Treatment evaluation of acute stroke for using in regenerative cell elements (TREASURE) trial: Rationale and design

Allogeneic Stem Cell Therapy for Acute Ischemic Stroke: The Phase 2/3 TREASURE Randomized Clinical Trial

Importance

Cell therapy is a promising treatment approach for stroke and other diseases. However, it is unknown whether MultiStem (HLCM051), a bone marrow-derived, allogeneic, multipotent adult progenitor cell product, has the potential to treat ischemic stroke.

Objective

To assess the efficacy and safety of MultiStem when administered within 18 to 36 hours of ischemic stroke onset.

Design, Setting, and Participants

The Treatment Evaluation of Acute Stroke Using Regenerative Cells (TREASURE) multicenter, double-blind, parallel-group, placebo-controlled phase 2/3 randomized clinical trial was conducted at 44 academic and clinical centers in Japan between November 15, 2017, and March 29, 2022. Inclusion criteria were age 20 years or older, presence of acute ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score of 8-20 at baseline), confirmed acute infarction involving the cerebral cortex and measuring more than 2 cm on the major axis (determined with diffusion-weighted magnetic resonance imaging), and a modified Rankin Scale (mRS) score of 0 or 1 before stroke onset. Data analysis was performed between May 9 and August 15, 2022.

Exposure

Patients were randomly assigned to either intravenous MultiStem in 1 single unit of 1.2 billion cells or intravenous placebo within 18 to 36 hours of ischemic stroke onset.

Main Outcomes and Measures

The primary end points were safety and excellent outcome at day 90, measured as a composite of a modified Rankin Scale (mRS) score of 1 or less, a NIHSS score of 1 or less, and a Barthel index score of 95 or greater. The secondary end points were excellent outcome at day 365, mRS score distribution at days 90 and 365, and mRS score of 0 to 1 and 0 to 2 at day 90. Statistical analysis of efficacy was performed using the Cochran-Mantel-Haenszel test.

Results

This study included 206 patients (104 received MultiStem and 102 received placebo). Their mean age was 76.5 (range, 35-95) years, and more than half of patients were men (112 [54.4%]). There were no between-group differences in primary and secondary end points. The proportion of excellent outcomes at day 90 did not differ significantly between the MultiStem and placebo groups (12 [11.5%] vs 10 [9.8%], P = .90; adjusted risk difference, 0.5% [95% CI, -7.3% to 8.3%]). The frequency of adverse events was similar between treatment groups.

Conclusions and Relevance

In this randomized clinical trial, intravenous administration of allogeneic cell therapy within 18 to 36 hours of ischemic stroke onset was safe but did not improve short-term outcomes. Further research is needed to determine whether MultiStem therapy for ischemic stroke has a beneficial effect in patients who meet specific criteria, as indicated by the exploratory analyses in this study.

Trial Registration

ClinicalTrials.gov Identifier: NCT02961504.

A review and meta-analysis of stem cell therapies in stroke patients: effectiveness and safety evaluation

PURPOSE

Stem cells have been extensively used during the last decade to improve clinical outcomes after stroke. The dramatic increase in trials in this field has led us to perform a systematic review and meta-analysis to understand the safety, effectiveness, and relative limitations of this type of intervention.

METHOD

This review summarizes the current evidence pooled from PubMed (Medline), EMBASE, EBSCOhost, http://clinicaltrials.gov , Scopus (Elsevier), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (Science Citation Index Expanded) databases for the use of stem cell therapies in stroke patients without combinations with other treatment modalities. The National Institutes of Health Stroke, modified Rankin Scales, and Barthel Index scores after external stem cell administration have been evaluated on the 3rd, 6th, and 12th months after treatment. The random effect analysis was performed using the Review Manager 5.4.1. The characteristics of stem cell sources and their adverse effects have been discussed as well.

FINDINGS

Although reasonably safe, the effectiveness evidence fluctuated to a large extent due to the heterogeneity of the clinical trials and the absence of a systematic approach. The stem cell sources and the administration window were not strongly associated with clinical outcomes.

CONCLUSION

Further studies should be conducted to understand the deep discrepancy between preclinical and clinical trials and to execute phase 3 clinical trials with robust control of study characteristics and outcomes.

A comprehensive review of quantum bioreactor cell manufacture: Research and clinical applications

The Quantum cell expansion system manufactured by Terumo-BCT is perhaps the most widely reported Good Manufacturing Practice-compliant bioreactor used for the expansion of adherent cell populations, both for research purposes and clinical cell-based therapies/trials. Although the system was originally designed for adherent cell expansion, more recently suspension cultures and extracellular vesicle manufacturing protocols have been published using the Quantum system. Cell therapy research and regenerative medicine in general is a rapidly expanding field and as such it is likely that the use of this system will become even more widespread and perhaps mandatory, for both research and development and in the clinic. The purpose of this review is to describe, compare and discuss the diverse range of research and clinical applications currently using the Quantum system, which to our knowledge has not previously been reviewed. In addition, current and future challenges will also be discussed.

Importance of microRNAs by mRNA-microRNA integration analysis in acute ischemic stroke patients

OBJECTS

The roles of mRNA and microRNA (miRNA) are well known in many diseases, including ischemic stroke; thus, integration analysis using mRNA and miRNA is important to elucidate pathogenesis. However, their contribution, especially that of miRNA-targeted mRNA, to the severity of acute ischemic stroke remains unclear. Therefore, we examined mRNA and miRNA integration analysis targeted for acute ischemic stroke to clarify the pathway related to acute stroke severity.

MATERIAL AND METHODS

We performed Ingenuity Pathway Analysis (IPA) using RNA extracted from the whole blood of four healthy controls, six minor acute ischemic stroke patients (MS; National Institutes of Health Stroke Scale [NIHSS] < 8), and six severe acute ischemic stroke patients (SS; NIHSS ≥ 8) on admission. mRNA and miRNA were measured using RNA sequencing and RNA expression variation; canonical pathway analysis (CPA) and upstream regulator analyses were performed.

RESULTS

Acute ischemic stroke patients demonstrated different RNA expressions to healthy controls. Compared to MS patients, in the SS patients, 1222 mRNA, 96 miRNA, and 935 miRNA-targeted mRNA expressions were identified among differentially expressed RNA expressions (p<0.05, |log2 fold change| >1.1). CPA by IPA using mRNAs or miRNA-targeted mRNAs showed that macrophage-stimulating protein (MSP)-recepteur d'origine nantais (RON) signaling was mostly activated in SS patients compared to in MS patients. In addition, upstream regulator analysis in IPA showed that most mRNAs located upstream are miRNAs.

CONCLUSIONS

In severe acute stroke, integration of mRNA and microRNA analysis showed activated MSP-RON signaling in macrophages, and multiple miRNAs comprehensively controlled the overall pathophysiology of stroke.

Dental-Pulp Stem Cells as a Therapeutic Strategy for Ischemic Stroke

Regenerative medicine aims to restore human functions by regenerating organs and tissues using stem cells or living tissues for the treatment of organ and tissue defects or dysfunction. Clinical trials investigating the treatment of cerebral infarction using mesenchymal stem cells, a type of somatic stem cell therapy, are underway. The development and production of regenerative medicines using somatic stem cells is expected to contribute to the treatment of cerebral infarction, a central nervous system disease for which there is no effective treatment. Numerous experimental studies have shown that cellular therapy, including the use of human dental pulp stem cells, is an attractive strategy for patients with ischemic brain injury. This review describes the basic research, therapeutic mechanism, clinical trials, and future prospects for dental pulp stem cell therapy, which is being investigated in Japan in first-in-human clinical trials for the treatment of patients with acute cerebral ischemia.

CREB Coactivator CRTC2 Plays a Crucial Role in Endothelial Function

The cAMP pathway is known to stabilize endothelial barrier function and maintain vascular physiology. The family of cAMP-response element binding (CREB)-regulated transcription coactivators (CRTC)1-3 activate transcription by targeting the basic leucine zipper domain of CREB. CRTC2 is a master regulator of glucose metabolism in liver and adipose tissue. However, the role of CRTC2 in endothelium remains unknown. The aim of this study was to evaluate the effect of CRTC2 on endothelial function. We focused the effect of CRTC2 in endothelial cells and its relationship with p190RhoGAP-A. We examined the effect of CRTC2 on endothelial function using a mouse aorta ring assay ex vivo and with photothrombotic stroke in endothelial cell-specific CRTC2-knock-out male mice in vivo CRTC2 was highly expressed in endothelial cells and related to angiogenesis. Among CRTC1-3, only CRTC2 was activated under ischemic conditions at endothelial cells, and CRTC2 maintained endothelial barrier function through p190RhoGAP-A expression. Ser¹⁷¹ was a pivotal regulatory site for CRTC2 intracellular localization, and Ser³⁰⁷ functioned as a crucial phosphorylation site. Endothelial cell-specific CRTC2-knock-out mice showed reduced angiogenesis ex vivo, exacerbated stroke via endothelial dysfunction, and impaired neurologic recovery via reduced vascular beds in vivo These findings suggest that CRTC2 plays a crucial protective role in vascular integrity of the endothelium via p190RhoGAP-A under ischemic conditions.SIGNIFICANCE STATEMENT Previously, the role of CRTC2 in endothelial cells was unknown. In this study, we firstly clarified that CRTC2 was expressed in endothelial cells and among CRTC1-3, only CRTC2 was related to endothelial function. Most importantly, only CRTC2 was activated under ischemic conditions at endothelial cells and maintained endothelial barrier function through p190RhoGAP-A expression. Ser³⁰⁷ in CRTC2 functioned as a crucial phosphorylation site. Endothelial cell-specific CRTC2-knock-out mice showed reduced angiogenesis ex vivo, exacerbated stroke via endothelial dysfunction, and impaired neurologic recovery via reduced vascular beds in vivo These results suggested that CRTC2 maybe a potential therapeutic target for reducing blood-brain barrier (BBB) damage and improving recovery.

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.

The effectiveness of various cytotherapeutic strategies for the treatment of ischemic stroke: a Bayesian network meta-analysis of randomized controlled trials

BACKGROUND

Cytotherapy is a potential treatment for ischemic stroke (IS) patients but lacks uniform procedures. We aimed to assess the impact of the time of intervention, cell type, dose, and route of administration on the clinical effects by network meta-analysis.

METHODS

We searched public electronic databases through July 7, 2019. Bayesian network meta-analyses were performed to compare differences among different cytotherapeutic strategies.

RESULTS

Cytotherapy can significantly improve patients' activity of daily living according to the modified Rankin Scale (standard mean difference (SMD) - 0.81; 95% confidence interval (CI) - 1.58, - 0.03; p = 0.0417) and Barthel Index (SMD 0.67; 95% CI 0.05, 1.30; p = 0.036) results as well as improve neurological recovery (SMD - 0.93; 95% CI - 1.29, - 0.57; p < 0.001). Network meta-analysis showed that the intra-arterial injection of large amounts of mononuclear cells (NCs) or aldehyde dehydrogenase (ALDH)-positive cells was beneficial for improving patients' activity of daily living, while CD34⁺ cells through intracerebral injection had an advantage in the recovery of injured nerve function. Intravenous injection of mesenchymal stem cells (MSCs) or endothelial progenitor cells (EPCs) was beneficial in reducing mortality and serious adverse event (SAE) onset.

CONCLUSIONS

In the subacute stage, the intra-arterial injection of NCs or ALDH cells improves patients' activity of daily living. Additionally, CD34⁺ cells through intracerebral injection had an advantage in the recovery of injured nerve function even in the chronic stage. Intravenous injection of MSCs or EPCs is a safety delivery route that can reduce mortality and SAE onset. However, further clinical studies are still needed to confirm these results.

Clinical neurorestorative cell therapies: Developmental process, current state and future prospective

Clinical cell therapies (CTs) for neurological diseases and cellular damage have been explored for more than 2 decades. According to the United States Food and Drug Administration, there are 2 types of cell categories for therapy, namely stem cell-derived CT products and mature/functionally differentiated cell-derived CT products. However, regardless of the type of CT used, the majority of reports of clinical CTs from either small sample sizes based on single-center phase 1 or 2 unblinded trials or retrospective clinical studies showed effects on neurological improvement and the ability to either partially or temporarily thwart the deteriorating cellular processes of the neurodegenerative diseases. There have been only a few prospective, multicenter, randomized, double- blind placebo-control clinical trials of CTs so far in this developing novel area that have shown negative results, and more clinical trials are needed. This will expand our knowledge in exploring the type of cells that yield promising results and restore damaged neurological structure and functions of the central nervous system based on higher level evidence-based medical data. In this review, we briefly introduce the developmental process, current state, and future prospective for clinical neurorestorative CT.

Cell-Based Therapies for Stroke: Are We There Yet?

Stroke is the second leading cause of death and physical disability, with a global lifetime incidence rate of 1 in 6. Currently, the only FDA approved treatment for ischemic stroke is the administration of tissue plasminogen activator (tPA). Stem cell clinical trials for stroke have been underway for close to two decades, with data suggesting that cell therapies are safe, feasible, and potentially efficacious. However, clinical trials for stroke account for <1% of all stem cell trials. Nevertheless, the resources devoted to clinical research to identify new treatments for stroke is still significant (53–64 million US$, Phase 1–4). Notably, a quarter of cell therapy clinical trials for stroke have been withdrawn (15.2%) or terminated (6.8%) to date. This review discusses the bottlenecks in delivering a successful cell therapy for stroke, and the cost-to-benefit ratio necessary to justify these expensive trials. Further, this review will critically assess the currently available data from completed stroke trials, the importance of standardization in outcome reporting, and the role of industry-led research in the development of cell therapies for stroke.

Immunomodulatory Therapeutic Strategies in Stroke

The role of immunity in all stages of stroke is increasingly being recognized, from the pathogenesis of risk factors to tissue repair, leading to the investigation of a range of immunomodulatory therapies. In the acute phase of stroke, proposed therapies include drugs targeting pro-inflammatory cytokines, matrix metalloproteinases, and leukocyte infiltration, with a key objective to reduce initial brain cell toxicity. Systemically, the early stages of stroke are also characterized by stroke-induced immunosuppression, where downregulation of host defences predisposes patients to infection. Therefore, strategies to modulate innate immunity post-stroke have garnered greater attention. A complementary objective is to reduce longer-term sequelae by focusing on adaptive immunity. Following stroke onset, the integrity of the blood–brain barrier is compromised, exposing central nervous system (CNS) antigens to systemic adaptive immune recognition, potentially inducing autoimmunity. Some pre-clinical efforts have been made to tolerize the immune system to CNS antigens pre-stroke. Separately, immune cell populations that exhibit a regulatory phenotype (T- and B- regulatory cells) have been shown to ameliorate post-stroke inflammation and contribute to tissue repair. Cell-based therapies, established in oncology and transplantation, could become a strategy to treat the acute and chronic stages of stroke. Furthermore, a role for the gut microbiota in ischaemic injury has received attention. Finally, the immune system may play a role in remote ischaemic preconditioning-mediated neuroprotection against stroke. The development of stroke therapies involving organs distant to the infarct site, therefore, should not be overlooked. This review will discuss the immune mechanisms of various therapeutic strategies, surveying published data and discussing more theoretical mechanisms of action that have yet to be exploited.

Modern Concepts in Regenerative Therapy for Ischemic Stroke: From Stem Cells for Promoting Angiogenesis to 3D-Bioprinted Scaffolds Customized via Carotid Shear Stress Analysis

Ischemic stroke is associated with a tremendous economic and societal burden, and only a few therapies are currently available for the treatment of this devastating disease. The main therapeutic approaches used nowadays for the treatment of ischemic brain injury aim to achieve reperfusion, neuroprotection and neurorecovery. Therapeutic angiogenesis also seems to represent a promising tool to improve the prognosis of cerebral ischemia. This review aims to present the modern concepts and the current status of regenerative therapy for ischemic stroke and discuss the main results of major clinical trials addressing the effectiveness of stem cell therapy for achieving neuroregeneration in ischemic stroke. At the same time, as a glimpse into the future, this article describes modern concepts for stroke prevention, such as the implantation of bioprinted scaffolds seeded with stem cells, whose 3D geometry is customized according to carotid shear stress.

Stem cell transplantation for ischemic stroke

BACKGROUND

Stroke is a leading cause of morbidity and mortality worldwide, with very large healthcare and social costs, and a strong demand for alternative therapeutic approaches. Preclinical studies have shown that stem cells transplanted into the brain can lead to functional improvement. However, to date, evidence for the benefits of stem cell transplantation in people with ischemic stroke is lacking. This is the first update of the Cochrane review published in 2010.

OBJECTIVES

To assess the efficacy and safety of stem cell transplantation compared with control in people with ischemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched August 2018), CENTRAL (last searched August 2018), MEDLINE (1966 to August 2018), Embase (1980 to August 2018), and BIOSIS (1926 to August 2018). We handsearched potentially relevant conference proceedings, screened reference lists, and searched ongoing trials and research registers (last searched August 2018). We also contacted individuals active in the field and stem cell manufacturers (last contacted August 2018).

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that recruited people with ischemic stroke, in any phase of the disease (acute, subacute or chronic), and an ischemic lesion confirmed by computerized tomography or magnetic resonance imaging scan. We included all types of stem cell transplantation, regardless of cell source (autograft, allograft, or xenograft; embryonic, fetal, or adult; from brain or other tissues), route of cell administration (systemic or local), and dosage. The primary outcome was efficacy (assessed as neurologic impairment or functional outcome) at longer term follow-up (minimum six months). Secondary outcomes included post-procedure safety outcomes (death, worsening of neurological deficit, infections, and neoplastic transformation).

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, assessed trial quality and risk of bias, and extracted data. If needed, we contacted study authors for additional information. We performed random effects meta-analyses when two or more RCTs were available for any outcome. We assessed the certainty of the evidence by using the GRADE approach.

MAIN RESULTS

In this updated review, we included seven completed RCTs with 401 participants. All tested adult human non-neural stem cells; cells were transplanted during the acute, subacute, or chronic phase of ischemic stroke; administered intravenously, intra-arterially, intracerebrally, or into the lumbar subarachnoid space. Follow-up ranged from six months to seven years. Efficacy outcomes were measured with the National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), or Barthel Index (BI). Safety outcomes included case fatality, and were measured at the end of the trial.Overall, stem cell transplantation was associated with a better clinical outcome when measured with the NIHSS (mean difference [MD] -1.49, 95% confidence interval [CI] -2.65 to -0.33; five studies, 319 participants; low-certainty evidence), but not with the mRS (MD -0.42, 95% CI -0.86 to 0.02; six studies, 371 participants; very low-certainty evidence), or the BI (MD 14.09, 95% CI -1.94 to 30.13; three studies, 170 participants; very low-certainty evidence). The studies in favor of stem cell transplantation had, on average, a higher risk of bias, and a sample size of 32 or fewer participants.No significant safety concerns associated with stem cell transplantation were raised with respect to death (risk ratio [RR] 0.66, 95% CI 0.39 to 1.14; six studies, participants; low-certainty evidence).We were not able to perform the sensitivity analysis according to the quality of studies, because all of them were at high risk of bias.

AUTHORS' CONCLUSIONS

Overall, in participants with ischemic stroke, stem cell transplantation was associated with a reduced neurological impairment, but not with a better functional outcome. No obvious safety concerns were raised. However, these conclusions came mostly from small RCTs with high risk of bias, and the certainty of the evidence ranged from low to very low. More well-designed trials are needed.

The spleen may be an important target of stem cell therapy for stroke

Stroke is the most common cerebrovascular disease, the second leading cause of death behind heart disease and is a major cause of long-term disability worldwide. Currently, systemic immunomodulatory therapy based on intravenous cells is attracting attention. The immune response to acute stroke is a major factor in cerebral ischaemia (CI) pathobiology and outcomes. Over the past decade, the significant contribution of the spleen to ischaemic stroke has gained considerable attention in stroke research. The changes in the spleen after stroke are mainly reflected in morphology, immune cells and cytokines, and these changes are closely related to the stroke outcomes. Autonomic nervous system (ANS) activation, release of central nervous system (CNS) antigens and chemokine/chemokine receptor interactions have been documented to be essential for efficient brain-spleen cross-talk after stroke. In various experimental models, human umbilical cord blood cells (hUCBs), haematopoietic stem cells (HSCs), bone marrow stem cells (BMSCs), human amnion epithelial cells (hAECs), neural stem cells (NSCs) and multipotent adult progenitor cells (MAPCs) have been shown to reduce the neurological damage caused by stroke. The different effects of these cell types on the interleukin (IL)-10, interferon (IFN), and cholinergic anti-inflammatory pathways in the spleen after stroke may promote the development of new cell therapy targets and strategies. The spleen will become a potential target of various stem cell therapies for stroke represented by MAPC treatment.

2018 Yearbook of Neurorestoratology

The Neurorestoratology discipline is getting worldwide attention from the clinicians, basic scientists, students and policy makers alike. Accordingly, this year too, the discipline has made profound advances and great achievements for the benefit of the mankind. In this report, of the 2018 Neurorestoratology Yearbook, salient features of new developments are summarized. This Yearbook consists 3 key themes namely (i) the new findings on pathogenesis of neurological diseases or degeneration; (ii) the new mechanisms of neurorestorative aspects; and (iii) the achievements and progresses made in the clinical field of neurorestorative therapies. The new trend has emerged in clinical studies that are based on greater levels of evidence-based medical practices both in clinical therapies and clinical trials based on standard designs.