Intracerebral, but not intravenous, transplantation of bone marrow stromal cells enhances functional recovery in rat cerebral infarct: An optical imaging study

Anti-stroke biologics: from recombinant proteins to stem cells and organoids

The use of biologics in various diseases has dramatically increased in recent years. Stroke, a cerebrovascular disease, is the second most common cause of death, and the leading cause of disability with high morbidity worldwide. For biologics applied in the treatment of acute ischaemic stroke, alteplase is the only thrombolytic agent. Meanwhile, current clinical trials show that two recombinant proteins, tenecteplase and non-immunogenic staphylokinase, are most promising as new thrombolytic agents for acute ischaemic stroke therapy. In addition, stem cell-based therapy, which uses stem cells or organoids for stroke treatment, has shown promising results in preclinical and early clinical studies. These strategies for acute ischaemic stroke mainly rely on the unique properties of undifferentiated cells to facilitate tissue repair and regeneration. However, there is a still considerable journey ahead before these approaches become routine clinical use. This includes optimising cell delivery methods, determining the ideal cell type and dosage, and addressing long-term safety concerns. This review introduces the current or promising recombinant proteins for thrombolysis therapy in ischaemic stroke and highlights the promise and challenges of stem cells and cerebral organoids in stroke therapy.

The Aging Immune System: A Critical Attack on Ischemic Stroke

Ischemic stroke caused by cerebrovascular embolism is an age-related disease with high rates of disability and mortality. Although the mechanisms of immune and inflammatory development after stroke have been of great interest, most studies have neglected the critical and unavoidable factor of age. As the global aging trend intensifies, the number of stroke patients is constantly increasing, emphasizing the urgency of finding effective measures to address the needs of elderly stroke patients. The concept of "immunosenescence" appears to explain the worse stroke outcomes in older individuals. Immune remodeling due to aging involves dynamic changes at all levels of the immune system, and the overall consequences of central (brain-resident) and peripheral (non-brain-resident) immune cells in stroke vary according to the age of the individual. Lastly, the review outlines recent strategies aimed at immunosenescence to improve stroke prognosis.

Intracerebral transplantation of MRI-trackable autologous bone marrow stromal cells for patients with subacute ischemic stroke

BACKGROUND

Ischemic stroke is one of the leading causes of death and neurological disability worldwide, and stem cell therapy is highly expected to reverse the sequelae. This phase 1/2, first-in-human study evaluated the safety, feasibility, and monitoring of an intracerebral-transplanted magnetic resonance imaging (MRI)-trackable autologous bone marrow stromal cell (HUNS001-01) for patients with subacute ischemic stroke.

METHODS

The study included adults with severe disability due to ischemic stroke. HUNS001-01 cultured with human platelet lysates and labeled with superparamagnetic iron oxide was stereotactically transplanted into the peri-infarct area 47-64 days after ischemic stroke onset (dose: 2 or 5 × 107 cells). Neurological and radiographic evaluations were performed throughout 1 year after cell transplantation. The trial was registered at UMIN Clinical Trial Registry (number UMIN000026130).

FINDINGS

All seven patients who met the inclusion criteria successfully achieved cell expansion, underwent intracerebral transplantation, and completed 1 year of follow-up. No product-related adverse events were observed. The median National Institutes of Health Stroke Scale and modified Rankin scale scores before transplantation were 13 and 4, which showed improvements of 1-8 and 0-2, respectively. Cell tracking proved that the engrafted cells migrated toward the infarction border area 1-6 months after transplantation, and the quantitative susceptibility mapping revealed that cell signals at the migrated area constantly increased throughout the follow-up period up to 34% of that of the initial transplanted site.

CONCLUSIONS

Intracerebral transplantation of HUNS001-01 was safe and well tolerated. Cell tracking shed light on the therapeutic mechanisms of intracerebral transplantation.

FUNDING

This work was supported by the Japan Agency for Medical Research and Development (AMED; JP17bk0104045 and JP20bk0104011).

Safety and efficacy of bone marrow mononuclear cell therapy for ischemic stroke recovery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Cell-based therapy represents a potential treatment for ischemic stroke (IS). Here, we performed a systematic review and meta-analysis to summarize the evidence provided by randomized controlled trials (RCTs) for the transplantation of bone marrow mononuclear cells (BMMNCs) in patients with IS in any phase after stroke.

METHODS

We searched several databases for relevant articles up to the 10th of March 2023, including MEDLINE, EMBASE, the Cochrane Library, and ClinicalTrials.gov. Subgroup analyses were implemented to evaluate the dose and route of BMMNC administration. Statistical data were analyzed by Review Manager version 5.3 software.

RESULTS

Six RCTs were included in this article, including 177 patients who were treated by the transplantation of BMMNCs and 166 patients who received medical treatment. The three-month National Institutes of Health Stroke Scale (NIHSS) score indicated a favorable outcome for the BMMNC transplantation group (standardized mean difference (SMD), - 0.34; 95% confidence interval (CI), - 0.57 to - 0.11; P = 0.004). There were no significant differences between the two groups at six months post-transplantation with regards to NIHSS score (SMD 0.00; 95% CI - 0.26 to 0.27; P = 0.97), modified Rankin Scale (risk ratio (RR) 1.10; 95% CI 0.75 to 1.63; P = 0.62), Barthel Index change (SMD 0.68; 95% CI - 0.59 to 1.95; P = 0.29), and infarct volume change (SMD - 0.08; 95% CI - 0.42 to 0.26; P = 0.64). In addition, there was no significant difference between the two groups in terms of safety outcome (RR 1.24; 95% CI 0.80 to 1.91; P = 0.33).

CONCLUSION

Our meta-analysis demonstrated that the transplantation of BMMNCs was safe; however, the efficacy of this procedure requires further validation in larger RTCs.

Intranasal Administration of Mesenchymal Stem Cell-Derived Exosome Alleviates Hypoxic-Ischemic Brain Injury

Hypoxic-ischemic brain injury arises from inadequate oxygen delivery to the brain, commonly occurring following cardiac arrest, which lacks effective treatments. Recent studies have demonstrated the therapeutic potential of exosomes released from mesenchymal stem cells. Given the challenge of systemic dilution associated with intravenous administration, intranasal delivery has emerged as a promising approach. In this study, we investigate the effects of intranasally administered exosomes in an animal model. Exosomes were isolated from the cell supernatants using the ultracentrifugation method. Brain injury was induced in Sprague-Dawley rats through a transient four-vessel occlusion model. Intranasal administration was conducted with 3 × 108 exosome particles in 20 µL of PBS or PBS alone, administered daily for 7 days post-injury. Long-term cognitive behavioral assessments, biodistribution of exosomes, and histological evaluations of apoptosis and neuroinflammation were conducted. Exosomes were primarily detected in the olfactory bulb one hour after intranasal administration, subsequently distributing to the striatum and midbrain. Rats treated with exosomes exhibited substantial improvement in cognitive function up to 28 days after the insult, and demonstrated significantly fewer apoptotic cells along with higher neuronal cell survival in the hippocampus. Exosomes were found to be taken up by microglia, leading to a decrease in the expression of cytotoxic inflammatory markers.

Efficacy and Safety of Bone Marrow Derived Stem Cell Therapy for Ischemic Stroke: Evidence from Network Meta-analysis

BACKGROUND

Several types of stem cells are available for the treatment of stroke patients. However, the optimal type of stem cell remains unclear.

OBJECTIVE

To analyze the effects of bone marrow-derived stem cell therapy in patients with ischemic stroke by integrating all available direct and indirect evidence in network meta-analyses.

METHODS

We searched several databases to identify randomized clinical trials comparing clinical outcomes of bone marrow-derived stem cell therapy vs. conventional treatment in stroke patients. Pooled relative risks (RRs) and mean differences (MDs) were reported. The surface under the cumulative ranking (SUCRA) was used to rank the probabilities of each agent regarding different outcomes.

RESULTS

Overall, 11 trials with 576 patients were eligible for analysis. Three different therapies, including mesenchymal stem cells (MSCs), mononuclear stem cells (MNCs), and multipotent adult progenitor cells (MAPCs), were assessed. The direct analysis demonstrated that stem cell therapy was associated with significantly reduced all-cause mortality rates (RR 0.55, 95% CI 0.33 to 0.93; I2=0%). Network analysis demonstrated MSCs ranked first in reducing mortality (RR 0.42, 95% CrI 0.15 to 0.86) and improving modified Rankin Scale score (MD -0.59 95% CI -1.09 to -0.09), with SUCRA values 80%, and 98%, respectively. Subgroup analysis showed intravenous transplantation was superior to conventional therapy in reducing all-cause mortality (RR 0.53, 95% CrI 0.29 to 0.88).

CONCLUSION

Using stem cell transplantation was associated with reduced risk of death and improved functional outcomes in patients with ischemic stroke. Additional large trials are warranted to provide more conclusive evidence.

Recent advances in tissue repair of the blood-brain barrier after stroke

The selective permeability of the blood-brain barrier (BBB) enables the necessary exchange of substances between the brain parenchyma and circulating blood and is important for the normal functioning of the central nervous system. Ischemic stroke inflicts damage upon the BBB, triggering adverse stroke outcomes such as cerebral edema, hemorrhagic transformation, and aggravated neuroinflammation. Therefore, effective repair of the damaged BBB after stroke and neovascularization that allows for the unique selective transfer of substances from the BBB after stroke is necessary and important for the recovery of brain function. This review focuses on four important therapies that have effects of BBB tissue repair after stroke in the last seven years. Most of these new therapies show increased expression of BBB tight-junction proteins, and some show beneficial results in terms of enhanced pericyte coverage at the injured vessels. This review also briefly outlines three effective classes of approaches and their mechanisms for promoting neoangiogenesis following a stroke.

Intracerebral Transplantation of Autologous Mesenchymal Stem Cells Improves Functional Recovery in a Rat Model of Chronic Ischemic Stroke

While treatments exist for the acute phase of stroke, there are limited options for patients with chronic infarcts and long-term disability. Allogenic mesenchymal stem cells (alloMSCs) show promise for the treatment of stroke soon after ischemic injury. There is, however, no information on the use of autologous MSCs (autoMSCs), delivered intracerebrally in rats with a chronic infarct. In this study, rats underwent middle cerebral artery occlusion (MCAO) to induce stroke followed by bone marrow aspiration and MSC expansion in a closed bioreactor. Four weeks later, brain MRI was obtained and autoMSCs (1 × 106, 2.5 × 106 or 5 × 106; n = 6 each) were stereotactically injected into the peri-infarct and compared to controls (MCAO only; MCAO + PBS; n = 6-9). Behavior was assessed using the modified neurological severity score (mNSS). For comparison, an additional cohort of MCAO rats were implanted with 2.5 × 106 alloMSCs generated from a healthy rat. All doses of autoMSCs produced significant improvement (54-70%) in sensorimotor function 60 days later. In contrast, alloMSCs improved only 31.7%, similar to that in PBS controls 30%. Quantum dot-labeled auto/alloMSCs were found exclusively at the implantation site throughout the post-transplantation period with no tumor formation on MRI or Ki67 staining of engrafted MSCs. Small differences in stroke volume and no differences in corpus callosum width were observed after MSC treatment. Stroke-induced glial reactivity in the peri-infarct was long-lasting and unabated by auto/alloMSC transplantation. These studies suggest that intracerebral transplantation of autoMSCs as compared to alloMSCs may be a promising treatment in chronic stroke.

Evolving Clinical-Translational Investigations of Cerebroprotection in Ischemic Stroke

Ischemic stroke is a highly morbid disease, with over 50% of large vessel stroke (middle cerebral artery or internal carotid artery terminus occlusion) patients suffering disability despite maximal acute reperfusion therapy with thrombolysis and thrombectomy. The discovery of the ischemic penumbra in the 1980s laid the foundation for a salvageable territory in ischemic stroke. Since then, the concept of neuroprotection has been a focus of post-stroke care to (1) minimize the conversion from penumbra to core irreversible infarct, (2) limit secondary damage from ischemia-reperfusion injury, inflammation, and excitotoxicity and (3) to encourage tissue repair. However, despite multiple studies, the preclinical-clinical research enterprise has not yet created an agent that mitigates post-stroke outcomes beyond thrombolysis and mechanical clot retrieval. These translational gaps have not deterred the scientific community as agents are under continuous investigation. The NIH has recently promoted the concept of cerebroprotection to consider the whole brain post-stroke rather than just the neurons. This review will briefly outline the translational science of past, current, and emerging breakthroughs in cerebroprotection and use of these foundational ideas to develop a novel paradigm for optimizing stroke outcomes.

Therapeutic Efficacy and Migration of Mesenchymal Stem Cells after Intracerebral Transplantation in Rats with Experimental Ischemic Stroke

We studied therapeutic efficacy and migration characteristics of mesenchymal stem cells isolated from the human placenta after their intracerebral (stereotactic) administration to rats with the experimental ischemic stroke. It was shown that cell therapy significantly improved animal survival rate and reduced the severity of neurological deficit. New data on the migration pathways of transplanted cells in the brain were obtained.

Transplantation of modified human bone marrow-derived stromal cells affords therapeutic effects on cerebral ischemia in rats

AIMS

SB623 cells are human bone marrow stromal cells transfected with Notch1 intracellular domain. In this study, we examined potential regenerative mechanisms underlying stereotaxic transplantation of SB623 cells in rats with experimental acute ischemic stroke.

METHODS

We prepared control group, empty capsule (EC) group, SB623 cell group (SB623), and encapsulated SB623 cell (eSB623) group. Transient middle cerebral artery occlusion (MCAO) was performed on day 0, and 24 h after MCAO, stroke rats received transplantation into the envisioned ischemic penumbra. Modified neurological severity score (mNSS) was evaluated, and histological evaluations were performed.

RESULTS

In the mNSS, SB623 and eSB623 groups showed significant improvement compared to the other groups. Histological analysis revealed that the infarction area in SB623 and eSB623 groups was reduced. In the eSB623 group, robust cell viability and neurogenesis were detected in the subventricular zone that increased significantly compared to all other groups.

CONCLUSION

SB623 cells with or without encapsulation showed therapeutic effects on ischemic stroke. Encapsulated SB623 cells showed enhanced neurogenesis and increased viability inside the capsules. This study reveals the mechanism of secretory function of transplanted SB623 cells, but not cell-cell interaction as primarily mediating the cells' functional benefits in ischemic stroke.

Intracerebral Transplantation of Mesenchymal Stromal Cell Compounded with Recombinant Peptide Scaffold against Chronic Intracerebral Hemorrhage Model

Background

Due to the lack of effective therapies, stem cell transplantation is an anticipated treatment for chronic intracerebral hemorrhage (ICH), and higher cell survival and engraftment are considered to be the key for recovery. Mesenchymal stromal cells (MSCs) compounded with recombinant human collagen type I scaffolds (CellSaics) have a higher potential for cell survival and engraftment compared with solo-MSCs, and we investigated the validity of intracerebral transplantation of CellSaic in a chronic ICH model.

Methods

Rat CellSaics (rCellSaics) were produced by rat bone marrow-derived MSC (rBMSCs). The secretion potential of neurotrophic factors and the cell proliferation rate were compared under oxygen-glucose deprivation (OGD) conditions. rCellSaics, rBMSCs, or saline were transplanted into the hollow cavity of a rat chronic ICH model. Functional and histological analyses were evaluated, and single-photon emission computed tomography for benzodiazepine receptors was performed to monitor sequential changes in neuronal integrity. Furthermore, human CellSaics (hCellSaics) were transplanted into a chronic ICH model in immunodeficient rats. Antibodies neutralizing brain-derived neurotrophic factor (BDNF) were used to elucidate its mode of action.

Results

rCellSaics demonstrated a higher secretion potential of trophic factors and showed better cell proliferation in the OGD condition. Animals receiving rCellSaics displayed better neurological recovery, higher intracerebral BDNF, and better cell engraftment; they also showed a tendency for less brain atrophy and higher benzodiazepine receptor preservation. hCellSaics also promoted significant functional recovery, which was reversed by BDNF neutralization.

Conclusion

Intracerebral transplantation of CellSaics enabled neurological recovery in a chronic ICH model and may be a good option for clinical application.

Intranasally applied human olfactory mucosa neural progenitor cells migrate to damaged brain regions

Aim:

To determine if intranasally administered olfactory mucosa progenitor cells (OMPCs) migrate to damaged areas of brain.

Materials & methods:

Rowett Nude (RNU) adult rats were injured using the Marmarou model then 2 weeks later received intranasally-delivered human OMPC. After 3 weeks, rats were sacrificed and brain sectioned. The mean distances from the human OMPCs to markers for degenerative neuronal cell bodies (p-c-Jun⁺), axonal swellings on damaged axons (β-APP⁺) and random points in immunostained sections were quantified. One-way ANOVA was used to analyze data.

Results:

The human OMPCs were seen in specific areas of the brain near degenerating cell bodies and damaged axons.

Conclusion:

Intranasally delivered human OMPC selectively migrate to brain injury sites suggesting a possible noninvasive stem cell delivery for brain injury.

As a first step toward helping those with brain or spinal cord injury, human stem cells from the nose were applied to the inside of the nose of brain injured rats. These stem cells migrated to specific areas of damage in the brain. Stem cells from the nose are special, in that these cells continuously divide and form nerve cells. This study may lead to an uncomplicated treatment where tissue is taken from one side of the nose and later the stem cells from the tissue are delivered to the other side of the nose.

Intravenous transplantation of amnion-derived mesenchymal stem cells promotes functional recovery and alleviates intestinal dysfunction after spinal cord injury

Spinal cord injury (SCI) is often accompanied by gastrointestinal dysfunction due to the disconnection of the spinal autonomic nervous system. Gastrointestinal dysfunction reportedly upregulates intestinal permeability, leading to bacterial translocation of the gut microbiome to the systemic circulation, which further activates systemic inflammation, exacerbating neuronal damage. Mesenchymal stem cells (MSC) reportedly ameliorate SCI. Here, we aimed to investigate their effect on the associated gastrointestinal dysfunction. Human amnion-derived MSC (AMSCs) were intravenously transplanted one day after a rat model of midthoracic SCI. Biodistribution of transplanted cells, behavioral assessment, and histological evaluations of the spinal cord and intestine were conducted to elucidate the therapeutic effect of AMSCs. Bacterial translocation of the gut microbiome was examined by in situ hybridization and bacterial culture of the liver. Systemic inflammations were examined by blood cytokines, infiltrating immune cells in the spinal cord, and the size of the peripheral immune tissue. AMSCs released various neurotrophic factors and were mainly distributed in the liver and lung after transplantation. AMSC-transplanted animals showed smaller spinal damage and better neurological recovery with preserved neuronal tract. AMSCs transplantation ameliorated intestinal dysfunction both morphologically and functionally, which prevented translocation of the gut microbiome to the systemic circulation. Systemic inflammations were decreased in animals receiving AMSCs in the chronic phase. Intravenous AMSC administration during the acute phase of SCI rescues both spinal damage and intestinal dysfunction. Reducing bacterial translocation may contribute to decreasing systemic inflammation.

Mesenchymal Stem Cell Sheet Promotes Functional Recovery and Palliates Neuropathic Pain in a Subacute Spinal Cord Injury Model

Stem cell therapy has been shown to reverse the sequelae of spinal cord injury (SCI). Although the ideal treatment route remains unknown, providing a large number of stem cells to the injured site using less invasive techniques is critical to achieving maximal recovery. This study was conducted to determine whether administration of bone marrow stem cell (BMSC) sheet made on its own without a scaffold is superior to intramedullary cell transplantation in a rat subacute SCI model. Adult female Sprague-Dawley rats were subjected to SCI by 30 g clip compression at the level of Th6 and Th7 and were administered BMSC cell sheet (7 × 10⁴ cells, subdural), cell suspension (7 × 10⁴ cells, intramedullary), or control seven days after the injury. Motor and sensory assessments, as well as histological evaluation, were performed to determine the efficacy of the different cell transplantation procedures. While both the cell sheet and cell intramedullary injection groups showed significant motor recovery compared to the control group, the cell sheet group showed better results. Furthermore, the cell sheet group displayed a significant sensory recovery compared to the other groups. A histological evaluation revealed that the cell sheet group showed smaller injury lesion volume, less inflammation, and gliosis compared to other groups. Sensory-related fibers of μ-opioid receptors (MOR, interneuron) and hydroxytryptamine transporters (HTT, descending pain inhibitory pathway), located around the dorsal horn of the spinal cord at the caudal side of the SCI, were preserved only in the cell sheet group. Stem cells could also be found inside the peri-injured spinal cord in the cell sheet group. BMSC cell sheets were able to promote functional recovery and palliate neuropathic pain more effectively than intramedullary injections, thus serving as a good treatment option for SCI.

Potential Mechanisms and Perspectives in Ischemic Stroke Treatment Using Stem Cell Therapies

Ischemic stroke (IS) remains one of the major causes of death and disability due to the limited ability of central nervous system cells to regenerate and differentiate. Although several advances have been made in stroke therapies in the last decades, there are only a few approaches available to improve IS outcome. In the acute phase of IS, mechanical thrombectomy and the administration of tissue plasminogen activator have been widely used, while aspirin or clopidogrel represents the main therapy used in the subacute or chronic phase. However, in most cases, stroke patients fail to achieve satisfactory functional recovery under the treatments mentioned above. Recently, cell therapy, especially stem cell therapy, has been considered as a novel and potential therapeutic strategy to improve stroke outcome through mechanisms, including cell differentiation, cell replacement, immunomodulation, neural circuit reconstruction, and protective factor release. Different stem cell types, such as mesenchymal stem cells, marrow mononuclear cells, and neural stem cells, have also been considered for stroke therapy. In recent years, many clinical and preclinical studies on cell therapy have been carried out, and numerous results have shown that cell therapy has bright prospects in the treatment of stroke. However, some cell therapy issues are not yet fully understood, such as its optimal parameters including cell type choice, cell doses, and injection routes; therefore, a closer relationship between basic and clinical research is needed. In this review, the role of cell therapy in stroke treatment and its mechanisms was summarized, as well as the function of different stem cell types in stroke treatment and the clinical trials using stem cell therapy to cure stroke, to reveal future insights on stroke-related cell therapy, and to guide further studies.

Research progress on the therapeutic effect of olfactory ensheathing cell transplantation on ischemic stroke

Olfactory ensheathing cells (OECs) are a special type of glial cell in the olfactory system, which exhibit neuroprotective, immunomodulatory, and angiogenic effects. Although many studies have focused on the reversal of demyelination and axonal degeneration (during spinal cord injury) by OECs, few reports have focused on the ability of OECs to repair ischemic nerve injury. This article reviews the protective effects of OEC transplantation in ischemic stroke and provides a theoretical basis and new strategy for OEC transplantation in the treatment of ischemic stroke.

Glial cell induced neural differentiation of bone marrow stromal cells

Background

Bone marrow stromal cells (BMSCs) have an important application prospect in the field of cell therapy for various neurodegenerative diseases, and inducing factors that regulate BMSC differentiation are proposed as a promising therapeutic strategy. In this study, we explored the effect of glial cell-derived neurotrophic factor (GDNF) on the course of BMSC differentiation.

Methods

BMSCs were isolated from rat bone marrow and induced by GDNF. The effects of GDNF on BMSC viability and proliferation were verified by cell counting kit-8, MTT, bromodeoxyuridine, and flow cytometry assays. Neuronal differentiation from BMSCs was detected by quantitative real-time polymerase chain reaction and immunofluorescence via measuring the expression of several neural specific markers.

Results

Compared to untreated BMSCs, GDNF induced the differentiation of BMSCs into neuron-like cells and enhanced the expression levels of neuronal markers including nestin and NCAM. Moreover, the expression of SCF was suppressed by GDNF stimulation.

Conclusion

GDNF could elevate the differentiation of BMSCs into neuron-like cells and could be considered as an effective candidate cell for future neuroscience research.

Clinical Trials of Stem Cell Therapy for Cerebral Ischemic Stroke

Despite recent developments in innovative treatment strategies, stroke remains one of the leading causes of death and disability worldwide. Stem cell therapy is currently attracting much attention due to its potential for exerting significant therapeutic effects on stroke patients. Various types of cells, including bone marrow mononuclear cells, bone marrow/adipose-derived stem/stromal cells, umbilical cord blood cells, neural stem cells, and olfactory ensheathing cells have enhanced neurological outcomes in animal stroke models. These stem cells have also been tested via clinical trials involving stroke patients. In this article, the authors review potential molecular mechanisms underlying neural recovery associated with stem cell treatment, as well as recent advances in stem cell therapy, with particular reference to clinical trials and future prospects for such therapy in treating stroke.

FTY720 Protects Against Ischemia-Reperfusion Injury by Preventing the Redistribution of Tight Junction Proteins and Decreases Inflammation in the Subacute Phase in an Experimental Stroke Model

Injury due to brain ischemia followed by reperfusion (I/R) may be an important therapeutic target in the era of thrombectomy. FTY720, a widely known sphingosine-1-phosphate receptor agonist, exerts various neuroprotective effects. The aim of this study was to examine the protective effect of FTY720 with respect to I/R injury, especially focusing on blood-brain barrier (BBB) protection and anti-inflammatory effects. Male rats were subjected to transient ischemia and administered vehicle or 0.5 or 1.5 mg/kg of FTY720 immediately before reperfusion. Positron emission tomography (PET) with [¹⁸F]DPA-714 was performed 2 and 9 days after the insult to serially monitor neuroinflammation. Bovine and rat brain microvascular endothelial cells (MVECs) were also subjected to oxygen-glucose deprivation (OGD) and reperfusion, and administered FTY720, phosphorylated-FTY720 (FTY720-P), or their inhibitor. FTY720 dose-dependently reduced cell death, the infarct size, cell death including apoptosis, and inflammation. It also ameliorated BBB disruption and neurological deficits compared to in the vehicle group. PET indicated that FTY720 significantly inhibited the worsening of inflammation in later stages. FTY720-P significantly prevented the intracellular redistribution of tight junction proteins but did not increase their mRNA expression. These results suggest that FTY720 can ameliorate I/R injury by protecting the BBB and regulating neuroinflammation.

Evaluation of Novel Stereotactic Cannula for Stem Cell Transplantation against Central Nervous System Disease

Cell therapy for central nervous system (CNS) disorders is beginning to prove its safety and efficiency. Intraparenchymal transplantation can be an option for cell delivery; however, one concern regarding this method is that the transplantation cannula may cause additional brain injuries. These include vessel damage, which results in brain hemorrhage, and clogging of the cannula by brain debris and/or cell clusters, which requires replacement of the cannula or forced injection causing jet flow of the cell suspension. We compared cannulas for cell delivery used in clinical trials, the Pittsburg and Mizuho cannulas, to a newly designed one, MK01, to assess their usability. MK01 has a spherical-shaped tip with a fan-like open orifice on the side of the cannula, which prevents vessel damage, clogging of brain debris, and jet flow phenomenon. We compared the extent of rat cervical and abdominal arterial damage with the cannula, the amount of debris in the cannula, the force needed to cause jet flow, and cell viability. While the viability of cells passed through the cannulas was almost the same among cannulas (approximately 95%), the Pittsburg cannula caused cervical arterial injury and subsequent hemorrhage, as it required a significantly smaller force to penetrate the arterial wall. Moreover, the Pittsburg cannula, but not the Mizuho and MK01 cannulas, showed high frequency of brain debris in the needle tip (approximately 80%) after brain puncture. While jet flow of the injection liquid was observed even when using smaller forces in the Pittsburg and Mizuho cannulas, MK01 constantly showed low jet flow occurrence. Thus, MK01 seems to be safer than the previously reported cannulas, although further investigation is necessary to validate its safety for clinical use.

Smart diagnostic nano-agents for cerebral ischemia

A summary of the latest developments on imaging techniques and smart nano-diagnostics used for ischemic stroke.

Research Progress of Near-Infrared Fluorescence Immunoassay

Near-infrared fluorescence probes (NIFPs) have been widely used in immunoassay, bio-imaging and medical diagnosis. We review the basic principles of near-infrared fluorescence and near-infrared detection technology, and summarize structures, properties and characteristics of NIFPs (i.e., cyanines, xanthenes fluorescent dyes, phthalocyanines, porphyrin derivates, single-walled carbon nanotubes (SWCNTs), quantum dots and rare earth compounds). We next analyze applications of NIFPs in immunoassays, and prospect the application potential of lateral flow assay (LFA) in rapid detection of pathogens. At present, our team intends to establish a new platform that has highly sensitive NIFPs combined with portable and simple immunochromatographic test strips (ICTSs) for rapid detection of food-borne viruses. This will provide technical support for rapid detection on the port.

Intravascular cell therapy in stroke: predicting the future trends

This short review examines the trends that have taken place during the last two decades in selecting delivery route and cell product in confirmatory preclinical stroke research. If there had been a major change, this might indicate a strategy with a high potential to enter early-phase clinical studies. The retrospective data show that intravenous cell delivery of mesenchymal stem cells remains the most popular approach in experimental research, clearly dominating early phase clinical studies. The advantages and risks of current practices are discussed in the hope that these will improve translational success and accelerate clinical development of safe and efficient cell products.

Combined treatment of sodium ferulate, n-butylidenephthalide, and ADSCs rehabilitates neurovascular unit in rats after photothrombotic stroke

The remodelling of structural and functional neurovascular unit (NVU) becomes a central therapeutic strategy after cerebral ischaemic stroke. In the present study, we investigated the effect of combined therapy of sodium ferulate (SF), n‐butylidenephthalide (BP) and adipose‐derived stromal cells (ADSCs) to ameliorate the injured NVU in the photochemically induced thrombotic stroke in rats. After solely or combined treatment, the neovascularization, activation of astrocytes, neurogenesis, expressions of vascular endothelial growth factor (VEGF) and claudin‐5 were assessed by immunohistochemical or immunofluorescence staining. In order to uncover the underlying mechanism of therapeutic effect, signalling of protein kinase B/mammalian target of rapamycin (AKT/mTOR), extracellular signal‐regulated kinase 1/2 (ERK1/2), and Notch1 in infarct zone were analysed by western blot. ¹⁸F‐2‐deoxy‐glucose/positron emission tomography, magnetic resonance imaging, Evans blue staining were employed to evaluate the glucose metabolism, cerebral blood flow (CBF), and brain‐blood barrier (BBB) permeability, respectively. The results showed that combined treatment increased the neovascularization, neurogenesis, and VEGF secretion, modulated the astrocyte activation, enhanced the regional CBF, and glucose metabolism, as well as reduced BBB permeability and promoted claudin‐5 expression, indicating the restoration of structure and function of NVU. The activation of ERK1/2 and Notch1 pathways and inhibition of AKT/mTOR pathway might be involved in the therapeutic mechanism. In summary, we have demonstrated that combined ADSCs with SF and BP, targeting the NVU remodelling, is a potential treatment for ischaemic stroke. These results may provide valuable information for developing future combined cellular and pharmacological therapeutic strategy for ischaemic stroke.

Repeated injections of human umbilical cord blood-derived mesenchymal stem cells significantly promotes functional recovery in rabbits with spinal cord injury of two noncontinuous segments

Background

Spinal cord injuries (SCIs) are sustained by an increasing number of patients each year worldwide. The treatment of SCIs has long been a hard nut to crack for doctors around the world. Mesenchymal stem cells (MSCs) have shown benefits for the repair of SCI and recovery of function. Our present study aims to investigate the effects of intravenously infused human umbilical cord blood-derived MSCs (hUCB-MSCs) on functional recovery after subacute spinal cord compression injury of two noncontinuous segments. In addition, we compared the effects of single infusion and repeated intravenous (i.v.) injections on the recovery of spinal cord function.

Methods

A total of 43 adult rabbits were randomly divided into four groups: control, single injection (SI), repeated injection at a 3-day (3RI) or repeated injection at a 7-day interval (7RI) groups. Non-immunosuppressed rabbits in the transplantation groups were infused with either a single complete dose or three divided doses of 2 × 10⁶ hUCB-MSCs (3-day or 7-day intervals) on the first day post decompression. Behavioural scores and somatosensory evoked potentials (SEPs) were used to evaluate hindlimb functional recovery. The survival and differentiation of the transplanted human cells and the activation of the host glial and inflammatory reaction in the injured spinal cord were studied by immunohistochemical staining.

Results

Our results showed that hUCB-MSCs survived, proliferated, and primarily differentiated into oligodendrocytes in the injured area. Treatment with hUCB-MSCs reduced the extent of astrocytic activation, increased axonal preservation, potentially promoted axonal regeneration, decreased the number of Iba-1+ and TUNEL+ cells, increased the amplitude and decreased the onset latency of SEPs and significantly promoted functional improvement. However, these effects were more pronounced in the 3RI group compared with the SI and 7RI groups.

Conclusions

Our results suggest that treatment with i.v. injected hUCB-MSCs after subacute spinal cord compression injury of two noncontinuous segments can promote functional recovery through the differentiation of hUCB-MSCs into specific cell types and the enhancement of anti-inflammatory, anti-astrogliosis, anti-apoptotic and axonal preservation effects. Furthermore, the recovery was more pronounced in the rabbits repeatedly injected with cells at 3-day intervals. The results of this study may provide a novel and useful treatment strategy for the transplantation treatment of SCI.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0879-0) contains supplementary material, which is available to authorized users.

Research on advanced intervention using novel bone marrOW stem cell (RAINBOW): a study protocol for a phase I, open-label, uncontrolled, dose-response trial of autologous bone marrow stromal cell transplantation in patients with acute ischemic stroke

Background

Stroke is a leading cause of death and disability, and despite intensive research, few treatment options exist. However, a recent breakthrough in cell therapy is expected to reverse the neurological sequelae of stroke. Although some pioneer studies on the use of cell therapy for treating stroke have been reported, certain problems remain unsolved. Recent studies have demonstrated that bone marrow stromal cells (BMSCs) have therapeutic potential against stroke. We investigated the use of autologous BMSC transplantation as a next-generation cell therapy for treating stroke. In this article, we introduce the protocol of a new clinical trial, the Research on Advanced Intervention using Novel Bone marrOW stem cell (RAINBOW).

Methods/design

RAINBOW is a phase 1, open-label, uncontrolled, dose-response study, with the primary aim to determine the safety of the autologous BMSC product HUNS001–01 when administered to patients with acute ischemic stroke. Estimated enrollment is 6–10 patients suffering from moderate to severe neurological deficits. Approximately 50 mL of the bone marrow is extracted from the iliac bone of each patient 15 days or later from the onset. BMSCs are cultured with allogeneic human platelet lysate (PL) as a substitute for fetal calf serum and are labeled with superparamagnetic iron oxide for cell tracking using magnetic resonance imaging (MRI). HUNS001–01 is stereotactically administered around the area of infarction in the subacute phase. Each patient will be administered a dose of 20 or 50 million cells. Neurological scoring, MRI for cell tracking, ¹⁸F–fuorodeoxyglucose positron emission tomography, and ¹²³I–Iomazenil single­photon emission computed tomography will be performed for 1 year after the administration.

Discussion

This is a first-in-human trial for HUNS001–01 to the patients with acute ischemic stroke. We expect that intraparenchymal injection can be a more favorable method for cell delivery to the lesion and improvement of the motor function than intravenous infusion. Moreover, it is expected that the bio-imaging techniques can clarify the therapeutic mechanisms.

Trial registration

The trial was registered at The University Hospital Medical Information Network on February 22, 2017 (UNIN ID: UMIN000026130). The findings of this trial will be disseminated to patients and through peer-reviewed publications and international presentations.

Preparation of gelatin nanospheres incorporating quantum dots and iron oxide nanoparticles for multimodal cell imaging

The objective of this study is to prepare a multimodal probe which can simultaneously visualize cells by optical and magnetic resonance (MR) imaging modalities. Gelatin nanospheres incorporating quantum dots (QD) and iron oxide nanoparticles (IONP) were prepared by the conventional emulsion method. The percentage of QD and IONP incorporated in gelatin nanospheres was changed by the concentrations of gelatin and glutaraldehyde used. However, the apparent size and surface zeta potential were hardly changed. Gelatin nanospheres incorporating QD and IONP were treated with octa-arginine (R8) of a cell-penetrating peptide. When incubated with normal human articular chondrocytes, gelatin nanospheres incorporating QD and IONP were efficiently internalized into the cells although their cytotoxicity was observed at the R8 concentration of 320 μM. The cells internalizing gelatin nanospheres incorporating QD and IONP could be visualized by both the optical and MR imaging modalities. It is concluded that gelatin nanospheres incorporating QD and IONP are promising for the probe of multimodal cell imaging.

Cell Therapy for Stroke: Review of Previous Clinical Trials and Introduction of Our New Trials

Stroke is still a leading cause of death and disability, and despite intensive research, few treatment options exist. A recent breakthrough in cell therapy is expected to reverse the neurological sequelae of stroke. Although some pioneer studies on the use of cell therapy for the treatment of stroke have been reported, certain problems still remain unsolved. We investigated the use of autologous bone marrow stromal cell (BMSC) transplantation for the treatment of stroke, to develop it as the next-generation cell therapy. In this study, we introduce the preparation of a new clinical trial, the Research on Advanced Intervention using Novel Bone marrow stem cell (RAINBOW) study. The trial will start in 2016, and we hope that it will not only be helpful for treating patients but also for clarifying the therapeutic mechanisms. Moreover, we review stem cell therapeutics as an emerging paradigm in stroke (STEPS) and the guidelines for the development of cell therapy for stroke in the United States as well as introduce the development of new guidelines in Japan. These guidelines are expected to encourage the development of cell therapy for stroke management.

Current Opinion of Bone Marrow Stromal Cell Transplantation for Ischemic Stroke

This article reviews recent advancement and perspective of bone marrow stromal cell (BMSC) transplantation for ischemic stroke, based on current information of basic and translational research. The author would like to emphasize that scientific approach would enable us to apply BMSC transplantation into clinical situation in near future.

Effectiveness and Safety of Autologous Bone Marrow Stromal Cells Transplantation After Ischemic Stroke: A Meta-Analysis

BACKGROUND

Autologous bone marrow stromal cells (BM-SCs) transplantation might be a potential therapy for stroke. Although a series of clinical trials were performed to assess the effectiveness and safety of BM-SCs transplantation after ischemic stroke, the results are still conflicting. This study aimed to pool previous controlled trials to assess the effectiveness of BM-SCs-based cell therapy after ischemic stroke.

MATERIAL AND METHODS

Relevant studies were searched among online databases. Barthel index (BI) or modified Barthel index (mBI), National Institutes of Health Stroke Scale (NIHSS), and Rankin Score (mRS) were used to assess therapeutic effects. The frequencies of adverse events were extracted for assessing safety of stem cell therapy. Data analysis was performed by using Review Manager 5.3.

RESULTS

Patients who received cell therapy had significantly lower NIHSS score (-1.85) than the controls. In addition, there might be some benefits in daily activity measured by mBI, but this meta-analysis failed to demonstrate significant benefits of BM-SCs-based cell therapy in increasing the proportion of mRS ≤2 patients. We did not find any severe adverse events associated with BM-SCs-based cell therapy.

CONCLUSIONS

Although BM-MNCs/MSCs transplantation might generate some benefits in lowering the grade of impairment caused by ischemic stroke, large RCTs are required to further confirm the effectiveness of BM-MSCs/MNCs-based cell therapy and to optimize the conditions require for best therapeutic effects.

Optimal Route for Mesenchymal Stem Cells Transplantation after Severe Intraventricular Hemorrhage in Newborn Rats

Recently, we showed that intracerebroventricular (IC) transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) significantly attenuates posthemorrhagic hydrocephalus (PHH) and brain damage after severe IVH in newborn rats. This study was performed to determine the optimal route for transplanting MSCs for severe IVH by comparing IC transplantation, intravenous (IV) transplantation, and IV transplantation plus mannitol infusion. Severe IVH was induced by injecting 100 uL of blood into each ventricle of Sprague-Dawley rats on postnatal day 4 (P4). After confirming severe IVH with brain magnetic resonance imaging (MRI) at P5, human UCB-derived MSCs were transplanted at P6 by an IC route (1×10⁵), an IV route (5×10⁵), or an IV route with mannitol infused. Follow-up brain MRIs and rotarod tests were performed. At P32, brain tissue samples were obtained for biochemical and histological analyses. Although more MSCs localized to the brain after IC than after IV delivery, both methods were equally effective in preventing PHH; attenuating impaired rotarod test; increasing the number of TUNEL-positive cells, inflammatory cytokines, and astrogliosis; and reducing corpus callosal thickness and myelin basic protein expression after severe IVH regardless of mannitol co-infusion. Despite the superior delivery efficacy with IC than with the IV route, both IC and IV transplantation of MSCs had equal therapeutic efficacy in protecting against severe IVH. These findings suggest that the less invasive IV route might be a good alternative for clinically unstable, very preterm infants that cannot tolerate a more invasive IC delivery of MSCs.

In vivo tracking of human adipose-derived stem cells labeled with ferumoxytol in rats with middle cerebral artery occlusion by magnetic resonance imaging

Ferumoxytol, an iron replacement product, is a new type of superparamagnetic iron oxide approved by the US Food and Drug Administration. Herein, we assessed the feasibility of tracking transplanted human adipose-derived stem cells labeled with ferumoxytol in middle cerebral artery occlusion-injured rats by 3.0 T MRI in vivo. 1 × 10⁴ human adipose-derived stem cells labeled with ferumoxytol-heparin-protamine were transplanted into the brains of rats with middle cerebral artery occlusion. Neurologic impairment was scored at 1, 7, 14, and 28 days after transplantation. T2-weighted imaging and enhanced susceptibility-weighted angiography were used to observe transplanted cells. Results of imaging tests were compared with results of Prussian blue staining. The modified neurologic impairment scores were significantly lower in rats transplanted with cells at all time points except 1 day post-transplantation compared with rats without transplantation. Regions with hypointense signals on T2-weighted and enhanced susceptibility-weighted angiography images corresponded with areas stained by Prussian blue, suggesting the presence of superparamagnetic iron oxide particles within the engrafted cells. Enhanced susceptibility-weighted angiography image exhibited better sensitivity and contrast in tracing ferumoxytol-heparin-protamine-labeled human adipose-derived stem cells compared with T2-weighted imaging in routine MRI.

Triggering receptor expressed on myeloid cells 2 (TREM2) deficiency attenuates phagocytic activities of microglia and exacerbates ischemic damage in experimental stroke

Clearing cellular debris after brain injury represents an important mechanism in regaining tissue homeostasis and promoting functional recovery. Triggering receptor expressed on myeloid cells-2 (TREM2) is a newly identified receptor expressed on microglia and is thought to phagocytose damaged brain cells. The precise role of TREM2 during ischemic stroke has not been fully understood. We explore TREM2 in both in vitro and in vivo stroke models and identify a potential endogenous TREM2 ligand. TREM2 knockdown in microglia reduced microglial activation to an amoeboid phenotype and decreased the phagocytosis of injured neurons. Phagocytosis and infarcted brain tissue resorption was reduced in TREM2 knock-out (KO) mice compared with wild-type (WT) mice. TREM2 KO mice also had worsened neurological recovery and decreased viable brain tissue in the ipsilateral hemisphere. The numbers of activated microglia and phagocytes in TREM2 KO mice were decreased compared with WT mice, and foamy macrophages were nearly absent in the TREM2 KO mice. Postischemia, TREM2 was highly expressed on microglia and TREM2-Fc fusion protein (used as a probe to identify potential TREM2 binding partners) bound to an unknown TREM2 ligand that colocalized to neurons. Oxygen glucose deprivation-exposed neuronal media, or cellular fractions containing nuclei or purified DNA, but not cytosolic fractions, stimulated signaling through TREM2. TREM2-Fc fusion protein pulled down nucleic acids from ischemic brain lysate. These findings establish the relevance of TREM2 in the phagocytosis of the infarcted brain and emphasize its role in influencing neurological outcomes following stroke. Further, nucleic acids may be one potential ligand of TREM2 in brain ischemia.

Effect of cell origin and timing of delivery for stem cell-based bone tissue engineering using biologically functionalized hydrogels

Despite progress in bone tissue engineering, the healing of critically sized diaphyseal defects remains a clinical challenge. A stem cell-based approach is an attractive alternative to current treatment techniques. The objective of this study was to examine the ability of adult stem cells to enhance bone formation when co-delivered with the osteoinductive factor bone morphogenetic protein-2 (BMP-2) in a biologically functionalized hydrogel. First, adipose and bone marrow-derived mesenchymal stem cells (ADSCs and BMMSCs) were screened for their potential to form bone when delivered in an RGD functionalized alginate hydrogel using a subcutaneous implant model. BMMSCs co-delivered with BMP-2 produced significantly more mineralized tissue compared with either ADSCs co-delivered with BMP-2 or acellular hydrogels containing BMP-2. Next, the ability of BMMSCs to heal a critically sized diaphyseal defect with a nonhealing dose of BMP-2 was tested using the alginate hydrogel as an injectable cell carrier. The effect of timing of therapeutic delivery on bone regeneration was also tested in the diaphyseal model. A 7 day delayed injection of the hydrogel into the defect site resulted in less mineralized tissue formation than immediate delivery of the hydrogel. By 12 weeks, BMMSC-loaded hydrogels produced significantly more bone than acellular constructs regardless of immediate or delayed treatment. For immediate delivery, bridging of defects treated with BMMSC-loaded hydrogels occurred at a rate of 75% compared with a 33% bridging rate for acellular-treated defects. No bridging was observed in any of the delayed delivery samples for any of the groups. Therefore, for this cell-based bone tissue engineering approach, immediate delivery of constructs leads to an overall enhanced healing response compared with delayed delivery techniques. Further, these studies demonstrate that co-delivery of adult stem cells, specifically BMMSCs, with BMP-2 enhances bone regeneration in a critically sized femoral segmental defect compared with acellular hydrogels containing BMP-2.

Lipoic acid and bone marrow derived cells therapy induce angiogenesis and cell proliferation after focal brain injury

Abstract Introduction: Traumatic brain injury is a main cause of disability and death in developed countries, above all among children and adolescents. The intrinsic inability of the central nervous system to efficiently repair traumatic injuries renders transplantation of bone marrow-derived cells (BMDC) a promising approach towards repair of brain lesions. On the other hand, many studies have reported the beneficial effect of Lipoic acid (LA), a potent antioxidant promoting cell survival, angiogenesis and neuroregeneration.

METHODS

In this study, the cortex of adult mice was cryo-injured in order to mimic local traumatic brain injury. Vehicle or freshly prepared BMDC were grafted in the cerebral penumbra area 24 hours after unilateral local injury alone or combined with intra-peritoneal LA administration as a new regenerative strategy.

RESULTS

Differences were found in the process of cell proliferation, angiogenesis and glial scar formation after local injury depending of the applied treatment, either LA or BMDC alone or in combination.

CONCLUSION

The data presented here suggest that transplantation of BMDC is a good alternative and valid strategy to treat a focal brain injury when LA could not be prescribed due to its non-desired secondary effects.

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

Near-infrared fluorescence (NIRF) imaging is an attractive modality for early cancer detection with high sensitivity and multi-detection capability. Due to convenient modification by conjugating with moieties of interests, NIRF probes are ideal candidates for cancer targeted imaging. Additionally, the combinatory application of NIRF imaging and other imaging modalities that can delineate anatomical structures extends fluorometric determination of biomedical information. Moreover, nanoparticles loaded with NIRF dyes and anticancer agents contribute to the synergistic management of cancer, which integrates the advantage of imaging and therapeutic functions to achieve the ultimate goal of simultaneous diagnosis and treatment. Appropriate probe design with targeting moieties can retain the original properties of NIRF and pharmacokinetics. In recent years, great efforts have been made to develop new NIRF probes with better photostability and strong fluorescence emission, leading to the discovery of numerous novel NIRF probes with fine photophysical properties. Some of these probes exhibit tumoricidal activities upon light radiation, which holds great promise in photothermal therapy, photodynamic therapy, and photoimmunotherapy. This review aims to provide a timely and concise update on emerging NIRF dyes and multifunctional agents. Their potential uses as agents for cancer specific imaging, lymph node mapping, and therapeutics are included. Recent advances of NIRF dyes in clinical use are also summarized.

Effect of repeated allogeneic bone marrow mononuclear cell transplantation on brain injury following transient focal cerebral ischemia in rats

AIMS

Transplantation of bone marrow mononuclear cells (BMMCs) exerts neuroprotection against cerebral ischemia. We examined the therapeutic timepoint of allogeneic BMMC transplantation in a rat model of focal cerebral ischemia, and determined the effects of repeated transplantation outside the therapeutic window.

MAIN METHODS

Male Sprague-Dawley rats were subjected to 90 minute focal cerebral ischemia, followed by intravenous administration of 1 × 10(7) allogeneic BMMCs or vehicle at 0, 3 or 6 h after reperfusion or 2 × 10(7) BMMCs 6 h after reperfusion. Other rats administered 1 × 10(7) BMMCs at 6 h after reperfusion received additional BMMC transplantation or vehicle 9 h after reperfusion. Infarct volumes, neurological deficit scores and immunohistochemistry were evaluated 24 or 72 h after reperfusion.

KEY FINDINGS

Infarct volumes at 24 h were significantly decreased in transplantation rats at 0 and 3 h, but not at 6 h, after reperfusion, compared to vehicle-treatment. Even high dose BMMC transplantation at 6h after reperfusion was ineffective. Repeated BMMC transplantation at 6 and 9h after reperfusion reduced infarct volumes and significantly improved neurological deficit scores at 24 and 72 h. Immunohistochemistry showed repeated BMMC transplantation reduced ionized calcium-binding adapter molecule 1, 4-hydroxy-2-nonenal and 8-hydroxydeoxyguanosine expression at 24 and 72 h after reperfusion.

SIGNIFICANCE

Intravenous allogeneic BMMCs were neuroprotective following transient focal cerebral ischemia, and the therapeutic time window of BMMC transplantation was >3 h and <6 h after reperfusion in this model. Repeated transplantation at 6 and 9 h after reperfusion suppressed inflammation and oxidative stress in ischemic brains, resulting in improved neuroprotection.

Cell based therapies for ischemic stroke: from basic science to bedside

Cell therapy is emerging as a viable therapy to restore neurological function after stroke. Many types of stem/progenitor cells from different sources have been explored for their feasibility and efficacy for the treatment of stroke. Transplanted cells not only have the potential to replace the lost circuitry, but also produce growth and trophic factors, or stimulate the release of such factors from host brain cells, thereby enhancing endogenous brain repair processes. Although stem/progenitor cells have shown a promising role in ischemic stroke in experimental studies as well as initial clinical pilot studies, cellular therapy is still at an early stage in humans. Many critical issues need to be addressed including the therapeutic time window, cell type selection, delivery route, and in vivo monitoring of their migration pattern. This review attempts to provide a comprehensive synopsis of preclinical evidence and clinical experience of various donor cell types, their restorative mechanisms, delivery routes, imaging strategies, future prospects and challenges for translating cell therapies as a neurorestorative regimen in clinical applications.

Mesenchymal stem cells and their subpopulation, pluripotent muse cells, in basic research and regenerative medicine

Mesenchymal stem cells (MSCs) have gained a great deal of attention for regenerative medicine because they can be obtained from easy accessible mesenchymal tissues, such as bone marrow, adipose tissue, and the umbilical cord, and have trophic and immunosuppressive effects to protect tissues. The most outstanding property of MSCs is their potential for differentiation into cells of all three germ layers. MSCs belong to the mesodermal lineage, but they are known to cross boundaries from mesodermal to ectodermal and endodermal lineages, and differentiate into a variety of cell types both in vitro and in vivo. Such behavior is exceptional for tissue stem cells. As observed with hematopoietic and neural stem cells, tissue stem cells usually generate cells that belong to the tissue in which they reside, and do not show triploblastic differentiation. However, the scientific basis for the broad multipotent differentiation of MSCs still remains an enigma. This review summarizes the properties of MSCs from representative mesenchymal tissues, including bone marrow, adipose tissue, and the umbilical cord, to demonstrate their similarities and differences. Finally, we introduce a novel type of pluripotent stem cell, multilineage-differentiating stress-enduring (Muse) cells, a small subpopulation of MSCs, which can explain the broad spectrum of differentiation ability in MSCs.

Triggering Receptor Expressed on Myeloid Cells-2 Correlates to Hypothermic Neuroprotection in Ischemic Stroke

Hypothermia is neuroprotective against many acute neurological insults, including ischemic stroke. We and others have previously shown that protection by hypothermia is partially associated with an anti-inflammatory effect. Phagocytes are thought to play an important role in the clearance of necrotic debris, paving the way for endogenous repair mechanisms to commence, but the effect of cooling and phagocytosis has not been extensively studied. Triggering receptor expressed on myeloid cells-2 (TREM2) is a newly identified surface receptor shown to be involved in phagocytosis. In this study, we examined the effect of therapeutic hypothermia on TREM2 expression. Mice underwent permanent middle cerebral artery occlusion (MCAO) and were treated with one of the two cooling paradigms: one where cooling (30°C) began at the onset of MCAO (early hypothermia [eHT]) and another where cooling began 1 hour later (delayed hypothermia [dHT]). In both groups, cooling was maintained for 2 hours. A third group was maintained at normothermia (NT) as a control (37°C). Mice from the NT and dHT groups had similar ischemic lesion sizes and neurological performance, but the eHT group showed marked protection as evidenced by a smaller lesion size and less neurological deficits up to 30 days after the insult. Microglia and macrophages increased after MCAO as early as 3 days, peaked at 7 days, and decreased by 14 days. Both hypothermia paradigms were associated with decreased numbers of microglia and macrophages at 3 and 7 days, with greater decreases in the early paradigm. However, the proportion of the TREM2-positive microglia/macrophages was actually increased among the eHT group at day 7. eHT showed a long-term neurological benefit, but neuroprotection did not correlate to immune suppression. However, hypothermic neuroprotection was associated with a relative increase in TREM2 expression, and suggests that TREM2 may serve a beneficial role in brain ischemia.

Multimodality molecular imaging of stem cells therapy for stroke

Stem cells have been proposed as a promising therapy for treating stroke. While several studies have demonstrated the therapeutic benefits of stem cells, the exact mechanism remains elusive. Molecular imaging provides the possibility of the visual representation of biological processes at the cellular and molecular level. In order to facilitate research efforts to understand the stem cells therapeutic mechanisms, we need to further develop means of monitoring these cells noninvasively, longitudinally and repeatedly. Because of tissue depth and the blood-brain barrier (BBB), in vivo imaging of stem cells therapy for stroke has unique challenges. In this review, we describe existing methods of tracking transplanted stem cells in vivo, including magnetic resonance imaging (MRI), nuclear medicine imaging, and optical imaging (OI). Each of the imaging techniques has advantages and drawbacks. Finally, we describe multimodality imaging strategies as a more comprehensive and potential method to monitor transplanted stem cells for stroke.

123 I-Iomazenil Single Photon Emission Computed Tomography Visualizes Recovery of Neuronal Integrity by Bone Marrow Stromal Cell Therapy in Rat Infarct Brain

Background and Purpose—

This study was aimed to assess whether 123 I-iomazenil (IMZ) single photon emission computed tomography can serially monitor the effects of bone marrow stromal cell (BMSC) transplantation on neuronal integrity in infarct brain of rats.

Methods—

The BMSCs were harvested from green fluorescent protein–transgenic rats and were cultured. The rats were subjected to permanent middle cerebral artery occlusion. Their motor function was serially quantified throughout the experiments. The BMSCs or vehicle was stereotactically transplanted into the ipsilateral striatum at 7 days after the insult. Using small-animal single photon emission computed tomography/computed tomography apparatus, the 123 I-IMZ uptake was serially measured at 6 and 35 days after the insult. Finally, fluorescence immunohistochemistry was performed to evaluate the distribution of engrafted cells and their phenotypes.

Results—

The distribution of 123 I-IMZ was markedly decreased in the ipsilateral neocortex at 6 days postischemia. The vehicle-transplanted animals did not show a significant change at 35 days postischemia. However, BMSC transplantation significantly improved the distribution of 123 I-IMZ in the peri-infarct neocortex as well as motor function. The engrafted BMSCs were densely distributed around cerebral infarct, and some of them expressed neuronal nuclear antigen and γ-aminobutyric acid type-A receptor.

Conclusions—

The present findings strongly suggest that the BMSCs may enhance functional recovery by improving the neuronal integrity in the peri-infarct area, when directly transplanted into the infarct brain at clinically relevant timing. 123 I-IMZ single photon emission computed tomography may be a promising modality to scientifically prove the beneficial effects of BMSC transplantation on the host brain in clinical situation.

Update on therapeutic mechanism for bone marrow stromal cells in ischemic stroke

Cerebral ischemia is a major cause of morbidity and mortality in the aged population, as well as a tremendous burden on the healthcare system. Despite timely treatment with thrombolysis and percutaneous intravascular interventions, many patients are often left with irreversible neurological deficits. Bone marrow stromal cells (BMSCs), also referred to as mesenchymal stem cells (MSCs), are a type of nonhematopoietic stem cells which exists in bone marrow mesh, with the potential to self-renew. Unlike cells in the central nervous system, BMSCs differentiate not only into mesodermal cells, but also endodermal and ectodermal cells. Moreover, it has been reported that BMSCs develop into cells with neural and vascular markers and play a role in recovery from ischemic stroke. These findings have fuelled excitement in regenerative medicine for neurological diseases, especially for ischemic stroke. There is now preclinical evidence to suggest that BMSCs grafted into the brain of ischemic models abrogate neurological deficits. Based on the overwhelming evidence from animal studies as well as in clinical trials, BMSC transplantation is considered a promising strategy for treatment of ischemic stroke. The goal of this review is to present an integrated consideration of molecular mechanisms in a chronological fashion and discuss an optimal BMSC delivery route for ischemic stroke.

Evidence for high translational potential of mesenchymal stromal cell therapy to improve recovery from ischemic stroke

Although ischemic stroke is a major cause of morbidity and mortality, current therapies benefit only a small proportion of patients. Transplantation of mesenchymal stromal cells (MSC, also known as mesenchymal stem cells or multipotent stromal cells) has attracted attention as a regenerative therapy for numerous diseases, including stroke. Mesenchymal stromal cells may aid in reducing the long-term impact of stroke via multiple mechanisms that include induction of angiogenesis, promotion of neurogenesis, prevention of apoptosis, and immunomodulation. In this review, we discuss the clinical rationale of MSC for stroke therapy in the context of their emerging utility in other diseases, and their recent clinical approval for treatment of graft-versus-host disease. An analysis of preclinical studies examining the effects of MSC therapy after ischemic stroke indicates near-universal agreement that MSC have significant favorable effect on stroke recovery, across a range of doses and treatment time windows. These results are interpreted in the context of completed and ongoing human clinical trials, which provide support for MSC as a safe and potentially efficacious therapy for stroke recovery in humans. Finally, we consider principles of brain repair and manufacturing considerations that will be useful for effective translation of MSC from the bench to the bedside for stroke recovery.

Multiple cell transplantation based on an intraparenchymal approach for patients with chronic phase stroke

Stroke is the third leading cause of death worldwide and a huge perpetrator in adult disability. This pilot clinical study investigates the possible benefits of transplanting multiple cells in chronic stroke. A total of 10 consecutive stroke patients were treated by combination cell transplantation on the basis of an intraparenchymal approach from November 2003 to April 2011. There were six males and four females. Their age ranged from 42 to 87 years, and the course of disease varied from 6 months to 20 years. Six patients suffered cerebral infarction, and four patients suffered a brain hemorrhage. The olfactory ensheathing cells, neural progenitor cells, umbilical cord mesenchymal cells, and Schwann cells were injected through selected routes including intracranial parenchymal implantation, intrathecal implantation, and intravenous administration, respectively. The clinical neurological function was assessed carefully and independently before treatment and during a long-term follow-up using the Clinic Neurologic Impairment Scale and the Barthel index. All patients were followed up successfully from 6 months to 2 years after cell transplantation. Every subject achieved neurological function amelioration including improved speech, muscle strength, muscular tension, balance, pain, and breathing; most patients had an increased Barthel index score and Clinic Neurologic Impairment Scale score. These preliminary results demonstrate the novel strategy of combined multiple cell therapy based on intraparenchymal delivery: it appears to be relatively clinically safe and at least initially beneficial for chronic stroke patients. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.