Stem Cell Conditioned Medium Treatment for Canine Spinal Cord Injury: Pilot Feasibility Study.

Spinal cord injury (SCI) involves nerve damage and often leads to motor, sensory and autonomic dysfunctions. In the present study, we have designed a clinical protocol to assess the feasibility of systemic delivery of allogenic canine bone marrow tissue-derived mesenchymal stem cell conditioned medium (BMMSC CM) to dogs with SCI. Four client-owned dogs with chronic SCI lasting more than six months underwent neurological and clinical evaluation, MRI imaging and blood tests before being enrolled in this study. All dogs received four intravenous infusions with canine allogenic BMMSC CM within one month. Between the infusions the dogs received comprehensive physiotherapy, which continued for three additional months. No adverse effects or complications were observed during the one, three and six months follow-up periods. Neither blood chemistry panel nor hematology profile showed any significant changes. All dogs were clinically improved as assessed using Olby locomotor scales after one, three and six months of BMMSC CM treatment. Furthermore, goniometric measurements revealed partial improvement in the range of joint motion. Bladder function improved in two disabled dogs. We conclude that multiple delivery of allogenic cell-derived conditioned medium to dogs with chronic SCI is feasible, and it might be clinically beneficial in combination with physiotherapy.

Transplantation of Neural Precursors Derived from Induced Pluripotent Cells Preserve Perineuronal Nets and Stimulate Neural Plasticity in ALS Rats.

A promising therapeutic strategy for amyotrophic lateral sclerosis (ALS) treatment is stem cell therapy. Neural progenitors derived from induced pluripotent cells (NP-iPS) might rescue or replace dying motoneurons (MNs). However, the mechanisms responsible for the beneficial effect are not fully understood. The aim here was to investigate the mechanism by studying the effect of intraspinally injected NP-iPS into asymptomatic and early symptomatic superoxide dismutase (SOD)1G93A transgenic rats. Prior to transplantation, NP-iPS were characterized in vitro for their ability to differentiate into a neuronal phenotype. Motor functions were tested in all animals, and the tissue was analyzed by immunohistochemistry, qPCR, and Western blot. NP-iPS transplantation significantly preserved MNs, slowed disease progression, and extended the survival of all treated animals. The dysregulation of spinal chondroitin sulfate proteoglycans was observed in SOD1G93A rats at the terminal stage. NP-iPS application led to normalized host genes expression (versican, has-1, tenascin-R, ngf, igf-1, bdnf, bax, bcl-2, and casp-3) and the protection of perineuronal nets around the preserved MNs. In the host spinal cord, transplanted cells remained as progenitors, many in contact with MNs, but they did not differentiate. The findings suggest that NP-iPS demonstrate neuroprotective properties by regulating local gene expression and regulate plasticity by modulating the central nervous system (CNS) extracellular matrix such as perineuronal nets (PNNs).

Concise review: reactive astrocytes and stem cells in spinal cord injury: good guys or bad guys?

Spinal cord injury (SCI) usually results in long lasting locomotor and sensory neuron degeneration below the injury. Astrocytes normally play a decisive role in mechanical and metabolic support of neurons, but in the spinal cord they cause injury, exerting well-known detrimental effects that contribute to glial scar formation and inhibition of axon outgrowth. Cell transplantation is considered a promising approach for replacing damaged cells and promoting neuroprotective and neuroregenerative repair, but the effects of the grafted cells on local tissue and the regenerative properties of endogenous neural stem cells in the injured spinal cord are largely unknown. During the last 2 decades cumulative evidence from diverse animal models has indicated that reactive astrocytes in synergy with transplanted cells could be beneficial for injury in multiple ways, including neuroprotection and axonal growth. In this review, we specifically focus on the dual opposing roles of reactive astrocytes in SCI and how they contribute to the creation of a permissive environment when combined with transplanted cells as the influential components for a local regenerative niche. Modulation of reactive astrocyte function might represent an extremely attractive new therapy to enhance the functional outcomes in patients.

Treatment of alkali-injured cornea by cyclosporine A-loaded electrospun nanofibers - An alternative mode of therapy.

In this study we tried to develop a new approach to suppress inflammation and neovascularization in the alkali-injured rabbit cornea. For this reason Cyclosporine A (CsA)-loaded electrospun nanofibers were transferred onto the ocular surface injured with alkali (0.25 N NaOH). Damaged corneas were divided into the following groups: untreated, treated with CsA eye drops, treated with nanofibers drug-free and treated with CsA-loaded nanofibers. Healthy rabbit corneas served as controls. Drug-free nanofibers and CsA-loaded nanofibers were transferred onto the damaged corneal surface immediately after the injury and sutured to conjunctiva. On day five after the injury the nanofibers were removed. The animals from all groups were sacrificed on day twelve after the injury. The extent of the inflammatory reaction and corneal healing were examined macroscopically, immunohistochemically and biochemically. The central corneal thickness was measured using an ultrasonic pachymeter. When compared with untreated injured corneas, injured corneas treated with drug-free nanofibers or injured corneas treated with CsA eye drops, the number of CD3-positive cells (T lymphocytes) and the production of pro-inflammatory cytokines were strongly reduced in corneas treated with CsA-loaded nanofibers, which was associated with the significantly decreased expression of matrix metalloproteinase 9, inducible nitric oxide synthase, vascular endothelial growth factor and active caspase-3. CsA-loaded nanofibers effectively suppressed corneal inflammation and corneal neovascularization. Central corneal thickness restored to levels before injury only in corneas treated with CsA-loaded nanofibers. Corneal transparency was highly restored in these corneas. It is suggested that the beneficial effect of CsA-loaded nanofibers was associated with the continuous release of CsA from nanofibers and continuous affection of damaged cornea by CsA. The suture of nanofibers to conjunctiva and the closed eyes contributed to beneficial corneal healing. This is in contrast to CsA eye drops, which are quickly washed from the ocular surface and the contact of CsA with the damaged cornea was limited. In conclusion, the approach with CsA-loaded nanofibers could represent an effective alternative mode of therapy for corneal chemical burns.

Mesenchymal Stem Cells Preserve Working Memory in the 3xTg-AD Mouse Model of Alzheimer's Disease.

The transplantation of stem cells may have a therapeutic effect on the pathogenesis and progression of neurodegenerative disorders. In the present study, we transplanted human mesenchymal stem cells (MSCs) into the lateral ventricle of a triple transgenic mouse model of Alzheimer's disease (3xTg-AD) at the age of eight months. We evaluated spatial reference and working memory after MSC treatment and the possible underlying mechanisms, such as the influence of transplanted MSCs on neurogenesis in the subventricular zone (SVZ) and the expression levels of a 56 kDa oligomer of amyloid ß (Aß*56), glutamine synthetase (GS) and glutamate transporters (Glutamate aspartate transporter (GLAST) and Glutamate transporter-1 (GLT-1)) in the entorhinal and prefrontal cortices and the hippocampus. At 14 months of age we observed the preservation of working memory in MSC-treated 3xTg-AD mice, suggesting that such preservation might be due to the protective effect of MSCs on GS levels and the considerable downregulation of Aß*56 levels in the entorhinal cortex. These changes were observed six months after transplantation, accompanied by clusters of proliferating cells in the SVZ. Since the grafted cells did not survive for the whole experimental period, it is likely that the observed effects could have been transiently more pronounced at earlier time points than at six months after cell application.

Intrathecal delivery of mesenchymal stromal cells protects the structure of altered perineuronal nets in SOD1 rats and amends the course of ALS.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder resulting in a lethal outcome. We studied changes in ventral horn perineuronal nets (PNNs) of superoxide dismutase 1 (SOD1) rats during the normal disease course and after the intrathecal application (5 × 10(5) cells) of human bone marrow mesenchymal stromal cells (MSCs) postsymptom manifestation. We found that MSCs ameliorated disease progression, significantly improved motor activity, and prolonged survival. For the first time, we report that SOD1 rats have an abnormal disorganized PNN structure around the spinal motoneurons and give different expression profiles of chondroitin sulfate proteoglycans (CSPGs), such as versican, aggrecan, and phosphacan, but not link protein-1. Additionally, SOD1 rats had different profiles for CSPG gene expression (Versican, Hapln1, Neurocan, and Tenascin-R), whereas Aggrecan and Brevican profiles remained unchanged. The application of MSCs preserved PNN structure, accompanied by better survival of motorneurons. We measured the concentration of cytokines (IL-1α, MCP-1, TNF-α, GM-CSF, IL-4, and IFN-γ) in the rats' cerebrospinal fluid and found significantly higher concentrations of IL-1α and MCP-1. Our results show that PNN and cytokine homeostasis are altered in the SOD1 rat model of ALS. These changes could potentially serve as biological markers for the diagnosis, assessment of treatment efficacy, and prognosis of ALS. We also show that the administration of human MSCs is a safe procedure that delays the loss of motor function and increases the overall survival of symptomatic ALS animals, by remodeling the recipients' pattern of gene expression and having neuroprotective and immunomodulatory effects.

Alzheimer's Disease: Mechanism and Approach to Cell Therapy.

Alzheimer's disease (AD) is the most common form of dementia. The risk of AD increases with age. Although two of the main pathological features of AD, amyloid plaques and neurofibrillary tangles, were already recognized by Alois Alzheimer at the beginning of the 20th century, the pathogenesis of the disease remains unsettled. Therapeutic approaches targeting plaques or tangles have not yet resulted in satisfactory improvements in AD treatment. This may, in part, be due to early-onset and late-onset AD pathogenesis being underpinned by different mechanisms. Most animal models of AD are generated from gene mutations involved in early onset familial AD, accounting for only 1% of all cases, which may consequently complicate our understanding of AD mechanisms. In this article, the authors discuss the pathogenesis of AD according to the two main neuropathologies, including senescence-related mechanisms and possible treatments using stem cells, namely mesenchymal and neural stem cells.

The Anti-Inflammatory Compound Curcumin Enhances Locomotor and Sensory Recovery after Spinal Cord Injury in Rats by Immunomodulation.

Well known for its anti-oxidative and anti-inflammation properties, curcumin is a polyphenol found in the rhizome of Curcuma longa. In this study, we evaluated the effects of curcumin on behavioral recovery, glial scar formation, tissue preservation, axonal sprouting, and inflammation after spinal cord injury (SCI) in male Wistar rats. The rats were randomized into two groups following a balloon compression injury at the level of T9-T10 of the spinal cord, namely vehicle- or curcumin-treated. Curcumin was applied locally on the surface of the injured spinal cord immediately following injury and then given intraperitoneally daily; the control rats were treated with vehicle in the same manner. Curcumin treatment improved behavioral recovery within the first week following SCI as evidenced by improved Basso, Beattie, and Bresnahan (BBB) test and plantar scores, representing locomotor and sensory performance, respectively. Furthermore, curcumin treatment decreased glial scar formation by decreasing the levels of MIP1α, IL-2, and RANTES production and by decreasing NF-κB activity. These results, therefore, demonstrate that curcumin has a profound anti-inflammatory therapeutic potential in the treatment of spinal cord injury, especially when given immediately after the injury.

[Stem cells in orthopaedics]. / Kmenové bunky v ortopedii.

Sharing new ideas and approaches is needed to advance basic scientific research as well as the clinical application of stem cells. In this newsletter we present the current knowledge in stem cell research and therapy within the field of orthopaedics, presenting the definitions, types and sources of the stem cells. The second part of this newsletter focuses on the clinical application of stem cells in the therapy of tissues with very limited capacity for self-regeneration; this includes tendons and ligaments, particularly found in rotator cuff rupture. The sever problems associated with articular cartilage repair have lead to the need for the development of clinical research, with the aim of finding efficient clinical applications of stem cell therapy in cartilage defects and osteoarthritis. However in addition to this, such therapy could be used for the regeneration of bone, as in bone defect repair. The clinical outcome of stem cell therapy is a promising option for the treatment of cartilage, bone and tendon defects; however an increased sample size and additional long-term prospective randomised studies are needed to confirm these preliminary results.

[New options for therapeutic revascularization in lower extremity limb ischemia linked to the diabetic foot syndrome by autologous stem cell transplantation]. / Nové moznosti terapeutické revaskularizace u ischemické choroby dolních koncetin v rámci syndromu diabetické nohy autologní transplantací kmenových bunek.

Type 2 diabetes incidence is growing worldwide. It is in up to 50% cases linked with diabetic foot syndrome. This is associated with peripheral neuropathy and peripheral artery disease which increases risk of defects with impaired healing. Resulting high number of amputations has major influence on the quality of life and constitutes serious clinical issue. In recent years numerous clinical studies have shown positive effect of new treatment modality using regenerative potential of the autologous stem cells transplantation. This review tries to summarize existing results of therapeutic revascularization using stem cell and to outline mechanism of their action.

Comparison of the effect of stem cell therapy and percutaneous transluminal angioplasty on diabetic foot disease in patients with critical limb ischemia.

BACKGROUND AIMS: The aim of our study was to compare the effect of autologous stem cell therapy (SCT) and percutaneous transluminal angioplasty (PTA) on diabetic foot disease (DFD) in patients with critical limb ischemia (CLI). METHODS: Thirty-one patients with DFD and CLI treated by autologous stem cells and 30 patients treated by PTA were included in the study; 23 patients with the same inclusion criteria who could not undergo PTA or SCT formed the control group. Amputation-free survival, transcutaneous oxygen pressure (TcPO2) and wound healing were assessed over 12 months. RESULTS: Amputation-free survival after 6 and 12 months was significantly greater in the SCT and PTA groups compared with controls (P = 0.001 and P = 0.0029, respectively) without significant differences between the active treatment groups. Increase in TcPO2 did not differ between SCT and PTA groups until 12 months (both Ps < 0.05 compared with baseline), whereas TcPO2 in the control group did not change over the follow-up period. More healed ulcers were observed up to 12 months in the SCT group compared with the PTA and control groups (84 versus 57.7 versus 44.4 %; P = 0.042). CONCLUSIONS: Our study showed comparable effects of SCT and PTA on CLI, a major amputation rate that was superior to conservative therapy in patients with diabetic foot and an observable effect of SCT on wound healing. Our results support SCT as a potential promising treatment in patients with CLI and diabetic foot.

Human multipotent mesenchymal stem cells improve healing after collagenase tendon injury in the rat.

BACKGROUND: Mesenchymal stromal cells attract much interest in tissue regeneration because of their capacity to differentiate into mesodermal origin cells, their paracrine properties and their possible use in autologous transplantations. The aim of this study was to investigate the safety and reparative potential of implanted human mesenchymal stromal cells (hMSCs), prepared under Good Manufacturing Practice (GMP) conditions utilizing human mixed platelet lysate as a culture supplement, in a collagenase Achilles tendon injury model in rats. METHODS: Eighty-one rats with collagenase-induced injury were divided into two groups. The first group received human mesenchymal stromal cells injected into the site of injury 3 days after lesion induction, while the second group received saline. Biomechanical testing, morphometry and semiquantitative immunohistochemistry of collagens I, II and III, versican and aggrecan, neovascularization, and hMSC survival were performed 2, 4, and 6 weeks after injury. RESULTS: Human mesenchymal stromal cell-treated rats had a significantly better extracellular matrix structure and a larger amount of collagen I and collagen III. Neovascularization was also increased in hMSC-treated rats 2 and 4 weeks after tendon injury. MTCO2 (Cytochrome c oxidase subunit II) positivity confirmed the presence of hMSCs 2, 4 and 6 weeks after transplantation. Collagen II deposits and alizarin red staining for bone were found in 6 hMSC- and 2 saline-treated tendons 6 weeks after injury. The intensity of anti-versican and anti-aggrecan staining did not differ between the groups. CONCLUSIONS: hMSCs can support tendon healing through better vascularization as well as through larger deposits and better organization of the extracellular matrix. The treatment procedure was found to be safe; however, cartilage and bone formation at the implantation site should be taken into account when planning subsequent in vivo and clinical trials on tendinopathy as an expected adverse event.

Characterization of human adipose tissue-derived stromal cells isolated from diabetic patient's distal limbs with critical ischemia.

Adipose tissue is an abundant source of autologous adult stem cells that may bring new therapeutic perspectives on the treatment of diabetes and its complications. It is unclear whether adipose tissue-derived stromal cells (ASCs) of diabetic patients, constantly influenced by hyperglycaemia, have the same properties as non-diabetic controls. As an alternative source of ASCs, adipose tissue from distal limbs of diabetic patients with critical ischemia was isolated. ASCs were characterized in terms of cell surface markers, multilineage differentiation and the expression of vascular endothelial growth factor (VEGFA), chemokine-related genes and compared with non-diabetic controls. Flow cytometry analysis confirmed mesenchymal phenotypes in both diabetic and non-diabetic ASCs. Nevertheless, 40% of diabetic and 20% of non-diabetic ASC samples displayed high expressions of fibroblast marker, which inversely correlated with the expression of CD105. In diabetic patients, significantly decreased expression of VEGFA and chemokine receptor CXCR4 was found in fibroblast-positive ASCs, compared with their fibroblast-negative counterparts. Reduced osteogenic differentiation and the downregulation of chemokine CXCL12 were found in fibroblast-negative diabetic ASCs. Both diabetic and non-diabetic ASCs were differentiated into adipocytes and chondrocytes and did not reveal islet-like cell differentiation. According to this study, adipose tissue from distal limbs of diabetic patients is not satisfactory as an autologous ASC source. Hyperglycaemic milieu as well as other metabolic disorders linked to diabetes may have an influence on endogenous stem cell properties. The present study investigated the feasibility of autologous stem cell therapy in diabetic patients. ASCs isolated from the ischemic limb of diabetic patients were found to be less potent when compared phenotypically and functionally to control non-diabetic counterparts with no signs of limb ischemia. High expression of fibroblast markers associated with reduced expression of VEGFA as well as reduced osteogenic differentiation may have an impact on the effectiveness of autologous cell therapies in diabetic patients.

Astroglial networks scale synaptic activity and plasticity.

Astrocytes dynamically interact with neurons to regulate synaptic transmission. Although the gap junction proteins connexin 30 (Cx30) and connexin 43 (Cx43) mediate the extensive network organization of astrocytes, their role in synaptic physiology is unknown. Here we show, by inactivating Cx30 and Cx43 genes, that astroglial networks tone down hippocampal synaptic transmission in CA1 pyramidal neurons. Gap junctional networking facilitates extracellular glutamate and potassium removal during synaptic activity through modulation of astroglial clearance rate and extracellular space volume. This regulation limits neuronal excitability, release probability, and insertion of postsynaptic AMPA receptors, silencing synapses. By controlling synaptic strength, connexins play an important role in synaptic plasticity. Altogether, these results establish connexins as critical proteins for extracellular homeostasis, important for the formation of functional synapses.

Human mesenchymal stem cells modulate inflammatory cytokines after spinal cord injury in rat.

Transplantation of mesenchymal stem cells (MSC) improves functional recovery in experimental models of spinal cord injury (SCI); however, the mechanisms underlying this effect are not completely understood. We investigated the effect of intrathecal implantation of human MSC on functional recovery, astrogliosis and levels of inflammatory cytokines in rats using balloon-induced spinal cord compression lesions. Transplanted cells did not survive at the lesion site of the spinal cord; however, functional recovery was enhanced in the MSC-treated group as was confirmed by the Basso, Beattie, and Bresnahan (BBB) and the flat beam test. Morphometric analysis showed a significantly higher amount of remaining white matter in the cranial part of the lesioned spinal cords. Immunohistochemical analysis of the lesions indicated the rearrangement of the glial scar in MSC-treated animals. Real-time PCR analysis revealed an increased expression of Irf5, Mrc1, Fgf2, Gap43 and Gfap. Transplantation of MSCs into a lesioned spinal cord reduced TNFα, IL-4, IL-1ß, IL-2, IL-6 and IL-12 and increased the levels of MIP-1α and RANTES when compared to saline-treated controls. Intrathecal implantation of MSCs reduces the inflammatory reaction and apoptosis, improves functional recovery and modulates glial scar formation after SCI, regardless of cell survival. Therefore, repeated applications may prolong the beneficial effects induced by MSC application.

Suppression of alkali-induced oxidative injury in the cornea by mesenchymal stem cells growing on nanofiber scaffolds and transferred onto the damaged corneal surface.

The purpose of this study was to investigate whether rabbit bone marrow-derived mesenchymal stem cells (MSCs) effectively decrease alkali-induced oxidative stress in the rabbit cornea. The alkali (0.15 N NaOH) was applied on the corneas of the right eyes and then rinsed with tap water. In the first group of rabbits the injured corneas remained untreated. In the second group MSCs were applied on the injured corneal surface immediately after the injury and eyelids sutured for two days. Then the sutures were removed. In the third group nanofiber scaffolds seeded with MSCs (and in the fourth group nanofibers alone) were transferred onto the corneas immediately after the injury and the eyelids sutured. Two days later the eyelid sutures were removed together with the nanofiber scaffolds. The rabbits were sacrificed on days four, ten or fifteen after the injury, and the corneas were examined immunohistochemically, morphologically, for the central corneal thickness (taken as an index of corneal hydration) using an ultrasonic pachymeter and by real-time PCR. Results show that in untreated injured corneas the expression of malondialdehyde (MDA) and nitrotyrosine (NT) (important markers of lipid peroxidation and oxidative stress) appeared in the epithelium. The antioxidant aldehyde dehydrogenase 3A1 (ALDH3A1) decreased in the corneal epithelium, particularly in superficial parts, where apoptotic cell death (detected by active caspase-3) was high. (In control corneal epithelium MDA and NT are absent and ALDH3A1 highly present in all layers of the epithelium. Cell apoptosis are sporadic). In injured untreated cornea further corneal disturbances developed: The expressions of matrix metalloproteinase 9 (MMP9) and proinflammatory cytokines, were high. At the end of experiment (on day 15) the injured untreated corneas were vascularized and numerous inflammatory cells were present in the corneal stroma. Vascular endothelial growth factor (VEGF) expression and number of macrophages were high. The results obtained in injured corneas covered with nanofiber scaffolds alone (without MSCs) or in injured corneas treated with MSCs only (transferred without scaffolds) did not significantly differ from the results found in untreated injured corneas. In contrast, in the injured corneas treated with MSCs on nanofiber scaffolds, ALDH3A1 expression remained high in the epithelium (as in the control cornea) and positive expression of the other immunohistochemical markers employed was very low (MMP9) or absent (NT, MDA, proinflammatory cytokines), also similarly as in the control cornea. Corneal neovascularization and the infiltration of the corneal stroma with inflammatory cells were significantly suppressed in the injured corneas treated with MSCs compared to the untreated injured ones. The increased central corneal thickness together with corneal opalescency appearing after alkali injury returned to normal levels over the course of ten days only in the injured corneas treated with MSCs on nanofiber scaffolds. The expression of genes for the proinflammatory cytokines corresponded with their immunohistochemical expression. In conclusion, MSCs on nanofiber scaffolds protected the formation of toxic peroxynitrite (detected by NT residues), lowered apoptotic cell death and decreased matrix metalloproteinase and pro-inflammatory cytokine production. This resulted in reduced corneal inflammation as well as neovascularization and significantly accelerated corneal healing.

The combination of mesenchymal stem cells and a bone scaffold in the treatment of vertebral body defects.

PURPOSE: Vertebral body defects represent one of the most common orthopedic challenges. In order to advance the transfer of stem cell therapies into orthopedic clinical practice, we performed this study to evaluate the safety and efficacy of a composite bioartificial graft based on a hydroxyapatite bone scaffold (CEM-OSTETIC(®)) combined with human mesenchymal stem cells (MSCs) in a rat model of vertebral body defects. METHODS: Under general isoflurane anesthesia, a defect in the body of the L2 vertebra was prepared and left to heal spontaneously (group 1), implanted with scaffold material alone (group 2), or implanted with a scaffold together with 0.5 million MSCs (group 3) or 5 million MSCs (group 4). The rats were killed 8 weeks after surgery. Histological and histomorphometrical evaluation of the implant as well as micro-CT imaging of the vertebrae were performed. RESULTS: We observed a significant effect on the formation of new bone tissue in the defect in group 4 when compared to the other groups and a reduced inflammatory reaction in both groups receiving a scaffold and MSCs. We did not detect any substantial pathological changes or tumor formation after graft implantation. CONCLUSIONS: MSCs in combination with a hydroxyapatite scaffold improved the repair of a model bone defect and might represent a safe and effective alternative in the treatment of vertebral bone defects.

Hepatocyte growth on polycapronolactone and 2-hydroxyethylmethacrylate nanofiber sheets enhanced by bone marrow-derived mesenchymal stromal cells.

BACKGROUND/AIMS: The development of hepatocyte-based Bioartificial Liver Assist Devices, intended for the therapy of chronic and fulminant liver failure, is one of the important tasks in the area of tissue engineering. New advances in the development of semipermeable non-woven nanofiber biomaterials and the co-cultivation of bone marrow mesenchymal stromal cells (BMSC) and hepatocytes could be utilized in order to maintain hepatocyte cultures in these devices. METHODOLOGY: We have compared rat hepatocyte growth on nanofiber biomaterials from different polymers, 2-hydroxyethylmethacrylate (HEMA) and ethoxyethylmethacrylate (EOEMA) copolymers, polyurethane (PUR), chitosan and polycapronolactone (PCL) spun from different solvent mixtures. RESULTS: In all cases the adhesion of hepatocytes to nanofibers was significantly better/stronger than to unstructured polymer surfaces; coating the nanofibers with collagen did not increase cell adhesion. We found the best hepatocyte adhesion on HEMA/EOEMA copolymer nanofibers and PCL nanofibers spun from a mixture of ethylacetate and dimethyl sulphoxide. Using a migration assay, we observed the migration of BMSC towards hepatocytes; hepatocytes cocultivated with BMSC excreted lower amounts of stress enzymes. CONCLUSIONS: The results demonstrate that nonwoven nanofiber layers, particularly those containing BMSC, are a suitable biocompatible support for functional hepatocyte cultures and that they can be used in a laboratory bioreactor or potentially in clinical setting.

Regenerative medicine for the treatment of spinal cord injury: more than just promises?

Spinal cord injury triggers a complex set of events that lead to tissue healing without the restoration of normal function due to the poor regenerative capacity of the spinal cord. Nevertheless, current knowledge about the intrinsic regenerative ability of central nervous system axons, when in a supportive environment, has made the prospect of treating spinal cord injury a reality. Among the range of strategies under investigation, cell-based therapies offer the most promising results, due to the multifactorial roles that these cells can fulfil. However, the best cell source is still a matter of debate, as are clinical issues that include the optimal cell dose as well as the timing and route of administration. In this context, the role of biomaterials is gaining importance. These can not only act as vehicles for the administered cells but also, in the case of chronic lesions, can be used to fill the permanent cyst, thus creating a more favourable and conducive environment for axonal regeneration in addition to serving as local delivery systems of therapeutic agents to improve the regenerative milieu. Some of the candidate molecules for the future are discussed in view of the knowledge derived from studying the mechanisms that facilitate the intrinsic regenerative capacity of central nervous system neurons. The future challenge for the multidisciplinary teams working in the field is to translate the knowledge acquired in basic research into effective combinatorial therapies to be applied in the clinic.

The extracellular matrix and diffusion barriers in focal cortical dysplasias.

Focal cortical dysplasias (FCDs) of the brain are recognized as a frequent cause of intractable epilepsy. To contribute to the current understanding of the mechanisms of epileptogenesis in FCD, our study provides evidence that not only cellular alterations and synaptic transmission, but also changed diffusion properties of the extracellular space (ECS), induced by modified extracellular matrix (ECM) composition and astrogliosis, might be involved in the generation or spread of seizures in FCD. The composition of the ECM in FCD and non-malformed cortex (in 163 samples from 62 patients) was analyzed immunohistochemically and correlated with the corresponding ECS diffusion parameter values determined with the real-time iontophoretic method in freshly resected cortex (i.e. the ECS volume fraction and the geometrical factor tortuosity, describing the hindrances to diffusion in the ECS). The ECS in FCD was shown to differ from that in non-malformed cortex, mainly by the increased accumulation of certain ECM molecules (tenascin R, tenascin C, and versican) or by their reduced expression (brevican), and by the presence of an increased number of astrocytic processes. The consequent increase of ECS diffusion barriers observed in both FCD type I and II (and, at the same time, the enlargement of the ECS volume in FCD type II) may alter the diffusion of neuroactive substances through the ECS, which mediates one of the important modes of intercellular communication in the brain - extrasynaptic volume transmission. Thus, the changed ECM composition and altered ECS diffusion properties might represent additional factors contributing to epileptogenicity in FCD.