Comparing the biological activity and composition of Cerebrolysin with other peptide preparations.

Neurological disorders, ranging from acute forms such as stroke and traumatic brain injury to neurodegenerative diseases like dementia, are the leading cause of disability-adjusted life years (DALYs) worldwide. A promising approach to address these conditions and promote nervous system regeneration is the use of the neuropeptide preparation Cerebrolysin, which has been shown to be effective in both clinical and preclinical studies. Despite claims of similar clinical efficacy and safety by several peptide preparations, concerns regarding their generic composition and efficacy have been previously raised. Based on these reports, we analyzed the peptide composition and neurotrophic activity of several peptide preparations allegedly similar to Cerebrolysin and approved in some countries for treating neurological diseases. Our results demonstrate that these preparations lack relevant biological activity and that the peptide composition is significantly different from Cerebrolysin. peptide.

Porcine Brain Enzyme Hydrolysate Enhances Immune Function and Antioxidant Defense via Modulation of Gut Microbiota in a Cyclophosphamide-Induced Immunodeficiency Model.

This study examined how consuming porcine brain enzyme hydrolysate (PBEH) affects the immune function and composition of the gut microbiota in an immunodeficient animal model. Male Wistar rats aged 6 weeks were fed casein (control), 100 mg/kg body weight (BW), red ginseng extract (positive-control), and 6, 13, and 26 mg PBEH per kg BW (PBEH-L, PBEH-M, and PBEH-H, respectively) daily for 4 weeks. At 30 min after consuming assigned compounds, they were orally administered cyclophosphamide (CTX; 5 mg/kg BW), an immunosuppressive agent, to suppress the immune system by inhibiting the proliferation of lymphocytes. The normal-control rats were fed casein and water instead of CTX. Natural killer cell activity and splenocyte proliferation induced by 1 µg/mL lipopolysaccharide were lower in the control group than the normal-control group, and they significantly increased with PBEH consumption, particularly at high doses. The PBEH consumption increased dose-dependently in the Th1/Th2 ratio compared to the control. The lipid peroxide contents were lower in the PBEH group than in the control group. Moreover, PBEH m and PBEH-H consumption mitigated white pulp cell damage, reduced red pulp congestion, and increased spleen mast cells in the histological analysis. Intestinal microbiota composition demonstrated differences between the groups at the genus levels, with Akkermansia being more abundant in the control group than the normal-control group and the PBEH-H group showing a decrease. However, Bifidobacterium decreased in the control group but increased in the PBEH-H group. The ß-diversity revealed distinct microbial communities of PBEH and positive-control groups compared to the control group (p < 0.05). The metagenome predictions revealed that PBEH-H influenced amino acid metabolism, antioxidant defense, insulin sensitivity, and longevity pathways. In conclusion, PBEH-H intake boosted immune responses and reduced lipid peroxides by modulating gut microbiota composition. These findings suggest that PBEH-H has the potential as a dietary supplement for improving immune function and gut health in individuals with immunodeficiency.

Experimental study on monitoring microwave ablation efficacy by real-time shear wave elastography in ex vivo porcine brain.

Objective: Glioma constitutes the most common primary malignant tumor in the central nervous system. In recent years, microwave ablation (MWA) was expected to be applied in the minimally invasive treatment of brain tumors. This study aims to evaluate the feasibility and accuracy of microwave ablation in ex vivo brain tissue by Shear Wave Elastography (SWE) to explore the application value of real-time SWE in monitoring the process of MWA of brain tissue.Methods: Thirty ex vivo brain tissues were treated with different microwave power and ablation duration. The morphologic and microscopic changes of MWA tissues were observed, and the diameter of the ablation areas was measured. In this experiment, SWE is used to quantitatively evaluate brain tissue's degree of thermal injury immediately after ablation.Results: This study It is found that the ablation range measured by SWE after ablation is in good consistency with the pathological range [ICCSWEL1-L1 = 0.975(95% CI:0.959 - 0.985), ICCSWEL2-L2 = 0.887(95% CI:0.779 - 0.938)]. At the same time, the SWE value after ablation is significantly higher than before (mean ± SD,9.88 ± 2.64 kPa vs.23.6 ± 13.75 kPa; p < 0.001). In this study, the SWE value of tissues in different pathological states was further analyzed by the ROC curve (AUC = 0.86), and the threshold for distinguishing normal tissue from tissue after ablation was 13.7 kPa. The accuracy of evaluating ablation tissue using SWE can reach 84.72%, providing data support for real-time quantitative observation of the ablation range.Conclusion: In conclusion the accurate visualization and real-time evaluation of the organizational change range of the MWA process can be realized by real-time SWE.

Neuroprotective Effect of Nosustrophine in a 3xTg Mouse Model of Alzheimer's Disease.

Neurodegeneration, characterized by the progressive deterioration of neurons and glial cells, is a feature of Alzheimer's disease (AD). The present study aims to demonstrate that the onset and early progression of neurodegenerative processes in transgenic mice models of AD can be delayed by a cocktail of neurotrophic factors and derived peptides named Nosustrophine, a nootropic supplement made by a peptide complex extracted from the young porcine brain, ensuring neuroprotection and improving neuro-functional recovery. Experimental 3xTg-APP/Bin1/COPS5 transgenic mice models of AD were treated with Nosustrophine at two different early ages, and their neuropathological hallmark and behavior response were analyzed. Results showed that Nosustrophine increased the activity of the immune system and reduced pathological changes in the hippocampus and cortex by halting the development of amyloid plaques, mainly seen in mice of 3-4 months of age, indicating that its effect is more preventive than therapeutic. Taken together, the results indicate the potent neuroprotective activity of Nosustrophine and its stimulating effects on neuronal plasticity. This study shows for the first time an effective therapy using nootropic supplements against degenerative diseases, although further investigation is needed to understand their molecular pathways.

Plasmalogen Profiling in Porcine Brain Tissues by LC-MS/MS.

Plasmalogen, a functional glycerophospholipid, is known for its beneficial nutritional effects, such as anti-oxidation and anti-inflammation. As the porcine brain is a plasmalogen-rich resource, this study aimed to explore its potential for plasmalogen-based health food product development, with special attention on whether and how the industrial production processes influence the plasmalogen content and composition. In the present work, plasmalogens from different porcine brain products were investigated using liquid chromatography-tandem mass spectrometry. The results indicated that all the porcine brain products showed abundant total plasmalogens, of which more than 95% were ethanolamine plasmalogen species. Acetone precipitation, ethanol extraction, and drying did not significantly affect the plasmalogen content, whereas repeated freeze-thaw cycles in the production process led to noticeable loss. The chemometric investigation suggested that raw products and glycerophospholipid products exhibited different profiles; furthermore, the concentration step seemed to impact the plasmalogen composition. The nutritional assessment revealed that porcine brain products showed favorable values of multiple indexes, including PUFA/SFA ratio, n-6/n-3 ratio, thrombogenicity index, and unsaturation index, suggesting a health-beneficial value. The current study not only shows the feasibility of producing porcine brain-derived plasmalogens, but also provides possible strategies for developing and quality-controlling dietary plasmalogen supplements and healthcare products.

Regulation of the ATP-binding cassette transporters ABCB1, ABCG2 and ABCC5 by nuclear receptors in porcine blood-brain barrier endothelial cells.

BACKGROUND AND PURPOSE: Blood-brain barrier (BBB) ABCB1, ABCG2 and ABCC5 transporters influence central therapeutic drug distribution. Transporter expression is regulated by the NR3C1, NR1I3 and NR1I2 nuclear receptors, but their precise roles in brain are poorly understood. We investigated the effects of selective ligand-based activation of NR3C1, NR1I3, NR1I2 and NR2B1 in porcine brain endothelial cells (PBECs). EXPERIMENTAL APPROACH: Primary cultures of PBECs were exposed to NR3C1, NR1I3 and NR1I2 ligands and ABCB1, ABCG2 and ABCC5 transporter activities determined by measuring intracellular accumulation of fluorescent probes. Western blotting was used to determine the effects of receptor ligands on expression of ABCB1, ABCG2, ABCC5, NR1I2, NR1I3, NR3C1 and NR2B1. Fluorescent immunocytochemistry was employed to assess the effects of receptor ligands on the cellular localisation of NR1I2 and NR1I3. KEY RESULTS: The NR1I2 agonist rifampicin significantly up-regulated ABCG2 activity, which is counteracted by co-treatment with NR1I2 antagonist l-sulforaphane. The NR1I3 agonist 6-(4-chlorophenyl)-imidazo[2,1-b]thiazole-5-carbaldehyde and inverse agonist meclizine significantly down-regulated ABCB1, ABCG2 and ABCC5 activity. NR3C1 agonist dexamethasone significantly increased ABCB1, ABCG2 and ABCC5 activity and ABCG2 and ABCC5 protein expression, which was counteracted by co-treatment with the NR3C1 antagonist mifepristone. This first study demonstrates that NR1I3 and NR3C1 regulate ABCC5 activity and protein expression in BBB endothelial cells. CONCLUSIONS AND IMPLICATIONS: In PBECs, expression of key ATP-binding cassette (ABC) transporters and nuclear receptors is differentially regulated by NR1I3, NR1I2, NR3C1 and NR2B1. This will help to better understand the response of the BBB to physiological and pharmacological activation of nuclear receptors.

Detection and Semi-quantification of Lipids on High-Performance Thin-Layer Chromatography Plate using Ceric Ammonium Molybdate Staining.

It is desirable to quickly check the composition of lipids in small size samples, but achieving this is challenging using the existing staining methods. Herein, we developed a highly sensitive and semi-quantitative method for analysis of lipid samples with ceric ammonium molybdate (CAM) staining. The CAM detection method was systematically evaluated with a wide range of lipid classes including phospholipids, sphingolipids, glycerolipids, fatty acids (FA) and sterols, demonstrating high sensitivity, stability, and overall efficiency. Additionally, CAM staining provides a clean yellow background in high performance thin-layer chromatography (HPTLC) which facilitates quantification of lipids using image processing software. Lipids can be stained with CAM reagent regardless of their head group types, position of the carbon-carbon double bonds, geometric isomerism and the variation in the length of FA chain, but staining is mostly affected by the degree of unsaturation of the FA backbone. The mechanism of the CAM staining of lipids was proposed on principles of the reduction-oxidation reaction, in which Mo(VI) oxidizes the unsaturated lipids into carbonyl compounds on the HPTLC plate upon heating, while itself being reduced to Mo(IV). This method was applied for the separation, identification, and quantification of lipid extracts from porcine brain.

Complex Permittivity of Ex-Vivo Human, Bovine and Porcine Brain Tissues in the Microwave Frequency Range.

Accurate knowledge about the dielectric properties of biological tissues in the microwave frequency range may lead to advancement of biomedical applications based on microwave technology. However, the published data are very scarce, especially for human brain tissues. The aim of this work was to measure and report the complex permittivity of brain white matter, grey matter and cerebellum. Complex permittivity was measured on human, bovine and porcine brain tissues in the microwave frequency range from 0.5 to 18 GHz using an open-ended coaxial probe. The results present a valuable addition to the available data on the brain tissue complex permittivity. Some noticeable variations between the results lead to several conclusions. Complex permittivity variation within the same tissue type of the individual species was comparable to interspecies variation. The difference was prominent between human brains obtained from autopsies, while bovine brains obtained from healthy animals showed very similar complex permittivity. We hypothesize that the difference might have been caused by the basic pathologies of the patients, where the associated therapies could have affected the brain water content. We also examined the effect of excised tissue degradation on its complex permittivity over the course of three days, and the results suggest the gradual dehydration of the samples.

An Improved In Vitro Porcine Blood-Brain Barrier Model for Permeability Screening and Functional Studies.

The availability of good in vitro blood-brain barrier (BBB) models that closely mimic in vivo BBB features are essential for central nervous system (CNS) drug permeability screening and BBB functionality studies. Of the currently available monoculture primary BBB models, porcine brain endothelial cell models have the best barrier properties, which make them highly suitable for CNS drug permeability screening. In addition, they retain major BBB features such as BBB transporters, receptors, and enzymes and express BBB tight junctions. Therefore, porcine BBB models are also suitable for BBB functionality studies. This paper describes a procedure for extraction of brain microvessels from fresh porcine brains and the culture of pure primary porcine brain endothelial cells. In addition, techniques to improve culture purity and quality, and increase barrier tightness without using co-cultures are given. Using this method, a robust and reproducible in vitro BBB model can be established for CNS permeability screening and studying BBB functionality.

Purification of Tubulin from Porcine Brain and its Fluorescence Dye Modification.

Filamentous microtubules, polymers of the heterodimeric protein tubulins play one of the major roles in the emergent nano-biotechnological devices. To develop the feature of those devices, it is important to understand the function of microtubule in in vitro, hence, the availability of purified αß-tubulin is required. Additionally, fluorescently labeled tubulin has become a powerful approach for extensively studying the dynamics of these components. In this chapter, the process of purifying the heterodimeric αß-tubulin from porcine brain will be described, as well as the process of labeling of the purified tubulin with fluorescence dye.

Long-Term Effect of Porcine Brain Enzyme Hydrolysate Intake on Scopolamine-Induced Memory Impairment in Rats.

No study has revealed the effect of porcine brain enzyme hydrolysate (PBEH) on memory impairment. We aimed to examine the hypothesis that PBEH intake modulates memory deficits and cognitive behavior in scopolamine (SC)-induced amnesia rats, and its mechanism, including gut microbiota changes, was determined. Sprague-Dawley male rats had intraperitoneal injections of SC (2 mg/kg body weight/day) at 30 min after daily feeding of casein (MD-control), PBEH (7 mg total nitrogen/mL) at 0.053 mL (Low-PBEH), 0.159 mL (Medium-PBEH), 0.478 mL (High-PBEH), or 10 mg donepezil (Positive-control) per kilogram body weight per day through a feeding needle for six weeks. The Normal-control rats had casein feeding without SC injection. PBEH dose-dependently protected against memory deficits determined by passive avoidance test, Y-maze, water-maze, and novel object recognition test in SC-induced rats compared to the MD-control. The High-PBEH group had a similar memory function to the Positive-control group. Systemic insulin resistance determined by HOMA-IR was lower in the PBEH groups than in the Normal-control but not the Positive-control. In parallel with systemic insulin resistance, decreased cholesterol and increased glycogen contents in the hippocampus in the Medium-PBEH and High-PBEH represented reduced brain insulin resistance. PBEH intake prevented the increment of serum TNF-α and IL-1ß concentrations in the SC-injected rats. Hippocampal lipid peroxide and TNF-α contents and mRNA TNF-α and IL-1ß expression were dose-dependently reduced in PBEH and Positive-control. PBEH decreased the hippocampal acetylcholinesterase activity compared to the MD-control, but not as much as the Positive-control. PBEH intake increased the α-diversity of the gut microbiota compared to the MD-control, and the gut microbiota community was separated from MD-control. In metagenome function analysis, PBEH increased the energy metabolism-related pathways of the gut microbiota, including citric acid cycle, oxidative phosphorylation, glycolysis, and amino acid metabolism, which were lower in the MD-control than the Normal-control. In conclusion, alleviated memory deficit by PBEH was associated potentially with not only reducing acetylcholinesterase activity but also improving brain insulin resistance and neuroinflammation potentially through modulating gut microbiota. PBEH intake (1.5-4.5 mL of 7 mg total nitrogen/mL for human equivalent) can be a potential therapeutic agent for improving memory impairment.

Efflux at the Blood-Brain Barrier Reduces the Cerebral Exposure to Ochratoxin A, Ochratoxin α, Citrinin and Dihydrocitrinone.

Recent studies have implied that environmental toxins, such as mycotoxins, are risk factors for neurodegenerative diseases. To act directly as neurotoxins, mycotoxins need to penetrate or affect the integrity of the blood-brain barrier, which protects the mammalian brain from potentially harmful substances. As common food and feed contaminants of fungal origin, the interest in the potential neurotoxicity of ochratoxin A, citrinin and their metabolites has recently increased. Primary porcine brain capillary endothelial cells were used to investigate cytotoxic or barrier-weakening effects of ochratoxin A, ochratoxin α, citrinin and dihydrocitrinone. The transfer and transport properties of the mycotoxins across the barrier formed by porcine brain capillary endothelial cell monolayers were analysed using HPLC-MS/MS. High levels of Ochratoxin A caused cytotoxic and barrier-weakening effects, whereas ochratoxin α, citrinin and dihydrocitrinone showed no adverse effects up to 10 µM. Likely due to efflux transporter proteins, the transfer to the brain compartment was much slower than expected from their high lipophilicity. Due to their slow transfer across the blood-brain barrier, cerebral exposure of ochratoxin A, ochratoxin α, citrinin and dihydrocitrinone is low and neurotoxicity is likely to play a subordinate role in their toxicity at common physiological concentrations.

Enhancement of acidic lipid analysis by nanoflow ultrahigh performance liquid chromatography-mass spectrometry.

Acidic lipids are associated with the regulation of the structure and function of membrane proteins. Therefore, accurate and highly precise analysis of acidic lipids is important for elucidating their biological roles and pathological mechanisms. In this study, an enhanced analytical method for the separation and quantification of acidic lipids, including phosphatidylserine (PS), phosphatidic acid (PA), cardiolipin, and their lyso-derivatives, was developed using nanoflow ultrahigh performance liquid chromatography-electrospray ionisation-tandem mass spectrometry. The separation and mass spectrometry detection of acidic lipids were optimised in terms of peak tailing and time-based separation efficiencies, with carbamate-embedded C18 as the stationary phase, in the presence of an appropriate liquid chromatography solvent modifier. This newly developed method was applied to analyse a lipid extract from porcine brain. A significant increase in the number of acidic lipids identified (176 vs. 134), including intact monolysocardiolipin (17 vs. 4), was observed with the new method compared with conventional C18. The quantification of acidic lipids was validated with plasma standard (NIST SRM 1950) spiked with a number of LPS and PS standards, and acceptable accuracy (<15%) was obtained. The present method was found to be reliable for the acidic lipid analysis based on qualitative results from tissue extract and plasma samples.

A face-to-face comparison of claudin-5 transduced human brain endothelial (hCMEC/D3) cells with porcine brain endothelial cells as blood-brain barrier models for drug transport studies.

BACKGROUND: Predictive in vitro models of the human blood-brain barrier (BBB) are essential in early drug discovery and development. Among available immortalized human brain capillary endothelial cell lines (BCECs), the hCMEC/D3 cell line has become the most widely used in vitro BBB model. However, monolayers of hCMEC/D3 cells form only moderately restrictive barriers, most likely because the major tight junction protein, claudin-5, is markedly downregulated. Thus, hCMEC/D3 monolayers cannot be used for vectorial drug transport experiments, which is a major disadvantage of this model. METHODS: Here we transduced hCMEC/D3 cells with a claudin-5 plasmid and compared the characteristics of these cells with those of hCMEC/D3 wildtype cells and primary cultured porcine BCECs. RESULTS: The claudin-5 transduced hCMEC/D3 exhibited expression levels (and junctional localization) of claudin-5 similar to those of primary cultured porcine BCECs. The transduced cells exhibited increased TEER values (211 Ω cm2) and reduced paracellular mannitol permeability (8.06%/h), indicating improved BBB properties; however, the barrier properties of porcine BCECs (TEER 1650 Ω cm2; mannitol permeability 3.95%/h) were not reached. Hence, vectorial transport of a selective P-glycoprotein substrate (N-desmethyl-loperamide) was not observed in claudin-5 transduced hCMEC/D3 (or wildtype) cells, whereas such drug transport occurred in porcine BCECs. CONCLUSIONS: The claudin-5 transduced hCMEC/D3 cells provide a tool to studying the contribution of claudin-5 to barrier tightness and how this can be further enhanced by additional transfections or other manipulations of this widely used in vitro model of the BBB.

Discovery of nitazoxanide-based derivatives as autophagy activators for the treatment of Alzheimer's disease.

Drug repurposing is an efficient strategy for new drug discovery. Our latest study found that nitazoxanide (NTZ), an approved anti-parasite drug, was an autophagy activator and could alleviate the symptom of Alzheimer's disease (AD). In order to further improve the efficacy and discover new chemical entities, a series of NTZ-based derivatives were designed, synthesized, and evaluated as autophagy activator against AD. All compounds were screened by the inhibition of phosphorylation of p70S6K, which was the direct substrate of mammalian target of rapamycin (mTOR) and its phosphorylation level could reflect the mTOR-dependent autophagy level. Among these analogs, compound 22 exhibited excellent potency in promoting ß-amyloid (Aß) clearance, inhibiting tau phosphorylation, as well as stimulating autophagy both in vitro and in vivo. What's more, 22 could effectively improve the memory and cognitive impairments in APP/PS1 transgenic AD model mice. These results demonstrated that 22 was a potential candidate for the treatment of AD.

Biomimetic carbon nanotubes for neurological disease therapeutics as inherent medication.

Nowadays, nanotechnology is revolutionizing the approaches to different fields from manufacture to health. Carbon nanotubes (CNTs) as promising candidates in nanomedicine have great potentials in developing novel entities for central nervous system pathologies, due to their excellent physicochemical properties and ability to interface with neurons and neuronal circuits. However, most of the studies mainly focused on the drug delivery and bioimaging applications of CNTs, while neglect their application prospects as therapeutic drugs themselves. At present, the relevant reviews are not available yet. Herein we summarized the latest advances on the biomedical and therapeutic applications of CNTs in vitro and in vivo for neurological diseases treatments as inherent therapeutic drugs. The biological mechanisms of CNTs-mediated bio-medical effects and potential toxicity of CNTs were also intensely discussed. It is expected that CNTs will exploit further neurological applications on disease therapy in the near future.

Therapeutic drugs modulate ATP-Binding cassette transporter-mediated transport of amyloid beta(1-42) in brain microvascular endothelial cells.

Deposition of amyloid-ß peptide (Aß(1-42)) is a hallmark of Alzheimer's disease. Clearance of Aß(1-42), across the blood-brain barrier (BBB), is mediated by ATP-binding Cassette (ABC) efflux transporters. Many therapeutic drugs inhibit ABC transporters, but little is known of the effect of therapeutic drugs on Aß(1-42) transport across BBB endothelial cells. The effects of selected, widely prescribed, therapeutic drugs on ABCB1, ABCC5 and ABCG2 activities were determined by measuring intracellular levels of calcein, GS-MF, and Hoechst 33342 respectively in primary porcine brain endothelial cells (PBECs). The ability of ABCB1, ABCC5 and ABCG2 to transport Aß(1-42) was determined using fluorescent Aß(1-42). The ability of the ABCB1, ABCC5 and ABCG2 inhibitor telmisartan to modify transcellular Aß(1-42) transport was investigated using PBEC monolayers housed in Transwell® inserts. Treatment of PBECs with ABC transporter inhibitory drugs (indomethacin, olanzapine, chlorpromazine, telmisartan, pantoprazole, quinidine, sulfasalazine and nefazodone) increased Aß(1-42) intracellular accumulation. Inhibition of ABCB1, ABCC5 and ABCG2 by telmisartan increased Aß(1-42) transport in the apical to basal direction and reduced its transport in basal to apical direction in PBEC monolayers. ABCB1, ABCC5 and ABCG2 mediate the efflux transport of Aß(1-42) in BBB endothelial cells. Inhibition of ABC transporters by therapeutic drugs, at plasma concentrations, could decrease Aß(1-42) clearance from brain, across BBB endothelial cells into blood, and potentially influence levels of the Aß(1-42) peptide within the brain.

A comprehensive study on the mechanical properties of different regions of 8-week-old pediatric porcine brain under tension, shear, and compression at various strain rates.

Young porcine brain is often used as a surrogate for studying the mechanical factors affecting traumatic brain injury in children. However, the mechanical properties of pediatric brain tissue derived from humans and piglets are very scarce, and this seriously detracts from the biofidelity of the developed finite element (FE) models of the pediatric head/brain. The present study addresses this issue by subjecting the cerebrum (white matter and gray matter), cerebellum, and brainstem specimens derived from 8-week-old piglets to tension and shear testing at strain rates of 0.01, 1, and 50/s. The experimental data are combined with the corresponding data derived from a previous study under compression to obtain comprehensive stress-strain curves of the pediatric porcine cerebrum, cerebellum, and brainstem tissue specimens. In general, the average stress level of the white matter is somewhat higher than that of the gray matter under the tension, shear and compression conditions, however, this difference does not reach a significant level. The stiffness of the cerebellum and the cerebrum does not differ significantly under tension and shear conditions, but the stiffness of the cerebellum is greater than that of the cerebrum under compression. The brainstem has significantly higher stiffness than the cerebrum and the cerebellum under all loading modes. In addition, the mechanical properties of brain tissue exhibit significant strain-rate dependences. With increasing strain rate from 0.01/s to 50/s, the average stress at a strain of 0.5 for all of the brain tissue increased by about 2.2 times under tension, about 2.4 times under shearing and about 2.2 times under compression. The variations in the stress as a function of the strain rate for brain tissue specimens were well characterized by exponential functions at strains of 0.25 and 0.5 under all three loading modes. The results of this study are useful for developing biofidelic FE models of the pediatric brain.

Compressive Mechanical Properties of Porcine Brain: Experimentation and Modeling of the Tissue Hydration Effects.

Designing protective systems for the human head-and, hence, the brain-requires understanding the brain's microstructural response to mechanical insults. We present the behavior of wet and dry porcine brain undergoing quasi-static and high strain rate mechanical deformations to unravel the effect of hydration on the brain's biomechanics. Here, native 'wet' brain samples contained ~80% (mass/mass) water content and 'dry' brain samples contained ~0% (mass/mass) water content. First, the wet brain incurred a large initial peak stress that was not exhibited by the dry brain. Second, stress levels for the dry brain were greater than the wet brain. Third, the dry brain stress-strain behavior was characteristic of ductile materials with a yield point and work hardening; however, the wet brain showed a typical concave inflection that is often manifested by polymers. Finally, finite element analysis (FEA) of the brain's high strain rate response for samples with various proportions of water and dry brain showed that water played a major role in the initial hardening trend. Therefore, hydration level plays a key role in brain tissue micromechanics, and the incorporation of this hydration effect on the brain's mechanical response in simulated injury scenarios or virtual human-centric protective headgear design is essential.

The endo-lysosomal system of bEnd.3 and hCMEC/D3 brain endothelial cells.

BACKGROUND: Brain endothelial cell-based in vitro models are among the most versatile tools in blood-brain barrier research for testing drug penetration to the central nervous system. Transcytosis of large pharmaceuticals across the brain capillary endothelium involves the complex endo-lysosomal system. This system consists of several types of vesicle, such as early, late and recycling endosomes, retromer-positive structures, and lysosomes. Since the endo-lysosomal system in endothelial cell lines of in vitro blood-brain barrier models has not been investigated in detail, our aim was to characterize this system in different models. METHODS: For the investigation, we have chosen two widely-used models for in vitro drug transport studies: the bEnd.3 mouse and the hCMEC/D3 human brain endothelial cell line. We compared the structures and attributes of their endo-lysosomal system to that of primary porcine brain endothelial cells. RESULTS: We detected significant differences in the vesicular network regarding number, morphology, subcellular distribution and lysosomal activity. The retromer-positive vesicles of the primary cells were distinct in many ways from those of the cell lines. However, the cell lines showed higher lysosomal degradation activity than the primary cells. Additionally, the hCMEC/D3 possessed a strikingly unique ratio of recycling endosomes to late endosomes. CONCLUSIONS: Taken together our data identify differences in the trafficking network of brain endothelial cells, essentially mapping the endo-lysosomal system of in vitro blood-brain barrier models. This knowledge is valuable for planning the optimal route across the blood-brain barrier and advancing drug delivery to the brain.