MiR-138-5p Upregulation during Neuronal Maturation Parallels with an Increase in Neuronal Survival.

Neuronal maturation is a process that plays a key role in the development and regeneration of the central nervous system. Although embryonic brain development and neurodegeneration have received considerable attention, the events that govern postnatal neuronal maturation are less understood. Among the mechanisms influencing such neuronal maturation processes, apoptosis plays a key role. Several regulators have been described to modulate apoptosis, including post-transcriptional regulation by microRNAs. This study aimed to analyze endogenous expression changes of miR-138-5p, as well as its main validated pro-apoptotic target caspase3, during the maturation of neuronal cultures and their response under apoptotic challenge. Our results point out that the observed opposite expression of miR-138-5p and its target caspase3 might modulate apoptosis favoring neuronal survival at distinct maturation stages. The unchanged expression of miR-138-5p in mature neurons contrasts with the significant downregulation in immature neurons upon apoptotic stimulation. Similarly, immunoblot and individual cellular assays confirmed that during maturation, not only the expression but processing of CASP-3 and caspase activity is reduced after apoptotic stimulation which results in a reduction of neuronal death. Further studies would be needed to determine a more detailed role of miR-138-5p in apoptosis during neuronal maturation and the synergistic action of several microRNAs acting cooperatively on caspase3 or other apoptotic targets.

Evaluation of Poly(N-Ethyl Pyrrolidine Methacrylamide) (EPA) and Derivatives as Polymeric Vehicles for miRNA Delivery to Neural Cells.

MicroRNAs (miRNAs) are endogenous, short RNA oligonucleotides that regulate the expression of hundreds of proteins to control cells' function in physiological and pathological conditions. miRNA therapeutics are highly specific, reducing the toxicity associated with off-target effects, and require low doses to achieve therapeutic effects. Despite their potential, applying miRNA-based therapies is limited by difficulties in delivery due to their poor stability, fast clearance, poor efficiency, and off-target effects. To overcome these challenges, polymeric vehicles have attracted a lot of attention due to their ease of production with low costs, large payload, safety profiles, and minimal induction of the immune response. Poly(N-ethyl pyrrolidine methacrylamide) (EPA) copolymers have shown optimal DNA transfection efficiencies in fibroblasts. The present study aims to evaluate the potential of EPA polymers as miRNA carriers for neural cell lines and primary neuron cultures when they are copolymerized with different compounds. To achieve this aim, we synthesized and characterized different copolymers and evaluated their miRNA condensation ability, size, charge, cytotoxicity, cell binding and internalization ability, and endosomal escape capacity. Finally, we evaluated their miRNA transfection capability and efficacy in Neuro-2a cells and rat primary hippocampal neurons. The results indicate that EPA and its copolymers, incorporating ß-cyclodextrins with or without polyethylene glycol acrylate derivatives, can be promising vehicles for miRNA administration to neural cells when all experiments on Neuro-2a cells and primary hippocampal neurons are considered together.

Overexpression of the X-Linked Inhibitor of Apoptosis Protein (XIAP) in Neurons Improves Cell Survival and the Functional Outcome after Traumatic Spinal Cord Injury.

Mechanical trauma to the spinal cord causes extensive neuronal death, contributing to the loss of sensory-motor and autonomic functions below the injury location. Apoptosis affects neurons after spinal cord injury (SCI) and is associated with increased caspase activity. Cleavage of X-linked inhibitor of apoptosis protein (XIAP) after SCI may contribute to this rise in caspase activity. Accordingly, we have shown that the elevation of XIAP resulted in increased neuronal survival after SCI and improved functional recovery. Therefore, we hypothesise that neuronal overexpression of XIAP can be neuroprotective after SCI with improved functional recovery. In line with this, studies of a transgenic mice with overexpression of XIAP in neurons revealed that higher levels of XIAP after spinal cord trauma favours neuronal survival, tissue preservation, and motor recovery after the spinal cord trauma. Using human SH-SY5Y cells overexpressing XIAP, we further showed that XIAP reduced caspase activity and apoptotic cell death after pro-apoptotic stimuli. In conclusion, this study shows that the levels of XIAP expression are an important factor for the outcome of spinal cord trauma and identifies XIAP as an important therapeutic target for alleviating the deleterious effects of SCI.

MicroRNA-138-5p Targets Pro-Apoptotic Factors and Favors Neural Cell Survival: Analysis in the Injured Spinal Cord.

The central nervous system microRNA miR-138-5p has attracted much attention in cancer research because it inhibits pro-apoptotic genes including CASP3. We hypothesize that miR-138-5p downregulation after SCI leads to overexpression of pro-apoptotic genes, sensitizing neural cells to noxious stimuli. This study aimed to identify miR-138-5p targets among pro-apoptotic genes overexpressed following SCI and to confirm that miR-138-5p modulates cell death in neural cells. Gene expression and histological analyses revealed that the drop in miR-138-5p expression after SCI is due to the massive loss of neurons and oligodendrocytes and its downregulation in neurons. Computational analyses identified 176 potential targets of miR-138-5p becoming dysregulated after SCI, including apoptotic proteins CASP-3 and CASP-7, and BAK. Reporter, RT-qPCR, and immunoblot assays in neural cell cultures confirmed that miR-138-5p targets their 3'UTRs, reduces their expression and the enzymatic activity of CASP-3 and CASP-7, and protects cells from apoptotic stimuli. Subsequent RT-qPCR and histological analyses in a rat model of SCI revealed that miR-138-5p downregulation correlates with the overexpression of its pro-apoptotic targets. Our results suggest that the downregulation of miR-138-5p after SCI may have deleterious effects on neural cells, particularly on spinal neurons.

miR-182-5p Regulates Nogo-A Expression and Promotes Neurite Outgrowth of Hippocampal Neurons In Vitro.

Nogo-A protein is a key myelin-associated inhibitor of axonal growth, regeneration, and plasticity in the central nervous system (CNS). Regulation of the Nogo-A/NgR1 pathway facilitates functional recovery and neural repair after spinal cord trauma and ischemic stroke. MicroRNAs are described as effective tools for the regulation of important processes in the CNS, such as neuronal differentiation, neuritogenesis, and plasticity. Our results show that miR-182-5p mimic specifically downregulates the expression of the luciferase reporter gene fused to the mouse Nogo-A 3'UTR, and Nogo-A protein expression in Neuro-2a and C6 cells. Finally, we observed that when rat primary hippocampal neurons are co-cultured with C6 cells transfected with miR-182-5p mimic, there is a promotion of the outgrowth of neuronal neurites in length. From all these data, we suggest that miR-182-5p may be a potential therapeutic tool for the promotion of axonal regeneration in different diseases of the CNS.

In Silico and In Vitro Analyses Validate Human MicroRNAs Targeting the SARS-CoV-2 3'-UTR.

COVID-19 pandemic is caused by betacoronavirus SARS-CoV-2. The genome of this virus is composed of a single strand of RNA with 5' and 3'-UTR flanking a region of protein-coding ORFs closely resembling cells' mRNAs. MicroRNAs are endogenous post-transcriptional regulators that target mRNA to modulate protein expression and mediate cellular functions, including antiviral defense. In the present study, we carried out a bioinformatics screening to search for endogenous human microRNAs targeting the 3'-UTR of SARS-CoV-2. Results from the computational techniques allowed us to identify 10 potential candidates. The capacity of 3 of them, together with hsa-miR-138-5p, to target the SARS-CoV-2 3'-UTR was validated in vitro by gene reporter assays. Available information indicates that two of these microRNAs, namely, hsa-miR-3941 and hsa-miR-138-5p, combine effective targeting of SARS-CoV-2 genome with complementary antiviral or protective effects in the host cells that make them potential candidates for therapeutic treatment of most, if not all, COVID-19 variants known to date. All information obtained while conducting the present analysis is available at Open Science Framework repository.

Alginate Hydrogels as Scaffolds and Delivery Systems to Repair the Damaged Spinal Cord.

Alginate (ALG) is a lineal hydrophilic polysaccharide present in brown algae cell walls, which turns into a gel state when hydrated. Gelation readily produces a series of three dimensional (3D) architectures like fibers, capillaries, and microspheres, used as biosensors and bio-actuators in a plethora of biomedical applications like drug delivery and wound healing. Hydrogels have made a great impact on regenerative medicine and tissue engineering because they are able to mimic the mechanical properties of natural tissues due to their high water content. Recent advances in neurosciences have led to promising strategies for repairing and/or regenerating the damaged nervous system. Spinal cord injury (SCI) is particularly challenging, owing to its devastating medical, human, and social consequences. Although effective therapies to repair the damaged spinal cord (SC) are still lacking, multiple pharmacological, genetic, and cell-based therapies are currently under study. In this framework, ALG hydrogels constitute a source of potential tools for the development of implants capable of promoting axonal growth and/or delivering cells or drugs at specific damaged sites, which may result in therapeutic strategies for SCI. In this mini-review, the current state of the art of ALG applications in neural tissues for repairing the damaged spinal cord is discussed.

MicroRNA-135a-5p reduces P2X7 -dependent rise in intracellular calcium and protects against excitotoxicity.

Excitotoxic cell death because of the massive release of glutamate and ATP contributes to the secondary extension of cellular and tissue loss following traumatic spinal cord injury (SCI). Evidence from blockage experiments suggests that over-expression and activation of purinergic receptors, especially P2X7 , produces excitotoxicity in neurodegenerative diseases and trauma of the central nervous system. We hypothesize that the down-regulation of specific miRNAs after the SCI contributes to the over-expression of P2X7 and that restorative strategies can be used to reduce the excitotoxic response. In the present study, we have employed bioinformatic analyses to identify microRNAs whose down-regulation following SCI can be responsible for P2X7 over-expression and excitotoxic activity. Additional luciferase assays validated microRNA-135a-5p (miR-135a) as a posttranscriptional modulator of P2X7 . Moreover, gene expression analysis in spinal cord samples from a rat SCI model confirmed that the decrease in miR-135a expression correlated with P2X7 over-expression after injury. Transfection of cultures of Neuro-2a neuronal cell line with a miR-135a inhibitory sequences (antagomiR-135a), simulating the reduction of miR-135a observed after SCI, resulted in the increase of P2X7 expression and the subsequent ATP-dependent rise in intracellular calcium concentration. Conversely, a restorative strategy employing miR-135a mimicked reduced P2X7 expression, attenuating the increase in intracellular calcium concentration that depends on this receptor and protecting cells from excitotoxic death. Therefore, we conclude that miR-135a is a potential therapeutic target for SCI and that restoration of its expression may reduce the deleterious effects of ATP-dependent excitotoxicity induced after a traumatic spinal cord injury.

Cell Specific Changes of Autophagy in a Mouse Model of Contusive Spinal Cord Injury.

Autophagy is an essential process of cellular waist clearance that becomes altered following spinal cord injury (SCI). Details on these changes, including timing after injury, underlying mechanisms, and affected cells, remain controversial. Here we present a characterization of autophagy in the mice spinal cord before and after a contusive SCI. In the undamaged spinal cord, analysis of LC3 and Beclin 1 autophagic markers reveals important differences in basal autophagy between neurons, oligodendrocytes, and astrocytes and even within cell populations. Following moderate contusion, western blot analyses of LC3 indicates that autophagy increases to a maximum at 7 days post injury (dpi), whereas unaltered Beclin 1 expression and increase of p62 suggests a possible blockage of autophagosome clearance. Immunofluorescence analyses of LC3 and Beclin 1 provide additional details that reveal a complex, cell-specific scenario. Autophagy is first activated (1 dpi) in the severed axons, followed by a later (7 dpi) accumulation of phagophores and/or autophagosomes in the neuronal soma without signs of increased initiation. Oligodendrocytes and reactive astrocytes also accumulate phagophores and autophagosomes at 7 dpi, but whereas the accumulation in astrocytes is associated with an increased autophagy initiation, it seems to result from a blockage of the autophagic flux in oligodendrocytes. Comparison with previous studies highlights the complex and heterogeneous autophagic responses induced by the SCI, leading in many cases to contradictory results and interpretations. Future studies should consider this complexity in the design of therapeutic interventions based on the modulation of autophagy to treat SCI.

BAMOS: A recording application for BAsso MOuse scale of locomotion in experimental models of spinal cord injury.

Transparency in science is increasingly a hot topic. Scientists are required to show not only results but also evidence of how they have achieved these results. In experimental studies of spinal cord injury, there are a number of standardized tests, such as the Basso-Beattie-Bresnahan locomotor rating scale for rats and Basso Mouse Scale for mice, which researchers use to study the pathophysiology of spinal cord injury and to evaluate the effects of experimental therapies. Although the standardized data from the Basso-Beattie-Bresnahan locomotor rating scale and the Basso Mouse Scale are particularly suited for storage and sharing in databases, systems of data acquisition and repositories are still lacking. To the best of our knowledge, both tests are usually conducted manually, with the data being recorded on a paper form, which may be documented with video recordings, before the data is transferred to a spreadsheet for analysis. The data thus obtained is used to compute global scores, which is the information that usually appears in publications, with a wealth of information being omitted. This information may be relevant to understand locomotion deficits or recovery, or even important aspects of the treatment effects. Therefore, this paper presents a mobile application to record and share Basso Mouse Scale tests, meeting the following criteria: i) user-friendly; ii) few hardware requirements (only a smartphone or tablet with a camera running under Android Operating System); and iii) based on open source software such as SQLite, XML, Java, Android Studio and Android SDK. The BAMOS app can be downloaded and installed from the Google Market repository and the app code is available at the GitHub repository. The BAMOS app demonstrates that mobile technology constitutes an opportunity to develop tools for aiding spinal cord injury scientists in recording and sharing experimental data.

XIAP Interacts with and Regulates the Activity of FAF1.

Cell death depends on the balance between the activities of pro- and anti-apoptotic factors. X-linked inhibitor of apoptosis protein (XIAP) plays an important role in the cytoprotective process by inhibiting the caspase cascade and regulating pro-survival signaling pathways. While searching for novel interacting partners of XIAP, we identified Fas-associated factor 1 (FAF1). Contrary to XIAP, FAF1 is a pro-apoptotic factor that also regulates several signaling pathways in which XIAP is involved. However, the functional relationship between FAF1 and XIAP is unknown. Here, we describe a new interaction between XIAP and FAF1 and describe the functional implications of their opposing roles in cell death and NF-κB signaling. Our results clearly demonstrate the interaction of XIAP with FAF1 and define the specific region of the interaction. We observed that XIAP is able to block FAF1-mediated cell death by interfering with the caspase cascade and directly interferes in NF-κB pathway inhibition by FAF1. Furthermore, we show that XIAP promotes ubiquitination of FAF1. Conversely, FAF1 does not interfere with the anti-apoptotic activity of XIAP, despite binding to the BIR domains of XIAP; however, FAF1 does attenuate XIAP-mediated NF-κB activation. Altered expression of both factors has been implicated in degenerative and cancerous processes; therefore, studying the balance between XIAP and FAF1 in these pathologies will aid in the development of novel therapies.

Diadenosine tetraphosphate (Ap4A) inhibits ATP-induced excitotoxicity: a neuroprotective strategy for traumatic spinal cord injury treatment.

Reducing cell death during the secondary injury is a major priority in the development of a cure for traumatic spinal cord injury (SCI). One of the earliest processes that follow SCI is the excitotoxicity resulting from the massive release of excitotoxicity mediators, including ATP, which induce an excessive and/or prolonged activation of their receptors and a deregulation of the calcium homeostasis. Diadenosine tetraphosphate (Ap4A) is an endogenous purinergic agonist, present in both extracellular and intracellular fluids, with promising cytoprotective effects in different diseases including neurodegenerative processes. In a search for efficient neuroprotective strategies for SCI, we have tested the capability of Ap4A to reduce the excitotoxic death mediated by the ATP-induced deregulation of calcium homeostasis and its consequences on tissue preservation and functional recovery in a mouse model of moderate contusive SCI. Our analyses with the murine neural cell line Neuro2a demonstrate that treatment with Ap4A reduces ATP-dependent excitotoxic death by both lowering the intracellular calcium response and decreasing the expression of specific purinergic receptors. Follow-up analyses in a mouse model of contusive SCI showed that acute administration of Ap4A following SCI reduces tissue damage and improves motor function recovery. These results suggest that Ap4A cytoprotection results from a decrease of the purinergic tone preventing the effects of a massive release of ATP after SCI, probably together with a direct induction of anti-apoptotic and pro-survival pathways via activation of P2Y2 proposed in previous studies. In conclusion, Ap4A may be a good candidate for an SCI therapy, particularly to reduce excitotoxicity in combination with other modulators and/or inhibitors of the excitotoxic process that are being tested.

Identification of axon growth promoters in the secretome of the deer antler velvet.

Every spring, deer cast their old antlers and initiate a regeneration process, which yields a new set of antlers of up to 1m in length. Over the course of three months, branches of the trigeminal nerve, originating from the frontal skull, innervate velvet, a modified skin that covers the regenerating antler. The rate of growth of these axons reaches up to 2cm per day making them the fastest regenerating axons in adult mammals. Here, we aim to identify the factors secreted by velvet that promote such high speed axon growth. Our experiments with cultures of adult rat trigeminal neurons demonstrate that conditioned medium harvested from velvet organotypic cultures has greater axon growth-promoting properties than a medium conditioned by normal skin. The axon growth-promoting effects of velvet act synergistically with the extracellular matrix (ECM) protein laminin, a component of the basal lamina present in the deer antler. Our proteomic analyses identified several axon growth promoters in the velvet-conditioned medium (VCM), including soluble proteins such as nerve growth factor (NGF) and apolipoprotein A-1, as well as matrix extracellular proteins, such as periostin and SPARC. Additional in vitro analyses allowed us to determine that a synergic relationship between periostin and NGF may contribute to neurite growth-promoting effects of velvet secretome. A combinatorial approach using these factors may promote regeneration at high speeds in patients with peripheral neuropathies.

Life-history traits of the Miocene Hipparion concudense (Spain) inferred from bone histological structure.

Histological analyses of fossil bones have provided clues on the growth patterns and life history traits of several extinct vertebrates that would be unavailable for classical morphological studies. We analyzed the bone histology of Hipparion to infer features of its life history traits and growth pattern. Microscope analysis of thin sections of a large sample of humeri, femora, tibiae and metapodials of Hipparion concudense from the upper Miocene site of Los Valles de Fuentidueña (Segovia, Spain) has shown that the number of growth marks is similar among the different limb bones, suggesting that equivalent skeletochronological inferences for this Hipparion population might be achieved by means of any of the elements studied. Considering their abundance, we conducted a skeletechronological study based on the large sample of third metapodials from Los Valles de Fuentidueña together with another large sample from the Upper Miocene locality of Concud (Teruel, Spain). The data obtained enabled us to distinguish four age groups in both samples and to determine that Hipparion concudense tended to reach skeletal maturity during its third year of life. Integration of bone microstructure and skeletochronological data allowed us to identify ontogenetic changes in bone structure and growth rate and to distinguish three histologic ontogenetic stages corresponding to immature, subadult and adult individuals. Data on secondary osteon density revealed an increase in bone remodeling throughout the ontogenetic stages and a lesser degree thereof in the Concud population, which indicates different biomechanical stresses in the two populations, likely due to environmental differences. Several individuals showed atypical growth patterns in the Concud sample, which may also reflect environmental differences between the two localities. Finally, classification of the specimens' age within groups enabled us to characterize the age structure of both samples, which is typical of attritional assemblages.

MicroRNA dysregulation in spinal cord injury: causes, consequences and therapeutics.

Trauma to the spinal cord causes permanent disability to more than 180,000 people every year worldwide. The initial mechanical damage triggers a complex set of secondary events involving the neural, vascular, and immune systems that largely determine the functional outcome of the spinal cord injury (SCI). Cellular and biochemical mechanisms responsible for this secondary injury largely depend on activation and inactivation of specific gene programs. Recent studies indicate that microRNAs function as gene expression switches in key processes of the SCI. Microarray data from rodent contusion models reveal that SCI induces changes in the global microRNA expression patterns. Variations in microRNA abundance largely result from alterations in the expression of the cells at the damaged spinal cord. However, microRNA expression levels after SCI are also influenced by the infiltration of immune cells to the injury site and the death and migration of specific neural cells after injury. Evidences on the role of microRNAs in the SCI pathophysiology have come from different sources. Bioinformatic analysis of microarray data has been used to identify specific variations in microRNA expression underlying transcriptional changes in target genes, which are involved in key processes in the SCI. Direct evidences on the role of microRNAs in SCI are scarcer, although recent studies have identified several microRNAs (miR-21, miR-486, miR-20) involved in key mechanisms of the SCI such as cell death or astrogliosis, among others. From a clinical perspective, different evidences make clear that microRNAs can be potent therapeutic tools to manipulate cell state and molecular processes in order to enhance functional recovery. The present article reviews the actual knowledge on how injury affects microRNA expression and the meaning of these changes in the SCI pathophysiology, to finally explore the clinical potential of microRNAs in the SCI.

Postnatal changes in the growth dynamics of the human face revealed from bone modelling patterns.

Human skull morphology results from complex processes that involve the coordinated growth and interaction of its skeletal components to keep a functional and structural balance. Previous histological works have studied the growth of different craniofacial regions and their relationship to functional spaces in humans up to 14 years old. Nevertheless, how the growth dynamics of the facial skeleton and the mandible are related and how this relationship changes through the late ontogeny remain poorly understood. To approach these two questions, we have compared the bone modelling activities of the craniofacial skeleton from a sample of subadult and adult humans. In this study, we have established for the first time the bone modelling pattern of the face and the mandible from adult humans. Our analyses reveal a patchy distribution of the bone modelling fields (overemphasized by the presence of surface islands with no histological information) reflecting the complex growth dynamics associated to the individual morphology. Subadult and adult specimens show important differences in the bone modelling patterns of the anterior region of the facial skeleton and the posterior region of the mandible. These differences indicate developmental changes in the growth directions of the whole craniofacial complex, from a predominantly downward growth in subadults that turns to a forward growth observed in the adult craniofacial skeleton. We hypothesize that these ontogenetic changes would respond to the physiological and physical requirements to enlarge the oral and nasal cavities once maturation of the brain and the closure of the cranial sutures have taken place during craniofacial development.

Influence of chitosan concentration on cell viability and proliferation in vitro by changing film topography.

PURPOSE: Chitosan is a natural polysaccharide which can form gels and scaffolds that support its use as a biomaterial in various tissue engineering applications. A useful feature of chitosan polymer is that you can manipulate its properties easily. Thus, in this work we studied the effect of varying chitosan concentration in the topography and the biological properties of the chitosan films, as well as the effects in the structure of 3D gels in order to be used as nerve bridges. METHODS: Analysis of film topographies were addressed by swelling test and atomic force microscopy (AFM). In vitro biological properties were assessed through MTT viability assays on cultures of blood-brain barrier forming endothelial (bEnd5), glioma (C6) and postmitotic neuron (NGF-differentiated PC12) cell lines. The structure of tridimensional gels was studied by environmental scanning electron microscopy.
 RESULTS: Topography of 1% chitosan films showed a AFM profile with higher nano-roughness profile than that observed in 2% films, which was smoother. Moreover, swelling rate was not affected. Topography changes affected cell viability as shown by the MTT assays. Our results showed that 2% chitosan films promoted higher proliferation and viability of C6 and PC12 respectively than 1% films. Conversely, neither 1% nor 2% films promoted viability of bEnd5 cells. In order to establish the
feasibility of both type of chitosan solutions as nerve bridges, we constructed 3D gels by alkaline precipitation. Resulting gels showed that only 2% gels were rigid enough to be effectively used as nerve bridges. CONCLUSIONS: These results establish that changes in chitosan concentration affects the polymer surface topography, which has a direct effect in the growing cell behavior. Additionally, higher concentration of chitosan gels are required to be used in neural tissue engineering.

MicroRNA dysregulation in the spinal cord following traumatic injury.

Spinal cord injury (SCI) triggers a multitude of pathophysiological events that are tightly regulated by the expression levels of specific genes. Recent studies suggest that changes in gene expression following neural injury can result from the dysregulation of microRNAs, short non-coding RNA molecules that repress the translation of target mRNA. To understand the mechanisms underlying gene alterations following SCI, we analyzed the microRNA expression patterns at different time points following rat spinal cord injury.The microarray data reveal the induction of a specific microRNA expression pattern following moderate contusive SCI that is characterized by a marked increase in the number of down-regulated microRNAs, especially at 7 days after injury. MicroRNA downregulation is paralleled by mRNA upregulation, strongly suggesting that microRNAs regulate transcriptional changes following injury. Bioinformatic analyses indicate that changes in microRNA expression affect key processes in SCI physiopathology, including inflammation and apoptosis. MicroRNA expression changes appear to be influenced by an invasion of immune cells at the injury area and, more importantly, by changes in microRNA expression specific to spinal cord cells. Comparisons with previous data suggest that although microRNA expression patterns in the spinal cord are broadly similar among vertebrates, the results of studies assessing SCI are much less congruent and may depend on injury severity. The results of the present study demonstrate that moderate spinal cord injury induces an extended microRNA downregulation paralleled by an increase in mRNA expression that affects key processes in the pathophysiology of this injury.

Differential adhesiveness and neurite-promoting activity for neural cells of chitosan, gelatin, and poly-L-lysine films.

Chitosan (Ch) and some of its derivatives have been proposed as good biomaterials for tissue engineering, to construct scaffolds promoting tissue regeneration. In this work we made composite films from Ch and mixtures of Ch with gelatin (G) and poly-l-lysine (PLL), and evaluated the growth on these films of PC12 and C6 lines as well as neurons and glial cells derived from cerebral tissue and dorsal root ganglia (DRG). C6 glioma cells proliferated on Ch, G, and Ch + G films, although metabolic activity was decreased by the presence of the G in the mixtures. NGF-differentiated PC12 cells, adhered preferentially on Ch and films containing PLL. Unlike NGF-treated PC12 cells, cortical and hippocampal neurons showed good adhesion to Ch and Ch + G films, where they extended neurites. Astrocytes adhered on Ch, Ch + G, and Ch + PLL mixtures, although viability decreased during the culture time. Olfactory ensheathing cells (OEC) adhered and proliferated to confluency on the wells covered with Ch + G films. Neurites from DRGs exhibited high extension on these films. These results demonstrate that Ch + G films have excellent adhesive properties for both neurons and regeneration-promoting glia (OEC). These films also promoted neurite extension from DRG, making them good candidates for tissue engineering of nerve repair.