateral to the biomechanical impact vs. the contralateral one. Images showed a major involvement of the ipsilateral thalamus characterized by the increase of arginine, lysine, histidine, and inosine and a significant reduction of glutamic acid, and N-acetylaspartic acid compared to the contralateral thalamus. These findings indicate high-resolution imaging mass spectrometry as a powerful tool to identify region-specific changes after a TBI to understand the metabolic changes underlying brain injury evolution.

Neurovascular Interventions for Neurotrauma: From Treatment of Injured Vessels to Treatment of the Injured Brain?

Traumatic brain injury is often associated with a direct or secondary neurovascular pathology. In this review, we present recent advancements in endovascular neurosurgery that enable accurate and effective vessel reconstruction with emphasis on its role in early diagnosis, the expanding use of flow diversion in pseudoaneurysms, and traumatic arteriovenous fistulas. In addition, future directions in which catheter-based interventions could potentially affect traumatic brain injury are described: targeting blood brain barrier integrity using the advantages of intra-arterial drug delivery of blood brain barrier stabilizers to prevent secondary brain edema, exploring the impact of endovascular venous access as a means to modulate venous outflow in an attempt to reduce intracranial pressure and augment brain perfusion, applying selective intra-arterial hypothermia as a neuroprotection method mitigating some of the risks conferred by systemic cooling, trans-vessel wall delivery of regenerative therapy agents, and shifting attention using multimodal neuromonitoring to post-traumatic vasospasm to further characterize the role it plays in secondary brain injury. Thus, we believe that the potential of endovascular tools can be expanded because they enable access to the "highways" governing perfusion and flow and call for further research focused on exploring these routes because it may contribute to novel endovascular approaches currently used for treating injured vessels, harnessing them for treatment of the injured brain.

Innovative Insights into Traumatic Brain Injuries: Biomarkers and New Pharmacological Targets

A traumatic brain injury (TBI) is a major health issue affecting many people across the world, causing significant morbidity and mortality. TBIs often have long-lasting effects, disrupting daily life and functionality. They cause two types of damage to the brain: primary and secondary. Secondary damage is particularly critical as it involves complex processes unfolding after the initial injury. These processes can lead to cell damage and death in the brain. Understanding how these processes damage the brain is crucial for finding new treatments. This review examines a wide range of literature from 2021 to 2023, focusing on biomarkers and molecular mechanisms in TBIs to pinpoint therapeutic advancements. Baseline levels of biomarkers, including neurofilament light chain (NF-L), ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1), Tau, and glial fibrillary acidic protein (GFAP) in TBI, have demonstrated prognostic value for cognitive outcomes, laying the groundwork for personalized treatment strategies. In terms of pharmacological progress, the most promising approaches currently target neuroinflammation, oxidative stress, and apoptotic mechanisms. Agents that can modulate these pathways offer the potential to reduce a TBI's impact and aid in neurological rehabilitation. Future research is poised to refine these therapeutic approaches, potentially revolutionizing TBI treatment.

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.

Regulatory T lymphocytes in traumatic brain injury

Traumatic brain injury (TBI) presents a significant global health challenge with no effective therapies developed to date. Regulatory T lymphocytes (Tregs) have recently emerged as a potential therapy due to their critical roles in maintaining immune homeostasis, reducing inflammation, and promoting brain repair. Following TBI, fluctuations in Treg populations and shifts in their functionality have been noted. However, the precise impact of Tregs on the pathophysiology of TBI remains unclear. In this review, we discuss recent advances in understanding the intricate roles of Tregs in TBI and other brain diseases. Increased knowledge about Tregs may facilitate their future application as an immunotherapy target for TBI treatment.

MesenchymAl stromal cells for Traumatic bRain Injury (MATRIx): a study protocol for a multicenter, double-blind, randomised, placebo-controlled phase II trial

BACKGROUND

Traumatic brain injury (TBI) is a significant cause of death and disability, with no effective neuroprotective drugs currently available for its treatment. Mesenchymal stromal cell (MSC)-based therapy shows promise as MSCs release various soluble factors that can enhance the injury microenvironment through processes, such as immunomodulation, neuroprotection, and brain repair. Preclinical studies across different TBI models and severities have demonstrated that MSCs can improve functional and structural outcomes. Moreover, clinical evidence supports the safety of third-party donor bank-stored MSCs in adult subjects. Building on this preclinical and clinical data, we present the protocol for an academic, investigator-initiated, multicenter, double-blind, randomised, placebo-controlled, adaptive phase II dose-finding study aiming to evaluate the safety and efficacy of intravenous administration of allogeneic bone marrow-derived MSCs to severe TBI patients within 48 h of injury.

METHODS/DESIGN

The study will be conducted in two steps. Step 1 will enrol 42 patients, randomised in a 1:1:1 ratio to receive 80 million MSCs, 160 million MSCs or a placebo to establish safety and identify the most promising dose. Step 2 will enrol an additional 36 patients, randomised in a 1:1 ratio to receive the selected dose of MSCs or placebo. The activity of MSCs will be assessed by quantifying the plasmatic levels of neurofilament light (NfL) at 14 days as a biomarker of neuronal damage. It could be a significant breakthrough if the study demonstrates the safety and efficacy of MSC-based therapy for severe TBI patients. The results of this trial could inform the design of a phase III clinical trial aimed at establishing the efficacy of the first neurorestorative therapy for TBI.

DISCUSSION

Overall, the MATRIx trial is a critical step towards developing an effective treatment for TBI, which could significantly improve the lives of millions worldwide affected by this debilitating condition. Trial Registration EudraCT: 2022-000680-49.

Protein Expression of the Microglial Marker Tmem119 Decreases in Association With Morphological Changes and Location in a Mouse Model of Traumatic Brain Injury

The activation of microglia and the infiltration of macrophages are hallmarks of neuroinflammation after acute brain injuries, including traumatic brain injury (TBI). The two myeloid populations share many features in the post-injury inflammatory response, thus, being antigenically indistinguishable. Recently Tmem119, a type I transmembrane protein specifically expressed by microglia under physiological conditions, was proposed as a tool to differentiate resident microglia from blood-borne macrophages, not expressing it. However, the validity of Tmem119 as a specific marker of resident microglia in the context of acute brain injury, where microglia are activated and macrophages are recruited, needs validation. Our purpose was to investigate Tmem119 expression and distribution in relation to the morphology of brain myeloid cells present in the injured area after TBI. Mice underwent sham surgery or TBI by controlled cortical impact (CCI). Brains from sham-operated, or TBI mice, were analyzed by in situ hybridization to identify the cells expressing Tmem119, and by Western blot and quantitative immunofluorescence to measure Tmem119 protein levels in the entire brain regions and single cells. The morphology of Iba1+ myeloid cells was analyzed at different times (4 and 7 days after TBI) and several distances from the contused edge in order to associate Tmem119 expression with morphological evolution of active microglia. In situ hybridization indicated an increased Tmem119 RNA along with increased microglial complement C1q activation in the contused area and surrounding regions. On the contrary, the biochemical evaluation showed a drop in Tmem119 protein levels in the same areas. The Tmem119 immunoreactivity decreased in Iba1+ myeloid cells found in the contused cortex at both time points, with the cells showing the hypertrophic ameboid morphology having no Tmem119 expression. The Tmem119 was present on ramifications of resident microglia and its presence was decreased as a consequence of microglial activation in cortical areas close to contusion. Based on the data, we conclude that the decrease of Tmem119 in reactive microglia may depend on the process of microglial activation, which involves the retracting of their branchings to acquire an ameboid shape. The Tmem119 immunoreactivity decreases in reactive microglia to similar levels than the blood-borne macrophages, thus, failing to discriminate the two myeloid populations 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.

IGF-1-Expressing Placenta-Derived Mesenchymal Stem Cells Promote Scalding Wound Healing

BACKGROUND

Stem cell-based regenerative therapy is a novel approach to severe damaged skin. Perinatal tissues such as placenta are considered as promising alternatives. The present study aimed to investigate the effect of insulin-like growth factor-1 (IGF-1)-expressing placenta-derived mesenchymal stem cells (hPMSCs) on healing of burn wounds.

MATERIALS AND METHODS

hPMSCs were isolated from human placenta, and IGF-1 was transducted into hPMSCs via lentivirus. Flow cytometry and MTT assay were performed to assess cell apoptosis and viability, respectively. Immunostaining of CK19 and ki67 was for evaluating epithelial differentiation ability and cell proliferation. For in vivo studies, we established a mouse model of scalding and performed local administration of IGF-1-expressing hPMSCs via subcutaneous injection. Wound histology was analyzed with H&E staining. The expression of fibrogenic cytokines was detected by western blot. The production of pro-inflammatory factors was measured by ELISA.

RESULTS

Overexpression of IGF-1 promoted cell proliferation and epithelial differentiation of hPMSCs in vitro and in vivo. Mice with burn injury displayed increased wound contraction and healing rates following treatment with IGF-1-expressing hPMSCs. There was less inflammatory infiltration and reduced collagen disposition in the presence of IGF-1 at the wound site. Administration of IGF-1-expressing hPMSCs suppressed inflammation by decreasing the levels of pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6. Besides, IGF-1 increased VEGF expression, and decreased TGF-β1, collagen I and collagen III expressions in vivo.

CONCLUSIONS

IGF-1-expressing PMSCs promotes cell proliferation and epithelial differentiation, inhibits inflammation and collagen deposition, and thus contributes to wound healing.

Combination of mesenchymal stem cells and FK506 prolongs heart allograft survival by inhibiting TBK1/IRF3-regulated-IFN-γ production

Lifelong immunosuppression use presents many serious side effects to transplant recipients. Previous studies have shown that mesenchymal stem cells (MSC) regulate the progress of inflammation and protect allograft function. However, the benefits of MSC combined with low-dose tacrolimus (FK506) has not been investigated in heart transplant recipients, and its mechanism deserves further investigation. SD Rat bone marrow-derived MSC were infused into recipient mouse (C57BL/6, B6) through the tail vein, followed by a BALB/c donor cervical ectopic heart transplantation on the next day of infusion. T-lymphocyte subsets and their functions were determined using flow cytometry, ELISA, and qPCR. Thereafter, in vitro and in vivo experiments were conducted to identify the mechanisms regarding MSC and FK506 combination (MF group) use in regulating IFN-γ signaling. MF group in the allogeneic heart transplantation mouse model inhibited acute rejection and prolonged mean survival time (MST) of grafts from 7 days (d) to 22d. Pathological examination of heart grafts suggested that inflammatory cell infiltration decreased, and tissue damage was significantly reduced in the MF group. IFN-γ mRNA expression levels in the grafts and recipients decreased, while IL-4 and TGF-β mRNA expression increased in the MF group. Phosphorylation of TBK1/IRF3 in recipient immune cells decreased under donor antigen stimulation. Combination use of MSC and FK506 can prolong graft survival, possibly by down-regulating TBK1/IRF3 phosphorylation, thus reducing IFN-γ production to prevent infiltration of inflammatory cells in the graft and extend graft survival. The findings provide a potential new approach to immunosuppression selection.

Long pentraxin PTX3 is upregulated systemically and centrally after experimental neurotrauma, but its depletion leaves unaltered sensorimotor deficits or histopathology

Long pentraxin PTX3, a pattern recognition molecule involved in innate immune responses, is upregulated by pro-inflammatory stimuli, contributors to secondary damage in traumatic brain injury (TBI). We analyzed PTX3 involvement in mice subjected to controlled cortical impact, a clinically relevant TBI mouse model. We measured PTX3 mRNA and protein in the brain and its circulating levels at different time point post-injury, and assessed behavioral deficits and brain damage progression in PTX3 KO mice. PTX3 circulating levels significantly increased 1-3 weeks after injury. In the brain, PTX3 mRNA was upregulated in different brain areas starting from 24 h and up to 5 weeks post-injury. PTX3 protein significantly increased in the brain cortex up to 3 weeks post-injury. Immunohistochemical analysis showed that, 48 h after TBI, PTX3 was localized in proximity of neutrophils, likely on neutrophils extracellular traps (NETs), while 1- and 2- weeks post-injury PTX3 co-localized with fibrin deposits. Genetic depletion of PTX3 did not affect sensorimotor deficits up to 5 weeks post-injury. At this time-point lesion volume and neuronal count, axonal damage, collagen deposition, astrogliosis, microglia activation and phagocytosis were not different in KO compared to WT mice. Members of the long pentraxin family, neuronal pentraxin 1 (nPTX1) and pentraxin 4 (PTX4) were also over-expressed in the traumatized brain, but not neuronal pentraxin 2 (nPTX2) or short pentraxins C-reactive protein (CRP) and serum amyloid P-component (SAP). The long-lasting pattern of activation of PTX3 in brain and blood supports its specific involvement in TBI. The lack of a clear-cut phenotype in PTX3 KO mice may depend on the different roles of this protein, possibly involved in inflammation early after injury and in repair processes later on, suggesting distinct functions in acute phases versus sub-acute or chronic phases. Brain long pentraxins, such as PTX4-shown here to be overexpressed in the brain after TBI-may compensate for PTX3 absence.

In-depth characterization of a mouse model of post-traumatic epilepsy for biomarker and drug discovery

Post-traumatic epilepsy (PTE) accounts for 5% of all epilepsies and 10–20% of the acquired forms. The latency between traumatic brain injury (TBI) and epilepsy onset in high-risk patients offers a therapeutic window for intervention to prevent or improve the disease course. However, progress towards effective treatments has been hampered by the lack of sensitive prognostic biomarkers of PTE, and of therapeutic targets. There is therefore a pressing clinical need for preclinical PTE models suitable for biomarker discovery and drug testing. We characterized in-depth a model of severe TBI induced by controlled cortical impact evolving into PTE in CD1 adult male mice. To identify sensitive measures predictive of PTE development and severity, TBI mice were longitudinally monitored by video-electrocorticography (ECoG), examined by MRI, and tested for sensorimotor and cognitive deficits and locomotor activity. At the end of the video-ECoG recording mice were killed for brain histological analysis. PTE occurred in 58% of mice with frequent motor seizures (one seizure every other day), as determined up to 5 months post-TBI. The weight loss of PTE mice in 1 week after TBI correlated with the number of spontaneous seizures at 5 months. Moreover, the recovery rate of the sensorimotor deficit detected by the SNAP test before the predicted time of epilepsy onset was significantly lower in PTE mice than in those without epilepsy. Neuroscore, beam walk and cognitive deficit were similar in all TBI mice. The increase in the contusion volume, the volume of forebrain regions contralateral to the lesioned hemisphere and white matter changes over time assessed by MRI were similar in PTE and no-PTE mice. However, brain histology showed a more pronounced neuronal cell loss in the cortex and hippocampus contralateral to the injured hemisphere in PTE than in no-PTE mice. The extensive functional and neuropathological characterization of this TBI model, provides a tool to identify sensitive measures of epilepsy development and severity clinically useful for increasing PTE prediction in high-risk TBI patients. The high PTE incidence and spontaneous seizures frequency in mice provide an ideal model for biomarker discovery and for testing new drugs.

Initiators of Classical and Lectin Complement Pathways Are Differently Engaged after Traumatic Brain Injury-Time-Dependent Changes in the Cortex, Striatum, Thalamus and Hippocampus in a Mouse Model

The complement system is involved in promoting secondary injury after traumatic brain injury (TBI), but the roles of the classical and lectin pathways leading to complement activation need to be clarified. To this end, we aimed to determine the ability of the brain to activate the synthesis of classical and lectin pathway initiators in response to TBI and to examine their expression in primary microglial cell cultures. We have modeled TBI in mice by controlled cortical impact (CCI), a clinically relevant experimental model. Using Real-time quantitative polymerase chain reaction (RT-qPCR) we analyzed the expression of initiators of classical the complement component 1q, 1r and 1s (C1q, C1r, and C1s) and lectin (mannose binding lectin A, mannose binding lectin C, collectin 11, ficolin A, and ficolin B) complement pathways and other cellular markers in four brain areas (cortex, striatum, thalamus and hippocampus) of mice exposed to CCI from 24 h and up to 5 weeks. In all murine ipsilateral brain structures assessed, we detected long-lasting, time- and area-dependent significant increases in the mRNA levels of all classical (C1q, C1s, C1r) and some lectin (collectin 11, ficolin A, ficolin B) initiator molecules after TBI. In parallel, we observed significantly enhanced expression of cellular markers for neutrophils (Cd177), T cells (Cd8), astrocytes (glial fibrillary acidic protein—GFAP), microglia/macrophages (allograft inflammatory factor 1—IBA-1), and microglia (transmembrane protein 119—TMEM119); moreover, we detected astrocytes (GFAP) and microglia/macrophages (IBA-1) protein level strong upregulation in all analyzed brain areas. Further, the results obtained in primary microglial cell cultures suggested that these cells may be largely responsible for the biosynthesis of classical pathway initiators. However, microglia are unlikely to be responsible for the production of the lectin pathway initiators. Immunofluorescence analysis confirmed that at the site of brain injury, the C1q is localized in microglia/macrophages and neurons but not in astroglial cells. In sum, the brain strongly reacts to TBI by activating the local synthesis of classical and lectin complement pathway activators. Thus, the brain responds to TBI with a strong, widespread and persistent upregulation of complement components, the targeting of which may provide protection in TBI.

Targeted deletions of complement lectin pathway genes improve outcome in traumatic brain injury, with MASP-2 playing a major role

The lectin pathway (LP) of complement activation is believed to contribute to brain inflammation. The study aims to identify the key components of the LP contributing to TBI outcome as possible novel pharmacological targets. We compared the long-term neurological deficits and neuropathology of wild-type mice (WT) to that of mice carrying gene deletions of key LP components after experimental TBI. WT or MASP-2 (Masp2-/-), ficolin-A (Fcna-/-), CL-11 (Colec11-/-), MASP-1/3 (Masp1-/-), MBL-C (Mbl2-/-), MBL-A (Mbl1-/-) or MBL-/- (Mbl1-/-/Mbl2-/-) deficient male C57BL/6J mice were used. Mice underwent sham surgery or TBI by controlled cortical impact. The sensorimotor response was evaluated by neuroscore and beam walk tests weekly for 4 weeks. To obtain a comparative analysis of the functional outcome each transgenic line was rated according to a health score calculated on sensorimotor performance. For selected genotypes, brains were harvested 6 weeks after injury for histopathological analysis. MASP-2-/-, MBL-/- and FCN-A-/- mice had better outcome scores compared to WT. Of these, MASP-2-/- mice had the best recovery after TBI, showing reduced sensorimotor deficits (by 33% at 3 weeks and by 36% at 4 weeks). They also showed higher neuronal density in the lesioned cortex with a 31.5% increase compared to WT. Measurement of LP functional activity in plasma from MASP-2-/- mice revealed the absence of LP functional activity using a C4b deposition assay. The LP critically contributes to the post-traumatic inflammatory pathology following TBI with the highest degree of protection achieved through the absence of the LP key enzyme MASP-2, underlining a therapeutic utility of MASP-2 targeting in TBI.

Mesenchymal stem cell therapy for the treatment of traumatic brain injury: progress and prospects

Traumatic brain injury (TBI) is a major cause of injury-related mortality and morbidity in the USA and around the world. The survivors may suffer from cognitive and memory deficits, vision and hearing loss, movement disorders, and different psychological problems. The primary insult causes neuronal damage and activates astrocytes and microglia which evokes immune responses causing further damage to the brain. Clinical trials of drugs to recover the neuronal loss are not very successful. Regenerative approaches for TBI using mesenchymal stem cells (MSCs) seem promising. Results of preclinical research have shown that transplantation of MSCs reduced secondary neurodegeneration and neuroinflammation, promoted neurogenesis and angiogenesis, and improved functional outcome in the experimental animals. The functional improvement is not necessarily related to cell engraftment; rather, immunomodulation by molecular factors secreted by MSCs is responsible for the beneficial effects of this therapy. However, MSC therapy has a few drawbacks including tumor formation, which can be avoided by the use of MSC-derived exosomes. This review has focused on the research works published in the field of regenerative therapy using MSCs after TBI and its future direction.

Human adipose-derived mesenchymal stem cells for acute and sub-acute TBI

In the U.S., approximately 1.7 million people suffer traumatic brain injury each year, with many enduring long-term consequences and significant medical and rehabilitation costs. The primary injury causes physical damage to neurons, glia, fiber tracts and microvasculature, which is then followed by secondary injury, consisting of pathophysiological mechanisms including an immune response, inflammation, edema, excitotoxicity, oxidative damage, and cell death. Most attempts at intervention focus on protection, repair or regeneration, with regenerative medicine becoming an intensively studied area over the past decade. The use of stem cells has been studied in many disease and injury models, using stem cells from a variety of sources and applications. In this study, human adipose-derived mesenchymal stromal cells (MSCs) were administered at early (3 days) and delayed (14 days) time points after controlled cortical impact (CCI) injury in rats. Animals were routinely assessed for neurological and vestibulomotor deficits, and at 32 days post-injury, brain tissue was processed by flow cytometry and immunohistochemistry to analyze neuroinflammation. Treatment with HB-adMSC at either 3d or 14d after injury resulted in significant improvements in neurocognitive outcome and a change in neuroinflammation one month after injury.

Mesenchymal stromal cell secretome as a therapeutic strategy for traumatic brain injury

Traumatic brain injury (TBI) is a global health problem that is a common cause of disability and mortality. Despite the availability of many treatment options, none is capable of restoring functional and structural recovery of the damaged brain. Both the results of preclinical and clinical studies suggest the use of mesenchymal stromal cells (MSCs) as a therapeutic strategy for structural and functional recovery in TBI. However, recent evidence shows that the neuroprotective potential of MSCs is due to multiple secretions of bioactive molecules that modulate tissue microenvironment for tissue repair and regeneration. The results of preclinical studies indicate the therapeutic benefits of MSC secretome in TBI. Soluble bioactive molecules and extracellular vesicles are the various factors secreted by MSCs that can induce neurogenesis, angiogenesis, neovascularization, and anti-inflammatory activities. This review highlights the neuroprotective effect of MSC secretome for the treatment of TBI. In addition, the possible challenges of secretome as biotherapeutics are identified and how some of the issues raised could be overcome for effective clinical application are also discussed.

Mannose-Binding Lectin Drives Platelet Inflammatory Phenotype and Vascular Damage After Cerebral Ischemia in Mice via IL (Interleukin)-1α

Supplemental Digital Content is available in the text.

Objective—

Circulating complement factors are activated by tissue damage and contribute to acute brain injury. The deposition of MBL (mannose-binding lectin), one of the initiators of the lectin complement pathway, on the cerebral endothelium activated by ischemia is a major pathogenic event leading to brain injury. The molecular mechanisms through which MBL influences outcome after ischemia are not understood yet.

Approach and Results—

Here we show that MBL-deficient (MBL^−/−) mice subjected to cerebral ischemia display better flow recovery and less plasma extravasation in the brain than wild-type mice, as assessed by in vivo 2-photon microscopy. This results in reduced vascular dysfunction as shown by the shift from a pro- to an anti-inflammatory vascular phenotype associated with MBL deficiency. We also show that platelets directly bind MBL and that platelets from MBL^−/− mice have reduced inflammatory phenotype as indicated by reduced IL-1α (interleukin-1α) content, as early as 6 hours after ischemia. Cultured human brain endothelial cells subjected to oxygen-glucose deprivation and exposed to platelets from MBL^−/− mice present less cell death and lower CXCL1 (chemokine [C-X-C motif] ligand 1) release (downstream to IL-1α) than those exposed to wild-type platelets. In turn, MBL deposition on ischemic vessels significantly decreases after ischemia in mice treated with IL-1 receptor antagonist compared with controls, indicating a reciprocal interplay between MBL and IL-1α facilitating endothelial damage.

Conclusions—

We propose MBL as a hub of pathogenic vascular events. It acts as an early trigger of platelet IL-1α release, which in turn favors MBL deposition on ischemic vessels promoting an endothelial pro-inflammatory phenotype.

Combined Genetic Deletion of IL (Interleukin)-4, IL-5, IL-9, and IL-13 Does Not Affect Ischemic Brain Injury in Mice

Background and Purpose—

After ischemic injury, microglia and infiltrated macrophages may acquire different polarization phenotypes promoting inflammation and injury (M1) or repair and protection (M2). There is evidence that immunomodulation, via type 2 helper T-cells (Th2) cytokines, exerts neuroprotection after ischemia. We investigated the consequences of simultaneous genetic deletion of Th2 cytokines (IL [interleukin]-4, IL-5, IL-9, IL-13) on the histopathologic outcome, microglia and infiltrated macrophages markers, and ischemic microenvironment at different time points after ischemic injury in mice subjected to permanent occlusion of the middle cerebral artery.

Methods—

Wild-type and Th2 cytokine-deficient mice (4KO) were subjected to permanent occlusion of the middle cerebral artery by electrocoagulation and followed up to 5 weeks after permanent occlusion of the middle cerebral artery. Neuropathologic outcome was assessed at 24 hours (n=6), 7 days (n=6), and 5 weeks (n=6–7) by examination of the ischemic lesion, neuronal count, microglia and infiltrated macrophages markers, brain atrophy, collagen deposition, and GFAP (glial fibrillary acidic protein) immunohistochemistry. Selected gene expression was investigated at 7 days (n=6).

Results—

4KO mice showed no difference in lesion and neuronal count 7 days and up to 5 weeks after permanent occlusion of the middle cerebral artery compared with wild type. Ischemic 4KO mice had lower CD16/32 expression at 24 hours, lower CD11b and CD16/32 expression at 7 days than wild type. They had higher CD206 expression at 24 hours, higher CD206 and arginase1 at 7 days, and increased mRNA for CXCL9 (chemokine [C-X-C motif] ligand 9) compared with wild type. Additional histopathologic analysis, including brain atrophy, gliotic scar, and collagenous scar confirmed no difference between genotypes at 5 weeks.

Conclusions—

This study casts light on the proposed neuroprotective function of Th2 cytokines, showing that combined IL-4, IL-5, IL-9, IL-13 deletion does not affect the neuropathologic response to ischemic stroke in the subacute and chronic phases. Our findings indicate that Th2 cytokines are not an essential neuroimmunological cue able to drive the brain’s ischemic outcome.

Mesenchymal Stromal Cell Therapeutic Delivery: Translational Challenges to Clinical Application

For several decades, multipotent mesenchymal stromal cells (MSCs) have been extensively studied for their therapeutic potential across a wide range of diseases. In the preclinical setting, MSCs demonstrate consistent ability to promote tissue healing, down-regulate excessive inflammation and improve outcomes in animal models. Several proposed mechanisms of action have been posited and demonstrated across an array of in vitro models. However, translation into clinical practice has proven considerably more difficult. A number of prominent well-funded late-phase clinical trials have failed, thus calling out for new efforts to optimize product delivery in the clinical setting. In this review, we discuss novel topics critical to the successful translation of MSCs from pre-clinical to clinical applications. In particular, we focus on the major routes of cell delivery, aspects related to hemocompatibility, and potential safety concerns associated with MSC therapy in the different settings.

Mesenchymal stem cells derived from induced pluripotent stem cells play a key role in immunomodulation during cardiopulmonary resuscitation

BACKGROUND/AIMS

Previous in vitro experiments have demonstrated the immunomodulatory functions of mesenchymal stem cells derived from induced pluripotent stem cells (iPSC-MSCs) in brain injury. We have tried to further understand these functions by investigating the neuroprotective effects of iPSC-MSCs in a rat model of cardiac arrest (CA).

METHODS

CA was induced in adult Sprague-Dawley rats by transcutaneous electrical epicardium stimulation. The rats were divided into four groups. In a separate cohort of sham operation animals, iPSC-MSCs or PBS was infused via the femoral vein after restoration of spontaneous circulation. Survival was evaluated every 2 h until 24 h after CA. Markers of classically activated macrophages (M1) and alternatively activated (M2) macrophages were assessed by qPCR and western blot analysis, and the gene expression profiles of the macrophages were studied in order to identify differentially expressed proteins.

RESULTS

The 24-h survival rate was significantly different between the CPR group and iPSC-MSC group (P = 0.033). Additionally, a significant number of mRNAs were differentially expressed between the iPSC-MSC and PBS group. Compared with the sham operation group, both M1 (27/29) and M2 (2/29) mRNAs showed a significant increase in expression in the CPR group, while only M2 (22) mRNAs showed a significant increase in expression in the iPSC-MSC group. Western blotting analysis showed that the expression of Arg-1 and CD14 (M2 macrophage markers) was increased in the iPSC-MSC group (P < 0.05), while CD86 and iNOS (M1 macrophage markers) expression was increased in the CPR group (P < 0.05).

CONCLUSION

IPSC-MSCs, which play a key role in immunomodulation, downregulate the level of M1 macrophages and upregulate the level of M2 macrophages after CA.

Neuroprotection in Traumatic Brain Injury: Mesenchymal Stromal Cells can Potentially Overcome Some Limitations of Previous Clinical Trials

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. In the last 30 years several neuroprotective agents, attenuating the downstream molecular and cellular damaging events triggered by TBI, have been extensively studied. Even though many drugs have shown promising results in the pre-clinical stage, all have failed in large clinical trials. Mesenchymal stromal cells (MSCs) may offer a promising new therapeutic intervention, with preclinical data showing protection of the injured brain. We selected three of the critical aspects identified as possible causes of clinical failure: the window of opportunity for drug administration, the double-edged contribution of mechanisms to damage and recovery, and the oft-neglected role of reparative mechanisms. For each aspect, we briefly summarized the limitations of previous trials and the potential advantages of a newer approach using MSCs.

Mesenchymal Stem Cell-Derived Exosomes Provide Neuroprotection and Improve Long-Term Neurologic Outcomes in a Swine Model of Traumatic Brain Injury and Hemorrhagic Shock

Combined traumatic brain injury (TBI) and hemorrhagic shock (HS) remains a leading cause of preventable death worldwide. Mesenchymal stem cell-derived exosomes have demonstrated promise in small animal models of neurologic injury. To investigate the effects of exosome treatment in a clinically realistic large animal model, Yorkshire swine underwent TBI and HS. Animals were maintained in shock for 2 h before resuscitation with normal saline (NS). Animals were then resuscitated either with NS (3 × volume of shed blood) or with the same volume of NS with delayed exosome administration (1 × 10¹³ particles/4 mL) (n = 5/cohort). Exosomes were administered 9 h post-injury, and on post-injury days (PID) 1, 5, 9, and 13. Neurologic severity scores (NSS) were assessed for 30 days, and neurocognitive functions were objectively measured. Exosome-treated animals had significantly lower NSS (p < 0.05) during the first five days of recovery. Exosome-treated animals also had a significantly shorter time to complete neurologic recovery (NSS = 0) compared with animals given NS alone (days to recovery: NS = 16.8 ± 10.6; NS + exosomes = 5.6 ± 2.8; p = 0.03). Animals treated with exosomes initiated neurocognitive testing earlier (days to initiation: NS = 9.6 ± 0.5 vs. NS + exosomes = 4.2 ± 0.8; p = 0.008); however, no difference was seen in time to mastery of tasks. In conclusion, treatment with exosomes attenuates the severity of neurologic injury and allows for faster neurologic recovery in a clinically realistic large animal model of TBI and HS.

Single severe traumatic brain injury produces progressive pathology with ongoing contralateral white matter damage one year after injury

There is increasing recognition that traumatic brain injury (TBI) may initiate long-term neurodegenerative processes, particularly chronic traumatic encephalopathy. However, insight into the mechanisms transforming an initial biomechanical injury into a neurodegenerative process remain elusive, partly as a consequence of the paucity of informative pre-clinical models. This study shows the functional, whole brain imaging and neuropathological consequences at up to one year survival from single severe TBI by controlled cortical impact in mice. TBI mice displayed persistent sensorimotor and cognitive deficits. Longitudinal T2 weighted magnetic resonance imaging (MRI) showed progressive ipsilateral (il) cortical, hippocampal and striatal volume loss, with diffusion tensor imaging demonstrating decreased fractional anisotropy (FA) at up to one year in the il-corpus callosum (CC: -30%) and external capsule (EC: -21%). Parallel neuropathological studies indicated reduction in neuronal density, with evidence of microgliosis and astrogliosis in the il-cortex, with further evidence of microgliosis and astrogliosis in the il-thalamus. One year after TBI there was also a decrease in FA in the contralateral (cl) CC (-17%) and EC (-13%), corresponding to histopathological evidence of white matter loss (cl-CC: -68%; cl-EC: -30%) associated with ongoing microgliosis and astrogliosis. These findings indicate that a single severe TBI induces bilateral, long-term and progressive neuropathology at up to one year after injury. These observations support this model as a suitable platform for exploring the mechanistic link between acute brain injury and late and persistent neurodegeneration.

Intravenous infusion of human bone marrow mesenchymal stromal cells promotes functional recovery and neuroplasticity after ischemic stroke in mice

Transplantation of human bone marrow mesenchymal stromal cells (hBM-MSC) promotes functional recovery after stroke in animal models, but the mechanisms underlying these effects remain incompletely understood. We tested the efficacy of Good Manufacturing Practices (GMP) compliant hBM-MSC, injected intravenously 3.5 hours after injury in mice subjected to transient middle cerebral artery occlusion (tMCAo). We addressed whether hBM-MSC are efficacious and if this efficacy is associated with cortical circuit reorganization using neuroanatomical analysis of GABAergic neurons (parvalbumin; PV-positive cells) and perineuronal nets (PNN), a specialized extracellular matrix structure which acts as an inhibitor of neural plasticity. tMCAo mice receiving hBM-MSC, showed early and lasting improvement of sensorimotor and cognitive functions compared to control tMCAo mice. Furthermore, 5 weeks post-tMCAo, hBM-MSC induced a significant rescue of ipsilateral cortical neurons; an increased proportion of PV-positive neurons in the perilesional cortex, suggesting GABAergic interneurons preservation; and a lower percentage of PV-positive cells surrounded by PNN, indicating an enhanced plastic potential of the perilesional cortex. These results show that hBM-MSC improve functional recovery and stimulate neuroprotection after stroke. Moreover, the downregulation of “plasticity brakes” such as PNN suggests that hBM-MSC treatment stimulates plasticity and formation of new connections in the perilesional cortex.

Double-Injected Human Stem Cells Enhance Rehabilitation in TBI Mice Via Modulation of Survival and Inflammation

Traumatic brain injury (TBI), a complicated form of brain damage, is a major cause of mortality in adults. Following mechanical and structural primary insults, a battery of secondary insults, including neurotransmitter-mediated cytotoxicity, dysregulation of calcium and macromolecule homeostasis, and increased oxidative stress, exacerbate brain injury and functional deficits. Although stem cell therapy is considered to be an alternative treatment for brain injuries, such as TBI and stroke, many obstacles remain. In particular, the time window for TBI treatment with either drugs or stem cells and their efficacy is still vague. Human placenta-derived mesenchymal stem cells (hpMSCs) have received extensive attention in stem cell therapy because they can be acquired in large numbers without ethical issues and because of their immune-modulating capacity and effectiveness in several diseases, such as Alzheimer’s disease and stroke. Here, we tested the feasibility of hpMSCs for TBI treatment with an animal model and attempted to identify appropriate time points for cell treatments. Double injections at 4 and 24 h post-injury significantly reduced the infarct size and suppressed astrocyte and microglial activation around the injury. With reduced damage, double-injected mice showed enhanced anti-inflammatory- and TNF-α receptor 2 (TNFR2)-associated survival signals and suppressed pro-inflammatory and oxidative responses. In addition, double-treated TBI mice displayed restored sensory motor functions and reduced neurotoxic Aβ₄₂ plaque formation around the damaged areas. In this study, we showed the extended therapeutic potentials of hpMSCs and concluded that treatment within an appropriate time window is critical for TBI recovery.

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.

Pharmacological inhibition of mannose-binding lectin ameliorates neurobehavioral dysfunction following experimental traumatic brain injury

Mannose-binding lectin is present in the contusion area of traumatic brain-injured patients and in that of traumatic brain-injured mice, where mannose-binding lectin-C exceeds mannose-binding lectin-A. The reduced susceptibility to traumatic brain injury of mannose-binding lectin double knock-out mice (mannose-binding lectin^-/-) when compared to wild type mice suggests that mannose-binding lectin may be a therapeutic target following traumatic brain injury. Here, we evaluated the effects of a multivalent glycomimetic mannose-binding lectin ligand, Polyman9, following traumatic brain injury in mice. In vitro surface plasmon resonance assay indicated that Polyman9 dose-dependently inhibits the binding to immobilized mannose residues of plasma mannose-binding lectin-C selectively over that of mannose-binding lectin-A. Male C57Bl/6 mice underwent sham/controlled cortical impact traumatic brain injury and intravenous treatment with Polyman9/saline. Ex-vivo surface plasmon resonance studies confirmed that Polyman9 effectively reduces the binding of plasma mannose-binding lectin-C to immobilized mannose residues. In vivo studies up to four weeks post injury, showed that Polyman9 induces significant improvement in sensorimotor deficits (by neuroscore and beam walk), promotes neurogenesis (73% increase in doublecortin immunoreactivity), and astrogliosis (28% increase in glial fibrillary acid protein). Polyman9 administration in brain-injured mannose-binding lectin^-/- mice had no effect on post-traumatic brain-injured functional deficits, suggestive of the specificity of its neuroprotective effects. The neurobehavioral efficacy of Polyman9 implicates mannose-binding lectin-C as a novel therapeutic target for traumatic brain injury.

Label-free monitoring of tissue biochemistry following traumatic brain injury using Raman spectroscopy

Traumatic brain injury (TBI) constitutes a major cause of death and long-term disability. At present, we lack methods to non-invasively track tissue biochemistry and hence select appropriate interventions for patients. We hypothesized that detailed label-free vibrational chemical analysis of focal TBI could provide such information. We assessed the early spatial and temporal changes in tissue biochemistry that are associated with brain injury in mice. Numerous differences were observed in the spectra of the contusion core and pericontusional tissue between 2 and 7 days. For example, a strong signal from haem was seen in the contusion core at 2 days due to haemorrhage, which subsequently resolved. More importantly, elevated cholesterol levels were demonstrated by 7 days, which may be a marker of important cell repair processes. Principal component analysis revealed an early 'acute' component dominated by haemorrhage and a delayed component reflecting changes in protein and lipid composition. Notably we demonstrated changes in Raman signature with time even in the contralateral hemisphere when compared to sham control mice. Raman spectroscopy therefore shows promise as a probe that is sensitive to important pathobiological processes in TBI and could be applied in future both in the experimental setting, as well as in the clinic.

Long term effect and safety of Wharton's jelly-derived mesenchymal stem cells on type 2 diabetes

Cellular therapies offer novel opportunities for the treatment of type 2 diabetes mellitus (T2DM). The present study evaluated the long-term efficacy and safety of infusion of Wharton's jelly-derived mesenchymal stem cells (WJ-MSC) on T2DM. A total of 61 patients with T2DM were randomly divided into two groups on the basis of basal therapy; patients in group I were administered WJ-MSC intravenous infusion twice, with a four-week interval, and patients in group II were treated with normal saline as control. During the 36-month follow-up period, the occurrence of any adverse effects and the results of clinical and laboratory examinations were recorded and evaluated. The lack of acute or chronic adverse effects in group I was consistent with group II.. Blood glucose, glycosylated hemoglobin, C-peptide, homeostasis model assessment of pancreatic islet β-cell function and incidence of diabetic complications in group I were significantly improved, as compared with group II during the 36-month follow-up. The results of the present study demonstrated that infusion of WJ-MSC improved the function of islet β-cells and reduced the incidence of diabetic complications, although the precise mechanisms are yet to be elucidated. The infusion of WJ-MSC may be an effective option for the treatment of patients with type 2 diabetes.

Cell-based therapy for traumatic brain injury

Traumatic brain injury is a major economic burden to hospitals in terms of emergency department visits, hospitalizations, and utilization of intensive care units. Current guidelines for the management of severe traumatic brain injuries are primarily supportive, with an emphasis on surveillance (i.e. intracranial pressure) and preventive measures to reduce morbidity and mortality. There are no direct effective therapies available. Over the last fifteen years, pre-clinical studies in regenerative medicine utilizing cell-based therapy have generated enthusiasm as a possible treatment option for traumatic brain injury. In these studies, stem cells and progenitor cells were shown to migrate into the injured brain and proliferate, exerting protective effects through possible cell replacement, gene and protein transfer, and release of anti-inflammatory and growth factors. In this work, we reviewed the pathophysiological mechanisms of traumatic brain injury, the biological rationale for using stem cells and progenitor cells, and the results of clinical trials using cell-based therapy for traumatic brain injury. Although the benefits of cell-based therapy have been clearly demonstrated in pre-clinical studies, some questions remain regarding the biological mechanisms of repair and safety, dose, route and timing of cell delivery, which ultimately will determine its optimal clinical use.

Fractalkine Receptor Deficiency Is Associated with Early Protection but Late Worsening of Outcome following Brain Trauma in Mice

An impaired ability to regulate microglia activation by fractalkine (CX3CL1) leads to microglia chronic sub-activation. How this condition affects outcome after acute brain injury is still debated, with studies showing contrasting results depending on the timing and the brain pathology. Here, we investigated the early and delayed consequences of fractalkine receptor (CX3CR1) deletion on neurological outcome and on the phenotypical features of the myeloid cells present in the lesions of mice with traumatic brain injury (TBI). Wild type (WT) and CX3CR1(-/-) C57Bl/6 mice were subjected to sham or controlled cortical impact brain injury. Outcome was assessed at 4 days and 5 weeks after TBI by neuroscore, neuronal count, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Compared with WT mice, CX3CR1(-/-) TBI mice showed a significant reduction of sensorimotor deficits and lower cellular damage in the injured cortex 4 days post-TBI. Conversely, at 5 weeks, they showed a worsening of sensorimotor deficits and pericontusional cell death. Microglia (M) and macrophage (μ) activation and polarization were assessed by quantitative immunohistochemistry for CD11b, CD68, Ym1, and inducible nitric oxide synthase (iNOS)-markers of M/μ activation, phagocytosis, M2, and M1 phenotypes, respectively. Morphological analysis revealed a decreased area and perimeter of CD11b(+) cells in CX3CR1(-/-) mice at 4 days post-TBI, whereas, at 5 weeks, both parameters were significantly higher, compared with WT mice. At 4 days, CX3CR1(-/-) mice showed significantly decreased CD68 and iNOS immunoreactivity, while at 5 weeks post-injury, they showed a selective increase of iNOS. Gene expression on CD11b(+) sorted cells revealed an increase of interleukin 10 and insulin-like growth factor 1 (IGF1) at 1 day and a decrease of IGF1 4 days and 5 weeks post-TBI in CX3CR1(-/-), compared with WT mice. These data show an early protection followed by a chronic exacerbation of TBI outcome in the absence of CX3CR1. Thus, longitudinal effects of myeloid cell manipulation at different stages of pathology should be investigated to understand how and when their modulation may offer therapeutic chances.

Systematic review and meta-analysis of efficacy of mesenchymal stem cells on locomotor recovery in animal models of traumatic brain injury

Introduction

The therapeutic potential of mesenchymal stem cells (MSCs) for traumatic brain injury (TBI) is attractive. Conducting systematic review and meta-analyses based on data from animal studies can be used to inform clinical trial design. To conduct a systematic review and meta-analysis to (i) systematically review the literatures describing the effect of MSCs therapy in animal models of TBI, (ii) determine the estimated effect size of functional locomotor recovery after experimental TBI, and (iii) to provide empirical evidence of biological factors associated with greater efficacy.

Methods

We conducted a systematic search of PubMed, EMBASE, and Web of Science and hand searched related references. Studies were selected if they reported the efficacy of MSCs in animal models of TBI. Two investigators independently assessed the identified studies. We extracted the details of individual study characteristics from each publication, assessed study quality, evaluated the effect sizes of MSCs treatment, and performed stratified meta-analysis and meta-regression, to assess the influence of study design on the estimated effect size. The presence of small effect sizes was investigated using funnel plots and Egger’s tests.

Results

Twenty-eight eligible controlled studies were identified. The study quality was modest. Between-study heterogeneity was large. Meta-analysis showed that MSCs exert statistically significant positive effects on sensorimotor and neurological motor function. For sensorimotor function, maximum effect size in studies with a quality score of 5 was found in the weight-drop impact injury TBI model established in male SD rats, to which syngeneic umbilical cord-derived MSCs intracerebrally at cell dose of (1–5) × 10⁶ was administered r 6 hours following TBI, using ketamine as anesthetic agent. For neurological motor function, effect size was maximum for studies with a quality score of 5, in which the weight-drop impact injury TBI models of the female Wistar rats were adopted, with administration syngeneic bone marrow-derived MSCs intravenously at cell dose of 5 × 10⁶ at 2 months after TBI, using sevofluorane as anesthetic agent.

Conclusions

We conclude that MSCs therapy may improve locomotor recovery after TBI. However, additional well-designed and well-reported animal studies are needed to guide further clinical studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0034-0) contains supplementary material, which is available to authorized users.

Shape descriptors of the "never resting" microglia in three different acute brain injury models in mice

BACKGROUND

The study of microglia and macrophage (M/M) morphology represents a key tool to understand the functional activation state and the pattern of distribution of these cells in acute brain injury. The identification of reliable quantitative morphological parameters is urgently needed to understand these cell roles in brain injury and to explore strategies aimed at therapeutically manipulating the inflammatory response.

METHODS

We used three different clinically relevant murine models of focal injury, namely, controlled cortical impact brain injury (traumatic brain injury (TBI)) and transient and permanent occlusion of middle cerebral artery (tMCAo and pMCAo, respectively). Twenty-four hours after injury, M/M cells were labeled by CD11b, and ×40 photomicrographs were acquired by unbiased sampling of the lesion core using a motorized stage microscope. Images were processed with Fiji software to obtain shape descriptors.

RESULTS

We validated several parameters, including area, perimeter, Feret's diameter (caliper), circularity, aspect ratio, and solidity, providing quantitative information on M/M morphology over wide tissue portions. We showed that the shape descriptors that best represent M/M ramification/elongation are area and perimeter, while circularity and solidity provide information on the ameboid shape. We also provide evidence of the involvement of different populations in local inflammatory events, with macrophages replacing microglia into the lesion core when reperfusion does not occur. Analysis of CD45(high)+ cell morphology, whose shape does not change, did not yield any difference, thus confirming the reliability of the approach.

CONCLUSIONS

We have defined specific morphological features that M/M acquire in response to different acute insults by applying a sensitive and readily applicable approach to cell morphological analysis in the brain tissue. Potential application of this method can be extended to all cell types able to change shape following activation, e.g., astrocytes, or to different disease states, including chronic pathologies.

Bone marrow mesenchymal stromal cells drive protective M2 microglia polarization after brain trauma

Microglia/macrophages (M) are major contributors to postinjury inflammation, but they may also promote brain repair in response to specific environmental signals that drive classic (M1) or alternative (M2) polarization. We investigated the activation and functional changes of M in mice with traumatic brain injuries and receiving intracerebroventricular human bone marrow mesenchymal stromal cells (MSCs) or saline infusion. MSCs upregulated Ym1 and Arginase-1 mRNA (p < 0.001), two M2 markers of protective M polarization, at 3 and 7 d postinjury, and increased the number of Ym1(+) cells at 7 d postinjury (p < 0.05). MSCs reduced the presence of the lysosomal activity marker CD68 on the membrane surface of CD11b-positive M (p < 0.05), indicating reduced phagocytosis. MSC-mediated induction of the M2 phenotype in M was associated with early and persistent recovery of neurological functions evaluated up to 35 days postinjury (p < 0.01) and reparative changes of the lesioned microenvironment. In vitro, MSCs directly counteracted the proinflammatory response of primary murine microglia stimulated by tumor necrosis factor-α + interleukin 17 or by tumor necrosis factor-α + interferon-γ and induced M2 proregenerative traits, as indicated by the downregulation of inducible nitric oxide synthase and upregulation of Ym1 and CD206 mRNA (p < 0.01). In conclusion, we found evidence that MSCs can drive the M transcriptional environment and induce the acquisition of an early, persistent M2-beneficial phenotype both in vivo and in vitro. Increased Ym1 expression together with reduced in vivo phagocytosis suggests M selection by MSCs towards the M2a subpopulation, which is involved in growth stimulation and tissue repair.