Neuro-regeneration therapy using human Muse cells is highly effective in a mouse intracerebral hemorrhage model

Investigating the Potential of Multilineage Differentiating Stress-Enduring Cells for Osteochondral Healing

OBJECTIVE

Multilineage differentiating stress-enduring (Muse) cells, a pluripotent stem cell subset of mesenchymal stem cells (MSCs), have shown promise for various tissue repairs due to their stress tolerance and multipotent capabilities. We aimed to investigate the differentiation potential in vitro, the dynamics in vivo, and the reparative contribution of Muse cells to osteochondral lesions.

DESIGN

Labeled MSCs were cultured and sorted into Muse and non-Muse (MSCs without Muse cells) groups. These cells were then formed into spheroids, and chondrogenic differentiation was assessed in vitro. Twenty-one immunocompromised mice were used as the in vivo models of osteochondral lesions. Live imaging, macroscopic evaluation, and histological and immunohistochemical analyses were conducted at the 4- and 8-week time points.

RESULTS

Muse cell spheroids were formed, which were larger and stained more intensely with toluidine blue than non-Muse spheroids, indicating better chondrogenic differentiation. Live imaging confirmed luminescence in all 4-week model knees, but only in a few knees at 8 weeks, suggesting cell persistence. Macroscopically and histologically, no significant differences were observed between the Muse and non-Muse groups at 4 and 8 weeks; however, both groups showed better cartilage repair than that of the vehicle group at 8 weeks. No collagen type II generation was observed in the repaired tissues.

CONCLUSION

The implantation of the spheroids of Muse and non-Muse cells resulted in better healing of osteochondral lesions than that of the controls, and Muse cells had a higher chondrogenic differentiation potential in vitro than non-Muse cells.

Multilineage-differentiating stress-enduring cells: a powerful tool for tissue damage repair

Multilineage-differentiating stress-enduring (Muse) cells are a type of pluripotent cell with unique characteristics such as non-tumorigenic and pluripotent differentiation ability. After homing, Muse cells spontaneously differentiate into tissue component cells and supplement damaged/lost cells to participate in tissue repair. Importantly, Muse cells can survive in injured tissue for an extended period, stabilizing and promoting tissue repair. In addition, it has been confirmed that injection of exogenous Muse cells exerts anti-inflammatory, anti-apoptosis, anti-fibrosis, immunomodulatory, and paracrine protective effects in vivo. The discovery of Muse cells is an important breakthrough in the field of regenerative medicine. The article provides a comprehensive review of the characteristics, sources, and potential mechanisms of Muse cells for tissue repair and regeneration. This review serves as a foundation for the further utilization of Muse cells as a key clinical tool in regenerative medicine.

Multilineage Differentiating Stress Enduring (Muse) Cells: A New Era of Stem Cell-Based Therapy

Stem cell transplantation has recently demonstrated a significant therapeutic efficacy in various diseases. Multilineage-differentiating stress-enduring (Muse) cells are stress-tolerant endogenous pluripotent stem cells that were first reported in 2010. Muse cells can be found in the peripheral blood, bone marrow and connective tissue of nearly all body organs. Under basal conditions, they constantly move from the bone marrow to peripheral blood to supply various body organs. However, this rate greatly changes even within the same individual based on physical status and the presence of injury or illness. Muse cells can differentiate into all three-germ-layers, producing tissue-compatible cells with few errors, minimal immune rejection and without forming teratomas. They can also endure hostile environments, supporting their survival in damaged/injured tissues. Additionally, Muse cells express receptors for sphingosine-1-phosphate (S1P), which is a protein produced by damaged/injured tissues. Through the S1P-S1PR2 axis, circulating Muse cells can preferentially migrate to damaged sites following transplantation. In addition, Muse cells possess a unique immune privilege system, facilitating their use without the need for long-term immunosuppressant treatment or human leucocyte antigen matching. Moreover, they exhibit anti-inflammatory, anti-apoptotic and tissue-protective effects. These characteristics circumvent all challenges experienced with mesenchymal stem cells and induced pluripotent stem cells and encourage the wide application of Muse cells in clinical practice. Indeed, Muse cells have the potential to break through the limitations of current cell-based therapies, and many clinical trials have been conducted, applying intravenously administered Muse cells in stroke, myocardial infarction, neurological disorders and acute respiratory distress syndrome (ARDS) related to novel coronavirus (SARS-CoV-2) infection. Herein, we aim to highlight the unique biological properties of Muse cells and to elucidate the advantageous difference between Muse cells and other types of stem cells. Finally, we shed light on their current therapeutic applications and the major obstacles to their clinical implementation from laboratory to clinic.

Multilineage-Differentiating Stress-Enduring Cells (Muse Cells): An Easily Accessible, Pluripotent Stem Cell Niche with Unique and Powerful Properties for Multiple Regenerative Medicine Applications

Cell-based therapy in regenerative medicine is a powerful tool that can be used both to restore various cells lost in a wide range of human disorders and in renewal processes. Stem cells show promise for universal use in clinical medicine, potentially enabling the regeneration of numerous organs and tissues in the human body. This is possible due to their self-renewal, mature cell differentiation, and factors release. To date, pluripotent stem cells seem to be the most promising. Recently, a novel stem cell niche, called multilineage-differentiating stress-enduring (Muse) cells, is emerging. These cells are of particular interest because they are pluripotent and are found in adult human mesenchymal tissues. Thanks to this, they can produce cells representative of all three germ layers. Furthermore, they can be easily harvested from fat and isolated from the mesenchymal stem cells. This makes them very promising, allowing autologous treatments and avoiding the problems of rejection typical of transplants. Muse cells have recently been employed, with encouraging results, in numerous preclinical studies performed to test their efficacy in the treatment of various pathologies. This review aimed to (1) highlight the specific potential of Muse cells and provide a better understanding of this niche and (2) originate the first organized review of already tested applications of Muse cells in regenerative medicine. The obtained results could be useful to extend the possible therapeutic applications of disease healing.

Multilineage-Differentiating Stress-Enduring Cells (Muse Cells): The Future of Human and Veterinary Regenerative Medicine

In recent years, several studies have been conducted on Muse cells mainly due to their pluripotency, high tolerance to stress, self-renewal capacity, ability to repair DNA damage and not being tumoral. Additionally, since these stem cells can be isolated from different tissues in the adult organism, obtaining them is not considered an ethical problem, providing an advantage over embryonic stem cells. Regarding their therapeutic potential, few studies have reported clinical applications in the treatment of different diseases, such as aortic aneurysm and chondral injuries in the mouse or acute myocardial infarction in the swine, rabbit, sheep and in humans. This review aims to describe the characterization of Muse cells, show their biological characteristics, explain the differences between Muse cells and mesenchymal stem cells, and present their contribution to the treatment of some diseases.

Overexpression of NT3P75-2 gene modified bone marrow mesenchymal stem cells supernatant promotes neurological function recovery in ICH rats

Intracerebral hemorrhage (ICH) is an acute cerebrovascular disease with high mortality and long-term disability rates. Stem cell transplantation and neurotrophic factor therapy have shown great potential in ICH. It has been established that mutated NT3 (NT3P75 - 2) can enhance the positive biological functions of NT3 by decreasing its affinity to the P75-2 receptor. The present study aimed to explore whether NT3P75-2 could further improve neurological recovery after ICH. First, we constructed three stable BMSC cell lines (GFP, GFP-NT3 overexpressed and GFP-NT3P75 - 2 overexpressed) by lentivirus infection. Next, rats were injected with fresh supernatants of these three cell lines on days 1 (24 h) and 3 (72 h) post-ICH induction. Behavioral evaluations were conducted to assess the neurological recovery of ICH rats. We further evaluated changes in microglia activation, neuron survival and proliferation of neural stem cells. Compared with the GFP group and the GFP-NT3 group, animals in the GFP-NT3P75 - 2 group exhibited better motor function improvements and milder neuroinflammation response. Meanwhile, overexpression of NT3P75 - 2 significantly decreased neuronal apoptosis and increased number of SOX2 - positive cells. Taken together, our study demonstrated that early administration of NT3P75 - 2 enriched BMMSC supernatants significantly enhanced neuro-functional recovery after ICH by regulating neuroinflammation response, neuronal survival and increasing neural stem cell number, providing a new therapeutic strategy and direction for early treatment of ICH.

Direct implantation of hair-follicle-associated pluripotent (HAP) stem cells repairs intracerebral hemorrhage and reduces neuroinflammation in mouse model

Intracerebral hemorrhage (ICH) is a leading cause of mortality with ineffective treatment. Hair-follicle-associated pluripotent (HAP) stem cells can differentiate into neurons, glial cells and many other types of cells. HAP stem cells have been shown to repair peripheral-nerve and spinal-cord injury in mouse models. In the present study, HAP stem cells from C57BL/6J mice were implanted into the injured brain of C57BL/6J or nude mice with induced ICH. After allo transplantation, HAP stem cells differentiated to neurons, astrocytes, oligodendrocytes, and microglia in the ICH site of nude mice. After autologous transplantation in C57BL/6J mice, HAP stem cells suppressed astrocyte and microglia infiltration in the injured brain. The mRNA expression levels of IL-10 and TGF-β1, measured by quantitative Real-Time RT-PCR, in the brain of C57BL/6J mice with ICH was increased by HAP-stem-cell implantation compared to the non-implanted mice. Quantitative sensorimotor function analysis, with modified limb-placing test and the cylinder test, demonstrated a significant functional improvement in the HAP-stem-cell-implanted C57BL/6J mice, compared to non-implanted mice. HAP stem cells have critical advantages over induced pluripotent stem cells, embryonic stem cells as they do not develop tumors, are autologous, and do not require genetic manipulation. The present study demonstrates future clinical potential of HAP-stem-cell repair of ICH, currently a recalcitrant disease.

Endogenous reparative pluripotent Muse cells with a unique immune privilege system: Hint at a new strategy for controlling acute and chronic inflammation

Multilineage-differentiating stress enduring (Muse) cells, non-tumorigenic endogenous pluripotent stem cells, reside in the bone marrow (BM), peripheral blood, and connective tissue as pluripotent surface marker SSEA-3(+) cells. They express other pluripotent markers, including Nanog, Oct3/4, and Sox2 at moderate levels, differentiate into triploblastic lineages, self-renew at a single cell level, and exhibit anti-inflammatory effects. Cultured mesenchymal stromal cells (MSCs) and fibroblasts contain several percent of SSEA-3(+)-Muse cells. Circulating Muse cells, either endogenous or administered exogenously, selectively accumulate at the damaged site by sensing sphingosine-1-phosphate (S1P), a key mediator of inflammation, produced by damaged cells and replace apoptotic and damaged cells by spontaneously differentiating into multiple cells types that comprise the tissue and repair the tissue. Thus, intravenous injection is the main route for Muse cell treatment, and surgical operation is not necessary. Furthermore, gene introduction or cytokine induction are not required for generating pluripotent or differentiated states prior to treatment. Notably, allogenic and xenogenic Muse cells escape host immune rejection after intravenous injection and survive in the tissue as functioning cells over 6 and ∼2 months, respectively, without immunosuppressant treatment. Since Muse cells survive in the host tissue for extended periods of time, therefore their anti-inflammatory, anti-fibrotic, and trophic effects are long-lasting. These unique characteristics have led to the administration of Muse cells via intravenous drip in clinical trials for stroke, acute myocardial infarction, epidermolysis bullosa, spinal cord injury, neonatal hypoxic ischemic encephalopathy, amyotrophic lateral sclerosis, and COVID-19 acute respiratory distress syndrome without HLA-matching or immunosuppressive treatment.

Muse cells: ushering in a new era of stem cell-based therapy for stroke

Stem cell-based regenerative therapies have recently become promising and advanced for treating stroke. Mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs) have received the most attention for treating stroke because of the outstanding paracrine function of MSCs and the three-germ-layer differentiation ability of iPSCs. However, the unsatisfactory homing ability, differentiation, integration, and survival time in vivo limit the effectiveness of MSCs in regenerative medicine. The inherent tumorigenic property of iPSCs renders complete differentiation necessary before transplantation, which is complicated and expensive and affects the consistency among cell batches. Multilineage differentiating stress-enduring (Muse) cells are natural pluripotent stem cells in the connective tissues of nearly every organ and thus are considered nontumorigenic. A single Muse cell can differentiate into all three-germ-layer, preferentially migrate to damaged sites after transplantation, survive in hostile environments, and spontaneously differentiate into tissue-compatible cells, all of which can compensate for the shortcomings of MSCs and iPSCs. This review summarizes the recent progress in understanding the biological properties of Muse cells and highlights the differences between Muse cells and other types of stem cells. Finally, we summarized the current research progress on the application of Muse cells on stroke and challenges from bench to bedside.

Umbilical Cord Mesenchymal Stem Cells Derived Neurospheres Promote Long-term functional recovery But Aggravate Acute Phase Inflammation in Experimental Stroke

Human umbilical cord mesenchymal stem cells (UC-MSCs) transplantation has been shown to ameliorate intracerebral hemorrhage (ICH) in animal and clinical studies. We previously reported an easy one-step method to induce UC-MSCs into neurospheres with much enhanced neurogenic and angiogenic potential. In the present study, we further evaluated the neuro-protective effects of these UC-MSCs derived neurospheres (UC-MSCs-NS) using a murine collagenase induced ICH model. We compared the effects of UC-MSCs or UC-MSCs-NS transplantation at two different time-points: 3 h after ICH induction (early transplantation) or three days after ICH induction (delayed transplantation). The results showed that UC-MSCs exhibited favorable effects at both time-points whereas UC-MSCs-NS early delivery led to increased cell apoptosis, exacerbated brain edema, enlarged ICH volume and deteriorated neurological function. In vivo inflammatory cytokine analysis indicated UC-MSCs transplantation was able to attenuate the acute phase secretion of inflammatory cytokines TNF-α and IL-1β whereas UC-MSCs-NS immediate transplantation led to increased levels of these cytokines. However, long-term follow-up experiment showed delayed UC-MSCs-NS transplantation was superior to UC-MSCs transplantation alone in terms of increased neurogenic reconstitution. Our results suggest both UC-MSCs and UC-MSCs-NS can exert favorable effects in ICH therapy but the infusion of UC-MSCs-NS should avoid the super-early phase of ICH. We believe UC-MSCs derived neurospheres should be further exploited for chronic refractory neurological disorders such as chronic phase of stroke and various neurodegenerative disorders such as Alzheimer's disease.

Central Nervous System Tissue Regeneration after Intracerebral Hemorrhage: The Next Frontier

Despite marked advances in surgical techniques and understanding of secondary brain injury mechanisms, the prognosis of intracerebral hemorrhage (ICH) remains devastating. Harnessing and promoting the regenerative potential of the central nervous system may improve the outcomes of patients with hemorrhagic stroke, but approaches are still in their infancy. In this review, we discuss the regenerative phenomena occurring in animal models and human ICH, provide results related to cellular and molecular mechanisms of the repair process including by microglia, and review potential methods to promote tissue regeneration in ICH. We aim to stimulate research involving tissue restoration after ICH.

Non-Tumorigenic Pluripotent Reparative Muse Cells Provide a New Therapeutic Approach for Neurologic Diseases

Muse cells are non-tumorigenic endogenous reparative pluripotent cells with high therapeutic potential. They are identified as cells positive for the pluripotent surface marker SSEA-3 in the bone marrow, peripheral blood, and connective tissue. Muse cells also express other pluripotent stem cell markers, are able to differentiate into cells representative of all three germ layers, self-renew from a single cell, and are stress tolerant. They express receptors for sphingosine-1-phosphate (S1P), which is actively produced by damaged cells, allowing circulating cells to selectively home to damaged tissue. Muse cells spontaneously differentiate on-site into multiple tissue-constituent cells with few errors and replace damaged/apoptotic cells with functional cells, thereby contributing to tissue repair. Intravenous injection of exogenous Muse cells to increase the number of circulating Muse cells enhances their reparative activity. Muse cells also have a specific immunomodulatory system, represented by HLA-G expression, allowing them to be directly administered without HLA-matching or immunosuppressant treatment. Owing to these unique characteristics, clinical trials using intravenously administered donor-Muse cells have been conducted for myocardial infarction, stroke, epidermolysis bullosa, spinal cord injury, perinatal hypoxic ischemic encephalopathy, and amyotrophic lateral sclerosis. Muse cells have the potential to break through the limitations of current cell therapies for neurologic diseases, including amyotrophic lateral sclerosis. Muse cells provide a new therapeutic strategy that requires no HLA-matching or immunosuppressant treatment for administering donor-derived cells, no gene introduction or differentiation induction for cell preparation, and no surgery for delivering the cells to patients.

Electroacupuncture Enhance Therapeutic Efficacy of Mesenchymal Stem Cells Transplantation in Rats With Intracerebral Hemorrhage

BACKGROUND

Previous studies have showed the beneficial effects of mesenchymal stem cells (MSCs) on experimental intracerebral hemorrhage (ICH) animal. Enhancement of the treatment efficacy of MSCs in ICH is essential, considering the diseases association with high rates of disability and mortality. Some auxiliary methods to enhance the beneficial efficacy of MSCs have been introduced. However, the effect of electroacupuncture (EA) on the therapeutic efficacy of MSCs transplantation in hemorrhagic stroke and its potential mechanism is not explored.

METHODS

ICH rat models were established using collagenase and heparin. 48 h after ICH induction, the rats were randomly divided into model control (MC), MSCs transplantation (MSCs), EA stimulation (EA) and MSCs transplantation combined with EA stimulation (MSCs + EA) groups. We used mNSS test and gait analysis to assess neurological function of rats, and PET/CT to evaluate the volume of hemorrhage focus and level of glucose uptake. The concentrations of MDA, SOD, NSE, S100B and MBP in serum or plasma were examined with ELISA. Neural differentiation of MSCs, and the expressions of Bcl-2, Bax, Arg-1 and iNOS proteins around hematoma were detected by immunofluorescence and immunohistochemistry staining respectively. Western blot was carried out to analyze the expression levels of COX4, OGDH, PDH-E1α, Bcl-2 and Bax proteins. TUNEL staining was used to estimate cell apoptosis and transmission electron microscopy (TEM) was used to observe the ultrastructure and number of mitochondria.

RESULTS

Our data showed that EA promoted neuron-like differentiation of transplanted MSCs and the expressions of BDNF and NGF proteins in ICH rats. The score of mNSS and the gait analysis showed that the recovery of the neurological function in the MSCs + EA group was better than that in the MSCs and EA groups. EA improved the structure of brain tissue, and alleviated brain injury further after MSCs transplantation in ICH rats. When compared with the MSCs and EA groups, the level of glucose uptake and numbers of mitochondria and Arg-1 positive cells in MSCs + EA group increased significantly, but the numbers of apoptotic cells and iNOS positive cells and volume of hemorrhage focus reduced. The expressional levels of COX4, OGDH, PDH-E1α and Bcl-2 proteins increased, while the expressional level of Bax protein decreased compared with those in the MSCs and EA groups.

CONCLUSIONS

Our results reveal that EA improve therapeutic efficacy of MSCs transplantation in ICH rats.

Neuroregeneration and functional recovery after stroke: advancing neural stem cell therapy toward clinical application

Stroke is a main cause of death and disability worldwide. The ability of the brain to self-repair in the acute and chronic phases after stroke is minimal; however, promising stem cell-based interventions are emerging that may give substantial and possibly complete recovery of brain function after stroke. Many animal models and clinical trials have demonstrated that neural stem cells (NSCs) in the central nervous system can orchestrate neurological repair through nerve regeneration, neuron polarization, axon pruning, neurite outgrowth, repair of myelin, and remodeling of the microenvironment and brain networks. Compared with other types of stem cells, NSCs have unique advantages in cell replacement, paracrine action, inflammatory regulation and neuroprotection. Our review summarizes NSC origins, characteristics, therapeutic mechanisms and repair processes, then highlights current research findings and clinical evidence for NSC therapy. These results may be helpful to inform the direction of future stroke research and to guide clinical decision-making.

Cell-Based Therapy for Stroke: Musing With Muse Cells

Stem cell-based regenerative therapies may rescue the central nervous system following ischemic stroke. Mesenchymal stem cells exhibit promising regenerative capacity in in vitro studies but display little to no incorporation in host tissue after transplantation in in vivo models of stroke. Despite these limitations, clinical trials using mesenchymal stem cells have produced some functional benefits ascribed to their ability to modulate the host's inflammatory response coupled with their robust safety profile. Regeneration of ischemic brain tissue using stem cells, however, remains elusive in humans. Multilineage-differentiating stress-enduring (Muse) cells are a distinct subset of mesenchymal stem cells found sporadically in connective tissue of nearly every organ. Since their discovery in 2010, these endogenous reparative stem cells have been investigated for their therapeutic potential against a variety of diseases, including acute myocardial infarction, stroke, chronic kidney disease, and liver disease. Preclinical studies have exemplified Muse cells' unique ability mobilize, differentiate, and engraft into damaged host tissue. Intravenously transplanted Muse cells in mouse lacunar stroke models afforded functional recovery and long-term engraftment into the host neural network. This mini-review article highlights these biological properties that make Muse cells an exceptional candidate donor source for cell therapy in ischemic stroke. Elucidating the mechanism behind the therapeutic potential of Muse cells will undoubtedly help optimize stem cell therapy for stroke and advance the field of regenerative medicine.

Regenerative potential of pluripotent nontumorgenetic stem cells: Multilineage differentiating stress enduring cells (Muse cells)

Multilineage differentiating stress enduring cells (Muse cells), double positive for SSEA-3 and CD105, can be isolated by fluorescence-activated cell sorting (FACS) or sever cellular conditions from dermal fibroblasts, bone marrow stem cells (BMSCs), adipose tissue derived stem cells (ADSCs), fresh bone marrow and liposuction fat. When cultured in a single-cell suspension, Muse cells can grow into characteristic cell clusters. Muse cells maintain pluripotency as evidenced by pluripotent markers in vitro. Besides, Muse cells have no tumorigenesis up to 6 months in SCID mice. Muse cells differentiate into cells representative of all three germ layers both spontaneously and under specific induction. In comparison to mesenchymal stem cells (MSCs), Muse cells show higher homing and migration capabilities to damaged sites which is predominantly attributed to S1P–S1PR2 axis. The regenerative effects of Muse cells have been demonstrated by many models in vivo or in vitro, including stroke, intracerebral hemorrhage, myocardial infarction, aortic aneurysm, lung injuries, liver fibrosis, focal segmental glomerulosclerosis, osteochondral defects and skin ulcer. In general, migration, differentiation and paracrine play a pivotal role in the regeneration capability. Here we review the isolation, core properties, preclinical studies as well as the underling molecular and cellular details to highlight their regenerative potential.

White matter repair and treatment strategy after intracerebral hemorrhage

The predilection site of intracerebral hemorrhage (ICH) is in the basal ganglia, which is rich in white matter (WM) fiber bundles, such as cerebrospinal tract in the internal capsule. ICH induced damage to this area can easily lead to severe neurological dysfunction and affects the prognosis and quality of life of patients. At present, the pathophysiological mechanisms of white matter injury (WMI) after ICH have attracted researchers' attention, but studies on the repair and recovery mechanisms and therapy strategies remain rare. In this review, we mainly summarized the WM recovery and treatment strategies after ICH by updating the WMI‐related content by reviewing the latest researches and proposing the bottleneck of the current research.

Neurons-derived extracellular vesicles promote neural differentiation of ADSCs: a model to prevent peripheral nerve degeneration

Potential mechanisms involved in neural differentiation of adipocyte derived stem cells (ADSCs) are still unclear. In the present study, extracellular vesicles (EVs) were tested as a potential mechanism involved in the neuronal differentiation of stem cells. In order to address this, ADSCs and neurons (BRC) were established in primary culture and co-culture at three timepoints. Furthermore, we evaluated protein and transcript levels of differentiated ADSCs from the same timepoints, to confirm phenotype change to neuronal linage. Importantly, neuron-derived EVs cargo and EVs originated from co-culture were analyzed and tested in terms of function, such as gene expression and microRNA levels related to the adult neurogenesis process. Ideal neuron-like cells were identified and, therefore, we speculated the in vivo function of these cells in acute sciatic nerve injury. Overall, our data demonstrated that ADSCs in indirect contact with neurons differentiated into neuron-like cells. Neuron-derived EVs appear to play an important role in this process carrying SNAP25, miR-132 and miR-9. Additionally, in vivo neuron-like cells helped in microenvironment modulation probably preventing peripheral nerve injury degeneration. Consequently, our findings provide new insight of future methods of ADSC induction into neuronal linage to be applied in peripheral nerve (PN) injury.

The Best for the Most Important: Maintaining a Pristine Proteome in Stem and Progenitor Cells

Pluripotent stem cells give rise to reproductively enabled offsprings by generating progressively lineage-restricted multipotent stem cells that would differentiate into lineage-committed stem and progenitor cells. These lineage-committed stem and progenitor cells give rise to all adult tissues and organs. Adult stem and progenitor cells are generated as part of the developmental program and play critical roles in tissue and organ maintenance and/or regeneration. The ability of pluripotent stem cells to self-renew, maintain pluripotency, and differentiate into a multicellular organism is highly dependent on sensing and integrating extracellular and extraorganismal cues. Proteins perform and integrate almost all cellular functions including signal transduction, regulation of gene expression, metabolism, and cell division and death. Therefore, maintenance of an appropriate mix of correctly folded proteins, a pristine proteome, is essential for proper stem cell function. The stem cells' proteome must be pristine because unfolded, misfolded, or otherwise damaged proteins would interfere with unlimited self-renewal, maintenance of pluripotency, differentiation into downstream lineages, and consequently with the development of properly functioning tissue and organs. Understanding how various stem cells generate and maintain a pristine proteome is therefore essential for exploiting their potential in regenerative medicine and possibly for the discovery of novel approaches for maintaining, propagating, and differentiating pluripotent, multipotent, and adult stem cells as well as induced pluripotent stem cells. In this review, we will summarize cellular networks used by various stem cells for generation and maintenance of a pristine proteome. We will also explore the coordination of these networks with one another and their integration with the gene regulatory and signaling networks.

Muse cells and Neurorestoratology

Multilineage-differentiating stress-enduring (Muse) cells were discovered in 2010 as a subpopulation of mesenchymal stroma cells (MSCs). Muse cells can self-renew and tolerate severe culturing conditions. These cells can differentiate into three lineage cells spontaneously or in induced medium but do not form teratoma in vitro or in vivo. Central nervous system (CNS) diseases, such as intracerebral hemorrhage (ICH), cerebral infarction, and spinal cord injury are normally disastrous. Despite numerous therapy strategies, CNS diseases are difficult to recover. As a novel kind of pluripotent stem cells, Muse cells have shown great regeneration capacity in many animal models, including acute myocardial infarction, hepatectomy, and acute cerebral ischemia (ACI). After injection into injury sites, Muse cells survived, migrated, and differentiated into functional neurons with synaptic junctions to local neurons and contributed to recovery of function. Furthermore, Muse cell differentiation did not need to be induced pre-transplantation and no tumors were observed post- transplantation. The Muse cell population is promising and may lead to a revolution in regenerative medicine. This review focuses on recent advances regarding the Muse cells therapies in Neurorestoratology and discusses future perspectives in this field.

Research Progress in Understanding the Relationship Between Heme Oxygenase-1 and Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a fatal acute cerebrovascular disease, with a high morbidity and mortality. Following ICH, erythrocytes release heme and several of its metabolites, thereby contributing to brain edema and secondary brain damage. Heme oxygenase is the initial and rate-limiting enzyme of heme catabolism, and the expression of heme oxygenase-1 (HO-1) is rapidly induced following acute brain injury. As HO-1 exerts it effects via various metabolites, its role during ICH remains complex. Therefore, in-depth studies regarding the role of HO-1 in secondary brain damage following ICH may provide a theoretical basis for neuroprotective function after ICH. The present review aims to summarize recent key studies regarding the effects of HO-1 following ICH, as well as its influence on ICH prognosis.

New Paradigms in Cell Therapy: Repeated Dosing, Intravenous Delivery, Immunomodulatory Actions, and New Cell Types

Perhaps the most important advance in the field of cell therapy for heart disease has been the recognition that all stem/progenitor cells (both adult and embryonic) fail to engraft in the heart to a significant extent and thus work via paracrine mechanisms. This fundamental advance has led to 4 new paradigms that are discussed in this review and that may importantly shape, or even revolutionize, the future of the field: (1) repeated cell therapy, (2) intravenous cell therapy, (3) immunomodulatory actions of cell therapy, and (4) new cell types. Because virtually all of our current knowledge of cell therapy is predicated on the effects of a single cell dose, the idea that the full therapeutic effects of a cell product require repeated doses is disruptive and has far-reaching implications. For example, inadequate dosing (single-dose protocols) may be responsible, at least in part, for the borderline or disappointing results obtained to date in clinical trials; furthermore, future studies (both preclinical and clinical) may need to incorporate repeated cell administrations. Another disruptive idea, supported by emerging preclinical and clinical evidence, is that intravenously injected cells can produce beneficial effects on the heart, presumably via release of paracrine factors in extracardiac organs or endocrine factors into the systemic circulation. Intravenous administration would obviate the need for direct delivery of cells to the heart, making cell therapy simpler, cheaper, safer, more scalable, and more broadly available, even on an outpatient basis. Although the mechanism of action of cell therapy remains elusive, there is compelling in vitro evidence that transplanted cells modulate the function of various immune cell types via release of paracrine factors, such as extracellular vesicles, although in vivo evidence is still limited. Investigation of the new paradigms reviewed herein should be a top priority because it may profoundly transform cell therapy and finally make it a reality.

Application of Muse Cell Therapy to Stroke

Stroke is defined as a sudden onset of neurologic deficits arising from cerebrovascular complications. It is the second common cause of death around the world and the major cause of disability. Because brain is an organ with complicated neural networks and neurons are highly differentiated, it has been traditionally considered to possess a limited potential for regeneration. The number of stroke patients is increasing, and stroke represents a serious problem from the viewpoint of the national medical economy. Even with the current sophisticated treatments, more than half of stroke patient survivors remain disabled. Therefore, it is imperative to develop a new treatment for promoting functional recovery and repair of the lost neurological circuit. Multilineage-differentiating stress-enduring (Muse) cells are endogenous non-tumorigenic stem cells with pluripotency. After transplantation, Muse cells recognize the injured site through their specific receptor for damage signal, home preferentially into these tissues and spontaneously differentiate into tissue-compatible cells to replace the lost cells, and repair the tissue, delivering functional and structural regeneration. These properties are desirable for the treatment of strokes and advantageous compared to other stem cell therapies. Here, we describe the current status of stem cell therapies for stroke and future possibilities of Muse cell therapy.

Future of Muse Cells

Discovered nearly 10 years ago by Professor Mari Dezawa and her colleagues, Muse cells are entering clinical trials faster than any other stem cell for three reasons. First, Muse cells have multiple fail-safe mechanisms to keep themselves from growing out of control and do not form tumors. In contrast, embryonic stem cells and induced pluripotent stem cells form tumors and must be differentiated before transplantation. Second, Muse cells possess potent anti-immune mechanisms, including human leukocyte antigen G and indoleamine 2,3-dioxygenase that prevent both cellular and humoral immunity. Muse cells engraft even though they do not match HLA antigens with the host. Third, Muse cells are able to determine what kind and how many cells they need to make for tissue repair. While the mechanisms responsible for these traits are not well understood, Muse cells are able to enter severely injured tissues of all kinds and repair them. Study of mechanisms underlying these traits of Muse cells is likely to yield new therapies for cancer prevention, autoimmune diseases, and repair of injured tissues. The future is bright for Muse cells.

Simvastatin improves intracerebral hemorrhage through NF-κB-mediated apoptosis via the MyD88/TRIF signaling pathway

The aim was to investigate the neuroprotective effects and potential mechanism mediated by simvastatin in a mouse model of intracerebral hemorrhage. CD-1 mice were subjected to infusion of collagenase type IV into the left striatum in order to induce intracerebral hemorrhage. Western blot analysis, the TUNEL assay and the modified neurological severity score were used in the present study to analyze the efficacy of simvastatin for intracerebral hemorrhage. The results demonstrated that simvastatin treatment improved the cerebral water content and blood-brain barrier disruption in the intracerebral hemorrhage animals. Intracerebral hemorrhage-induced neuronal cell death was downregulated by simvastatin treatment compared with the vehicle-treated model group. In addition, the expression levels of aquaporin-4, matrix metallopeptidase 9 and caspase-3 were downregulated and B-cell lymphoma-2 was upregulated by simvastatin treatment compared with the vehicle-treated model. Simvastatin treatment also significantly reduced the Evans blue leakage into the injured hemispheres and improved motor function. Mechanism analysis further indicated that simvastatin treatment downregulated nuclear factor (NF)-κB expression, and upregulated the myeloid differentiation primary response 88 (MyD88) and TIR domain-containing adaptor protein inducing interferon-β (TRIF) expression levels in neuronal cells in experimental mice. Furthermore, the results revealed that NF-κB overexpression abolished the simvastatin-downregulated MyD88 and TRIF expression levels, as well as the apoptosis of neuronal cells. In conclusion, these results indicated that simvastatin was able to attenuate brain edema and reduce cellular apoptosis by suppressing the NF-κB-mediated MyD88/TRIF signaling pathway subsequent to the induction of intracerebral hemorrhage in mice.

Pluripotent nontumorigenic multilineage differentiating stress enduring cells (Muse cells): a seven-year retrospective

Multilineage differentiating stress enduring (Muse) cells, discovered in the spring of 2010 at Tohoku University in Sendai, Japan, were quickly recognized by scientists as a possible source of pluripotent cells naturally present within mesenchymal tissues. Muse cells normally exist in a quiescent state, singularly activated by severe cellular stress in vitro and in vivo. Muse cells have the capacity for self-renewal while maintaining pluripotent cell characteristics indicated by the expression of pluripotent stem cell markers. Muse cells differentiate into cells representative of all three germ cell layers both spontaneously and under media-specific induction. In contrast to embryonic stem and induced pluripotent stem cells, Muse cells exhibit low telomerase activity, a normal karyotype, and do not undergo tumorigenesis once implanted in SCID mice. Muse cells efficiently home into damaged tissues and differentiate into specific cells leading to tissue regeneration and functional recovery as described in different animal disease models (i.e., fulminant hepatitis, muscle degeneration, skin ulcers, liver cirrhosis, cerebral stroke, vitiligo, and focal segmental glomerulosclerosis). Circulating Muse cells have been detected in peripheral blood, with higher levels present in stroke patients during the acute phase. Furthermore, Muse cells have inherent immunomodulatory properties, which could contribute to tissue generation and functional repair in vivo. Genetic studies in Muse cells indicate a highly conserved cellular mechanism as seen in more primitive organisms (yeast, Saccharomyces cerevisiae, Caenorhabditis elegans, chlamydomonas, Torpedo californica, drosophila, etc.) in response to cellular stress and acute injury. This review details the molecular and cellular properties of Muse cells as well as their capacity for tissue repair and functional recovery, highlighting their potential for clinical application in regenerative medicine.

Rehabilitation and the Neural Network After Stroke

Stroke remains a major cause of disability throughout the world: paralysis, cognitive impairment, aphasia, and so on. Surgical or medical intervention is curative in only a small number of cases. Nearly all stroke cases require rehabilitation. Neurorehabilitation generally improves patient outcome, but it sometimes has no effect or even a mal-influence. The aim of this review is the clarification of the mechanisms of neurorehabilitation. We systematically reviewed recently published articles on neural network remodeling, especially from 2014 to 2016. Finally, we summarize progress in neurorehabilitation and discuss future prospects.

Preclinical Studies and Translational Applications of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) which refers to bleeding in the brain is a very deleterious condition with high mortality and disability rate. Surgery or conservative therapy remains the treatment option. Various studies have divided the disease process of ICH into primary and secondary injury, for which knowledge into these processes has yielded many preclinical and clinical treatment options. The aim of this review is to highlight some of the new experimental drugs as well as other treatment options like stem cell therapy, rehabilitation, and nanomedicine and mention some translational clinical applications that have been done with these treatment options.