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Background/Aim: Peripheral neurotoxicity is a dose-limiting factor of many chemotherapeutic agents, including cisplatin. Mesenchymal stem cells are promising for the treatment of several neurological disorders, and our aim was to verify the neuroprotective potential of human mesenchymal stem cells (hMSCs) on dorsal root ganglia (DRG) exposed to cisplatin. Materials and Methods: DRG were exposed to different cisplatin concentrations and then co-cultured with hMSCs or with hMSC-conditioned medium. Results: hMSCs showed a neuroprotective effect on cisplatininduced death of DRG, mediated by direct contact. Moreover, DRG exhibited an MSC-dependent promotion of neurite outgrowth, in particular at early time points. For this effect, the expression of Neurite Outgrowth Inhibitor (NOGO) and Myelin Associated Glycoprotein (MAG) by hMSCs was pivotal. Conclusion: hMSCs are a promising tool for reducing the neurotoxic effect of cisplatin.

Neurobasal medium (NBM) is a widely used medium for neuronal cultures, originally formulated to support survival of rat hippocampal neurons, but then optimized for several other neuronal subtypes. In the present study, the toxic effect of NBM on long-term cortical neuron cultures has been reported and investigated. A significant neuronal cell loss was observed 24 h after the total medium change performed at days in vitro 10. The neurotoxic effect was specifically because of NBM-A, a commercially derived modification of classic NBM, as neurons exposed to minimum essential medium for 24 h did not show the same mortality rate. We showed that the toxic effect was mediated by the N-methyl-d-aspartate receptor (NMDAr) as its inactivation partly prevented NBM-induced neuronal loss, and the addition of NMDAr activators, such as l-cysteine or glycine to minimum essential medium, reproduced the same toxicity rate observed in NBM. Besides the toxicity associated with NMDAr activation, the decreased antioxidative defenses also worsen (because of glutathione depletion) neuronal death, thus amplifying the effect of excitotoxic amino acids. Indeed, glutathione supplementation by the addition of its precursor N-acetyl-cysteine resulted in an increase in neuronal survival that partially prevented NBM-A toxicity. These results evidenced, on the one hand, the unsuitability of NBM-A for long-term neuronal culture, and on the other, they highlight the importance of selection of more suitable culture conditions.

The clinical usability of pancreatic islet transplantation for the treatment of type I diabetes, despite some encouraging results, is currently hampered by the short lifespan of the transplanted tissue. In vivo studies have demonstrated that co-transplantation of Mesenchymal Stem Cells (MSCs) with transplanted pancreatic islets is more effective with respect to pancreatic islets alone in ensuring glycemia control in diabetic rats, but the molecular mechanisms of this action are still unclear. The aim of this study was to elucidate the molecular mechanisms of the positive effect of MSCs on pancreatic islet functionality by setting up direct, indirect and mixed co-cultures. MSCs were both able to prolong the survival of pancreatic islets, and to directly differentiate into an "insulin-releasing" phenotype. Two distinct mechanisms mediated these effects: i) the survival increase was observed in pancreatic islets indirectly co-cultured with MSCs, probably mediated by the trophic factors released by MSCs; ii) MSCs in direct contact with pancreatic islets started to express Pdx1, a pivotal gene of insulin production, and then differentiated into insulin releasing cells. These results demonstrate that MSCs may be useful for potentiating pancreatic islets' functionality and feasibility.

There are promising studies which demonstrate that Mesenchymal Stem Cells (MSCs) are able to release neutrophic factors, to increase neuronal survival and as a consequence to repair nervous damages. For these reasons MSCs based therapeutic approach was proposed for diseases of both central and peripheral nervous system. In order to evaluate a putative positive effect of MSCs on neuronal damage recovery, two different experimental models were set up using cortical and sensory neurons. The toxic stimuli used were: Glutamate, whose toxicity is associated to Multiple Sclerosis; Cisplatin and Paclitaxel, chemotherapic drugs, which induce peripheral neuropathies. For the evaluation of the effect of MSCs, direct and indirect co-cultures were set up with rat MSCs (rMSCs); rMSCs Conditioned Medium effect was also evaluated. Our results demonstrate an important difference between cortical and sensory neurons in fact in term of susceptibility cortical neurons are much more sensible to drugs treatment. About sensory neurons we observed a protective action in direct co-cultures on Cisplatin and Glutamate treated neurons and in indirect co-cultures on Paclitaxel treated neurons; conditioned medium didn’t have any protective action. However direct and indirect co-cultures and condition medium were unable to protect cortical neurons form toxic drugs. These data could indicate that a possible MSCs based therapy would be more promising for treating peripheral nervous system diseases rather than central one.

Transplantation of pancreatic islets is an innovative and promising clinical option to treat patients with type 1 diabetes [1]. This is a minimally invasive therapeutic approach, which allows a good metabolic control and a long-term insulin independence [2]. The therapeutic feasibility of pancreatic islets transplantation is however limited by the poor yield of pancreatic islet explants and even more the immune graft rejection, which have as a consequence the very limited lifespan of transplanted tissue [3]. To avoid these side effects besides the treatment with immunosuppressive drugs, promising results have been obtained in vivo with the use of Mesenchymal Stem cells (MSCs), already known in literature to be able to support the cellular survival through direct contact [4, 5] by the release of trophic factors [6], and by their immunomodulatory properties [7]. By means of these particular features it can be surmised that MSCs may improve the survival of pancreatic islets and, therefore, the success of the transplantation. Several in vivo studies have demonstrated the positive effect of islet-MSC co-transplantation in diabetic rats, but the mechanisms of these encouraging results are still unknown [8]. In this in vitro study we shed light on the concealed molecular mechanisms of MSC positive action, by analyzing the effect of both direct and indirect co-cultures of rat MSCs with pancreatic islets.

Oxygen and glucose deprivation (OGD) due to ischemic events or trauma in the brain result in neuronal loss. The therapeutic approaches available for the treatment of these conditions are not and often the outcome is unfavorable for the patient or at least unpredictable. Stem cells could be useful for the treatment of OGD injured-neurons. Mesenchymal Stem Cells (MSCs), isolated from bone marrow as well as from various tissues, have poor immunogenicity and neuroprotective properties being able to alleviate ischemic brain injuries in animal models. The Endothelial Progenitor Cells (EPCs) are present at low frequencies both in the bone marrow and in the peripheral blood and can be mobilized by the administration of drugs such as statins. They are thought to play a role in the recovery of cerebrovasculature integrity after stroke. In the present study we evaluated the potential neuroprotective effect of human MSC and human EPCs on rat embryonic cortical neurons injured by OGD. OGD was induced by incubating the cortical neurons in a hypoxia chamber in a 95% N2 + 5% CO2 atmosphere at 37°C without glucose for periods ranging from 30 minutes and 6 hours. When the neurons were returned in normoxic atmosphere they were 1) co-cultured with either MSCs or EPCs seeded on a cell culture avoiding neurons and MSCs or EPCs direct contact while sharing the same medium, or 2) cultured in a medium previously conditioned by either MSCs or EPCs. Neuronal survival was evaluated by MTT assay and viable cellular counting. Also neuronal morphology was taken into account to evaluate the potential MSCs and EPCs neuroprotective effect. Both MSCs and EPCs increased neuronal survival after ODG. This effect was observed in absence of a direct contact between MSCs or EPCs and the injured neurons, suggesting that the release of soluble factors may be the main mechanism of action. In conclusion both MSCs and EPCs could represent a potential therapeutic approach for the treatment of brain ischemic inju

Multiple Sclerosis (MS) is a crippling chronic disease of the Central Nervous System caused by the presence of self-antibodies which progressively damage axonal myelin sheath, leading to axonal transmission impairment and to the development of neurological symptoms. MS is characterized by a Relapsing-Remitting course, and current therapies rely only on the use of immunosuppressive drugs, which are however unable to reverse disease progression. Encouraging results have been obtained in preclinical studies with the administration of Mesenchymal Stem Cells (MSCs) before disease onset (Zappia et al., 2005). Here, we investigate the therapeutic potential of MSC administration after disease onset into an animal model of MS, represented by Dark Agouti rats affected by chronic Relapsing-Remitting Experimental Autoimmune Encephalomyelitis (EAE) (Cavaletti et al., 2004). 106 MSC were intravenously injected in EAE rats after disease onset. Clinical score was assessed daily, and after 45 days rats were sacrificed and histological analysis of spinal cords performed to evaluate the demyelinating lesions. After the first peak of disease, no further relapses were observed in EAE rats treated with MSCs, differently from what observed in EAE group. Histological analysis demonstrated the presence of demyelinated plaques in spinal cords of EAE rats, (Luxol fast Blue staining and anti-MBP immunohystochemistry). On the contrary the therapeutic schedule with MSCs significantly reduces the number and the extension of demyelinated areas in the spinal cords, confirming clinical score evaluations. These results demonstrated that MSCs ameliorate the clinical course of EAE and hamper the disease relapsing by reducing the areas of demyelinated lesions.

Over the last few years the therapeutic approach to demyelinating diseases has radically changed, strategies having been developed aimed at partnering the classic symptomatic treatments with the most advanced regenerative medicine tools. At first, the transplantation of myelinogenic cells, Schwann cells or oligodendrocytes was suggested, but the considerable technical difficulties, (poor availability, difficulties in harvesting and culturing, and the problem of rejection in the event of non-autologous sources), shifted attention towards more versatile cellular types, such as Mesenchymal Stem Cells (MSCs). Recent studies have already demonstrate both in vitro and in vivo that glially-primed MSCs (through exposure to chemical cocktails) have myelogenic abilities. In spite of a large number of papers on glially-differentiated MSCs, little is known about the ability of undifferentiated MSCs to myelinate axons and processes. Here we have demonstrated that also undifferentiated MSCs have the ability to myelinate, since they induce the myelination of rat DRG neuron processes after direct co-culturing. In this process a pivotal role is performed by the p75 receptor. © 2013 Elsevier Inc.

The induction of a peripheral neuropathy is a very common side effect of many chemotherapeutic agents, including platinum compounds, and it often represents the dose limiting factor for drug clinical use. Several strategies have been suggested to reduce drug neurotoxicity without affecting the antineoplastic potential, but up to now results were not encouraging. Recently, it has been demonstrated that Mesenchymal Stem Cells (MSCs) are able to promote the survival and the maturation of untreated sensory neurons of dorsal root ganglia (DRG), which represent also the target of drug neurotoxicity. Aim of this work is to verify the neuroprotective potential of MSCs on rat DRG exposed to cisplatin (CDDP), a chemotherapeutic and neurotoxic agent. DRG post-mitotic explants from E15 rat embryos were exposed for 24 hours to different cisplatin concentrations. After 24 hours, medium was changed and DRG were directly co-cultured with human MSCs (hMSCs) or with hMSCs conditioned medium (hMSC-CM). DRG explants were photographed every day up to 1 month, and the longest neurite of each DRG was measured to evaluate neurotoxicity. DRG survival was estimated by measuring the death area percentage. The survival of CDDP-treated DRG was increased after the co-cultures with hMSCs, and both hMSCs and hMSC-CM were able to improve the neurite outgrowth of untreated and CDDP-treated DRG after 48 hours. This MSC-dependent increase of neurite length was however no longer evident at later times (1 month). This effect on neurite elongation was probably mediated by CSPG, MAG and Nogo, some proteins involved in the modulation of neurite elongation, which resulted expressed and released in the culture medium of hMSCS. Our results demonstrated a neuroprotective effect of hMSCs on CDDP toxicity and evidenced the ability of these cells to modulate neurite elongation. In this way MSCs could represent a possible mean to limit the neurotoxicity on DRG which arises after cisplatin therapy.

Mesenchymal Stem Cells (MSCs) are frequently proposed as potentially suitable for the regenerative therapeutic approach for several neurological diseases both of the central nervous system, such as Multiple Sclerosis, and at the same way also of the peripheral nervous system, thanks to their ability to increase neuronal survival and to release neurotrophic factors. Since there are great differences between neurons of the central and of the peripheral nervous system, in this study we have verified the existence of a different susceptibility of cortical and sensory neurons to the effect of MSCs after different toxic stimuli, in order to mimic the damages observed in some neurological diseases. For this aim we set up direct and indirect co-cultures of MSCs and cortical or sensory neurons previousl exposed to toxic doses of glutamate, as a paradigm of Multiple Sclerosis, or treated with two widely used chemotherapeutic drugs, cisplatin and paclitaxel, which induce peripheral neuropathies. On the same cells we evaluated also the effect of conditioned medium of MSCs, by using morphological and molecular analysis. Neuronal viability was assessed by MTT test and by count of viable cells. Our results demonstrated the protective action of MSC direct and indirect co-cultures only on sensory neurons previously exposed to the toxic agents, while conditioned medium was ineffective to rescue it. On the contrary MSCs failed at all to protect cortical neurons from the drugs used, and their conditioned medium further reduces neuronal viability. We are now investigating the putative interference of MSCs with apoptotic molecules in sensory neurons, while in cortical neurons we are evaluating the possible causes of MSC-medium toxicity by analyzing the factors released. The different effect of MSCs on cortical and sensory neurons protection observed in vitro may be not the same in vivo, where the environments differ, anyway, it suggests to address the use of MSCs against the diseases aff

Multiple sclerosis (MS) is a chronic immuno-mediated inflammatory and demyelinating disease characterised by the presence of both demyelinating lesions and axonal degeneration, which lead to the reduction of nerve conduction velocity and the development of concomitant neurological deficits. Recently, Mesenchymal Stem Cells (MSCs) have been proposed in in vivo studies as promising therapeutic treatment for MS mainly for their capacity to modulate the immune response, moreover, during our previous experiments we found that rat undifferentiated MSC promote Dorsal Root Ganglia neurons survival and maturation. The aim of this study is to verify the potential protective effect of MSCs on an in vitro model of MS represented by rat primary cultures of cortical neurons. Since glutamate excitotoxicity is an important mechanism in neurodegenerative diseases, and it induces neuronal alterations similar to those observed in advanced MS, cortical neurons cultures were treated with different concentrations of glutamate (25, 50, 100, 200 and 500 µM) for 24 hours. After the treatment cortical neurons show a suffering appearance, with damaged axons and cellular degeneration. Neuronal viability, assessed by DAPI staining and by count of viable cells, was glutamate dose-dependent. In order to evaluate the possible positive effect of MSCs on neuronal survival, both direct and indirect co-cultures of MSCs and cortical neurons were set up, and the survival after glutamate treatment analyzed. Cortical neurons treated with glutamate were still suffering after the direct co-cultures with MSCs, while in indirect co-cultures with MSCs neurons were alive, without important signs of axonal degeneration. These preliminary findings suggest that MSCs are able to reduce the cellular death induced by glutamate exposure in cortical neurons and encouraged the further study and characterization of their positive effect

The positive effect of adult undifferentiated mesenchymal stem cells (MSCs) on neuronal survival has already been reported, although the mechanisms by which MSCs exert their effect are still a matter of debate. Here we have demonstrated that MSCs are able to prolong the survival of dorsal root ganglion (DRG) neurons mainly by inhibiting some proteolytic enzymes, and in particular the pathway of metalloproteinases (MMPs), a family of proteins that are involved in many neuronal processes, including survival. The inhibition of MMPs was both direct, by acting on MT-MMP1, and indirect, by acting on those proteins that regulate MMPs' activation, such as Timp-1 and Sparc. The importance of the MMPs' down-regulation for neuronal survival was also demonstrated by using N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycyl hydroxamic acid (NNGH), a wide range inhibitor of metalloproteinases, which was able to increase the survival of DRG neurons in a significant manner. The down-regulation of MMPs, obtained both by MSC contact and by chemical inhibition, led to the inactivation of caspase 3, the executor of apoptotic death in DRG neurons cultured alone, while caspase 7 was found to be irrelevant for the apoptotic process. The capacity of MSCs to prevent apoptosis mainly by inactivating the metalloproteinase pathway is an important finding that sheds light on MSCs' mechanism of action, making undifferentiated MSCs a promising tool for the treatment of many different neurodegenerative pathologies.

Multiple sclerosis (MS) is a chronic immuno-mediated inflammatory and demyelinating disease characterised by both demyelinating lesions and axonal degeneration, leading to the reduction of nerve conduction velocity and the development of neurological deficits. Recently, some in vivo studies have proposed Mesenchymal Stem Cells (MSCs) as promising therapeutic treatment for MS mainly for their capacity to modulate the immune response, although it is not yet known if other mechanisms, different from immune modulation, are involved in MSCs positive. We investigate the therapeutic potential and the clinical effects of MSCs by using an animal model of multiple sclerosis, represented by Lewis rats affected by acute experimental autoimmune encephalomyelitis (EAE). MSCs were intravenously administered immediately after EAE induction (T0) or one week later (T7), in both the cases before disease onset. The clinical course of acute EAE was ameliorated only in EAE animals in which MSCs were injected one week after disease induction, while EAE rats and EAE rats with MSCs injected at T0 showed similar clinical scores. Moreover, the EAE rats which received MSCs at T7 displayed a cytokines pattern expression comparable to untreated control rats, while both EAE group and EAE+MSCs (T0) group showed an increased expression of pro-inflammatory cytokines. These results evidenced that the intravenous administration of MSCs one week after EAE induction (and before disease onset) induces the amelioration of the clinical scores of EAE-rats, thus supporting the potential role for MSCs in cell therapy in multiple sclerosis. We are now investigating the molecular mechanisms of this positive effect, focusing our attention on the Metalloproteinases pathway, involved in multiple sclerosis and modulated by MSCs.

The involvement of the Mitogen-Activated Protein Kinases (MAPKs) family in platinum derivative-induced peripheral neuropathy has already been demonstrated. In particular, it has been evidenced that in Dorsal Root Ganglion (DRG) neurons prolonged exposure to oxaliplatin (OHP) induces early activation of p38 and ERK1/2, which mediate neuronal apoptosis, while the neuroprotective action of JNK/Sapk is downregulated by the drug treatment. In this study, the exposure of OHP-treated neurons to a neuroprotective stimulus, represented by a high dose of NGF, counteracts OHP-induced neuronal mortality. This effect was achieved by restoring the MAPK activation existing in untreated control cells. Increased viability occurred also after the administration of retinoic acid (RA), a pro-differentiative agent able to activate both JNK/Sapk and ERK1/2. The use of specific chemical inhibitors of MAPKs confirms the importance of this class of proteins for the neuroprotective pathway, since they reverse the protective effect. In summary, our findings assess the validity of MAPKs as the target of neuroprotective therapies during chemotherapeutic treatment. Moreover they also describe a double role for ERK1/2, depending on cellular stimulation, since it mediates neuronal apoptosis after OHP exposure. However, it is also important, as is JNK/Sapk, in preserving the correct cellular differentiation that is pivotal for neuronal survival

The aim of this work was the study of trophic properties of MSCs on sensitive neurons in culture. In particular we tested the MSCs’s capacity of myelination in order to use these cells for demyelinating disease therapies. MSCs are adult, multipotent and undifferentiated stem cells derived from bone marrow and isolated by plastic adherence. DRG from 15-day old Sprague-Dawley rat embryos were removed and cultured on a substrate of rat-tail collagen in AN2 medium supplemented with 5 ng/ml NGF. In a previous study our lab demonstrated that MSCs are able to rescue DRG dissociated neurons and to support their long-lasting survival in presence of NGF when co-cultured at direct contact. In this work we characterized cultured DRG neurons cellular death by means of cytofluorimetric, immunofluorescences and electron microscopy tecniques, demonstrating that neuronal cultures died for apoptosis and that MSCs protected neurons from this kind of death. We then investigate if the trophic role of MSCs was mediated by the release of soluble factors. We demonstrated that cocultures MSCs conditioned medium didn’t improve neuronal survival. We also investigated if MSC express constitutively on their surface some molecules able to improve neuronal survival by plating neurons on paraformaldehyde fixed MSCs (0,5%, 4%) and even in this case neurons died as the untreated control neurons. Therefore we concluded that the effect of MSCs on neuronal survival was mainly mediated by direct contact. We also observe in electron microscopy some point of contact between MSCs and neurons, and using a vital fluorescent cytoplasmatic stain we demonstrated the possibility of a passage of material between the two populations. By immunofluorescences we observed the presence only in cocultures of connexin 32, 36 and 42, which are proteins involved in neuronal gap junction formation. Connexin 32 was found in correspondence of neuronal and MSC membrane, suggesting that there were connection between neurons and

Chemotherapy induced Peripheral Neuropathy (CIPN) is a a well known complication limiting Cisplatin (CDDP) and Docetaxel (DOCE) chemotherapy in patients with cancer. Erythropoietin (EPO) is an heamatopoietic growth factor that has been reported to display neurothrophic properties, in particular it has proved to be neuroprotective in several rodent models of nervous system damage, including CDDP induced peripheral neuropathy. In this study we evaluated the neuroprotective ability of EPO against CDDP and DOCE induced neurotoxicity in primary cultures of sensitive neurons dissociated from Dorsal Root Ganglia (DRG) obtained from 15-day-old rat embryos, aiming to investigate the mechanism underlying EPO neuroprotective action. Briefly, primary cultures of sensitive neurons have been exposed to CDDP (25M), DOCE (100nM) or to the same doses of the chemotherapics but in the presence of EPO (10nM). In this in vitro model EPO turned out to be protective against both CDDP and DOCE induced neurotoxicity, in fact an increased neuronal survival was evident in cultures exposed to the combination treatment with CDDP plus EPO and DOCE plus EPO. Several evidences suggest that AKT pathway may play an important role in EPO neuroprotective action. Therefore we analyzed by western blot the levels of expression and activation (phosphorylation) of AKT in neurons exposed to the CDDP, DOCE or to the cotreatment with EPO. Results obtained indicated that modulation of the levels of phosphorylated AKT (pAKT) occurs following 14 hours treatment with CDDP, when a sharp decrease in the levels of activated AKT was highlighted, on the contrary DOCE induced only a sligth increase in the level of pAKT. Cotreatment with EPO was able to partially prevent CDDP induced decrease in the level of pAKT. Using a specific inhibitor of AKT activation (Wortmannin) we therefore investigate the role of AKT in EPO neuroprotection. The presence of Wortmannin (100nM) did prevent EPO neuroprotective action against CDD

An unsolved question is how platinum derivatives used for solid cancer therapy cause peripheral neuropathy in patients and apoptosis in "in vitro" models of chemotherapy-induced peripheral neuropathy. DRG neurons from E15 rat embryos were treated with toxic doses of oxaliplatin or cisplatin. Here, the role of MAPKs in neuronal apoptosis was studied. Both oxaliplatin and cisplatin induced a dose-dependent neuronal apoptosis, modulated by the proteins of Bcl-2 family. Regarding MAPKs, platinum derivatives activated p38 while they reduced the active form and the total amount of JNK/Sapk. Both oxaliplatin and cisplatin activated ERKs at early stages, although they behaved differently at later stages. By using specific inhibitors of the various MAPKs it was demonstrated that the platinum-induced neuronal apoptosis is mediated by early p38 and ERK1/2 activation, while JNK/Sapk has a neuroprotective role. These results suggest a role for the different MAPKs in peripheral neuropathies characterized by apoptosis of DRG neurons.

Mesenchymal stem cells (MSCs) have been found to be useful in the management of different models of neurological diseases. In the present study, we tested the possible protective effect of MSCs on sensory dorsal root ganglia (DRG) explants exposed to the toxic effect of CDDP, a widely used anticancer drug. DRG explants cultured on a collagen layer and exposed to NGF for 2 h (differentiating neurons) or for 5 days (fully differentiated neurons) were treated with CDDP and subsequently co-cultured with MSCs. MSCs were able to support the survival of both differentiating and fully differentiated DRG neurons up to 2 months after the drug treatment, reducing the CDDP-induced death of DRG neurons. MSCs were, however, unable to restore the correct length of DRG neurites compromised by CDDP treatment. The positive effect on neuronal survival was exerted through the contact between DRG and MSCs, and not mediated by neurotrophic factors released by the MSCs. Our observations could represent a starting point for designing a neuroprotective strategy to limit CDDP induced neuropathy without interfering with its anticancer properties.