FM19G11 favors spinal cord injury regeneration and stem cell self-renewal by mitochondrial uncoupling and glucose metabolism induction

FM19G11-loaded nanoparticles modulate energetic status and production of reactive oxygen species in myoblasts from ALS mice

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons. Considerable evidence indicates that early skeletal muscle atrophy plays a crucial role in the disease pathogenesis, leading to an altered muscle-motor neuron crosstalk that, in turn, may contribute to motor neuron degeneration. Currently, there is no effective treatment for ALS, highlighting the need to dig deeper into the pathological mechanisms for developing innovative therapeutic strategies. FM19G11 is a novel drug able to modulate the global cellular metabolism, but its effects on ALS skeletal muscle atrophy and mitochondrial metabolism have never been evaluated, yet. This study investigated whether FM19G11-loaded nanoparticles (NPs) may affect the bioenergetic status in myoblasts isolated from G93A-SOD1 mice at different disease stages. We found that FM19G1-loaded NP treatment was able to increase transcriptional levels of Akt1, Akt3, Mef2a, Mef2c and Ucp2, which are key genes associated with cell proliferation (Akt1, Akt3), muscle differentiation (Mef2c), and mitochondrial activity (Ucp2), in G93A-SOD1 myoblasts. These cells also showed a significant reduction of mitochondrial area and networks, in addition to decreased ROS production after treatment with FM19G11-loaded NPs, suggesting a ROS clearance upon the amelioration of mitochondrial dynamics. Our overall findings demonstrate a significant impact of FM19G11-loaded NPs on muscle cell function and bioenergetic status in G93A-SOD1 myoblasts, thus promising to open new avenues towards possible adoption of FM19G11-based nanotherapies to slow muscle degeneration in the frame of ALS and muscle disorders.

Stem Cell Therapies for Restorative Treatments of Central Nervous System Ischemia-Reperfusion Injury

Ischemic damage to the central nervous system (CNS) is a catastrophic postoperative complication of aortic occlusion subsequent to cardiovascular surgery that can cause brain impairment and sometimes even paraplegia. Over recent years, numerous studies have investigated techniques for protecting and revascularizing the nervous system during intraoperative ischemia; however, owing to a lack of knowledge of the physiological distinctions between the brain and spinal cord, as well as the limited availability of testing techniques and treatments for ischemia-reperfusion injury, the cause of brain and spinal cord ischemia-reperfusion injury remains poorly understood, and no adequate response steps are currently available in the clinic. Given the limited ability of the CNS to repair itself, it is of great clinical value to make full use of the proliferative and differentiation potential of stem cells to repair nerves in degenerated and necrotic regions by stem cell transplantation or mobilization, thereby introducing a novel concept for the treatment of severe CNS ischemia-reperfusion injury. This review summarizes the most recent advances in stem cell therapy for ischemia-reperfusion injury in the brain and spinal cord, aiming to advance basic research and the clinical use of stem cell therapy as a promising treatment for this condition.

Future Perspectives in Spinal Cord Repair: Brain as Saviour? TSCI with Concurrent TBI: Pathophysiological Interaction and Impact on MSC Treatment

Traumatic spinal cord injury (TSCI), commonly caused by high energy trauma in young active patients, is frequently accompanied by traumatic brain injury (TBI). Although combined trauma results in inferior clinical outcomes and a higher mortality rate, the understanding of the pathophysiological interaction of co-occurring TSCI and TBI remains limited. This review provides a detailed overview of the local and systemic alterations due to TSCI and TBI, which severely affect the autonomic and sensory nervous system, immune response, the blood-brain and spinal cord barrier, local perfusion, endocrine homeostasis, posttraumatic metabolism, and circadian rhythm. Because currently developed mesenchymal stem cell (MSC)-based therapeutic strategies for TSCI provide only mild benefit, this review raises awareness of the impact of TSCI-TBI interaction on TSCI pathophysiology and MSC treatment. Therefore, we propose that unravelling the underlying pathophysiology of TSCI with concomitant TBI will reveal promising pharmacological targets and therapeutic strategies for regenerative therapies, further improving MSC therapy.

Zinc Regulates Glucose Metabolism of the Spinal Cord and Neurons and Promotes Functional Recovery after Spinal Cord Injury through the AMPK Signaling Pathway

Spinal cord injury (SCI) is a traumatic disease that can cause severe nervous system dysfunction. SCI often causes spinal cord mitochondrial dysfunction and produces glucose metabolism disorders, which affect neuronal survival. Zinc is an essential trace element in the human body and plays multiple roles in the nervous system. This experiment is intended to evaluate whether zinc can regulate the spinal cord and neuronal glucose metabolism and promote motor functional recovery after SCI. Then we explore its molecular mechanism. We evaluated the function of zinc from the aspects of glucose uptake and the protection of the mitochondria in vivo and in vitro. The results showed that zinc elevated the expression level of GLUT4 and promoted glucose uptake. Zinc enhanced the expression of proteins such as PGC-1α and NRF2, reduced oxidative stress, and promoted mitochondrial production. In addition, zinc decreased neuronal apoptosis and promoted the recovery of motor function in SCI mice. After administration of AMPK inhibitor, the therapeutic effect of zinc was reversed. Therefore, we concluded that zinc regulated the glucose metabolism of the spinal cord and neurons and promoted functional recovery after SCI through the AMPK pathway, which is expected to become a potential treatment strategy for SCI.

Activation of Neurogenesis in Multipotent Stem Cells Cultured In Vitro and in the Spinal Cord Tissue After Severe Injury by Inhibition of Glycogen Synthase Kinase-3

The inhibition of glycogen synthase kinase-3 (GSK-3) can induce neurogenesis, and the associated activation of Wnt/β-catenin signaling via GSK-3 inhibition may represent a means to promote motor function recovery following spinal cord injury (SCI) via increased astrocyte migration, reduced astrocyte apoptosis, and enhanced axonal growth. Herein, we assessed the effects of GSK-3 inhibition in vitro on the neurogenesis of ependymal stem/progenitor cells (epSPCs) resident in the mouse spinal cord and of human embryonic stem cell-derived neural progenitors (hESC-NPs) and human-induced pluripotent stem cell-derived neural progenitors (hiPSC-NPs) and in vivo on spinal cord tissue regeneration and motor activity after SCI. We report that the treatment of epSPCs and human pluripotent stem cell-derived neural progenitors (hPSC-NPs) with the GSK-3 inhibitor Ro3303544 activates β-catenin signaling and increases the expression of the bIII-tubulin neuronal marker; furthermore, the differentiation of Ro3303544-treated cells prompted an increase in the number of terminally differentiated neurons. Administration of a water-soluble, bioavailable form of this GSK-3 inhibitor (Ro3303544-Cl) in a severe SCI mouse model revealed the increased expression of bIII-tubulin in the injury epicenter. Treatment with Ro3303544-Cl increased survival of mature neuron types from the propriospinal tract (vGlut1, Parv) and raphe tract (5-HT), protein kinase C gamma-positive neurons, and GABAergic interneurons (GAD65/67) above the injury epicenter. Moreover, we observed higher numbers of newly born BrdU/DCX-positive neurons in Ro3303544-Cl-treated animal tissues, a reduced area delimited by astrocyte scar borders, and improved motor function. Based on this study, we believe that treating animals with epSPCs or hPSC-NPs in combination with Ro3303544-Cl deserves further investigation towards the development of a possible therapeutic strategy for SCI.

Role of Insulin in Neurotrauma and Neurodegeneration: A Review

Insulin is a hormone typically associated with pancreatic release and blood sugar regulation. The brain was long thought to be “insulin-independent,” but research has shown that insulin receptors (IR) are expressed on neurons, microglia and astrocytes, among other cells. The effects of insulin on cells within the central nervous system are varied, and can include both metabolic and non-metabolic functions. Emerging data suggests that insulin can improve neuronal survival or recovery after trauma or during neurodegenerative diseases. Further, data suggests a strong anti-inflammatory component of insulin, which may also play a role in both neurotrauma and neurodegeneration. As a result, administration of exogenous insulin, either via systemic or intranasal routes, is an increasing area of focus in research in neurotrauma and neurodegenerative disorders. This review will explore the literature to date on the role of insulin in neurotrauma and neurodegeneration, with a focus on traumatic brain injury (TBI), spinal cord injury (SCI), Alzheimer’s disease (AD) and Parkinson’s disease (PD).

Ependymal cells in the spinal cord as neuronal progenitors

Ependymal cells are neural progenitors and form part of the central canal of the spinal cord. Therefore, ependymal cells could serve as a potential source of neural progenitors for regenerative medicine applications. Such applications consist of endogenous activation or exogenous transplantation, alone or in combination with pharmacological treatments, to repair spinal cord injuries. This mini review describes the main phenotypical characteristics of ependymal cells from spinal cord and the opportunities offered for spinal cord injury therapeutic application.

FM19G11-Loaded Gold Nanoparticles Enhance the Proliferation and Self-Renewal of Ependymal Stem Progenitor Cells Derived from ALS Mice

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons. In ALS mice, neurodegeneration is associated with the proliferative restorative attempts of ependymal stem progenitor cells (epSPCs) that normally lie in a quiescent in the spinal cord. Thus, modulation of the proliferation of epSPCs may represent a potential strategy to counteract neurodegeneration. Recent studies demonstrated that FM19G11, a hypoxia-inducible factor modulator, induces epSPC self-renewal and proliferation. The aim of the study was to investigate whether FM19G11-loaded gold nanoparticles (NPs) can affect self-renewal and proliferation processes in epSPCs isolated from G93A-SOD1 mice at disease onset. We discovered elevated levels of SOX2, OCT4, AKT1, and AKT3, key genes associated with pluripotency, self-renewal, and proliferation, in G93A-SOD1 epSPCs at the transcriptional and protein levels after treatment with FM19G11-loaded NPs. We also observed an increase in the levels of the mitochondrial uncoupling protein (UCP) gene in treated cells. FM19G11-loaded NPs treatment also affected the expression of the cell cycle-related microRNA (miR)-19a, along with its target gene PTEN, in G93A-SOD1 epSPCs. Overall our findings establish the significant impact of FM19G11-loaded NPs on the cellular pathways involved in self-renewal and proliferation in G93A-SOD1 epSPCs, thus providing an impetus to the design of novel tailored approaches to delay ALS disease progression.

MicroRNA-451 Inhibits Migration of Glioblastoma while Making It More Susceptible to Conventional Therapy

Malignant glioblastoma (GBM, glioma) is the most common and aggressive primary adult brain tumor. The prognosis of GBM patients remains poor, despite surgery, radiation and chemotherapy. The major obstacles for successful remedy are invasiveness and therapy resistance of GBM cells. Invasive glioma cells leave primary tumor core and infiltrate surrounding normal brain leading to inevitable recurrence, even after surgical resection, radiation and chemotherapy. Therapy resistance allowing for selection of more aggressive and resistant sub-populations including GBM stem-like cells (GSCs) upon treatment is another serious impediment to successful treatment. Through their regulation of multiple genes, microRNAs can orchestrate complex programs of gene expression and act as master regulators of cellular processes. MicroRNA-based therapeutics could thus impact broad cellular programs, leading to inhibition of invasion and sensitization to radio/chemotherapy. Our data show that miR-451 attenuates glioma cell migration in vitro and invasion in vivo. In addition, we have found that miR-451 sensitizes glioma cells to conventional chemo- and radio-therapy. Our data also show that miR-451 is regulated in vivo by AMPK pathway and that AMPK/miR-451 loop has the ability to switch between proliferative and migratory pattern of glioma cells behavior. We therefore postulate that AMPK/miR-451 negative reciprocal feedback loop allows GBM cells/GSCs to adapt to tumor “ecosystem” by metabolic and behavioral flexibility, and that disruption of such a loop reduces invasiveness and diminishes therapy resistance.

Significant therapeutic effects of adult human multipotent neural cells on spinal cord injury

Neural stem cells are emerging as a regenerative therapy for spinal cord injury (SCI), since they differentiate into functional neural cells and secrete beneficial paracrine factors into the damaged microenvironment. Previously, we successfully isolated and cultured adult human multipotent neural cells (ahMNCs) from the temporal lobes of epileptic patients. In this study, we investigated the therapeutic efficacy and treatment mechanism of ahMNCs for SCI using rodent models. When 1 × 10⁶ ahMNCs were transplanted into injured spinal cords at 7 days after contusion, the injection group showed significantly better functional recovery than the control group (media injection after contusion), which was determined by the Basso, Beattie and Bresnahan (BBB) score. Although transplanted ahMNCs disappeared continuously, remained cells expressed differentiated neural cell markers (Tuj1) or astrocyte marker (GFAP) in the injured spinal cords. Moreover, the number of CD31-positive microvessels significantly increased in the injection group than that of the control group. The paracrine pro-angiogenic activities of ahMNCs were confirmed by in vitro tube formation assay and in vivo Matrigel plug assay. Together, these results indicate that ahMNCs have significant therapeutic efficacy in SCI via replacement of damaged neural cells and pro-angiogenic effects on the microenvironment of SCI.

Priming of the Cells: Hypoxic Preconditioning for Stem Cell Therapy

Objective:

Stem cell-based therapies are promising in regenerative medicine for protecting and repairing damaged brain tissues after injury or in the context of chronic diseases. Hypoxia can induce physiological and pathological responses. A hypoxic insult might act as a double-edged sword, it induces cell death and brain damage, but on the other hand, sublethal hypoxia can trigger an adaptation response called hypoxic preconditioning or hypoxic tolerance that is of immense importance for the survival of cells and tissues.

Data Sources:

This review was based on articles published in PubMed databases up to August 16, 2017, with the following keywords: “stem cells,” “hypoxic preconditioning,” “ischemic preconditioning,” and “cell transplantation.”

Study Selection:

Original articles and critical reviews on the topics were selected.

Results:

Hypoxic preconditioning has been investigated as a primary endogenous protective mechanism and possible treatment against ischemic injuries. Many cellular and molecular mechanisms underlying the protective effects of hypoxic preconditioning have been identified.

Conclusions:

In cell transplantation therapy, hypoxic pretreatment of stem cells and neural progenitors markedly increases the survival and regenerative capabilities of these cells in the host environment, leading to enhanced therapeutic effects in various disease models. Regenerative treatments can mobilize endogenous stem cells for neurogenesis and angiogenesis in the adult brain. Furthermore, transplantation of stem cells/neural progenitors achieves therapeutic benefits via cell replacement and/or increased trophic support. Combinatorial approaches of cell-based therapy with additional strategies such as neuroprotective protocols, anti-inflammatory treatment, and rehabilitation therapy can significantly improve therapeutic benefits. In this review, we will discuss the recent progress regarding cell types and applications in regenerative medicine as well as future applications.

Effects of Mitochondrial Transplantation on Bioenergetics, Cellular Incorporation, and Functional Recovery after Spinal Cord Injury

Our previous studies reported that pharmacological maintenance of mitochondrial bioenergetics after experimental spinal cord injury (SCI) provided functional neuroprotection. Recent evidence indicates that endogenous mitochondrial transfer is neuroprotective as well, and, therefore, we extended these studies with a novel approach to transplanting exogenous mitochondria into the injured rat spinal cord. Using a rat model of L1/L2 contusion SCI, we herein report that transplantation of exogenous mitochondria derived from either cell culture or syngeneic leg muscle maintained acute bioenergetics of the injured spinal cord in a concentration-dependent manner. Moreover, transplanting transgenically labeled turbo green fluorescent (tGFP) PC12-derived mitochondria allowed for visualization of their incorporation in both a time-dependent and cell-specific manner at 24 h, 48 h, and 7 days post-injection. tGFP mitochondria co-localized with multiple resident cell types, although they were absent in neurons. Despite their contribution to the maintenance of normal bioenergetics, mitochondrial transplantation did not yield long-term functional neuroprotection as assessed by overall tissue sparing or recovery of motor and sensory functions. These experiments are the first to investigate mitochondrial transplantation as a therapeutic approach to treating spinal cord injury. Our initial bioenergetic results are encouraging, and although they did not translate into improved long-term outcome measures, caveats and technical hurdles are discussed that can be addressed in future studies to potentially increase long-term efficacy of transplantation strategies.

Stem Cells Therapy for Spinal Cord Injury

Spinal cord injury (SCI), a serious public health issue, most likely occurs in previously healthy young adults. Current therapeutic strategies for SCI includes surgical decompression and pharmacotherapy, however, there is still no gold standard for the treatment of this devastating condition. Inefficiency and adverse effects of standard therapy indicate that novel therapeutic strategies are required. Because of their neuroregenerative and neuroprotective properties, stem cells are a promising tool for the treatment of SCI. Herein, we summarize and discuss the promising therapeutic potential of human embryonic stem cells (hESC), induced pluripotent stem cells (iPSC) and ependymal stem/progenitor cells (epSPC) for SCI.

FM19G11 and Ependymal Progenitor/Stem Cell Combinatory Treatment Enhances Neuronal Preservation and Oligodendrogenesis after Severe Spinal Cord Injury

Spinal cord injury (SCI) suffers from a lack of effective therapeutic strategies. We have previously shown that individual therapeutic strategies, transplantation of ependymal stem/progenitor cells of the spinal cord after injury (epSPCi) or FM19G11 pharmacological treatment, induce moderate functional recovery after SCI. Here, the combination of treatments has been assayed for functional and histological analysis. Immediately after severe SCI, one million epSPCi were intramedullary injected, and the FM19G11 compound or dimethyl sulfoxide (DMSO) (as the vehicle control) was administrated via intrathecal catheterization. The combination of treatments, epSPCi and FM19G11, improves locomotor tasks compared to the control group, but did not significantly improve the Basso, Beattie, Bresnahan (BBB) scores for locomotor analysis in comparison with the individual treatments. However, the histological analysis of the spinal cord tissues, two months after SCI and treatments, demonstrated that when we treat the animals with both epSPCi and FM19G11, an improved environment for neuronal preservation was generated by reduction of the glial scar extension. The combinatorial treatment also contributes to enhancing the oligodendrocyte precursor cells by inducing the expression of Olig1 in vivo. These results suggest that a combination of therapies may be an exciting new therapeutic treatment for more efficient neuronal activity recovery after severe SCI.

Novel direct AMPK activator suppresses non-small cell lung cancer through inhibition of lipid metabolism

Drug resistance is becoming an obstacle in anti-cancer therapies. For target-based therapy of lung cancer, gefitinib, as the first generation of tyrosine kinase inhibitors (TKIs), demonstrated good initial response to the non-small cell lung cancer (NSCLC) patients whom harbors epidermal growth factor receptor (EGFR) mutation. However, within one year, additional EGFR mutation occurred, leading to eventual gefitinib-resistance. Therefore, it is urgently to discover novel effective small molecule inhibitors for those patients. Abnormal energy metabolism is accepted as new cancer hallmark. Recently, a metabolism rate-limiting enzyme 5’-adenosine menophosphate-activated protein kinase (AMPK) has become a promising anti-cancer target. In this study, we have identified a novel direct AMPK agonist, D561-0775 from a compound library by using molecular docking screening technique. We demonstrated that D561-0775 exhibited significant inhibitory effect on gefitinib-resistant NSCLC cell lines but less cytotoxicity on normal cells. Furthermore, D561-0775 demonstrated a remarkable in vitro AMPK enzyme activation effect. Taken together, D561-0775 showed potential anti-cancer activity via inducing apoptosis, cell cycle arrest, suppressing glycolysis and cholesterol synthesis after activation of AMPK in gefitinib-resistant H1975 cells. D561-0775 has provided a new chemical structure that could be developed as cancer drug for gefitinib-resistant NSCLC patients through inhibition lipid metabolism by directly targeting at AMPK directly.

Optimization of mitochondrial isolation techniques for intraspinal transplantation procedures

BACKGROUND

Proper mitochondrial function is essential to maintain normal cellular bioenergetics and ionic homeostasis. In instances of severe tissue damage, such as traumatic brain and spinal cord injury, mitochondria become damaged and unregulated leading to cell death. The relatively unexplored field of mitochondrial transplantation following neurotrauma is based on the theory that replacing damaged mitochondria with exogenous respiratory-competent mitochondria can restore overall tissue bioenergetics.

NEW METHOD

We optimized techniques in vitro to prepare suspensions of isolated mitochondria for transplantation in vivo. Mitochondria isolated from cell culture were genetically labeled with turbo-green fluorescent protein (tGFP) for imaging and tracking purposes in vitro and in vivo.

RESULTS

We used time-lapse confocal imaging to reveal the incorporation of exogenous fluorescently-tagged mitochondria into PC-12 cells after brief co-incubation. Further, we show that mitochondria can be injected into the spinal cord with immunohistochemical evidence of host cellular uptake within 24h.

COMPARISON TO EXISTING METHODS

Our methods utilize transgenic fluorescent labeling of mitochondria for a nontoxic and photostable alternative to other labeling methods. Substrate addition to isolated mitochondria helped to restore state III respiration at room temperature prior to transplantation. These experiments delineate refined methods to use transgenic cell lines for the purpose of isolating well coupled mitochondria that have a permanent fluorescent label that allows real time tracking of transplanted mitochondria in vitro, as well as imaging in situ.

CONCLUSIONS

These techniques lay the foundation for testing the potential therapeutic effects of mitochondrial transplantation following spinal cord injury and other animal models of neurotrauma.

Prospects for therapeutic mitochondrial transplantation

Mitochondrial dysfunction has been implicated in a multitude of diseases and pathological conditions- the organelles that are essential for life can also be major players in contributing to cell death and disease. Because mitochondria are so well established in our existence, being present in all cell types except for red blood cells and having the responsibility of providing most of our energy needs for survival, then dysfunctional mitochondria can elicit devastating cellular pathologies that can be widespread across the entire organism. As such, the field of "mitochondrial medicine" is emerging in which disease states are being targeted therapeutically at the level of the mitochondrion, including specific antioxidants, bioenergetic substrate additions, and membrane uncoupling agents. New and compelling research investigating novel techniques for mitochondrial transplantation to replace damaged or dysfunctional mitochondria with exogenous healthy mitochondria has shown promising results, including tissue sparing accompanied by increased energy production and decreased oxidative damage. Various experimental techniques have been attempted and each has been challenged to accomplish successful transplantation. The purpose of this review is to present the history of mitochondrial transplantation, the different techniques used for both in vitro and in vivo delivery, along with caveats and pitfalls that have been discovered along the way. Results from such pioneering studies are promising and could be the next big wave of "mitochondrial medicine" once technical hurdles are overcome.

Cocktail of chemical compounds robustly promoting cell reprogramming protects liver against acute injury

Tissue damage induces cells into reprogramming-like cellular state, which contributes to tissue regeneration. However, whether factors promoting the cell reprogramming favor tissue regeneration remains elusive. Here we identified combination of small chemical compounds including drug cocktails robustly promoting in vitro cell reprogramming. We then administrated the drug cocktails to mice with acute liver injuries induced by partial hepatectomy or toxic treatment. Our results demonstrated that the drug cocktails which promoted cell reprogramming in vitro improved liver regeneration and hepatic function in vivo after acute injuries. The underlying mechanism could be that expression of pluripotent genes activated after injury is further upregulated by drug cocktails. Thus our study offers proof-of-concept evidence that cocktail of clinical compounds improving cell reprogramming favors tissue recovery after acute damages, which is an attractive strategy for regenerative purpose.

Distinct Effects of miR-210 Reduction on Neurogenesis: Increased Neuronal Survival of Inflammation But Reduced Proliferation Associated with Mitochondrial Enhancement

Neurogenesis is essential to brain development and plays a central role in the response to brain injury. Stroke and head trauma stimulate proliferation of endogenous neural stem cells (NSCs); however, the survival of young neurons is sharply reduced by postinjury inflammation. Cellular mitochondria are critical to successful neurogenesis and are a major target of inflammatory injury. Mitochondrial protection was shown to improve survival of young neurons. This study tested whether reducing cellular microRNA-210 (miR-210) would enhance mitochondrial function and improve survival of young murine neurons under inflammatory conditions. Several studies have demonstrated the potential of miR-210 inhibition to enhance and protect mitochondrial function through upregulation of mitochondrial proteins. Here, miR-210 inhibition significantly increased neuronal survival and protected the activity of mitochondrial enzymes cytochrome c oxidase and aconitase in differentiating NSC cultures exposed to inflammatory mediators. Unexpectedly, we found that reducing miR-210 significantly attenuated NSC proliferation upon induction of differentiation. Further investigation revealed that increased mitochondrial function suppressed the shift to primarily glycolytic metabolism and reduced mitochondrial length characteristic of dividing cells. Activation of AMP-regulated protein kinase-retinoblastoma signaling is important in NSC proliferation and the reduction of this activation observed by miR-210 inhibition is one mechanism contributing to the reduced proliferation. Postinjury neurogenesis occurs as a burst of proliferation that peaks in days, followed by migration and differentiation over weeks. Our studies suggest that mitochondrial protective miR-210 inhibition should be delayed until after the initial burst of proliferation, but could be beneficial during the prolonged differentiation stage.SIGNIFICANCE STATEMENT Increasing the success of endogenous neurogenesis after brain injury holds therapeutic promise. Postinjury inflammation markedly reduces newborn neuron survival. This study found that enhancement of mitochondrial function by reducing microRNA-210 (miR-210) levels could improve survival of young neurons under inflammatory conditions. miR-210 inhibition protected the activity of mitochondrial enzymes cytochrome c oxidase and aconitase. Conversely, we observed decreased precursor cell proliferation likely due to suppression of the AMP-regulated protein kinase-retinoblastoma axis with miR-210 inhibition. Therefore, mitochondrial protection is a double-edged sword: early inhibition reduces proliferation, but inhibition later significantly increases neuroblast survival. This explains in part the contradictory published reports of the effects of miR-210 on neurogenesis.

Stem Cells and Labeling for Spinal Cord Injury

Spinal cord injury (SCI) is a devastating condition that usually results in sudden and long-lasting locomotor and sensory neuron degeneration below the lesion site. During the last two decades, the search for new therapies has been revolutionized with the improved knowledge of stem cell (SC) biology. SCs therapy offers several attractive strategies for spinal cord repair. The transplantation of SCs promotes remyelination, neurite outgrowth and axonal elongation, and activates resident or transplanted progenitor cells across the lesion cavity. However, optimized growth and differentiation protocols along with reliable safety assays should be established prior to the clinical application of SCs. Additionally, the ideal method of SCs labeling for efficient cell tracking after SCI remains a challenging issue that requires further investigation. This review summarizes the current findings on the SCs-based therapeutic strategies, and compares different SCs labeling approaches for SCI.

Connexin 50 modulates Sox2 expression in spinal-cord-derived ependymal stem/progenitor cells

Ion channels included in the family of Connexins (Cx) have been reported to influence the secondary expansion of traumatic spinal cord injury (SCI) and neuropathic pain following SCI. However, Cxs also contribute to spinal cord neurogenesis during the remyelinating process and functional recovery after SCI. Certain Cxs have been recently related to the control of cell proliferation and the differentiation of neuronal progenitors. Adult spinal-cord-derived ependymal stem progenitor cells (epSPC) show high expression levels of Cx50 in non-pathological conditions and lower expression when they actively proliferate after injury (epSPCi). We explore the role of Cx50 in the ependymal population in the modulation of Sox2, a crucial factor of neural progenitor self-renewal and a promising target for promoting neuronal-cell-fate induction for neuronal tissue repair. Short-interfering-RNA ablation or over-expression of Cx50 regulates the expression of Sox2 in both epSPC and epSPCi. Interestingly, Cx50 and Sox2 co-localize at the nucleus indicating a potential role for this ion channel beyond cell-to-cell communication in the spinal cord. In vivo and in vitro experiments with Clotrimazole, a specific pharmacological modulator of Cx50, show the convergent higher expression of Cx50 and Sox2 in the isolated epSPC/epSPCi and in spinal cord tissue. Therefore, the pharmacological modulation of Cx50 might constitute an interesting mechanism for Sox2 induction to modulate the endogenous regenerative potential of neuronal tissue with a potential application in regenerative therapies.

(18)F-FDG-PET imaging of rat spinal cord demonstrates altered glucose uptake acutely after contusion injury

Spinal cord injury (SCI) results in an acute reduction in neuronal and glial cell viability, disruption in axonal tract integrity, and prolonged increases in glial activity and inflammation, all of which can influence regional metabolism and glucose utilization. To date, the understanding of glucose uptake and utilization in the injured spinal cord is limited. Positron emission tomography (PET)-based measurements of glucose uptake may therefore serve as a novel biomarker for SCI. This study aimed to determine the acute and sub-acute glucose uptake pattern after SCI to determine its potential as a novel non-invasive tool for injury assessment and to begin to understand the glucose uptake pattern following acute SCI. Briefly, adult male Sprague-Dawley rats were subjected to moderate contusion SCI, confirmed by locomotor function and histology. PET imaging with [(18)F] Fluorodeoxyglucose (FDG) was performed prior to injury and at 6 and 24h and 15days post-injury (dpi). FDG-PET imaging revealed significantly depressed glucose uptake at 6h post-injury at the lesion epicenter that returned to sham/naïve levels at 24h and 15 dpi after moderate injury. FDG uptake at 15 dpi was likely influenced by a combination of elevated glial presence and reduced neuronal viability. These results show that moderate SCI results in acute depression in glucose uptake followed by an increase in glucose uptake that may be related to neuroinflammation. This acute and sub-acute uptake, which is dependent on cellular responses, may represent a therapeutic target.

FM19G11 reverses endothelial dysfunction in rat and human arteries through stimulation of the PI3K/Akt/eNOS pathway, independently of mTOR/HIF-1α activation

BACKGROUND AND PURPOSE

FM19G11 up-regulates mammalian target of rapamycin (mTOR)/hypoxia inducible factor-1α (HIF-1α) and PI3K/Akt pathways, which are involved in endothelial function. We evaluated the effects of FM19G11 on defective endothelial vasodilatation in arteries from rats and humans and investigated the mechanisms involved.

EXPERIMENTAL APPROACH

Effects of chronic in vivo administration of FM19G11 on aortic endothelial vasodilatation were evaluated together with ex vivo treatment in aortic and mesenteric arteries from control and insulin-resistant rats (IRR). Its effects on vasodilator responses of penile arteries (HPRAs) and corpus cavernosum (HCC) from men with vasculogenic erectile dysfunction (ED) (model of human endothelial dysfunction) were also evaluated. Vascular expression of phosphorylated-endothelial NOS (p-eNOS), phosphorylated-Akt (p-Akt) and HIF-1α was determined by immunodetection and cGMP by elisa.

KEY RESULTS

Chronic administration of FM19G11 reversed the impaired endothelial vasodilatation in IRR. Ex vivo treatment with FM19G11 also significantly improved endothelium-dependent vasodilatation in aorta and mesenteric arteries from IRR. These effects were accompanied by the restoration of p-eNOS and cGMP levels in IRR aorta and were prevented by either NOS or PI3K inhibition. p-Akt and p-eNOS contents were increased by FM19G11 in aortic endothelium of IRR. FM19G11-induced restoration of endothelial vasodilatation was unaffected by mTOR/HIF-1α inhibitors. FM19G11 also restored endothelial vasodilatation in HPRA and HCC from ED patients.

CONCLUSIONS AND IMPLICATIONS

Stimulation of the PI3K/Akt/eNOS pathway by FM19G11 alleviates impaired NO-mediated endothelial vasodilatation in rat and human arteries independently of mTOR/HIF-1α activation. This pharmacological strategy could be beneficial for managing pathological conditions associated with endothelial dysfunction, such as ED.

The multifaceted activities of AMPK in tumor progression--why the "one size fits all" definition does not fit at all?

AMP-activated kinase (AMPK) is a central cellular energetic biosensor and regulator of a broad array of cellular metabolic routes activated by nutrient deprivation, mitochondrial dysfunction, oxidative stress, and cytokines. The activation of AMPK maintains ATP levels in response to hypoxia, mitochondrial dysfunction, and shortage of essential metabolic fuels. Activated AMPK turns on energy sparing pathways and promotes antiapoptotic functions thereby permitting cells to survive extremely hostile conditions for prolonged periods of time. Cancer cells in solid tumors are generally subjected to such harsh conditions; however, they manage to efficiently survive and proliferate. This is likely due, in great part, to a peculiar form of metabolism that is heavily reliant on glycolysis and which promotes cancer cell adaptation and tumor progression. AMPK controls the influx and utilization of glucose by cancer cells and therefore has emerged as an attractive target to treat cancer. Investigations exploring this possibility demonstrated that activators or inhibitors of AMPK impact cancer cell viability and possibly cancer progression. For example, the AMPK activator metformin induces apoptosis in a variety of cancer cell lines and models. A major problem with many of the studies on metformin is that little effort has been invested in unraveling how metformin activates AMPK in the many contexts it has been tested. This is significant because many AMPK-independent effects of metformin have been documented. The notion that AMPK acts solely as a tumor suppressor also conflicts with findings that it confers resistance to nutrient deprivation, sustains NADPH levels in cancer cells, facilitates stress-induced gene transcription, promotes cell survival via antiapoptotic function upregulation, intermediates epithelial-to-mesenchymal transition, and increases malignant transformation. These are all recognized steps necessary for the successful evolution of tumors. This review highlights some of these findings and proposes that the role of AMPK in cancer should be reconsidered in light of the complex roles of AMPK under different metabolic conditions.

Fgf2 improves functional recovery-decreasing gliosis and increasing radial glia and neural progenitor cells after spinal cord injury

OBJECTIVES

A major impediment for recovery after mammalian spinal cord injury (SCI) is the glial scar formed by proliferating reactive astrocytes. Finding factors that may reduce glial scarring, increase neuronal survival, and promote neurite outgrowth are of major importance for improving the outcome after SCI. Exogenous fibroblast growth factor (Fgf) has been shown to decrease injury volume and improve functional outcome; however, the mechanisms by which this is mediated are still largely unknown.

METHODS

In this study, Fgf2 was administered for 2 weeks in mice subcutaneously, starting 30 min after spinal cord hemisection.

RESULTS

Fgf2 treatment decreased the expression of TNF-a at the lesion site, decreased monocyte/macrophage infiltration, and decreased gliosis. Fgf2 induced astrocytes to adopt a polarized morphology and increased expression of radial markers such as Pax6 and nestin. In addition, the levels of chondroitin sulfate proteoglycans (CSPGs), expressed by glia, were markedly decreased. Furthermore, Fgf2 treatment promotes the formation of parallel glial processes, "bridges," at the lesion site that enable regenerating axons through the injury site. Additionally, Fgf2 treatment increased Sox2-expressing cells in the gray matter and neurogenesis around and at the lesion site. Importantly, these effects were correlated with enhanced functional recovery of the left paretic hind limb.

CONCLUSIONS

Thus, early pharmacological intervention with Fgf2 following SCI is neuroprotective and creates a proregenerative environment by the modulation of the glia response.

Methacrylate-endcapped caprolactone and FM19G11 provide a proper niche for spinal cord-derived neural cells

Spinal cord injury (SCI) is a cause of paralysis. Although some strategies have been proposed to palliate the severity of this condition, so far no effective therapies have been found to reverse it. Recently, we have shown that acute transplantation of ependymal stem/progenitor cells (epSPCs), which are spinal cord-derived neural precursors, rescue lost neurological function after SCI in rodents. However, in a chronic scenario with axon repulsive reactive scar, cell transplantation alone is not sufficient to bridge a spinal cord lesion, therefore a combinatorial approach is necessary to fill cavities in the damaged tissue with biomaterial that supports stem cells and ensures that better neural integration and survival occur. Caprolactone 2-(methacryloyloxy) ethyl ester (CLMA) is a monomer [obtained as a result of ε-caprolactone and 2-hydroxyethyl methacrylate (HEMA) ring opening/esterification reaction], which can be processed to obtain a porous non-toxic 3D scaffold that shows good biocompatibility with epSPC cultures. epSPCs adhere to the scaffolds and maintain the ability to expand the culture through the biomaterial. However, a significant reduction of cell viability of epSPCs after 6 days in vitro was detected. FM19G11, which has been shown to enhance self-renewal properties, rescues cell viability at 6 days. Moreover, addition of FM19G11 enhances the survival rates of mature neurons from the dorsal root ganglia when cultured with epSPCs on 3D CLMA scaffolds. Overall, CLMA porous scaffolds constitute a good niche to support neural cells for cell transplantation approaches that, in combination with FM19G11, offer a new framework for further trials in spinal cord regeneration.

A specialized microvascular domain in the mouse neural stem cell niche

The microenvironment of the subependymal zone (SEZ) neural stem cell niche is necessary for regulating adult neurogenesis. In particular, signaling from the microvasculature is essential for adult neural stem cell maintenance, but microvascular structure and blood flow dynamics in the SEZ are not well understood. In this work, we show that the mouse SEZ constitutes a specialized microvascular domain defined by unique vessel architecture and reduced rates of blood flow. Additionally, we demonstrate that hypoxic conditions are detectable in the ependymal layer that lines the ventricle, and in a subpopulation of neurons throughout the SEZ and striatum. Together, these data highlight previously unidentified features of the SEZ neural stem cell niche, and further demonstrate the extent of microvascular specialization in the SEZ microenvironment.