Intraparenchymal treatment with bone marrow mesenchymal stem cell-conditioned medium exerts neuroprotection following intracerebral hemorrhage

An Injectable Hydrogel Loaded with GMSCs-Derived Neural Lineage Cells Promotes Recovery after Stroke

Ischemic stroke is a devastating medical condition with poor prognosis due to the lack of effective treatment modalities. Transplantation of human neural stem cells or primary neural cells is a promising treatment approach, but this is hindered by limited suitable cell sources and low in vitro expansion capacity. This study aimed (1) use small molecules (SM) to reprogram gingival mesenchymal stem cells (GMSCs) commitment to the neural lineage cells in vitro, and (2) use hyaluronic acid (HA) hydrogel scaffolds seeded with GMSCs-derived neural lineage cells to treat ischemic stroke in vivo. Neural induction was carried out with a SM cocktail-based one-step culture protocol over a period of 24 h. The induced cells were analyzed for expression of neural markers with immunocytochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). The Sprague-Dawley (SD) rats (n = 100) were subjected to the middle cerebral artery occlusion (MCAO) reperfusion ischemic stroke model. Then, after 8 days post-MCAO, the modeled rats were randomly assigned to six study groups (n = 12 per group): (1) GMSCs, (2) GMSCs-derived neural lineage cells, (3) HA and GMSCs-derived neural lineage cells, (4) HA, (5) PBS, and (6) sham transplantation control, and received their respective transplantation. Evaluation of post-stroke recovery were performed by behavioral tests and histological assessments. The morphologically altered nature of neural lineages has been observed of the GMSCs treated with SMs compared to the untreated controls. As shown by the qRT-PCR and immunocytochemistry, SMs further significantly enhanced the expression level of neural markers of GMSCs as compared with the untreated controls (all p < 0.05). Intracerebral injection of self-assembling HA hydrogel carrying GMSCs-derived neural lineage cells promoted the recovery of neural function and reduced ischemic damage in rats with ischemic stroke, as demonstrated by histological examination and behavioral assessments (all p < 0.05). In conclusion, the SM cocktail significantly enhanced the differentiation of GMSCs into neural lineage cells. The HA hydrogel was found to facilitate the proliferation and differentiation of GMSCs-derived neural lineage cells. Furthermore, HA hydrogel seeded with GMSCs-derived neural lineage cells could promote tissue repair and functional recovery in rats with ischemic stroke and may be a promising alternative treatment modality for stroke.

Current Status and Progress in Stem Cell Therapy for Intracerebral Hemorrhage

Intracerebral hemorrhage is a highly prevalent and prognostically poor disease, imposing immeasurable harm on human life and health. However, the treatment options for intracerebral hemorrhage are severely limited, particularly in terms of improving the microenvironment of the lesion, promoting neuronal cell survival, and enhancing neural function. This review comprehensively discussed the application of stem cell therapy for intracerebral hemorrhage, providing a systematic summary of its developmental history, types of transplants, transplantation routes, and transplantation timing. Moreover, this review presented the latest research progress in enhancing the efficacy of stem cell transplantation, including pretransplantation preconditioning, genetic modification, combined therapy, and other diverse strategies. Furthermore, this review pioneeringly elaborated on the barriers to clinical translation for stem cell therapy. These discussions were of significant importance for promoting stem cell therapy for intracerebral hemorrhage, facilitating its clinical translation, and improving patient prognosis.

Simultaneous Pericytes and M2 Microglia Transplantation Improve Cognitive Function in Mice Model of mPFC Ischemia

Cerebral ischemia is one of the major problems threatening global health. Many of the cerebral ischemia survivors would suffer from the physical and cognitive disabilities for their whole lifetime. Cell based-therapies have been introduced as a therapeutic approach for alleviating ischemia-enforced limitations. Photothrombotic stroke model was applied on the left medial prefrontal cortex (mPFC) of adult male BALB/c mice. Then, pericytes isolated from brain microvessels of adult male BALB/c mice, microglia isolated from brain cortices of the neonatal male BALB/c mice, and M2 phenotype shifted microglia by IL-4 treatment were used for transplantation into the injured area after 24 h of ischemia induction. The behavioural outcomes evaluated by social interaction and Barnes tests and the levels of growth associated protein (GAP)-43 and inflammatory cytokine interleukin (IL)-1 protein were assessed by western blotting 7 days after cell transplantation. Animals in both of the microglia + pericytes and microglia M2 + pericytes transplanted groups showed better performance in social memory as well as enhanced spatial learning and memory compared to ischemic controls. Also, improved escape latency was only observed in microglia M2 + pericytes (p < 0.01) group compared to ischemic controls. GAP-43 showed significant protein expression in microglia + pericytes and microglia M2 + pericytes groups compared to the control group. Conversely, IL-1 levels diminished in all of the pericytes microglia + pericytes, and microglia M2 + pericytes groups compared to the ischemic controls. Current study highlights efficiency of M2 microglia and pericytes combinatory transplantation therapeutic role on relieving ischemic stroke outcomes.

Stem Cell Therapies for Intracerebral Hemorrhage: Review of Preclinical and Clinical Studies

Despite recent developments in the treatments for ischemic stroke, such as tissue plasminogen activator (t-PA) and thrombectomy, effective therapies for intracerebral hemorrhage (ICH) remain scarce. Stem cell therapies have attracted considerable attention owing to their potential neuro-regenerative ability; preclinical and clinical studies have been conducted to explore strategies for achieving functional recovery following ICH. In this review, we summarize the findings of preclinical studies on stem cell therapies of ICH, with a focus on different animal models, stem cell sources, transplantation methods, and their potential mechanisms of action. We also provide an overview of data from clinical trials to discuss the current status and future perspectives. Understanding the effectiveness and limitations of stem cell therapy and the future prospects could expand the applications of this novel therapeutic approach for ICH.

Paracrine Effects of Mesenchymal Stem Cells in Ischemic Stroke: Opportunities and Challenges

It is well acknowledged that neuroprotective effects of transplanted mesenchymal stem cells (MSCs) in ischemic stroke are attributed to their paracrine-mediated actions or bystander effects rather than to cell replacement in infarcted areas. This therapeutic plasticity is due to MSCs' ability to secrete a broad range of bioactive molecules including growth factors, trophic factors, cytokines, chemokines, and extracellular vesicles, overall known as the secretome. The secretome derivatives, such as conditioned medium (CM) or purified extracellular vesicles (EVs), exert remarkable advantages over MSC transplantation in stroke treating. Here, in this review, we used published information to provide an overview on the secretome composition of MSCs, underlying mechanisms of therapeutic effects of MSCs, and preclinical studies on MSC-derived products application in stroke. Furthermore, we discussed current advantages and challenges for successful bench-to-bedside translation.

Application of stem cells and exosomes in the treatment of intracerebral hemorrhage: an update

Non-traumatic intracerebral hemorrhage is a highly destructive intracranial disease with high mortality and morbidity rates. The main risk factors for cerebral hemorrhage include hypertension, amyloidosis, vasculitis, drug abuse, coagulation dysfunction, and genetic factors. Clinically, surviving patients with intracerebral hemorrhage exhibit different degrees of neurological deficits after discharge. In recent years, with the development of regenerative medicine, an increasing number of researchers have begun to pay attention to stem cell and exosome therapy as a new method for the treatment of intracerebral hemorrhage, owing to their intrinsic potential in neuroprotection and neurorestoration. Many animal studies have shown that stem cells can directly or indirectly participate in the treatment of intracerebral hemorrhage through regeneration, differentiation, or secretion. However, considering the uncertainty of its safety and efficacy, clinical studies are still lacking. This article reviews the treatment of intracerebral hemorrhage using stem cells and exosomes from both preclinical and clinical studies and summarizes the possible mechanisms of stem cell therapy. This review aims to provide a reference for future research and new strategies for clinical treatment.

Recent Stem Cell Research on Hemorrhagic Stroke : An Update

Although technological advances and clinical studies on stem cells have been increasingly reported in stroke, research targeting hemorrhagic stroke is still lacking compared to that targeting ischemic stroke. Studies on hemorrhagic stroke are also being conducted, mainly in the USA and China. However, little research has been conducted in Korea. In reality, stem cell research or treatment is unfamiliar to many domestic neurosurgeons. Nevertheless, given the increased interest in regenerative medicine and the increase of life expectancy, attention should be paid to this topic. In this paper, we summarized pre-clinical rodent studies and clinical trials using stem cells for hemorrhagic stroke. In addition, we discussed results of domestic investigations and future perspectives on stem cell research for a better understanding.

Extracellular vesicles derived from bone marrow mesenchymal stem cells alleviate neuroinflammation after diabetic intracerebral hemorrhage via the miR-183-5p/PDCD4/NLRP3 pathway

OBJECTIVES

Intracerebral hemorrhage (ICH) induced by diabetes results in further brain injury and nerve cell death. Bone marrow mesenchymal stem cell (BMSC) transplantation contributes to attenuating neurological deficits after ICH. This study investigated the mechanism of extracellular vesicles (EVs) derived from BMSCs in reducing neuroinflammation after diabetic ICH.

METHODS

BMSC-EVs were isolated and identified. The rat model of db/db-ICH was established and the model rats were administered with EVs. miR-183-5p expression in brain tissues of db/db-ICH rats was detected. The brain injury of db/db-ICH rats was evaluated by measuring neurobehavioral score, brain water content and inflammatory factors. BV2 cells were cultured in vitro to establish high-glucose (HG)-Hemin-BV2 cell model. The levels of reactive oxygen species (ROS) and inflammatory factors in BV2 cells were measured, and BV2 cell viability and apoptosis were assessed. The targeting relationship between miR-183-5p and PDCD4 was predicted and verified. The activation of PDCD4/NLRP3 pathway in rat brain tissues and BV2 cells was detected.

RESULTS

miR-183-5p expression was reduced in db/db-ICH rats brain tissues. BMSC-EVs ameliorated cranial nerve function, decreased brain water content and repressed inflammatory response by carrying miR-183-5p. BMSC-EVs mitigated HG-Hemin-BV2 cell injury, reduced ROS level and suppressed inflammatory response. miR-183-5p targeted PDCD4. PDCD4 promoted BV2 cell inflammation by activating the NLRP3 pathway. BMSC-EVs inhibited HG-Hemin-BV2 cell inflammation through the miR-183-5p/PDCD4/NLRP3 pathway, and inhibition of miR-183-5p reversed the protective effect of EVs.

CONCLUSION

BMSC-EVs carried miR-183-5p into db/db-ICH rat brain tissues and repressed the NLRP3 pathway by targeting PDCD4, thus alleviating neuroinflammation after diabetic ICH.

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

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

Regenerative Potential of Hydrogels for Intracerebral Hemorrhage: Lessons from Ischemic Stroke and Traumatic Brain Injury Research

Intracerebral hemorrhage (ICH) is a deadly and debilitating type of stroke, caused by the rupture of cerebral blood vessels. To date, there are no restorative interventions approved for use in ICH patients, highlighting a critical unmet need. ICH shares some pathological features with other acute brain injuries such as ischemic stroke (IS) and traumatic brain injury (TBI), including the loss of brain tissue, disruption of the blood-brain barrier, and activation of a potent inflammatory response. New biomaterials such as hydrogels have been recently investigated for their therapeutic benefit in both experimental IS and TBI, owing to their provision of architectural support for damaged brain tissue and ability to deliver cellular and molecular therapies. Conversely, research on the use of hydrogels for ICH therapy is still in its infancy, with very few published reports investigating their therapeutic potential. Here, the published use of hydrogels in experimental ICH is commented upon and how approaches reported in the IS and TBI fields may be applied to ICH research to inform the design of future therapies is described. Unique aspects of ICH that are distinct from IS and TBI that should be considered when translating biomaterial-based therapies between disease models are also highlighted.

Hypoxic Preconditioning Enhances the Efficacy of Mesenchymal Stem Cells-Derived Conditioned Medium in Switching Microglia toward Anti-inflammatory Polarization in Ischemia/Reperfusion

Activation of pro-inflammatory microglia is an important mechanism of the cerebral ischemia-reperfusion (I/R)-induced neuronal injury and dysfunction. Mesenchymal stem cells (MSCs) together with their paracrine factors demonstrated curative potential in immune disorders and inflammatory diseases, as well as in ischemic diseases. However, it remains unclear whether conditioned medium from MSCs could effectively regulate the activation and polarization of microglia exposed to I/R stimulation. In this study, we investigated the effects of conditioned medium from bone marrow MSCs (BMSCs-CM) on I/R-stimulated microglia and the potential mechanism involved, as well as the way to obtain more effective BMSCs-CM. First, cell model of oxygen-glucose deprivation/reoxygenation (OGD/R) was established in microglia to mimic the I/R. BMSCs-CM from different culture conditions (normoxic: 21% O2; hypoxic: 1% O2; hypoxia preconditioning: preconditioning with 1% O2 for 24 h) was used to treat the microglia. Our results showed that BMSCs-CM effectively promoted the survival and alleviated the injury of microglia. Moreover, in microglia exposed to OGD/R, BMSCs-CM inhibited significantly the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), CD86 and inducible nitric oxide synthase, whereas upregulated the levels of anti-inflammatory cytokine (IL-10), CD206 and Arginase-1. These results suggested that BMSCs-CM promoted the polarization of anti-inflammatory microglia. In particular, BMSCs-CM from cultures with hypoxia preconditioning was more effective in alleviating cell injury and promoting anti-inflammatory microglia polarization than BMSCs-CM from normoxic cultures and from hypoxic cultures. Furthermore, inhibition of exosomes secretion could largely mitigate these effects of BMSCs-CM. In conclusion, our results suggested that hypoxia preconditioning of BMSCs could enhance the efficacy of BMSCs-CM in alleviating OGD/R-induced injury and in promoting the anti-inflammatory polarization of microglia, and these beneficial effects of BMSCs-CM owed substantially to exosomes.

The conditioned medium of human embryonic stem cell-derived mesenchymal stem cells alleviates neurological deficits and improves synaptic recovery in experimental stroke

The transplantation of mesenchymal stem cells (MSCs) is of main approaches in regenerative therapy for stroke. Due to the potential tumorigenicity and low survival rate of transplanted cells, focuses have been shifted from cell replacement to their paracrine effects. Therefore, stem cell-conditioned medium (CM) therapy has emerged as an alternative candidate. Here, we investigated the effect of CM derived from human embryonic MSCs on experimental ischemic stroke. Wistar rats underwent ischemic stroke by the right middle cerebral artery occlusion (MCAO). CM was infused either one time (1 hr post-MCAO) or three times (1, 24, and 48 hr post-MCAO) through guide cannula into the left lateral ventricle. Neurological functions were evaluated using Bederson's test and modified Neurological Severity Score on Days 1, 3, and 7 following MCAO. Infarction volumes and cerebral edema were measured on Days 3 and 7. growth-associated protein-43, synaptophysin, cAMP response element-binding protein, and phosphorylated-cAMP response element-binding protein levels were also assessed in peri-ischemic cortical tissue on Day 7 postsurgery. Our results indicated that three times injections of CM could significantly reduce body weight loss, mortality rate, infarct volumes, cerebral edema, and improve neurological deficits in MCAO rats. Moreover, three injections of CM could restore decreased levels of synaptic markers in MCAO rats up to its normal levels observed in the sham group. Our data suggest that using the CM obtained from embryonic stem cells-MSCs could be a potent therapeutic approach to attenuate cerebral ischemia insults which may be partly mediated through modulation of synaptic plasticity.

Stroke treatment: Is exosome therapy superior to stem cell therapy?

Stroke is one of the most common causes of disability and death, and currently, ideal clinical treatment is lacking. Stem cell transplantation is a widely-used treatment approach for stroke. When compared with other types of stem cells, bone marrow mesenchymal stem cells (BMSCs) have been widely studied because of their many advantages. The paracrine effect is the primary mechanism for stem cells to play their role, and exosomes play an essential role in the paracrine effect. When compared with cell therapy, cell-free exosome therapy can prevent many risks and difficulties, and therefore, represents a promising and novel approach for treatment. In this study, we reviewed the research progress in the application of BMSCs-derived exosomes (BMSCs-exos) and BMSCs in the treatment of stroke. In addition, the advantages and disadvantages of cell therapy and cell-free exosome therapy were described, and the possible factors that hinder the introduction of these two treatments into the clinic were analyzed. Furthermore, we reviewed the current optimization methods of cell therapy and cell-free exosome therapy. Taken together, we hypothesize that cell-free exosome therapy will have excellent research prospects in the future, and therefore, it is worth further exploring. There are still some issues that need to be further addressed. For example, differences between the in vivo microenvironment and in vitro culture conditions will affect the paracrine effect of stem cells. Most importantly, we believe that more preclinical and clinical design studies are required to compare the efficacy of stem cells and exosomes.

Elevated miR-29a Contributes to Axonal Outgrowth and Neurological Recovery After Intracerebral Hemorrhage via Targeting PTEN/PI3K/Akt Pathway

Spontaneous intracerebral hemorrhage (ICH) is a clinical challenge with high disability and lacks an effective treatment. miR-29a strongly expressed in the brain has been implicated in various neurological disorders. In this study, we investigated the biological roles of miR-29a in axonal outgrowth and neurological outcomes after ICH and relevant molecular mechanism. The rat model of ICH was established by injection of autologous whole blood into the right basal ganglia. First, a significant decrease in miR-29a level was found in perihematomal brain tissues and cerebrospinal fluid (CSF) after ICH in vivo and hemin-treated neurons in vitro. Further study documented that lentivirus-mediated miR-29a overexpression could remarkably attenuate hemorrhagic brain injury, promoted regenerative outgrowth of injured axons and improved neurobehavioral and cognitive impairments after ICH in rats. In addition, we also identified that overexpression of miR-29a obviously alleviated neuronal damage and mitochondrial dysfunctions, and facilitated neurite outgrowth in cultured neurons exposed to hemin in vitro. Furthermore, luciferase reporter assay showed that miR-29a directly targeted the 3'-UTR region of phosphatase and tensin homolog (PTEN) mRNA and negatively regulated its expression. More importantly, pharmacological inhibition of PTEN has similar neuroprotective effects as miR-29a overexpression involving activation of the PI3K/Akt pathway after hemorrhagic stroke. Collectively, these results suggested that elevated miR-29a could contribute to axonal outgrowth and neurological recovery through targeting PTEN/PI3K/Akt pathway after ICH, thereby providing a potential therapeutic target for patients with ICH.

Potential of stem cell therapy in intracerebral hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is a common disease associated with high mortality and morbidity. The treatment of patients with ICH includes medical and surgical interventions. New areas of surgical intervention have been focused on the evacuation of hematoma through minimally invasive neurosurgery. In contrast, there have been no significant advances in the development of medical interventions for functional recovery after ICH. Stem cells exert multiple therapeutic functions and have emerged as a promising treatment strategy. Herein, we summarized the pathophysiology of ICH and its treatment targets, and we introduced the therapeutic mechanisms of stem cells (e.g. neutrotrophy and neuroregeneration). Moreover, we reviewed and summarized the experimental designs of the preclinical studies, including the types of cells and the timing and routes of stem cell administration. We further listed and reviewed the completed/published and ongoing clinical trials supporting the safety and efficacy of stem cell therapy in ICH. The limitations of translating preclinical studies into clinical trials and the objectives of future studies were discussed. In conclusion, current literatures showed that stem cell therapy is a promising treatment in ICH and further translation research on judiciously selected group of patients is warranted before it can be extensively applied in clinical practice.

Bone mesenchymal stem cell-conditioned medium attenuates the effect of oxidative stress injury on NSCs by inhibiting the Notch1 signaling pathway

Numerous studies have demonstrated the therapeutic effect of bone mesenchymal stem cells on spinal cord injury (SCI), especially on neural stem cells (NSCs). However, the predominant mechanisms of bone mesenchymal stem cells (BMSCs) are unclear. Recently, some researchers have found that paracrine signaling plays a key role in the therapeutic capacity of BMSCs and emphasized that the protective effect of BMSCs may be due to paracrine factors. In this study, we aimed to investigate the potential mechanisms of BMSCs to protect NSCs. NSCs were identified by immunocytochemistry. The oxidative stress environment was simulated by H₂ O₂ (50, 100, 200 μM) for 2 h. The apoptotic rate of the NSCs was detected via flow cytometry. Lactate dehydrogenase (LDH), malondialdehyde (MDA), and superoxide dismutase (SOD) activity were evaluated via corresponding assay kits. Western blot was used to detect the expressions of Notch1, HES1, caspase-3, cleave caspase-3, Bax, and Bcl-2. We found that H₂ O₂ could significantly induce the apoptosis of NSCs, increase LDH, MDA levels, and decrease SOD activity by activating the Notch1 signaling pathway. DAPT (the specific blocker of Notch1) and BMSC-conditioned medium (BMSC-CM) could significantly prevent the apoptotic effect and oxidative stress injury on NSCs that were treated with H₂ O₂ . We also revealed that BMSC-CM could decrease the expression of Notch1, Hes1, cleave caspase-3, Bax, and increases the expression of Bcl-2 in NSCs, which was induced by H₂ O₂ . These results have revealed that BMSC-CM can neutralize the effect against oxidative stress injury on the apoptosis of NSCs by inhibiting the Notch1 signaling pathway.

Mesenchymal stem cells for hemorrhagic stroke: status of preclinical and clinical research

Significant progress has been made during the past few decades in stem cell therapy research for various diseases and injury states; however this has not been overwhelmingly translated into approved therapies, despite much public attention and the rise in unregulated ‘regenerative clinics’. In the last decade, preclinical research focusing on mesenchymal stem/stromal cell (MSC) therapy in experimental animal models of hemorrhagic stroke has gained momentum and has led to the development of a small number of human trials. Here we review the current studies focusing on MSC therapy for hemorrhagic stroke in an effort to summarize the status of preclinical and clinical research. Preliminary evidence indicates that MSCs are both safe and tolerable in patients, however future randomized controlled trials are required to translate the promising preclinical research into an effective therapy for hopeful patients.

Bone marrow mesenchymal stem cells conditioned medium protects VSC4.1 cells against 2,5-hexanedione-induced autophagy via NGF-PI3K/Akt/mTOR signaling pathway

We aimed to investigate the effects of bone marrow mesenchymal stem cell conditioned medium (BMSC-CM) in preventing 2,5-hexanedione (HD)-induced damage to motoneurons, and examined the molecular mechanisms that mediate these effects. VSC4.1 cells were exposed to 25 mM HD for 24 h followed by incubation with DMEM for 24 h. HD-treated cells were incubated with BMSC-CM at varied concentrations. Incubation with BMSC-CM ameliorated the decreased cell viability and reduced LDH release from cells exposed to HD. BMSC-CM suppressed the elevated number of autophagic vacuoles, cells with LC3 puncta, increased LC3-II/LC3-I ratio, and decreased p62 caused by HD exposure. BMSC-CM elevated NGF and p-TrkA expressions in HD-treated cells. Administration of NGF inhibited autophagy, an effect that was similar to that observed after BMSC-CM treatment; this effect was abolished by the addition of NGF-neutralizing antibodies. BMSC-CM or NGF elevated p-protein kinase B (Akt) and p-mammalian target of rapamycin (mTOR) in HD-exposed cells, which was interrupted by TrkA inhibitor, K252a and mTOR inhibitor, rapamycin. BMSC-CM prevented HD-induced autophagic cell damage in VSC4.1 cells. The neuroprotective effect of BMSC-CM appeared to be at least partly associated with its ability to trigger the NGF-phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR signaling pathway.

Mesenchymal Stem Cell-Conditioned Medium Reduces Disease Severity and Immune Responses in Inflammatory Arthritis

We evaluated the therapeutic potential of mesenchymal stem cell-conditioned medium (CM-MSC) as an alternative to cell therapy in an antigen-induced model of arthritis (AIA). Disease severity and cartilage loss were evaluated by histopathological analysis of arthritic knee joints and immunostaining of aggrecan neoepitopes. Cell proliferation was assessed for activated and naïve CD4+ T cells from healthy mice following culture with CM-MSC or co-culture with MSCs. T cell polarization was analysed in CD4+ T cells isolated from spleens and lymph nodes of arthritic mice treated with CM-MSC or MSCs. CM-MSC treatment significantly reduced knee-joint swelling, histopathological signs of AIA, cartilage loss and suppressed TNFα induction. Proliferation of CD4+ cells from spleens of healthy mice was not affected by CM-MSC but reduced when cells were co-cultured with MSCs. In the presence of CM-MSC or MSCs, increases in IL-10 concentration were observed in culture medium. Finally, CD4+ T cells from arthritic mice treated with CM-MSC showed increases in FOXP3 and IL-4 expression and positively affected the Treg:Th17 balance in the tissue. CM-MSC treatment reduces cartilage damage and suppresses immune responses by reducing aggrecan cleavage, enhancing Treg function and adjusting the Treg:Th17 ratio. CM-MSC may provide an effective cell-free therapy for inflammatory arthritis.