Effects of mesenchymal stem cell therapy, in association with pharmacologically active microcarriers releasing VEGF, in an ischaemic stroke model in the rat

Magnetic resonance imaging of hypoxia in acute stroke compared with fluorine-18 fluoromisonidazole-positron emission tomography: A cross-validation study?

Acute ischemic stroke results in an ischemic core surrounded by a tissue at risk, named the penumbra, which is potentially salvageable. One way to differentiate the tissues is to measure the hypoxia status. The purpose of the current study is to correlate the abnormal brain tissue volume derived from magnetic resonance-based imaging of brain oxygen saturation (S_t O₂ -MRI) to the fluorine-18 fluoromisonidazole ([¹⁸ F]FMISO) positron emission tomography (PET) volume for hypoxia imaging validation, and to analyze the ability of S_t O₂ -MRI to depict the different hypoxic tissue types in the acute phase of stroke. In a pertinent model of stroke in the rat, the volume of tissue with decreased S_t O₂ -MRI signal and that with increased uptake of [¹⁸ F]FMISO were equivalent and correlated (r = 0.706; p = 0.015). The values of S_t O₂ in the tissue at risk were significantly greater than those quantified in the core of the lesion, and were less than those for healthy tissue (52.3% ± 2.0%; 43.3% ± 1.9%, and 67.9 ± 1.4%, respectively). A threshold value for S_t O₂ of ≈60% as the cut-off for the identification of the tissue at risk was calculated. Tissue volumes with reduced S_t O₂ -MRI correlated with the final lesion (r = 0.964, p < 0.0001). The findings show that the S_t O₂ -MRI approach is sensitive for the detection of hypoxia and for the prediction of the final lesion after stroke. Once validated in acute clinical settings, this approach might be used to enhance the stratification of patients for potential therapeutic interventions.

Ginsenoside Rg1 Nanoparticles Induce Demethylation of H3K27me3 in VEGF-A and Jagged 1 Promoter Regions to Activate Angiogenesis After Ischemic Stroke

BACKGROUND

Compared with traditional drugs, nanomaterial drugs have the benefits of improving the solubility, bioavailability, and absorption rate of insoluble drugs. Nanoporous complexes can increase the efficiency with which drugs can penetrate the blood-brain barrier and reach target organs. Ginsenoside Rg1 is an effective drug that promotes angiogenesis. Ginsenoside Rg1 composite nanoparticles were employed to induce the expression of several key epigenetic enzymes and then activate the VEGF and Notch pathways after the onset of ischemic brain lesions.

METHODS

We constructed nanoparticles to fully encapsulate the therapeutic drug (ginsenoside Rg1), which can be transferred into brain tissue via the receptor-mediated transfer of drug-encapsulated nanoparticles. Evaluation of the therapeutic effect of ginsenoside Rg1 complex nanovesicles (CNV) was performed by in vitro and in vivo experiments. Real-time polymerase chain reaction (RT- PCR), Western blot, immunohistochemistry staining (IHC), and Co-immunoprecipitation (co-IP) were employed to screen for epigenetic enzymes with an up-regulated expression post ginsenoside Rg1-CNV intervention. RNA sequencing, shRNA knockdown, and chromatin Immunoprecipitation (ChIP) sequencing were performed to detect the target genes of ginsenoside Rg1-CNV that regulate angiogenesis. Then, bioinformatic analysis was performed to investigate the mechanism of action of epigenetic modifying enzymes in regulating target genes.

RESULTS

The average of the synthesized ginsenoside Rg1-CNV was 203.78±6.83 nm, the polydispersion index was 0.135±0.007, and the Zeta potential was 23.13±1.65 mV. Through in vivo and in vitro experiments, we found that it promotes the proliferation, migration, and tubular formation of brain microvascular endothelial cells (BMECs). Meanwhile, the intervention of ginsenoside Rg1-CNV promoted the demethylation of H3K27me3 within the promoter region of VEGF-A and Jagged1 genes and reduced the H3K27me3 modification within this region.

CONCLUSION

The ginsenoside Rg1 nanoparticles may be an available blood-brain barrier penetrating agent for ischemic stroke.

Overexpression of vascular endothelial growth factor enhances the neuroprotective effects of bone marrow mesenchymal stem cell transplantation in ischemic stroke

Although bone marrow mesenchymal stem cells (BMSCs) might have therapeutic potency in ischemic stroke, the benefits are limited. The current study investigated the effects of BMSCs engineered to overexpress vascular endothelial growth factor (VEGF) on behavioral defects in a rat model of transient cerebral ischemia, which was induced by middle cerebral artery occlusion. VEGF-BMSCs or control grafts were injected into the left striatum of the infarcted hemisphere 24 hours after stroke. We found that compared with the stroke-only group and the vehicle- and BMSCs-control groups, the VEGF-BMSCs treated animals displayed the largest benefits, as evidenced by attenuated behavioral defects and smaller infarct volume 7 days after stroke. Additionally, VEGF-BMSCs greatly inhibited destruction of the blood-brain barrier, increased the regeneration of blood vessels in the region of ischemic penumbra, and reducedneuronal degeneration surrounding the infarct core. Further mechanistic studies showed that among all transplant groups, VEGF-BMSCs transplantation induced the highest level of brain-derived neurotrophic factor. These results suggest that BMSCs transplantation with vascular endothelial growth factor has the potential to treat ischemic stroke with better results than are currently available.

Bioorthogonal DOPA-NGF activated tissue engineering microunits for recovery from traumatic brain injury by microenvironment regulation

Stem cell treatment is vital for recovery from traumatic brain injury (TBI). However, severe TBI usually leads to excessive inflammation and neuroinhibitory factors in the injured brain, resulting in poor neural cell survival and uncontrolled formation of glial scars. In this study, a bioorthogonal microenvironment was constructed on biodegradable poly(lactide-co-glycolide) (PLGA) microcarriers through immobilization of mussel-inspired bioorthogonal 3,4-dihydroxyphenylalanine-containing recombinant nerve growth factor (DOPA-NGF) and human umbilical cord mesenchymal stem cells (hUMSCs) for minimally invasive therapy of TBI. Cell culture and RNA-seq analysis revealed enhanced extracellular matrix (ECM) secretion and viability of hUMSCs on PLGA microcarriers compared to 2D culture. Immobilized DOPA-NGF further promoted adhesion, proliferation, and gene expression in RSC96 neurotrophic cells and hUMSCs. Specifically, the neurotrophin receptor of NT-3 (NTRK3) in hUMSCs was activated by DOPA-NGF, leading to MYC transcription and paracrine enhancement to build an adjustable biomimetic microenvironment. After transplantation of microunits in animal models, the motor and learning-memory ability of TBI mice were improved through rollbacks of overactivated inflammatory reaction regulation, neuronal death, and glial scar formation after injury. This was attributed to the paracrine enhancement of hUMSCs activated by the DOPA-NGF. Our study provides a neural regenerative microenvironment-based therapeutic strategy to advance the effects of transplanted hUMSCs in cell-based regenerative medicine for TBI therapy. STATEMENT OF SIGNIFICANCE: Extensive studies have demonstrated the importance of the microenvironment for posttraumatic brain injury recovery. However, an efficient method that can mimic the neural regenerative microenvironment to strengthen stem cell therapy and brain injury recovery is still absent. In this study, the minimally invasive transplantation of DOPA-NGF immobilized biodegradable microcarriers with mesenchymal stem cells was found to be an effective method for regeneration of injured brain. Moreover, transcriptome analysis revealed that neurotrophin receptor of NT-3 (NTRK3) was activated by DOPA-NGF for MYC transcription and paracrine enhancement to build a kind of adjustable biomimetic microenvironment for brain injury therapy. This study provides a neural regenerative microenvironment-based therapeutic strategy to advance the transplanted hUMSCs in cell-based regenerative medicine for neural recovery.

Novel Angiogenic Regulators and Anti-Angiogenesis Drugs Targeting Angiogenesis Signaling Pathways: Perspectives for Targeting Angiogenesis in Lung Cancer

Lung cancer growth is dependent on angiogenesis. In recent years, angiogenesis inhibitors have attracted more and more attention as potential lung cancer treatments. Current anti-angiogenic drugs targeting VEGF or receptor tyrosine kinases mainly inhibit tumor growth by reducing angiogenesis and blocking the energy supply of lung cancer cells. However, these drugs have limited efficiency, raising concerns about limited scope of action and mechanisms of patient resistance to existing drugs. Therefore, current basic research on angiogenic regulators has focused more on screening carcinogenic/anticancer genes, miRNAs, lncRNAs, proteins and other biomolecules capable of regulating the expression of specific targets in angiogenesis signaling pathways. In addition, new uses for existing drugs and new drug delivery systems have received increasing attention. In our article, we analyze the application status and research hotspots of angiogenesis inhibitors in lung cancer treatment as a reference for subsequent mechanistic research and drug development.

Perspective Insights to Bio-Nanomaterials for the Treatment of Neurological Disorders

The significance of biomaterials is well appreciated in nanotechnology, and its use has resulted in major advances in biomedical sciences. Although, currently, very little data is available on the clinical trial studies for treatment of neurological conditions, numerous promising advancements have been reported in drug delivery and regenerative therapies which can be applied in clinical practice. Among the commonly reported biomaterials in literature, the self-assembling peptides and hydrogels have been recognized as the most potential candidate for treatment of common neurological conditions such as Alzheimer's, Parkinson's, spinal cord injury, stroke and tumors. The hydrogels, specifically, offer advantages like flexibility and porosity, and mimics the properties of the extracellular matrix of the central nervous system. These factors make them an ideal scaffold for drug delivery through the blood-brain barrier and tissue regeneration (using stem cells). Thus, the use of biomaterials as suitable matrix for therapeutic purposes has emerged as a promising area of neurosciences. In this review, we describe the application of biomaterials, and the current advances, in treatment of statistically common neurological disorders.

Surface Modification of Alginate Microcarriers for Improvement of Their Biological Properties

The obtaining of microcarriers for the cell culture and delivery is an urgent task of tissue engineering and regenerative medicine. The novel method of surface modification of alginate microcarriers in the form of microspheres with a diameter of 200-300 μm was developed. The described method consists in covalent crosslinking between collagen and surface of alginate microcarriers. It was shown that the method makes it possible to completely modify the surface of the alginate microcarrier, which can be used to improve the biological properties of the microcarrier. Such microcarriers with improved biological properties can be considered as effective systems for cell delivery and culture.

Effect of synthetic oxygen-generating system on cell survival under hypoxic condition in vitro

A significant challenge in the tissue engineering of injured sites is the lack of vascularization in the engineered sites due to insufficient oxygen supply. A scaffolding system is required to support seeded cells as vascularization develops. In this study, we examined the effects of hypoxic conditions and oxygen release on cell survival in a synthetic system. We developed a three-dimensional system using CaO2/poly(lactic-co-glycolic acid) microspheres suspended in a hydrogel. The system material was evaluated using stem cells under hypoxic conditions alongside controls to evaluate its oxygen-generating potential over a period of 21 days. The hydrogel acted as a flexible carrier supporting cell attachment and growth, protecting microspheres, and prolonging oxygen release. The system generated oxygen and supported cell growth, which are together expected to promote stem cell survival and growth in the weeks following implantation.

Active stealth and self-positioning biomimetic vehicles achieved effective antitumor therapy

Mesenchymal stem cells (MSCs) are recognized as promising drug delivery vehicles. However, the limitation of drug loading capacity and safety considerations are two obstacles to the further application of MSCs. Here, we report MSC membrane-coated mesoporous silica nanoparticles (MSN@M) that maintain the active stealth and self-positioning drug delivery abilities of MSCs and resolve issues related to MSCs-mediated drug delivery. MSN@M was established through uniformly integrating MSC membrane onto a mesoporous silica nanoparticle (MSN) core by sonication. Reduced clearance of phagocytes mediated by CD47 marker on MSC membrane was observed in vitro, which explained the only ~ 25% clearance rate of MSN@M compared with MSN in vivo within 24 h. MSN@M also showed stronger tumor targeting and penetration ability compared with MSN in HepG2 tumor bearing mice. Simultaneously, MSN@M exhibited strong capacity for drug loading and sustained drug release ability of MSN when loaded with doxorubicin (DOX), the drug loading of MSN@M increased ~ 5 folds compared with MSC membrane. In HepG2 xenograft mice, DOX-loaded MSN@M effectively inhibited the growth of tumors and decreased the side effects of treatment by decreasing the exposure of other tissues to DOX. Consequently, our MSN@M may serve as alternative vehicles for MSCs and provide more options for antitumor treatment.

Analysis of Molecular Mechanism of YiqiChutan Formula Regulating DLL4-Notch Signaling to Inhibit Angiogenesis in Lung Cancer

In order to explore the specific mechanism of YiqiChutan formula (YQCTF) in inhibiting the angiogenesis of lung cancer and its relationship with delta-like ligand 4- (DLL4-) Notch signaling, 30 healthy BALB/c-nu/nu rats were selected and divided into three groups: A549 group (implanted with lung adenocarcinoma cell line A549), NCI-H460 group (implanted with human lung large-cell carcinoma cell line NCI-H460), and NCI-H446 group (implanted with human lung small cell carcinoma cell line NCI-H446) for constructing lung cancer transplanted tumor models. After modeling, the group treated with normal saline was taken as control group, 200 mg/kg of YQCTF was adopted for intervention, and the tumor volume and growth inhibition rate were compared with the vascular targeted inhibitor Sorafenib. HE staining, CD31 fluorescent antibody staining, and microelectron microscopy were adopted to observe the neovascular endothelial cells of the transplanted tumor. The expression of VEGF, HIF-1α, DLL4, and Notch-1 in the transplanted tumors in each group was detected by Western blot and RT-PCR at the protein level or mRNA level. Compared with the control group, the YQCTF-treated group had obvious inhibitory effect on lung cancer transplanted tumor and lung cancer angiogenesis. In the YQCTF-treated group, the density of angiogenesis decreased significantly and the vascular lumen structure also decreased, and the expression levels of VEGF, HIF-1α, DLL4, and Notch-1 in the YQCTF-treated group were all lower than those in the control group. YQCTF could inhibit the growth of lung cancer transplanted tumor through antiangiogenesis, and it could also reduce the amount of angiogenesis in lung cancer transplanted tumor. In addition, the generation of lumen structure was also hindered, which was realized through the VEGF signaling pathway and DLL4-Notch signaling pathway.

The potential of biomaterials for central nervous system cellular repair

The central nervous system (CNS) can be injured or damaged through a variety of insults including traumatic injury, stroke, and neurodegenerative or demyelinating diseases, including Alzheimer's disease, Parkinson's disease and multiple sclerosis. Existing pharmacological and other therapeutics strategies are limited in their ability to repair or regenerate damaged CNS tissue meaning there are significant unmet clinical needs facing patients suffering CNS damage and/or degeneration. Through a variety of mechanisms including neuronal replacement, secretion of therapeutic factors, and stimulation of host brain plasticity, cell-based repair offers a potential mechanism to repair and heal the damaged CNS. However, over the decades of its evolution as a therapeutic strategy, cell-based CNS repair has faced significant hurdles that have prevented its translation to widespread clinical practice. In recent years, advances in cell technologies combined with advances in biomaterial-based regenerative medicine and tissue engineering have meant there is very real potential for many of these hurdles to be overcome. This review will provide an overview of the main CNS conditions that lend themselves to cellular repair and will then outline the potential of biomaterial-based approaches for improving the outcome of cellular repair in these conditions.

Activated Mesenchymal Stem Cells Induce Recovery Following Stroke Via Regulation of Inflammation and Oligodendrogenesis

Background Brain repair mechanisms fail to promote recovery after stroke, and approaches to induce brain regeneration are scarce. Mesenchymal stem cells (MSC) are thought to be a promising therapeutic option. However, their efficacy is not fully elucidated, and the mechanism underlying their effect is not known. Methods and Results The middle cerebral artery occlusion model was utilized to determine the efficacy of interferon-γ-activated mesenchymal stem cells (aMSCγ) as an acute therapy for stroke. Here we show that treatment with aMSCγ is a more potent therapy for stroke than naive MSC. aMSCγ treatment results in significant functional recovery assessed by the modified neurological severity score and open-field analysis compared with vehicle-treated animals. aMSCγ-treated animals showed significant reductions in infarct size and inhibition of microglial activation. The aMSCγ treatment suppressed the hypoxia-induced microglial proinflammatory phenotype more effectively than treatment with naive MSC. Importantly, treatment with aMSCγ induced recruitment and differentiation of oligodendrocyte progenitor cells to myelin-producing oligodendrocytes in vivo. To elucidate the mechanism underlying high efficacy of aMSCγ therapy, we examined the secretome of aMSCγ and compared it to that of naive MSC. Intriguingly, we found that aMSCγ but not nMSC upregulated neuron-glia antigen 2, an important extracellular signal and a hallmark protein of oligodendrocyte progenitor cells. Conclusions These results suggest that activation of MSC with interferon-γ induces a potent proregenerative, promyelinating, and anti-inflammatory phenotype of these cells, which increases the potency of aMSCγ as an effective therapy for ischemic stroke.

The Potential of Biomaterial-Based Approaches as Therapies for Ischemic Stroke: A Systematic Review and Meta-Analysis of Pre-clinical Studies

Background: In recent years pre-clinical stroke research has shown increased interest in the development of biomaterial-based therapies to promote tissue repair and functional recovery. Such strategies utilize biomaterials as structural support for tissue regeneration or as delivery vehicles for therapeutic agents. While a range of biomaterials have been tested in stroke models, currently no overview is available for evaluating the benefit of these approaches. We therefore performed a systematic review and meta-analysis of studies investigating the use of biomaterials for the treatment of stroke in experimental animal models. Methods: Studies were identified by searching electronic databases (PubMed, Web of Science) and reference lists of relevant review articles. Studies reporting lesion volume and/or neurological score were included. Standardized mean difference (SMD) and 95% confidence intervals were calculated using DerSimonian and Laird random effects. Study quality and risk of bias was assessed using the CAMARADES checklist. Publication bias was visualized by funnel plots followed by trim and fill analysis of missing publications. Results: A total of 66 publications were included in the systematic review, of which 44 (86 comparisons) were assessed in the meta-analysis. Overall, biomaterial-based interventions improved both lesion volume (SMD: -2.98, 95% CI: -3.48, -2.48) and neurological score (SMD: -2.3, 95% CI: -2.85, -1.76). The median score on the CAMARADES checklist was 5.5/10 (IQR 4.25-6). Funnel plots of lesion volume and neurological score data revealed pronounced asymmetry and publication bias. Additionally, trim and fill analysis estimated 19 "missing" studies for the lesion volume outcome adjusting the effect size to -1.91 (95% CI: -2.44, -1.38). Conclusions: Biomaterials including scaffolds and particles exerted a positive effect on histological and neurological outcomes in pre-clinical stroke models. However, heterogeneity in the field, publication bias and study quality scores which may be another source of bias call for standardization of outcome measures and improved study reporting.

Therapeutic strategy against ischemic stroke with the concept of neurovascular unit

Stroke is one of the leading causes of death and disability globally. Although thrombolytic therapy by t-PA and mechanical thrombectomy have improved outcomes of ischemic stroke patients, both of these approaches are applicable to limited numbers of patients owing to their time constraints. Therefore, development of other treatment approaches such as developing neuroprotective drugs and nerve regeneration therapy is required to overcome ischemic stroke. The concept of the neurovascular unit (NVU) was formalized by the Stroke Progress Review Group of the National Institute of Neurological Disorders and Stroke in 2001. This concept emphasizes the importance not just of neurons but of the interactions between neurons, endothelial cells, astroglia, microglia and associated tissue matrix proteins to investigate the pathological condition of ischemic stroke. Many reports have been published about these interactions. This review focuses on the roles of cells that surround cerebral vasculature, especially endothelial cells, and reports therapeutic strategies against ischemic stroke from four points of view including angiogenesis, neurotrophic effects, protection of NVU components and regenerative therapy.

Exosomes Derived from Human Primed Mesenchymal Stem Cells Induce Mitosis and Potentiate Growth Factor Secretion

Mesenchymal stem cells (MSCs) facilitate functional recovery in numerous animal models of inflammatory and ischemic tissue-related diseases with a growing body of research suggesting that exosomes mediate many of these therapeutic effects. It remains unclear, however, which types of proteins are packaged into exosomes compared with the cells from which they are derived. In this study, using comprehensive proteomic analysis, we demonstrated that human primed MSCs secrete exosomes (pMEX) that are packaged with markedly higher fractions of specific protein subclasses compared with their cells of origin, indicating regulation of their contents. Notably, we found that pMEX are also packaged with substantially elevated levels of extracellular-associated proteins. Fibronectin was the most abundant protein detected, and data established that fibronectin mediates the mitogenic properties of pMEX. In addition, treatment of SHSY5Y cells with pMEX induced the secretion of growth factors known to possess mitogenic and neurotrophic properties. Taken together, our comprehensive analysis indicates that pMEX are packaged with specific protein subtypes, which may provide a molecular basis for their distinct functional properties.

A heparan sulfate-based matrix therapy reduces brain damage and enhances functional recovery following stroke

Alteration of the extracellular matrix (ECM) is one of the major events in the pathogenesis of brain lesions following ischemic stroke. Heparan sulfate mimetics (HSm) are synthetic pharmacologically active polysaccharides that promote ECM remodeling and tissue regeneration in various types of lesions. HSm bind to growth factors, protect them from enzymatic degradation and increase their bioavailability, which promotes tissue repair. As the ECM is altered during stroke and HSm have been shown to restore the ECM, we investigated the potential of HSm4131 (also named RGTA-4131®) to protect brain tissue and promote regeneration and plasticity after a stroke. Methods: Ischemic stroke was induced in rats using transient (1 h) intraluminal middle cerebral artery occlusion (MCAo). Animals were assigned to the treatment (HSm4131; 0.1, 0.5, 1.5, or 5 mg/kg) or vehicle control (saline) groups at different times (1, 2.5 or 6 h) after MCAo. Brain damage was assessed by MRI for the acute (2 days) and chronic (14 days) phases post-occlusion. Functional deficits were evaluated with a battery of sensorimotor behavioral tests. HSm4131-^99mTc biodistribution in the ischemic brain was analyzed between 5 min and 3 h following middle cerebral artery reperfusion. Heparan sulfate distribution and cellular reactions, including angiogenesis and neurogenesis, were evaluated by immunohistochemistry, and growth factor gene expression (VEGF-A, Ang-2) was quantified by RT-PCR. Results: HSm4131, administered intravenously after stroke induction, located and remained in the ischemic hemisphere. HSm4131 conferred long-lasting neuroprotection, and significantly reduced functional deficits with no alteration of physiological parameters. It also restored the ECM, and increased brain plasticity processes, i.e., angiogenesis and neurogenesis, in the affected brain hemisphere. Conclusion: HSm represent a promising ECM-based therapeutic strategy to protect and repair the brain after a stroke and favor functional recovery.

Oxygen producing microscale spheres affect cell survival in conditions of oxygen-glucose deprivation in a cell specific manner: implications for cell transplantation

This study outlines the synthesis of microscale oxygen producing spheres, which, when used in conjunction with catalase, can raise the dissolved oxygen content of cell culture media for 16-20 hours. In conditions of oxygen and glucose deprivation, designed to mimic the graft environment in vivo, the spheres rescue SH-SY5Y cells and meschymal stem cells, showing that oxygen producing biomaterials may hold potential to improve the survival of cells post-transplantation.

Cortical Reshaping and Functional Recovery Induced by Silk Fibroin Hydrogels-Encapsulated Stem Cells Implanted in Stroke Animals

The restitution of damaged circuitry and functional remodeling of peri-injured areas constitute two main mechanisms for sustaining recovery of the brain after stroke. In this study, a silk fibroin-based biomaterial efficiently supports the survival of intracerebrally implanted mesenchymal stem cells (mSCs) and increases functional outcomes over time in a model of cortical stroke that affects the forepaw sensory and motor representations. We show that the functional mechanisms underlying recovery are related to a substantial preservation of cortical tissue in the first days after mSCs-polymer implantation, followed by delayed cortical plasticity that involved a progressive functional disconnection between the forepaw sensory (FLs₁) and caudal motor (cFLm₁) representations and an emergent sensory activity in peri-lesional areas belonging to cFLm₁. Our results provide evidence that mSCs integrated into silk fibroin hydrogels attenuate the cerebral damage after brain infarction inducing a delayed cortical plasticity in the peri-lesional tissue, this later a functional change described during spontaneous or training rehabilitation-induced recovery. This study shows that brain remapping and sustained recovery were experimentally favored using a stem cell-biomaterial-based approach.

Long-Term Intravitreal Ranibizumab as a Potential Additional Risk Factor for Neurodegeneration in Parkinson's Disease: A Case Report

In November 2012, a 72-year old patient was diagnosed with left eye wet age-related macular degeneration. The patient received three monthly intravitreal injections of ranibizumab, with complete resolution of retinal hemorrhage and edema and reinstatement of visual acuity. In May 2015, symptomatic relapse was detected. The patient was again treated with intravitreal ranibizumab, with overall six injections till the end of February 2016. In May 2016, the patient complained of left hand resting tremor, bradykinesia, and postural rigidity of head and trunk. A diagnosis of clinically established PD was made based on new criteria of the Movement Disorders Society. Single Photon Emission Computerized Tomography of the Dopamine Transporter with (123I) ioflupane documented a low Dopamine Transporter (DAT) uptake mostly in the right striatum. Due to the documented protective role of vascular endothelial growth factor (VEGF) on the dopaminergic neurons, intensive intravitreal injections of the anti-VEGF agent ranibizumab may have played as an additional risk factor accelerating the neurodegeneration process related to PD and the onset of the related clinical signs and symptoms.

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.

Pharmacological approaches promoting stem cell-based therapy following ischemic stroke insults

Stroke can lead to long-term neurological deficits. Adult neurogenesis, the continuous generation of newborn neurons in distinct regions of the brain throughout life, has been considered as one of the appoaches to restore the neurological function following ischemic stroke. However, ischemia-induced spontaneous neurogenesis is not suffcient, thus cell-based therapy, including infusing exogenous stem cells or stimulating endogenous stem cells to help repair of injured brain, has been studied in numerous animal experiments and some pilot clinical trials. While the effects of cell-based therapy on neurological function during recovery remains unproven in randomized controlled trials, pharmacological agents have been administrated to assist the cell-based therapy. In this review, we summarized the limitations of ischemia-induced neurogenesis and stem-cell transplantation, as well as the potential proneuroregenerative effects of drugs that may enhance efficacy of cell-based therapies. Specifically, we discussed drugs that enhance proliferation, migration, differentiation, survival and function connectivity of newborn neurons, which may restore neurobehavioral function and improve outcomes in stroke patients.

Effects of thalidomide on growth and VEGF-A expression in SW480 colon cancer cells

Lymphatic and hematogenous spread are the most common ways for tumors to metastasize. Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor (VEGF) particularly VEGF-A is important in the process of angiogenesis. The current research has indicated that thalidomide (THD) may be able to inhibit angiogenesis, stimulate the activity of the immune system and inhibit the adherence of cancer cells to stromal cells. These changes may lead to suppression of tumor occurrence and development. To date, to the best of our knowledge, the effects of THD on colon cancer SW480 cells have not been reported. In the present study, the effects of THD and a combination of THD and oxaliplatin (L-OHP) on the proliferation of SW480 cells have been investigated. Furthermore, the expression of VEGF-A and hypoxia-inducible factor 1 (HIF-1) was analyzed using MTT assay, quantitative polymerase chain reaction and western blot analysis. The results indicated that THD was able to inhibit SW480 cells in dose-and-time dependent manner and inhibit the expression of VEGF-A and HIF-1α. Furthermore, treatment with THD and L-OHP had synergistic inhibitory effect, which may provide a novel treatment strategy for advanced colorectal cancer.

Comparisons of the therapeutic effects of three different routes of bone marrow mesenchymal stem cell transplantation in cerebral ischemic rats

Bone marrow mesenchymal stem cells (BMSCs) are mainly administered via three routes: intra-arterial, intravenous and intracerebral. It has been reported that BMSC administration via each route ameliorates the functional deficits after cerebral ischemia. However, there have been no comparisons of the therapeutic benefits of BMSC administration through different delivery routes. In this study, we injected BMSCs into a rat model of transient middle cerebral artery occlusion (MCAO) through the intra-arterial, intravenous, or intracerebral route at day 7 after MCAO. Control animals received only the vehicle. Neurological function was assessed at post-ischemic days (PIDs) 1, 7, 14, 21, 28 and 35 using behavioral tests (modified Neurological Severity Score (mNSS) and the adhesive removal test). At PID 35, the rat brain tissues were processed for histochemical and immunohistochemical staining. Our results showed that BMSC transplantation via the intra-arterial, intravenous, and intracerebral routes induced greater improvement in neurological functions than the control treatments; furthermore, the intra-arterial route showed the greatest degree and speed of neurological functional recovery. Moreover, BMSCs treatment through each route enhanced reconstruction of axonal myelination in the area of the corpus callosum on the infarct side of the cerebral hemisphere, increased the expression of SYN and Ki-67, and decreased the expression of Nogo-A in the brain. These effects were more apparent in the intra-arterial group than in the intravenous and intracerebral groups. These data suggest that BMSCs transplantation, especially through intra-arterial delivery, can effectively improve neurological function intra-arterial. The underlying mechanism may include the promotion of synaptogenesis, endogenous cell proliferation, and axonal regeneration.

Regenerative potential of primary adult human neural stem cells on micropatterned bio-implants boosts motor recovery

Background

The adult brain is unable to regenerate itself sufficiently after large injuries. Therefore, hopes rely on therapies using neural stem cell or biomaterial transplantation to sustain brain reconstruction. The aim of the present study was to evaluate the improvement in sensorimotor recovery brought about by human primary adult neural stem cells (hNSCs) in combination with bio-implants.

Methods

hNSCs were pre-seeded on implants micropatterned for neurite guidance and inserted intracerebrally 2 weeks after a primary motor cortex lesion in rats. Long-term behaviour was significantly improved after hNSC implants versus cell engraftment in the grip strength test. MRI and immunohistological studies were conducted to elucidate the underlying mechanisms of neuro-implant integration.

Results

hNSC implants promoted tissue reconstruction and limited hemispheric atrophy and glial scar expansion. After 3 months, grafted hNSCs were detected on implants and expressed mature neuronal markers (NeuN, MAP2, SMI312). They also migrated over a short distance to the reconstructed tissues and to the peri-lesional tissues, where 26% integrated as mature neurons. Newly formed host neural progenitors (nestin, DCX) colonized the implants, notably in the presence of hNSCs, and participated in tissue reconstruction. The microstructured bio-implants sustained the guided maturation of both grafted hNSCs and endogenous progenitors.

Conclusions

These immunohistological results are coherent with and could explain the late improvement observed in sensorimotor recovery. These findings provide novel insights into the regenerative potential of primary adult hNSCs combined with microstructured implants.

Fabrication of Innovative Silk/Alginate Microcarriers for Mesenchymal Stem Cell Delivery and Tissue Regeneration

The aim of this study was to exploit silk fibroin’s properties to develop innovative composite microcarriers for mesenchymal stem cell (MSCs) adhesion and proliferation. Alginate microcarriers were prepared, added to silk fibroin solution, and then treated with ethanol to induce silk conformational transition. Microcarriers were characterized for size distribution, coating stability and homogeneity. Finally, in vitro cytocompatibility and suitability as delivery systems for MSCs were investigated. Results indicated that our manufacturing process is consistent and reproducible: silk/alginate microcarriers were stable, with spherical geometry, about 400 μm in average diameter, and fibroin homogeneously coated the surface. MSCs were able to adhere rapidly onto the microcarrier surface and to cover the surface of the microcarrier within three days of culture; moreover, on this innovative 3D culture system, stem cells preserved their metabolic activity and their multi-lineage differentiation potential. In conclusion, silk/alginate microcarriers represent a suitable support for MSCs culture and expansion. Since it is able to preserve MSCs multipotency, the developed 3D system can be intended for cell delivery, for advanced therapy and regenerative medicine applications.

Effect of dental pulp stem cells in MPTP-induced old-aged mice model

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disease caused by the loss of dopaminergic (DA-ergic) neurons in the substantia nigra (SN) and represented as a huge threat to the geriatric population. Cell replacement therapies (CRTs) have been proposed as a promising strategy to slow down or replace neuronal loss. Among the widely available cell sources, dental pulp stem cells (DPSCs) portray as an attractive source primarily due to their neural crest origin, ease of tissue procurement and less ethical hurdles.

MATERIALS AND METHODS

We first demonstrated the in vitro differentiation ability of DPSCs towards DA-ergic-like cells before evaluating their neuro-protection/neuro-restoration capacities in MPTP-induced mice. Transplantation via intrathecal was performed with behavioural assessments being evaluated every fortnight. Subsequent analysis investigating their immuno-modulatory behaviour was conducted using neuronal and microglial cell lines.

RESULTS

It was apparent that the behavioural parameters began to improve corresponding to tyrosine hydroxylase (TH), dopamine transporter (DAT) and dopamine decarboxylase (AADC) immunostaining in SN and striatum as early as 8-week post-transplantation (P < 0·05). About 60% restoration of DA-ergic neurons was observed at SN in MPTP-treated mice after 12-week post-transplantation. Similarly, their ability to reduce toxic effects of MPTP (DNA damages, reactive oxygen species and nitric oxide release) and regulate cytokine levels was distinctly noted (P < 0·05) upon exposure in in vitro model.

CONCLUSIONS

Our results suggest that DPSCs may provide a therapeutic benefit in the old-aged PD mice model and may be explored in stem cell-based CRTs especially in geriatric population as an attempt towards 'personalized medicine'.

Nanoprecipitated catestatin released from pharmacologically active microcarriers (PAMs) exerts pro-survival effects on MSC

Catestatin (CST), a fragment of Chromogranin-A, exerts angiogenic, arteriogenic, vasculogenic and cardioprotective effects. CST is a very promising agent for revascularization purposes, in "NOOPTION" patients. However, peptides have a very short half-life after administration and must be conveniently protected. Fibronectin-coated pharmacologically active microcarriers (FN-PAM), are biodegradable and biocompatible polymeric microspheres that can convey mesenchymal stem cell (MSCs) and therapeutic proteins delivered in a prolonged manner. In this study, we first evaluated whether a small peptide such as CST could be nanoprecipitated and incorporated within FN-PAMs. Subsequently, whether CST may be released in a prolonged manner by functionalized FN-PAMs (FN-PAM-CST). Finally, we assessed the effect of CST released by FN-PAM-CST on the survival of MSCs under stress conditions of hypoxia-reoxygenation. An experimental design, modifying three key parameters (ionic strength, mixing and centrifugation time) of protein nanoprecipitation, was used to define the optimum condition for CST. An optimal nanoprecipitation yield of 76% was obtained allowing encapsulation of solid CST within FN-PAM-CST, which released CST in a prolonged manner. In vitro, MSCs adhered to FN-PAMs, and the controlled release of CST from FN-PAM-CST greatly limited hypoxic MSC-death and enhanced MSC-survival in post-hypoxic environment. These results suggest that FN-PAM-CST are promising tools for cell-therapy.

Stem cell therapies for ischemic stroke: current animal models, clinical trials and biomaterials

We report the facilitation of stem cell therapy in stroke by tissue engineering and applications of biomaterials.

Intracerebral and Intravenous Transplantation Represents a Favorable Approach for Application of Human Umbilical Cord Mesenchymal Stromal Cells in Intracerebral Hemorrhage Rats

Background

Intracerebral hemorrhage (ICH) is one severe subtype of stroke, with a very complex pathology. Stem cell-based therapy holds promising potential in the treatment of neurological disorders. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) have a therapeutic effect in recovery from brain damage following ICH. The aim of this study was to identify an effective and convenient way of using UC-MSCs in the ICH rat model.

Material/Methods

CM-DiI-labeled human UC-MSCs were transplanted intracerebrally or intravenously into collagenase VII-induced ICH rat models. Neurological function was evaluated before ICH and at 0, 7, 14, 21, and 28 days after treatment. ICH rats were sacrificed to evaluate the injury volume. Neurogenesis and angiogenesis and vascular areas were investigated using microtubule-associated protein 2 (MAP2), glial fibrillary acidic protein (GFAP), and 4′,6-diamidino-2-phenylindole (DAPI) immunohistochemistry at two weeks after transplantation.

Results

The intracerebral and intravenous administration of UC-MSCs both resulted in significant improvement in neurological function and decrease in injury volume of ICH rats. Transplanted UC-MSCs were chemotactic in vivo and showed a predominant distribution around the ICH region. In addition, UC-MSCs could integrate into the cerebral vasculature in both groups.

Conclusions

Both intracerebral and intravenous administration of UC-MSCs could have a favorable effect on recovery of neurological function in ICH rats, although the fundamental mechanisms may be different between the two groups. Our data suggest that intravenous implantation of UC-MSCs could serve as a favorable approach for cell-based therapy in central nervous system (CNS) diseases according to clinical needs.

Proteomic Analysis of the Peri-Infarct Area after Human Umbilical Cord Mesenchymal Stem Cell Transplantation in Experimental Stroke

Among various therapeutic approaches for stroke, treatment with human umbilical cord mesenchymal stem cells (hUC-MSCs) has acquired some promising results. However, the underlying mechanisms remain unclear. We analyzed the protein expression spectrum of the cortical peri-infarction region after ischemic stroke followed by treatment with hUC-MSCs, and found 16 proteins expressed differentially between groups treated with or without hUC-MSCs. These proteins were further determined by Gene Ontology term analysis and network with CD200-CD200R1, CCL21-CXCR3 and transcription factors. Three of them: Abca13, Grb2 and Ptgds were verified by qPCR and ELISA. We found the protein level of Abca13 and the mRNA level of Grb2 consistent with results from the proteomic analysis. Finally, the function of these proteins was described and the potential proteins that deserve to be further studied was also highlighted. Our data may provide possible underlying mechanisms for the treatment of stroke using hUC-MSCs.

Association of VEGF gene polymorphisms with sporadic Parkinson's disease in Chinese Han population

Recent evidence indicates that vascular endothelial growth factor (VEGF) is capable of protecting dopaminergic (DA) neurons. Parkinson's disease (PD) is a progressive neurodegenerative disease caused by the degeneration of nigrostriatal dopaminergic neurons. To evaluate the role of VEGF single nucleotide polymorphisms (SNPs) and haplotypes in PD, we performed a case-control study including 400 PD patients and 400 healthy-matched controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and DNA sequencing were used to detect the rs699947, rs2010963 and rs3025039 polymorphisms of the VEGF gene in cases and controls. Our study revealed that T allelic frequency of rs3025039 polymorphism was significantly higher in PD subjects (OR 1.497, 95 % CI 1.099-2.040, P = 0.013) than that in controls. Significant association for rs3025039 could be found in additive model (TT vs. CT vs. CC: OR 1.489, 95 % CI 1.018-2.177, P = 0.040) and dominant model (TT + CT vs. CC: OR 1.538, 95 % CI 1.068-2.216, P = 0.021). Subgroup analyses performed by gender suggested that this association could be found in male, but not in female. Moreover, it also demonstrated a significant association in the subgroup of late-onset PD (LOPD). However, for rs699947 and rs2010963 polymorphisms, genotype or allele frequencies did not differ between groups. No significant association could be found between rs699947 and rs2010963 polymorphism and PD risk. None of the observed haplotypes showed significant association with PD. Therefore, these results suggested that the VEGF gene might be associated with risk of developing sporadic PD in Han Chinese and the rs3025039 polymorphism may be a risk factor for sporadic PD.

Regenerative repair of Pifithrin-α in cerebral ischemia via VEGF dependent manner

Promoting regenerative repair, including neurogenesis and angiogenesis, may provide a new therapeutic strategy for treatment of stroke. P53, a well-documented transcription factor, has been reported to be involved in cerebral ischemia and also serves as an important regulator of vascular endothelial growth factor (VEGF). However, the role of p53 in endogenous regenerative repair after brain ischemia is poorly understood. In this study, we investigated the effects of PFT-α, a specific p53 inhibitor on neurogenesis and angiogenesis improvement and associated signal pathways in rats impaired by cerebral artery occlusion (MCAo). PFT-α induced neuroprotection, reduced infarct volume and neurological functional impairment after ischemic stroke. More importantly, neurogenesis and angiogenesis were greatly enhanced by PFT-α, and accompanied by increased expression of VEGF. Moreover, we got consistent results in neural stem cells (NSCs) isolated from fetal rats. In contrast, application of the anti-VEGF neutralizing antibody (RB-222) partially reversed PFT-α-induced neuroprotection and rescued p53 expression. Noteworthily, inhibition of p53 after ischemic stroke in these rats improved their outcomes via promotion of regenerative repair. In conclusion, PFT-α could serve as a promising therapeutic strategy for ischemic stroke by promoting regenerative repair.

Extrinsic and Intrinsic Mechanisms by Which Mesenchymal Stem Cells Suppress the Immune System

Mesenchymal stem cells (MSCs) are a group of fibroblast-like multipotent mesenchymal stromal cells that have the ability to differentiate into osteoblasts, adipocytes, and chondrocytes. Recent studies have demonstrated that MSCs possess a unique ability to exert suppressive and regulatory effects on both adaptive and innate immunity in an autologous and allogeneic manner. A vital step in stem cell transplantation is overcoming the potential graft-versus-host disease, which is a limiting factor to transplantation success. Given that MSCs attain powerful differentiation capabilities and also present immunosuppressive properties, which enable them to survive host immune rejection, MSCs are of great interest. Due to their ability to differentiate into different cell types and to suppress and modulate the immune system, MSCs are being developed for treating a plethora of diseases, including immune disorders. Moreover, in recent years, MSCs have been genetically engineered to treat and sometimes even cure some diseases, and the use of MSCs for cell therapy presents new perspectives for overcoming tissue rejection. In this review, we discuss the potential extrinsic and intrinsic mechanisms that underlie MSCs' unique ability to modulate inflammation, and both innate and adaptive immunity.

Stem cell approaches to glaucoma: from aqueous outflow modulation to retinal neuroprotection

Long-term pharmacological management of glaucoma currently relies on self-administered drugs to regulate intraocular pressure (IOP). A number of approaches using stem cells have recently shown promise as potential future treatment strategies complementary to IOP lowering. Several sources of endogenous stem cells have been identified in the eye, some of which may be able to repair the damaged trabecular meshwork and restore functional regulation of aqueous outflow. Neural and mesenchymal stem cells secrete growth factors which provide neuroprotective effects, reducing loss of retinal ganglion cells (RGCs) in animal models. In the future, stem cells may even replace RGCs to reform functional connections between the eye and the brain, although the complexity of such a repair task is formidable. With advances in biomaterial cell scaffolds and concurrent efforts in other neural systems, stem cell therapies are becoming a realistic option for treating multiple eye diseases, and despite ongoing challenges, there are reasons for optimism that stem cells may play a role in the treatment of human glaucoma in the future.