Brain Cell Membranes Research Articles

Cholesterol-Dependent Serotonin Insertion Controlled by Gangliosides in Model Lipid Membranes.

Serotonin is distinct among synaptic neurotransmitters because it is amphipathic and released from synaptic vesicles at concentrations superior to its water solubility limit (270 mM in synaptic vesicles for a solubility limit of 110 mM). Hence, serotonin is mostly aggregated in the synaptic cleft, due to extensive aromatic stacking. This important characteristic has received scant attention, as most representations of the serotonergic synapse take as warranted that serotonin molecules are present as monomers after synaptic vesicle exocytosis. Using a combination of in silico and physicochemical approaches and a new experimental device mimicking synaptic conditions, we show that serotonin aggregates are efficiently dissolved by gangliosides (especially GM1) present in postsynaptic membranes. This initial interaction, driven by electrostatic forces, attracts serotonin from insoluble aggregates and resolves micelles into monomers. Serotonin also interacts with cholesterol via a set of CH-π and van der Waals interactions. Thus, gangliosides and cholesterol act together as a functional serotonin-collecting funnel on brain cell membranes. Based on this unique mode of interaction with postsynaptic membranes, we propose a new model of serotonergic transmission that takes into account the post-exocytosis solubilizing effect of gangliosides and cholesterol on serotonin aggregates.

Altered Cytokine Profile in Clinically Suspected Seronegative Autoimmune Associated Epilepsy.

Autoimmune-associated epilepsy (AAE), a condition which responds favorably to immune therapies but not traditional anti-seizure interventions, is emerging as a significant contributor to cases of drug-resistant epilepsy. Current standards for the diagnosis of AAE rely on screening for known neuronal autoantibodies in patient serum or cerebrospinal fluid. However, this diagnostic method fails to capture a subset of drug-resistant epilepsy patients with suspected AAE who respond to immunotherapy yet remain seronegative (snAAE) for known autoantibodies. To identify potential biomarkers for snAAE, we evaluated the most comprehensive panel of assayed cytokines and autoantibodies to date, comparing patients with snAAE, anti-seizure medication (ASM) responsive epilepsy, and patients with other neuroinflammatory diseases. We found a unique signature of 14 cytokines significantly elevated in snAAE patients including: GM-CSF, MCP-2/CCL8, MIP-1a/CCL3, IL-1RA, IL-6, IL-8, IL-9, IL-10, IL-15, IL-20, VEGF-A, TNF-b, LIF, and TSLP. Based on prior literature, we highlight IL-6, IL-8, IL-10, IL-13, VEGF-A, and TNF-b as potentially actionable cytokine biomarkers for snAAE, which could be of diagnostic utility in clinical evaluations of snAAE patients. Autoantibody-ome screening failed to identify autoantibodies targeting neuronal channel proteins in snAAE patients. Interestingly, ASM-responsive epilepsy patients displayed elevations in the proportion of autoantibodies targeting brain plasma membrane proteins, possibly pointing to the presence of immune hyperactivity/dysfunction despite well-controlled seizure activity and suggesting ASM-responsive patients may experience disease progression independent of seizure activity (PISA). Overall, our findings suggest that simply expanding existing autoantibody screens may not sufficiently enhance diagnostic power for snAAE. Instead, we propose that cytokine analysis may serve as a promising diagnostic avenue for identifying immune dysregulation in AAE patients and enabling opportunities for trials of immunotherapies.

Creation of a novel zebrafish model with low DHA status to study the role of maternal nutrition during neurodevelopment.

Docosahexaenoic acid (DHA), a dietary omega-3 fatty acid, is a major building block of brain cell membranes. Offspring rely on maternal DHA transfer to meet their neurodevelopmental needs, but DHA sources are lacking in the American diet. Low DHA status is linked to altered immune responses, white matter defects, impaired vision, and an increased risk of psychiatric disorders during development. However, the underlying cellular mechanisms involved are largely unknown, and advancements in the field have been limited by the existing tools and animal models. Zebrafish are an excellent model for studying neurodevelopmental mechanisms. Embryos undergo rapid external development and are optically transparent, enabling direct observation of individual cells and dynamic cell-cell interactions in a way that is not possible in rodents. Here, we create a novel DHA-deficient zebrafish model by 1) disrupting elovl2, a key gene in the DHA biosynthesis pathway, via CRISPR-Cas9 genome editing, and 2) feeding mothers a DHA-deficient diet. We show that low DHA status during development is associated with a small eye morphological phenotype and demonstrate that even the morphologically normal siblings exhibit dysregulated gene pathways related to vision and stress response. Future work using our zebrafish model could reveal the cellular and molecular mechanisms by which low DHA status leads to neurodevelopmental abnormalities and provide insight into maternal nutritional strategies that optimize infant brain health.

Identification of Human TRIAC Transmembrane Transporters.

Background: 3,5,3'-Triiodothyroacetic acid (TRIAC) is a T3-receptor agonist pharmacologically used in patients to mitigate T3 resistance. It is additionally explored to treat some symptoms of patients with inactivating mutations in the thyroid hormone (TH) transporter monocarboxylate transporter 8 (MCT8, SLC16A2). MCT8 is expressed along the blood-brain barrier, on neurons, astrocytes, and oligodendrocytes. Hence, pathogenic variants in MCT8 limit the access of TH into and their functions within the brain. TRIAC was shown to enter the brain independently of MCT8 and to modulate expression of TH-dependent genes. The aim of the study was to identify transporters that facilitate TRIAC uptake into cells. Methods: We performed a whole-genome RNAi screen in HepG2 cells stably expressing a T3-receptor-dependent luciferase reporter gene. Validation of hits from the primary and confirmatory secondary screen involved a counter screen with siRNAs and compared the cellular response to TRIAC to the effect of T3, in order to exclude siRNAs targeting the gene expression machinery. MDCK1 cells were stably transfected with cDNA encoding C-terminally myc-tagged versions of the identified TRIAC-preferring transporters. Several individual clones were selected after immunocytochemical characterization for biochemical characterization of their 125I-TRIAC transport activities. Results: We identified SLC22A9 and SLC29A2 as transporters mediating cellular uptake of TRIAC. SLC22A9 encodes the organic anion transporter 7 (OAT7), a sodium-independent organic anion transporter expressed in the plasma membrane in brain, pituitary, liver, and other organs. Competition with the SLC22A9/OAT7 substrate estrone-3-sulfate reduced 125I-TRIAC uptake. SLC29A2 encodes the equilibrative nucleoside transporter 2 (ENT2), which is ubiquitously expressed, including pituitary and brain. Coincubation with the SLC29A2/ENT2 inhibitor nitrobenzyl-6-thioinosine reduced 125I-TRIAC uptake. Moreover, ABCD1, an ATP-dependent peroxisomal pump, was identified as a 125I-TRIAC exporter in transfected MDCK1 cells. Conclusions: Knowledge of TRIAC transporter expression patterns, also during brain development, may thus in the future help to interpret observations on TRIAC effects, as well as understand why TRIAC may not show a desirable effect on cells or organs not expressing appropriate transporters. The identification of ABCD1 highlights the sensitivity of our established screening assay, but it may not hold significant relevance for patients undergoing TRIAC treatment.

REGULATION OF THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS BY PHYTOSTEROL: ACTIONS AND MECHANISM OF ACTION

Phytosterols (PS), commonly referred to as plant sterols, are naturally occurring chemicals found in plants that resemble cholesterol in structure but have an additional methyl (campesterol) or ethyl (β-sitosterol) group in the side chain. The present review was based on the regulation of the hypothalamic-pituitary-adrenal axis by phytosterol: actions and mechanism of action. PS have been shown to have endocrine-disrupting properties, and studies on humans, rats, mice, goldfish (Carassius auratus), and Japanese quail have all reported experiencing this effect. Dietary PS has been shown to accumulate in the brain lately. Dietary β-sitosterol has the ability to cross the blood–brain barrier (BBB) and build up permanently in the membranes of brain cells. The stress response, which consists of a complex interplay between elements of the central nervous system (CNS) and peripheral systems such the endocrine, immunological, and cardiovascular systems, is triggered by exposure to environmental, physical, or physiological stressors. Under stressful circumstances, the HPA axis mediates the physiological maintenance of homeostasis. In conclusion, adult male quails fed PS alone had lower testosterone concentrations in their plasma and pituitary without appreciably changing their levels of LH. Furthermore, LH release from the pituitary gland and testosterone release from the testes were both markedly increased by cGnRH-1 stimulation. In contrast to control animals, quails fed PS had lower amounts of testosterone and LH.

A birdcage transmit, 24-channel conformal receive array coil for sensitive 31P magnetic resonance spectroscopic imaging of the human brain at 7 T.

Phosphorus (31P) magnetic resonance spectroscopic imaging (MRSI) can serve as a critical tool for more direct quantification of brain energy metabolism, tissue pH, and cell membrane turnover. However, the low concentration of 31P metabolites in biological tissue may result in low signal-to-noise ratio (SNR) in 31P MRS images. In this work, we present an innovative design and construction of a 31P radiofrequency coil for whole-brain MRSI at 7 T. Our coil builds on current literature in ultra-high field 31P coil design and offers complete coverage of the brain, including the cerebellum and brainstem. The coil consists of an actively detunable volume transmit (Tx) resonator and a custom 24-channel receive (Rx) array. The volume Tx resonator is a 16-rung high-pass birdcage coil. The Rx coil consists of a 24-element phased array composed of catered loop shapes and sizes built onto a custom, close-fitting, head-shaped housing. The Rx array was designed to provide complete coverage of the head, while minimizing mutual coupling. The Rx configuration had a mean reflection coefficient better than -20 decibels (dB) when the coil was loaded with a human head. The mean mutual coupling ( ) among Rx elements, when loaded with a human head, was -16 dB. In phantom imaging, the phased array produced a central SNR that was 4.4-fold higher than the corresponding central SNR when operating the 31P birdcage as a transceiver. The peripheral SNR was 12-fold higher when applying the optimized phased array. In vivo 3D 31P MRSI experiments produced high-quality spectra in the cerebrum gray and white matter, as well as in the cerebellum. Characteristic phosphorus metabolites related to adenosine triphosphate metabolism and cell membrane turnover were distinguishable across all brain regions. In summary, our results demonstrate the potential of our novel coil for accurate, whole-brain 31P metabolite quantification.

Proteinase resistance of carnosine, pyrrolylcarnosine, and salicylcarnosine

The stability of carnosine, pyrrolylcarnosine (PC) and salicylcarnosine (SC) to the action of leucine aminopeptidase, carboxypeptidases B and Y was evaluated. It was found that proteolysis of carnosine, PC and SC under the action of leucine aminopeptidase does not occur. Carboxypeptidases B and Y, as well as the enzyme system of blood plasma and plasma membranes of rat brain cells, degraded peptides containing β-alanyl, N-pyrrolyl, N-salicylic fragments to varying degrees. In all cases, histidine is formed. The formation of pyrrole or salicylic acid does not occur. It was found that carnosine, PC and SC showed high stability to the action of amino- and carboxypeptidases in in vitro experiments.

Molecular Modeling of Shockwave-Mediated Blood-Brain Barrier Opening for Targeted Drug Delivery.

Bubble-enhanced shock waves induce the transient opening of the blood-brain barrier (BBB) providing unique advantages for targeted drug delivery of brain tumor therapy, but little is known about the molecular details of this process. Based on our BBB model including 28 000 lipids and 280 tight junction proteins and coarse-grained dynamics simulations, we provided the molecular-level delivery mechanism of three typical drugs for the first time, including the lipophilic paclitaxel, hydrophilic gemcitabine, and siRNA encapsulated in liposome, across the BBB. The results show that the BBB is more difficult to be perforated by shock-induced jets than the human brain plasma membrane (PM), requiring higher shock wave speeds. For the pores formed, the BBB exhibits a greater ability to self-heal than PM. Hydrophobic paclitaxel can cross the BBB and be successfully absorbed, but the amount is only one-third of that of PM; however, the absorption of hydrophilic gemcitabine was almost negligible. Liposome-loaded siRNAs only stayed in the first layer of the BBB. The mechanism analysis shows that increasing the bubble size can promote drug absorption while reducing the risk of higher shock wave overpressure. An exponential function was proposed to describe the relation between bubble and overpressure, which can be extended to the experimental microbubble scale. The calculated overpressure is consistent with the experimental result. These molecular-scale details on shock-assisted BBB opening for targeted drug delivery would guide and assist experimental attempts to promote the application of this strategy in the clinical treatment of brain tumors.

The Relationship Between Citicoline Administration and the National Institute of Health Stroke Scale in Hemorrhagic Stroke Patients at Dr. Regional General Hospital Chasbullah Abdulmadjid Bekasi City in 2022

Background: Hemorrhagic stroke is a focal or generalized neurological deficit that occurs suddenly within seconds or hours caused by a ruptured blood vessel. Hemorrhagic stroke can be divided into Intracerebral Hemorrhage (ICH) and Subarachnoid Hemorrhage (SAH). The prevalence of stroke in Indonesia, according to Riskesdas, in 2018 reached 10.9%; the highest cases occurred at the age of ≥55 years and were dominated by men. Treatment of hemorrhagic stroke can use citicoline as a neuroprotectant to repair brain cell membranes. One of the tools that can be used if there is a neurological deficit is the National Institute of Health Stroke Scale (NIHSS), which is useful for assessing the state of improvement of post-stroke patients. Purpose: To determine the relationship between the administration of citicoline and the NIHSS of hemorrhagic stroke patients. Methods: Descriptive analytics with a cross-sectional design using medical record data from the Regional General Hospital dr. Chasbullah Abdulmadjid Bekasi City had 95 patients based on the inclusion criteria. Results: The data from this study were processed using the Chi-Square test, which showed a significant relationship between citicoline administration and the NIHSS in hemorrhagic stroke patients with p-value = 0.017 (p <0.05). Conclusion: The administering of citicoline therapy in hemorrhagic stroke patients improved the NIHSS score. Keywords: Hemorrhagic stroke, Citicoline, NIHSS

Myelination- and migration-associated genes are downregulated after phagocytosis in cultured oligodendrocyte precursor cells.

In the central nervous system, microglia are responsible for removing infectious agents, damaged/dead cells, and amyloid plaques by phagocytosis. Other cell types, such as astrocytes, are also recently recognized to show phagocytotic activity under some conditions. Oligodendrocyte precursor cells (OPCs), which belong to the same glial cell family as microglia and astrocytes, may have similar functions. However, it remains largely unknown whether OPCs exhibit phagocytic activity against foreign materials like microglia. To answer this question, we examined the phagocytosis activity of OPCs using primary rat OPC cultures. Since innate phagocytosis activity could trigger cell death pathways, we also investigated whether participating in phagocytosis activity may lead to OPC cell death. Our data shows that cultured OPCs phagocytosed myelin-debris-rich lysates prepared from rat corpus callosum, without progressing to cell death. In contrast to OPCs, mature oligodendrocytes did not show phagocytotic activity against the bait. OPCs also exhibited phagocytosis towards lysates of rat brain cortex and cell membrane debris from cultured astrocytes, but the percentage of OPCs that phagocytosed beta-amyloid was much lower than the myelin debris. We then conducted RNA-seq experiments to examine the transcriptome profile of OPC cultures and found that myelination- and migration-associated genes were downregulated 24 h after phagocytosis. On the other hand, there were a few upregulated genes in OPCs 24 h after phagocytosis. These data confirm that OPCs play a role in debris removal and suggest that OPCs may remain in a quiescent state after phagocytosis.

Modified Korean MIND Diet: A Nutritional Intervention for Improved Cognitive Function in Elderly Women through Mitochondrial Respiration, Inflammation Suppression, and Amino Acid Metabolism Regulation.

Mild cognitive impairment is associated with a high prevalence of dementia. The study examines the benefits of a modified Korean MIND (K-MIND) diet and explores biomarkers using multi-omics analysis. The K-MIND diet, tailored to the elderly Korean population, includes perilla oil, milk, or fermented milk, and avoids alcohol consumption. As a result, the K-MIND diet significantly improves subjects "orientation to place" in the Korean version of the Mini-Mental State Examination, 2nd edition test. According to multi-omics analysis, the K-MIND diet upregulates genes associated with mitochondrial respiration, including ubiquinone oxidoreductase, cytochrome C oxidase, and ATP synthase, and immune system processes, and downregulates genes related to nuclear factor kappa B activity and inflammatory responses. In addition, K-MIND affects the metabolic pathways of glycine, serine, threonine, tryptophan, and sphingolipids, which are closely linked to cognitive function through synthesis of neurotransmitters and structures of brain cell membranes. The findings imply that the K-MIND diet improves cognitive function by upregulating key genes involved in oxidative phosphorylation and downregulating pro-inflammatory cytokines.

N-(levodopa) chitosan derivative based on click chemistry shows biological functionality in brain cells

Objective To develop N-(levodopa) chitosan derivatives through click chemistry to study their effect in brain cells. Significance: This study presents a proof-of-concept that macromolecules such as N-(Levodopa) chitosan derivatives traverse brain cell membranes and induce biomedical functionalities. Methods Through click chemistry, we developed N-(levodopa) chitosan derivatives. They were physically and chemically characterized by FT-IR, 1H-NMR, TGA and Dynamic Light Scattering analyses. Solution and nanoparticles of N-(levodopa) chitosan derivatives were tested in primary cell cultures from the postnatal rat olfactory bulb, substantia nigra and corpus callosum. Ca2+ imaging and UPLC experiments were used to investigate if the biomaterial modulated the brain cell physiology. Results N-(levodopa) chitosan derivatives induced intracellular Ca2+ responses in primary cell cultures of the rat brain. UPLC experiments indicated that levodopa attached to chitosan was converted into dopamine by brain cells. Conclusion The present study shows that N-(levodopa) chitosan may be useful to develop new treatment strategies, which could serve as molecular reservoirs of biomedical drugs to treat degenerative disorders of the nervous system.

Prospects of pharmacological regulation of aquaporin function in CNS diseases

The review analyzes the results of scientific research on the role of aquaporins in the pathogenesis of CNS diseases and the possibility of their pharmacological regulation.
 Aquaporins (AQP) are proteins involved in the transmembrane transport of water and other substances. They form the water channels of cell membranes and are widely represented in various mammalian cells, including the membranes of human brain and spinal cord cells. To date, about 300 types of proteins of the aquaporin family have been discovered, of which 13 (AQP0AQP12) have been identified in human cells. Localization of different types of AQP in CNS structures, their functional activity and involvement in the development of CNS diseases differ. There are mainly three types of AQPs in the central nervous system: AQP1, AQP4 and AQP9. The results of scientific research indicate the most important role of AQP in maintaining water-salt homeostasis and ensuring physiological processes in the central nervous system, and also confirm the role of AQP in the pathogenesis of a number of diseases of the central nervous system (cerebral edema of various genesis, invasion of tumor cells and the formation of peritumorous edema, in the development of autoimmune diseases opticomyelitis, Alzheimers disease). Pharmacological regulation of the functional activity of aquaporins can influence the course of these diseases. Therefore, there is a natural interest in drugs that can change the expression of AQP.
 Proteins of the aquaporin family provide transmembrane transport of water and play an essential role in the development of pathological conditions of the central nervous system. They can be potential targets for pharmacological effects in a number of diseases of the central nervous system. The search and study of drugs affecting the expression and functional activity of AQP is pathogenetically justified and is a promising direction in the development of pharmacotherapy strategies for cerebral edema, malignant brain tumors and other CNS diseases.

Prospects of pharmacological regulation of aquaporin function in CNS diseases

The review analyzes the results of scientific research on the role of aquaporins in the pathogenesis of CNS diseases and the possibility of their pharmacological regulation.
 Aquaporins (AQP) are proteins involved in the transmembrane transport of water and other substances. They form the water channels of cell membranes and are widely represented in various mammalian cells, including the membranes of human brain and spinal cord cells. To date, about 300 types of proteins of the aquaporin family have been discovered, of which 13 (AQP0AQP12) have been identified in human cells. Localization of different types of AQP in CNS structures, their functional activity and involvement in the development of CNS diseases differ. There are mainly three types of AQPs in the central nervous system: AQP1, AQP4 and AQP9. The results of scientific research indicate the most important role of AQP in maintaining water-salt homeostasis and ensuring physiological processes in the central nervous system, and also confirm the role of AQP in the pathogenesis of a number of diseases of the central nervous system (cerebral edema of various genesis, invasion of tumor cells and the formation of peritumorous edema, in the development of autoimmune diseases opticomyelitis, Alzheimers disease). Pharmacological regulation of the functional activity of aquaporins can influence the course of these diseases. Therefore, there is a natural interest in drugs that can change the expression of AQP.
 Proteins of the aquaporin family provide transmembrane transport of water and play an essential role in the development of pathological conditions of the central nervous system. They can be potential targets for pharmacological effects in a number of diseases of the central nervous system. The search and study of drugs affecting the expression and functional activity of AQP is pathogenetically justified and is a promising direction in the development of pharmacotherapy strategies for cerebral edema, malignant brain tumors and other CNS diseases.

Synthetic corticotropins and the GABA-receptor system: Direct and delayed effects.

The central effectors of the stress system are greatly interconnected and include, among others, a large group of peptides derived from proopiomelanocortin. In addition to natural corticotropins, a number of artificial molecules that contain some ACTH fragments in their structure are also referred to members of this family. Some of them possess a wide range of biological activity. The molecular mechanism underlying the biological activity of such peptides is partly based on allosteric modulation of various receptors. We analyzed the ability of some biologically active synthetic corticotropins (ACTH(4-7)PGP, ACTH(6-9)PGP, ACTH(7-10)PGP), and glyproline PGPL to affect the GABA-receptor system of rat brain. The effects of the peptides were studied in the isolated plasma membranes of brain cells, as well as after systemic peptide administration in the rat model of acute restraint stress. The delayed effect of stress or preadministration of each of the studied peptides on [3 H]GABA binding was different for its high- and low-affinity-specific sites. The studied peptides individually affected the binding of [3 H]GABA in their own way. Acute restraint stress caused a decrease in [3 H]GABA binding at its low-affine site and did not affected the high-affine site. Preliminary peptide administration did not influence this effect of stress.

Homotypic Membrane-Enhanced Blood-Brain Barrier Crossing and Glioblastoma Targeting for Precise Surgical Resection and Photothermal Therapy.

The crossing of blood-brain barrier (BBB) is essential for glioblastoma (GBM) therapy, and homotypic targeting is an effective strategy to achieve BBB crossing. In this work, GBM patient-derived tumor cell membrane (GBM-PDTCM) is prepared to cloak gold nanorods (AuNRs). Relying on the high homology of the GBM-PDTCM to the brain cell membrane, GBM-PDTCM@AuNRs realize efficient BBB crossing and selective GBM targeting. Meanwhile, owing to the functionalization of Raman reporter and lipophilic fluorophore, GBM-PDTCM@AuNRs are able to generate fluorescence and Raman signals at GBM lesion, and almost all tumor can be precisely resected in 15 min by the guidance of dual signals, ameliorating the surgical treatment for advanced GBM. In addition, photothermal therapy for orthotopic xenograft mice is accomplished by intravenous injection of GBM-PDTCM@AuNRs, doubling the median survival time of the mice, which improves the nonsurgical treatment for early GBM. Therefore, benefiting from homotypic membrane-enhanced BBB crossing and GBM targeting, all-stage GBM can be treated with GBM-PDTCM@AuNRs in distinct ways, providing an alternative idea for the therapy of tumor in the brain.

Aptamer functionalized cell membrane for brain and nerve cell sensing with high sensitivity and stability

Accurate dopamine (DA) monitoring with high stability is essential for investigating the chemical basis of brain function and pathology. Electrochemical-based tissue-implantable carbon fiber electrodes (CFEs) show great potential in sensing the dynamics of neurochemicals at a sub-second timescale. However, their anti-fouling property, selectivity, and stability pose challenges. Here, we presented a novel strategy to enhance electrode biocompatibility and stability by modifying CFE with a chitosan (CS) film, brain cell membrane (M), and aptamer cholesterol amphiphiles (DNA-cho). We found that CFE was uniformly covered by a cicada-like membrane after being modified. Electrochemical characterizations indicated that DNA-cho-M–CS–CFE exhibited a wide linear range of DA concentration and showed high sensitivity, specificity, and stability. The electrode also presented excellent fouling resistance and biocompatibility. Moreover, the biosensor was used to detect DA in K+-induced brain slices and PC12 cells with a satisfactory stability and sensitivity and to prove that LPS treatment leads to the delayed and decreased release of DA. DNA-cho-M–CS–CFE showed excellent electrochemical performance and unique advantages for long-term in vivo sensing of living cells, thus providing a new feasible scheme for studying neurochemical kinetics and brain diseases.

Molecular modelling of shockwave-mediated delivery of paclitaxel aggregates across the neuronal plasma membrane.

Shock-assisted paclitaxel (PTX) transport across the blood-brain barrier offers a promising treatment strategy for brain tumors. Here, based on a realistically complex human brain plasma membrane (PM) model, we investigated the dynamic transmembrane behavior of a PTX cluster by shock induced bubble collapse, focusing on the effect of impulse (I), bubble diameter (D) and arrays. The results show that all three factors can control the transport depth (ΔDPM) of PTX. For a fixed D, the ΔDPM grows exponentially with I, ΔDPM ∼ exp (I), and eventually reaches a critical depth. But the depth, ΔDPM, can be adjusted linearly in a wider range of D. This mainly depends on the size of jets from bubble collapse. For bubble arrays, the bubbles in series can transport PTX deeper than a single bubble, while the parallel does the opposite. In addition, only PTX clusters in the range of jet action can be successfully transported. Finally, the absorption of PTX clusters was examined via recovery simulation. Not all PTX clusters across the membrane can be effectively absorbed by cells. The shallow PTX clusters are quickly attracted by the membrane and embedded into it. The critical depth at which PTX clusters can be effectively absorbed is about 20 nm. These molecular-level mechanisms and dynamic processes of PTX clusters crossing the PM membrane may be helpful in optimizing the application of shock-induced bubble collapse for the delivery of PTX to tumor cells.

Analysis of Factors Affecting 5-ALA Fluorescence Intensity in Visualizing Glial Tumor Cells-Literature Review.

Glial tumors are one of the most common lesions of the central nervous system. Despite the implementation of appropriate treatment, the prognosis is not successful. As shown in the literature, maximal tumor resection is a key element in improving therapeutic outcome. One of the methods to achieve it is the use of fluorescent intraoperative navigation with 5-aminolevulinic acid. Unfortunately, often the level of fluorescence emitted is not satisfactory, resulting in difficulties in the course of surgery. This article summarizes currently available knowledge regarding differences in the level of emitted fluorescence. It may depend on both the histological type and the genetic profile of the tumor, which is reflected in the activity and expression of enzymes involved in the intracellular metabolism of fluorescent dyes, such as PBGD, FECH, UROS, and ALAS. The transport of 5-aminolevulinic acid and its metabolites across the blood–brain barrier and cell membranes mediated by transporters, such as ABCB6 and ABCG2, is also important. Accompanying therapies, such as antiepileptic drugs or steroids, also have an impact on light emission by tumor cells. Accurate determination of the factors influencing the fluorescence of 5-aminolevulinic acid-treated cells may contribute to the improvement of fluorescence navigation in patients with highly malignant gliomas.

Focal opening of the neuronal plasma membrane by shock-induced bubble collapse for drug delivery: a coarse-grained molecular dynamics simulation.

Cell permeabilization using shock-induced bubble collapse provides an attractive choice for drug delivery systems. In this work, based on a realistically human brain plasma membrane (PM) model, we investigated the focal opening of this complex model by the jet from cavitation, focusing on the effect of characteristic membrane components, particle velocity (up) and bubble diameters (D). Both high levels of cholesterol and specific cerebrosides in the PM model limit the pore opening of cavitation jets. Sphingomyelin is the opposite, but has little effect due to its low content. Two adjustable parameters of up and D can be coupled to control the opening size. The relationship between them and the maximum pore area was provided for the first time. The maximum pore area increases with the up (or the impulse that is positively related to up) in the low-speed range, which agrees with the experimentally observed impulse determinism. However, the maximum area drops in the high-speed range. Combined with D, we proposed that the jet size determines the pore size, not the impulse. Larger bubbles that can create a larger pore in the membrane have a larger jet size, but their impulse is relatively small. Finally, the recovery simulation shows that the membrane with a small pore can be quickly recovered within 300 ps, while that with a larger pore did not recover until 2 μs. These rules from this work may be helpful to optimize the choice of shock waves for the delivery of different drugs across membranes.