CIAO1 and MMS19 deficiency: A lethal neurodegenerative phenotype caused by cytosolic Fe-S cluster protein assembly disorders.

PURPOSE: The functionality of many cellular proteins depends on cofactors; yet, they have only been implicated in a minority of Mendelian diseases. Here, we describe the first 2 inherited disorders of the cytosolic iron-sulfur protein assembly system. METHODS: Genetic testing via genome sequencing was applied to identify the underlying disease cause in 3 patients with microcephaly, congenital brain malformations, progressive developmental and neurologic impairments, recurrent infections, and a fatal outcome. Studies in patient-derived skin fibroblasts and zebrafish models were performed to investigate the biochemical and cellular consequences. RESULTS: Metabolic analysis showed elevated uracil and thymine levels in body fluids but no pathogenic variants in DPYD, encoding dihydropyrimidine dehydrogenase. Genome sequencing identified compound heterozygosity in 2 patients for missense variants in CIAO1, encoding cytosolic iron-sulfur assembly component 1, and homozygosity for an in-frame 3-nucleotide deletion in MMS19, encoding the MMS19 homolog, cytosolic iron-sulfur assembly component, in the third patient. Profound alterations in the proteome, metabolome, and lipidome were observed in patient-derived fibroblasts. We confirmed the detrimental effect of deficiencies in CIAO1 and MMS19 in zebrafish models. CONCLUSION: A general failure of cytosolic and nuclear iron-sulfur protein maturation caused pleiotropic effects. The critical function of the cytosolic iron-sulfur protein assembly machinery for antiviral host defense may well explain the recurrent severe infections occurring in our patients.

Compounded topographical and physicochemical cueing by micro-engineered chitosan substrates on rat dorsal root ganglion neurons and human mesenchymal stem cells.

Given the intertwined physicochemical effects exerted in vivo by both natural and synthetic (e.g., biomaterial) interfaces on adhering cells, the evaluation of structure-function relationships governing cellular response to micro-engineered surfaces for applications in neuronal tissue engineering requires the use of in vitro testing platforms which consist of a clinically translatable material with tunable physiochemical properties. In this work, we micro-engineered chitosan substrates with arrays of parallel channels with variable width (20 and 60 µm). A citric acid (CA)-based crosslinking approach was used to provide an additional level of synergistic cueing on adhering cells by regulating the chitosan substrate's stiffness. Morphological and physicochemical characterization was conducted to unveil the structure-function relationships which govern the activity of rat dorsal root ganglion neurons (DRGs) and human mesenchymal stem cells (hMSCs), ultimately singling out the key role of microtopography, roughness and substrate's stiffness. While substrate's stiffness predominantly affected hMSC spreading, the modulation of the channels' design affected the neuronal architecture's complexity and guided the morphological transition of hMSCs. Finally, the combined analysis of tubulin expression and cell morphology allowed us to cast new light on the predominant role of the microtopography over substrate's stiffness in the process of hMSCs neurogenic differentiation.

[11C]meta-hydroxyephedrine PET evaluation in experimental pulmonary arterial hypertension: Effects of carvedilol of right ventricular sympathetic function.

BACKGROUND: Little is known about the sequelae of chronic sympathetic nervous system (SNS) activation in patients with pulmonary arterial hypertension (PAH) and right heart failure (RHF). We aimed to, (1) validate the use of [11C]-meta-hydroxyephedrine (HED) for assessing right ventricular (RV) SNS integrity, and (2) determine the effects of ß-receptor blockade on ventricular function and myocardial SNS activity in a PAH rat model. METHODS: PAH was induced in male Sprague-Dawley rats (N = 36) using the Sugen+chronic hypoxia model. At week 5 post-injection, PAH rats were randomized to carvedilol (15 mg·kg-1·day-1 oral; N = 16) or vehicle (N = 16) for 4 weeks. Myocardial SNS function was assessed with HED positron emission tomography(PET). RESULTS: With increasing PAH disease severity, immunohistochemistry confirmed selective sympathetic denervation within the RV and sparing of parasympathetic nerves. These findings were confirmed on PET with a significant negative relationship between HED volume of distribution(DV) and right ventricular systolic pressure (RVSP) in the RV (r = -0.90, p = 0.0003). Carvedilol did not reduce hemodynamic severity compared to vehicle. RV ejection fraction (EF) was lower in both PAH groups compared to control (p < 0.05), and was not further reduced by carvedilol. Carvedilol improved SNS function in the LV with significant increases in the HED DV, and decreased tracer washout in the LV (p < 0.05) but not RV. CONCLUSIONS: PAH disease severity correlated with a reduction in HED DV in the RV. This was associated with selective sympathetic denervation. Late carvedilol treatment did not lead to recovery of RV function. These results support the role of HED imaging in assessing SNS innervation in a failing right ventricle.

Separating the Wheat from the Chaff: The Use of Upstream Regulator Analysis to Identify True Differential Expression of Single Genes within Transcriptomic Datasets.

The development of DNA microarray and RNA-sequencing technology has led to an explosion in the generation of transcriptomic differential expression data under a wide range of biologic systems including those recapitulating the monogenic muscular dystrophies. Data generation has increased exponentially due in large part to new platforms, improved cost-effectiveness, and processing speed. However, reproducibility and thus reliability of data remain a central issue, particularly when resource constraints limit experiments to single replicates. This was observed firsthand in a recent rare disease drug repurposing project involving RNA-seq-based transcriptomic profiling of primary cerebrocortical cultures incubated with clinic-ready blood-brain penetrant drugs. Given the low validation rates obtained for single differential expression genes, alternative approaches to identify with greater confidence genes that were truly differentially expressed in our dataset were explored. Here we outline a method for differential expression data analysis in the context of drug repurposing for rare diseases that incorporates the statistical rigour of the multigene analysis to bring greater predictive power in assessing individual gene modulation. Ingenuity Pathway Analysis upstream regulator analysis was applied to the differentially expressed genes from the Care4Rare Neuron Drug Screen transcriptomic database to identify three distinct signaling networks each perturbed by a different drug and involving a central upstream modulating protein: levothyroxine (DIO3), hydroxyurea (FOXM1), dexamethasone (PPARD). Differential expression of upstream regulator network related genes was next assessed in in vitro and in vivo systems by qPCR, revealing 5× and 10× increases in validation rates, respectively, when compared with our previous experience with individual genes in the dataset not associated with a network. The Ingenuity Pathway Analysis based gene prioritization may increase the predictive value of drug-gene interactions, especially in the context of assessing single-gene modulation in single-replicate experiments.

Educational Research Report Correlation between Student Self-Assessment and Proctor Evaluation in a Veterinary Surgical Laboratory.

Self-assessment has been shown to facilitate learning, goal setting, and professional development. We sought to evaluate whether veterinary students in a surgical curriculum would have self-assessments that differed from proctor evaluations and whether high-performing students would differ from low-performing students in self-assessment characteristics. Student and proctor assessments were compared for 8 weeks of a spay/neuter surgical laboratory taking place in the second year of the curriculum. Eight students were classified as high-performing, and 10 students were classified as low-performing. A quantitative evaluation of the scores and a qualitative assessment of written comments were completed. Proctors assigned higher scores to high-performing students compared to low-performing students, but no difference was observed overall in self-assessment scores assigned by students. When only anesthesia students were evaluated, we found a difference in self-assessment scores for high- versus low-performers, but this was not true for surgery students. Differences between proctor and student assessment scores diminished over time for all students and for anesthesia students, but not for surgery students. High-performing student anesthetists self-assessed and received proctor assessments with higher scores in technical skills. Comments from high-performing students tended to be less reflective and more positive. Low-performing students were more defensive and more likely to use I-statements in their comments. Overall, quantitative analysis did not reveal a difference in self-assessment between high-performers and low-performers; however, specific differences existed in qualitative characteristics, surgery versus anesthesia students, and proctor assessments. The differences in self-assessment between high- and low-performing students suggest areas of further investigation for the use of reflection in education.

Transcriptomic RNAseq drug screen in cerebrocortical cultures: toward novel neurogenetic disease therapies.

Rare monogenic diseases affect millions worldwide; although over 4500 rare disease genotypes are known, disease-modifying drugs are available for only 5% of them. The sheer number of these conditions combined with their rarity precludes traditional costly drug discovery programs. An economically viable alternative is to repurpose established drugs for rare diseases. Many genetic diseases result from increased or decreased protein activity and identification of clinically approved drugs which moderate this pathogenic dosage holds therapeutic potential. To identify such agents for neurogenetic diseases, we have generated genome-wide transcriptome profiles of mouse primary cerebrocortical cultures grown in the presence of 218 blood-brain barrier (BBB) penetrant clinic-tested drugs. RNAseq and differential expression analyses were used to generate transcriptomic profiles; therapeutically relevant drug-gene interactions related to rare neurogenetic diseases identified in this fashion were further analyzed by quantitative reverse transcriptase-polymerase chain reaction, western blot and immunofluorescence. We have created a transcriptome-wide searchable database for easy access to the gene expression data resulting from the cerebrocortical drug screen (Neuron Screen) and have mined this data to identify a novel link between thyroid hormone and expression of the peripheral neuropathy associated gene Pmp22. Our results demonstrate the utility of cerebrocortical cultures for transcriptomic drug screening, and the database we have created will foster further discovery of novel links between over 200 clinic-tested BBB penetrant drugs and genes related to diverse neurologic conditions.

Microparticles generated during chronic cerebral ischemia deliver proapoptotic signals to cultured endothelial cells.

Circulating microparticles (MPs) are involved in many physiological processes and numbers are increased in a variety of cardiovascular disorders. The present aims were to characterize levels of MPs in a rodent model of chronic cerebral hypoperfusion (CCH) and to determine their signaling properties. MPs were isolated from the plasma of rats exposed to CCH and quantified by flow cytometry. When MPs were added to cultured endothelial cells or normal rat kidney cells they induced cell death in a time and dose dependent manner. Analysis of pellets by electron microscopy indicates that cell death signals are carried by particles in the range of 400 nm in diameter or less. Cell death involved the activation of caspase 3 and was not a consequence of oxidative stress. Inhibition of the Fas/FasL signaling pathway also did not improve cell survival. MPs were found to contain caspase 3 and treating the MPs with a caspase 3 inhibitor significantly reduced cell death. A TNF-α receptor blocker and a TRAIL neutralizing antibody also significantly reduced cell death. Levels of circulating MPs are elevated in a rodent model of chronic cerebral ischemia. MPs with a diameter of 400 nm or less activate the TNF-α and TRAIL signaling pathways and may deliver caspase 3 to cultured cells.

Microparticles: biomarkers and beyond.

Membrane microparticles are submicron fragments of membrane shed into extracellular space from cells under conditions of stress/injury. They may be distinguished from other classes of extracellular vesicles (i.e. exosomes) on the basis of size, content and mechanism of formation. Microparticles are found in plasma and other biological fluids from healthy individuals and their levels are altered in various diseases, including diabetes, chronic kidney disease, pre-eclampsia and hypertension among others. Accordingly, they have been considered biomarkers of vascular injury and pro-thrombotic or pro-inflammatory conditions. In addition to this, emerging evidence suggests that microparticles are not simply a consequence of disease, but that they themselves may contribute to pathological processes. Thus microparticles appear to serve as both markers and mediators of pathology. The present review examines the evidence for microparticles as both biomarkers of, and contributors to, the progression of disease. Approaches for the detection of microparticles are summarized and novel concepts relating to the formation of microparticles and their biological effects are examined.

The Physiological and Molecular Links Between Physical Activity and Brain Health: A Review.

There is currently an epidemic of sedentary behavior throughout the world, leading to negative impacts on physical health and contributing to both mortality and burden of disease. The consequences of this also impact the brain, where increased levels of cognitive decline are observed in individuals who are more sedentary. This review explores the physiological and molecular responses to our sedentary propensity, its contribution to several medical conditions and cognitive deficits, and the benefits of moderate levels of physical activity and exercise. Also presented is the recommended level of activity for overall physical health improvement.

LIM domain only 4 protein promotes granulocyte colony-stimulating factor-induced signaling in neurons.

Granulocyte colony-stimulating factor (GCSF) is currently in clinical trials to treat neurodegenerative diseases and stroke. Here, we tested whether LIM domain only 4 protein (LMO4), a hypoxia-inducible gene that protects neurons from ischemic injury, could modulate the neuroprotective effect of GCSF. We showed that GCSF treatment acetylates and phosphorylates Stat3, activates expression of a Stat3-dependent anti-apoptotic gene, p27, and increases neuron survival from ischemic injury. LMO4 participates in Stat3 signaling in hepatocytes and associates with histone deacetylase 2 (HDAC2) in cancer cells. In the absence of LMO4, GCSF fails to rescue neurons from ischemic insults. In wild-type neurons, inhibition of HDAC promoted Stat3 acetylation and the antiapoptotic effect of GCSF. In LMO4 null cortical neurons, expression of wild-type but not HDAC-interaction-deficient LMO4 restored GCSF-induced Stat3 acetylation and p27 expression. Thus, our results indicate that LMO4 enhances GCSF-induced Stat3 signaling in neurons, in part by sequestering HDAC.

Electrophysiological Alterations of Pyramidal Cells and Interneurons of the CA1 Region of the Hippocampus in a Novel Mouse Model of Dravet Syndrome.

Dravet syndrome is a developmental epileptic encephalopathy caused by pathogenic variation in SCN1A To characterize the pathogenic substitution (p.H939R) of a local individual with Dravet syndrome, fibroblast cells from the individual were reprogrammed to pluripotent stem cells and differentiated into neurons. Sodium currents of these neurons were compared with healthy control induced neurons. A novel Scn1aH939R/+ mouse model was generated with the p.H939R substitution. Immunohistochemistry and electrophysiological experiments were performed on hippocampal slices of Scn1aH939R/+ mice. We found that the sodium currents recorded in the proband-induced neurons were significantly smaller and slower compared to wild type (WT). The resting membrane potential and spike amplitude were significantly depolarized in the proband-induced neurons. Similar differences in resting membrane potential and spike amplitude were observed in the interneurons of the hippocampus of Scn1aH939R/+ mice. The Scn1aH939R/+ mice showed the characteristic features of a Dravet-like phenotype: increased mortality and both spontaneous and heat-induced seizures. Immunohistochemistry showed a reduction in amount of parvalbumin and vesicular acetylcholine transporter in the hippocampus of Scn1aH939R/+ compared to WT mice. Overall, these results underline hyper-excitability of the hippocampal CA1 circuit of this novel mouse model of Dravet syndrome which, under certain conditions, such as temperature, can trigger seizure activity. This hyper-excitability is due to the altered electrophysiological properties of pyramidal neurons and interneurons which are caused by the dysfunction of the sodium channel bearing the p.H939R substitution. This novel Dravet syndrome model also highlights the reduction in acetylcholine and the contribution of pyramidal cells, in addition to interneurons, to network hyper-excitability.

Rescue of neurons from ischemic injury by peroxisome proliferator-activated receptor-gamma requires a novel essential cofactor LMO4.

Activation of peroxisome proliferator-activated receptor-gamma (PPARgamma) signaling after stroke may reduce brain injury, but this effect will depend on the levels of receptor and cofactors. Here, we showed that the direct effect of PPARgamma signaling to protect neurons from ischemic injury requires a novel cofactor LMO4, because this effect was lost in LMO4-null cortical neurons. PPARgamma agonist also failed to reduce cerebral infarction after transient focal ischemia in CaMKIIalphaCre/LMO4loxP mice with LMO4 ablated in neurons of the forebrain. Expressing LMO4 in LMO4-null cortical neurons rescued the PPARgamma-protective effect. PPARgamma signaling activates the promoter of the antioxidant gene SOD2 and this process requires LMO4. Addition of a superoxide dismutase mimetic MnTBAP [manganese(III)tetrakis(4-benzoic acid)porphyrin] bypassed the deficiency in PPARgamma signaling and was able to directly rescue LMO4-null cortical neurons from ischemic injury. Like LMO4, PPARgamma and PGC1alpha (PPARgamma coactivator 1alpha) levels in neurons are elevated by hypoxic stress, and absence of LMO4 impairs their upregulation. Coimmunoprecipitation and mammalian two-hybrid assays revealed that LMO4 interacts in a ligand-dependent manner with PPARgamma. LMO4 augments PPARgamma-dependent gene activation, in part, by promoting RXRalpha (retinoid X receptor-alpha) binding to PPARgamma and by increasing PPARgamma binding to its target DNA sequence. Together, our results identify LMO4 as an essential hypoxia-inducible cofactor required for PPARgamma signaling in neurons. Thus, upregulation of LMO4 expression after stroke is likely to be an important determinant of neuron survival.

ATP release by way of connexin 36 hemichannels mediates ischemic tolerance in vitro.

Spreading depression (SD) is a self-propagating wave of neuronal and glial depolarization that may occur in virtually any gray matter region in the brain. One consequence of SD is an increased tolerance to ischemia. It has been shown that during cortical SD ATP is released into the extracellular space and activation of purinergic receptors leads to the induction of ischemic tolerance. In the present study we show that depolarization of cultured neurons induces ischemic tolerance which is mediated by purinergic receptor activation. Depolarization causes the release of ATP into the extracellular medium, which may be prevented by treatment with the connexin hemichannel blockers flufenamic acid and quinine, but not the pannexin hemichannel blocker carbenoxolone. Knockdown of connexin 36 expression by siRNA greatly reduces the amount of ATP released during depolarization and the subsequent degree of ischemic tolerance. We conclude that during depolarization neurons release ATP by way of connexin 36 hemichannels.

Anisomycin Activates Utrophin Upregulation Through a p38 Signaling Pathway.

Duchenne muscular dystrophy is a recessive X-linked disease characterized by progressive muscle wasting; cardiac or respiratory failure causes death in most patients by the third decade.  The disease is caused by mutations in the dystrophin gene that lead to a loss of functional dystrophin protein. Although there are currently few treatments for Duchenne muscular dystrophy, previous reports have shown that upregulating the dystrophin paralog utrophin in Duchenne muscular dystrophy mouse models is a promising therapeutic strategy. We conducted in silico mining of the Connectivity Map database for utrophin-inducing agents, identifying the p38-activating antibiotic anisomycin. Treatments of C2C12, undifferentiated murine myoblasts, and mdx primary myoblasts with anisomycin conferred increases in utrophin protein levels through p38 pathway activation.  Anisomycin also induced utrophin protein levels in the diaphragm of mdx mice.  Our study shows that repositioning small molecules such as anisomycin may prove to have Duchenne muscular dystrophy clinical utility.

Cortical spreading depression releases ATP into the extracellular space and purinergic receptor activation contributes to the induction of ischemic tolerance.

Cortical Spreading Depression (CSD) is a well-studied model of preconditioning that provides a high degree of tolerance to a subsequent ischemic event in the brain. The present study was undertaken in order to determine whether the release of ATP during CSD could contribute to the induction of ischemic tolerance. Direct measurement of ATP levels during CSD indicates that with each CSD wave ATP is released into the extracellular space at levels exceeding 100 microM. Cultures of rat primary cortical neurons exposed to low levels of extracellular ATP developed tolerance to subsequent oxygen-glucose deprivation (OGD) or metabolic hypoxia. The preconditioning effect requires new protein synthesis and develops with time, suggesting that a complex genomic response is required for the induction of tolerance. Multiple purinergic receptors are involved in mediating tolerance, with P2Y receptor activation having the greatest effect. Although extracellular adenosine or glutamate may make a small contribution, most of the tolerance was found to be induced independently of adenosine or glutamate receptor activation. Multiple signal transduction pathways mediate the response to extracellular ATP with the protein kinase A pathway and activation of phospholipase C contributing the most. The results are consistent with the proposal that CSD releases ATP into the extracellular space and the subsequent activation of P2Y receptors makes a major contribution to the induction of ischemic tolerance in the brain.

CRHR1 exacerbates the glial inflammatory response and alters BDNF/TrkB/pCREB signaling in a rat model of global cerebral ischemia: implications for neuroprotection and cognitive recovery.

This study examined the impact of corticotropin-releasing hormone type 1 receptor (CRHR1) blockade using Antalarmin (ANT) on the expression of markers of neuroplasticity and inflammation, as well as neuroprotection and behavioral recovery following global cerebral ischemia. Male Wistar rats (N=50) were treated with ANT (2µg/2µl; icv) or a vehicle solution prior to a sham or four vessel (4VO) occlusion. Seven days post ischemia, anxiety was assessed in the Elevated Plus Maze and Open Field tests, and fear and spatial learning in a Y-Maze Passive Avoidance Task and the Barnes Maze. Thirty days post ischemia, brain derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) receptor expression, hippocampal neuronal death and inflammation were determined by analyzing immunoreactivity (ir) of neuron-specific nuclear protein (NeuN), microglia (IBA1, ionized calcium binding adaptor molecule 1), astrocytes (GFAP, glial fibrillary acidic protein) and TNFα (tumor necrosis factor alpha) a pro-inflammatory cytokine. Our findings revealed that ANT improved behavioral impairments, while conferring neuroprotection and blunting neuroinflammation in all hippocampal sub-regions post ischemia. We also observed reduced BDNF and TrkB mRNA and protein levels at the hippocampus, and increased expression at the hypothalamus and amygdala post ischemia, site-specific alterations which were regularized by pre-ischemic CRHR1 blockade. These findings support that CRHR1 actively contributes to altered brain plasticity, neuronal inflammation and injury and recovery of function following ischemic brain insults.

Microparticles generated during chronic cerebral ischemia increase the permeability of microvascular endothelial barriers in vitro.

Numbers of circulating microparticles (MPs) are elevated in a variety of cardiovascular disorders, and recent studies indicate that they are involved in inflammatory intercellular signaling. In the present study the signaling properties of MPs were assessed in an in vitro model of the blood brain barrier. MPs isolated from the plasma of rats exposed to chronic cerebral ischemia caused a significant reduction in the transendothelial electrical resistance (TEER) when applied to in vitro endothelial barriers, while MPs isolated from an equal volume of plasma from unoperated or sham operated rats did not. The reduction in TEER was attenuated by treating endothelial barriers prior to exposure to MPs with the caspase 3 inhibitor AC-DEVD-CHO, the TNF-α inhibitor SPD304, the tumor necrosis factor alpha-converting enzyme (TACE, ADAM 17) inhibitor TAPI-0-1 and the Rho kinase (ROCK) inhibitor Y-27632, and by treating the MPs themselves with these inhibitors prior to applying them to cultured cells. This observation indicates that MPs generated during cerebral ischemia contain pro-TNF-α, active TACE and active ROCK. ROCK and Ras homolog gene family member A (RhoA) were detected in MPs by western blot. The growth factor VEGF stimulated transcellular transport in endothelial barriers while exposure to MPs did not. We conclude that the increase in permeability of artificial barriers induced by MPs is primarily due to enhanced apoptosis induced by activation of the TNF-α pathway and activated caspase 3 and Rho kinases delivered to endothelial cells by MPs.

Activation of CRHR1 receptors regulates social and depressive-like behaviors and expression of BDNF and TrkB in mesocorticolimbic regions following global cerebral ischemia.

Increased HPA axis activation and CRH release characterize the brain's response to global cerebral ischemia. Recently, CRH via activation of CRH type 1 receptors (CRHR1) has been shown to regulate Brain Derived Neurotrophic Factor (BDNF) secretion and emotional behavior. The current study investigates the impact of CRHR1 blockade on BDNF/TrkB signaling expression in the mesolimbic circuitry, and social and depressive-like behavior following global ischemia. Adult male Wistar rats were injected with Antalarmin (2µg/µl) or a vehicle 30min prior to 10min global cerebral ischemia (4VO model) or sham occlusion. The Three Chamber Social Approach Test (SIT) assessed sociability and preference for social novelty, and the novelty suppressed feeding test (NSFT), forced swim test (FST), and sucrose preference test characterized anxiety and depression. Corticosterone levels and organ (thymus, seminal and adrenal glands) weights were determined as additional physiological indices of stress. Immunohistochemistry, Western blot and Rt-PCR were used to assess BDNF and TrkB receptor levels in subregions of the medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and ventral tegmental area (VTA) 30days post-ischemia. Our findings indicate reduced BDNF and TrkB protein and mRNA expression in the mPFC post-ischemia, while heightened levels were found in the NAc. Ischemia increased immobility in the FST and reduced sucrose preference and led to reduced latency to feed in the NSFT and heightened sociability and social novelty preference in the SIT. Antalarmin treatment normalized post-ischemic biochemical/behavioral changes. Our findings support lasting effects of CRHR1 activation on brain plasticity markers, likely playing a role in emotional impairments following cardio- or cerebro-vascular accidents.

Evaluation of the direct effects of poly(dopamine) on the in vitro response of human osteoblastic cells.

Functional polymeric coatings have rapidly become one of the most efficient strategies to endow biomaterials with enhanced bioactive properties. Among the bio-inspired polymers used for biomedical applications, mussel-derived poly(dopamine) (PDA) has increasingly attracted considerable interest because of its unique characteristics. In this work, we carried out detailed physicochemical characterization of a PDA film deposited on nanoporous titanium. In particular, we employed spectroscopic techniques (Raman and ATR-FTIR) and Digital Pulsed Force Mode Atomic Force microscopy (DPFM-AFM) to probe the chemical makeup and the nanomechanical properties of PDA-coated surfaces. In addition, we investigated protein adsorption by ATR-FTIR and quantified it with ten different serum proteins by Liquid Chromatography Mass spectroscopy (LC-MS), aiming at elucidating their potential contribution to the subsequent cell colonization. Successively, we assessed the response of MG-63 human osteoblastic cells to PDA-coated titanium both the multiple- and single-cell levels. Results for this study demonstrate that, compared to bare and nanoporous titanium, the PDA coating positively influences the adhesion and proliferation of MG-63 cells. In addition, we focus on how the three different substrates influence cell morphology (i.e. aspect ratio and form factor), the establishment of focal adhesions and the expression of RhoA, a protein involved in cell contractility. In conclusion, our work provides a deeper insight on the in vitro response of human osteoblastic cells to poly(dopamine) by closing in on specific aspects of cell-PDA interactions, ultimately reaffirming the potential of this bio-inspired polymer as a functional coating for bone tissue engineering applications.

A rapid and efficient method for dissociated cultures of mouse myenteric neurons.

BACKGROUND: The enteric nervous system controls gastrointestinal functions such as secretion and smooth muscle contraction/relaxation. Neuronal enteric dysfunction is a feature of many direct gastrointestinal disorders and can be secondary to central nervous system disorders. Research in this field has been limited and there are few published methods on dissociated enteric cultures. NEW METHOD: Here we describe a quick and efficient method for culturing myenteric neurons which optimizes neuronal yield. A simplified technique is presented to easily dissect the myenteric plexus and longitudinal muscle from the outside of the intestinal wall reducing non-neuronal cell and bacterial contamination from the final culture. These segments are subjected to enzymatic dissociation and the resulting neurons are placed into an optimal growth media for long term culture. RESULTS: This protocol produces a high yield of neuronal cells. Multiple neuronal subtypes reflecting the in vivo population are observed. Cultures are optimal at 3 weeks in vitro but can be sustained for at least 5 weeks. COMPARISON WITH EXISTING METHODS: Unlike other protocols our method does not require a time consuming challenging dissection, long enzymatic treatment times or the use of specialized equipment. Resulting cultures are of higher quality and can be sustained longer permitting proper neuronal recovery. In addition cell attachment to culture substrates have been optimized. CONCLUSION: We provide a novel method for researchers to dissociate and grow high quality enteric neuronal cultures. Our method can be used for studies on gastrointestinal diseases caused by enteric neuronal dysfunction and to explore possible pharmacological interventions in vitro.