Rational Design of Pectin-Chitosan Polyelectrolyte Nanoparticles for Enhanced Temozolomide Delivery in Brain Tumor Therapy.

Conventional chemotherapeutic approaches currently used for brain tumor treatment have low efficiency in targeted drug delivery and often have non-target toxicity. Development of stable and effective drug delivery vehicles for the most incurable diseases is one of the urgent biomedical challenges. We have developed polymer nanoparticles (NPs) with improved temozolomide (TMZ) delivery for promising brain tumor therapy, performing a rational design of polyelectrolyte complexes of oppositely charged polysaccharides of cationic chitosan and anionic pectin.

Preparation and Characterization of Hydrogel Films and Nanoparticles Based on Low-Esterified Pectin for Anticancer Applications.

Prospective adjuvant anticancer therapy development includes the establishing of drug delivery systems based on biocompatible and biodegradable carriers. We have designed films and nanoparticles (NPs) based on low-esterified pectin hydrogel using the ionic gelation method. We investigated morphology, nanomechanical properties, biocompatibility and anticancer activity.

How to Develop Drug Delivery System Based on Carbohydrate Nanoparticles Targeted to Brain Tumors.

Brain tumors are the most difficult to treat, not only because of the variety of their forms and the small number of effective chemotherapeutic agents capable of suppressing tumor cells, but also limited by poor drug transport across the blood-brain barrier (BBB). Nanoparticles are promising drug delivery solutions promoted by the expansion of nanotechnology, emerging in the creation and practical use of materials in the range from 1 to 500 nm. Carbohydrate-based nanoparticles is a unique platform for active molecular transport and targeted drug delivery, providing biocompatibility, biodegradability, and a reduction in toxic side effects.

Preparation of Hydrogels Based on Modified Pectins by Tuning Their Properties for Anti-Glioma Therapy.

The extracellular matrix (ECM) of the central nervous system (CNS), characterized by low stiffness and predominance of carbohydrates on protein components, mediates limited cell proliferation and migration. Pectins are polysaccharides derived from plants and could be very promising for a tunable hydrogel design that mimics the neural ECM. Aiming to regulate gel structure and viscoelastic properties, we elaborated 10 variants of pectin-based hydrogels via tuning the concentration of the polymer and the number of free carboxyl groups expressed in the degree of esterification (DE).

Novel assay to measure chromosome instability identifies extract that elevates CIN and has a potential for tumor- suppressing therapies.

Human artificial chromosomes (HACs) have provided a useful tool to study kinetochore structure and function, gene delivery, and gene expression. The HAC propagates and segregates properly in the cells. Recently, we have developed an experimental high-throughput imaging (HTI) HAC-based assay that allows the identification of genes whose depletion leads to chromosome instability (CIN).

Cell and Tissue Nanomechanics: From Early Development to Carcinogenesis.

Cell and tissue nanomechanics, being inspired by progress in high-resolution physical mapping, has recently burst into biomedical research, discovering not only new characteristics of normal and diseased tissues, but also unveiling previously unknown mechanisms of pathological processes. Some parallels can be drawn between early development and carcinogenesis. Early embryogenesis, up to the blastocyst stage, requires a soft microenvironment and internal mechanical signals induced by the contractility of the cortical actomyosin cytoskeleton, stimulating quick cell divisions.

Hydrogels based on modified pectins capable of modulating neural cell behavior as prospective biomaterials in glioblastoma treatment.

Glioblastoma is the most common malignant tumor of the brain, but its treatment outcomes can be improved by new therapeutic techniques using biocompatible materials. Utilizing controllable alkaline de-esterification we obtained pectin preparation with 27.4% esterification degree and used it for bio-artificial matrix production.

The Extracellular Matrix and Biocompatible Materials in Glioblastoma Treatment.

During cancer genesis, the extracellular matrix (ECM) in the human brain undergoes important transformations, starting to resemble embryonic brain cell milieu with a much denser structure. However, the stiffness of the tumor ECM does not preclude cancer cells from migration. The importance of the ECM role in normal brain tissue as well as in tumor homeostasis has engaged much effort in trials to implement ECM as a target and an instrument in the treatment of brain cancers.

In vitro antitumor and immunotropic activity of carrageenans from red algae Chondrus armatus and their low-molecular weight degradation products.

Antitumor and immunotropic effects of κ-, λ-carrageenan from red marine algae Chondrus armatus and their low-molecular weight (LMW) degradation products were explored. Effects on human esophageal cancer cell lines KYSE30 and FLO1 viability and ability to induce production of pro- and anti-inflammatory cytokines by human monocytes was assessed. All polysaccharides demonstrated antimetabolic and cytostatic activity towards cancer lines, with high-molecular weight carrageenans possessing higher antimetabolic and lower cytostatic activity than their LMW degradation products.

A potential role for neuronal connexin 36 in the pathogenesis of amyotrophic lateral sclerosis.

Neuronal gap junctional protein connexin 36 (Cx36) contributes to neuronal death following a range of acute brain insults such as ischemia, traumatic brain injury and epilepsy. Whether Cx36 contributes to neuronal death and pathological outcomes in chronic neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), is not known. We show here that the expression of Cx36 is significantly decreased in lumbar segments of the spinal cord of both human ALS subjects and SOD1 mice as compared to healthy human and wild-type mouse controls, respectively.

Gap junctions and hemichannels: communicating cell death in neurodevelopment and disease.

Gap junctions are unique membrane channels that play a significant role in intercellular communication in the developing and mature central nervous system (CNS). These channels are composed of connexin proteins that oligomerize into hexamers to form connexons or hemichannels. Many different connexins are expressed in the CNS, with some specificity with regard to the cell types in which distinct connexins are found, as well as the timepoints when they are expressed in the developing and mature CNS.

Death of Neurons following Injury Requires Conductive Neuronal Gap Junction Channels but Not a Specific Connexin.

Pharmacological blockade or genetic knockout of neuronal connexin 36 (Cx36)-containing gap junctions reduces neuronal death caused by ischemia, traumatic brain injury and NMDA receptor (NMDAR)-mediated excitotoxicity. However, whether Cx36 gap junctions contribute to neuronal death via channel-dependent or channel-independent mechanism remains an open question. To address this, we manipulated connexin protein expression via lentiviral transduction of mouse neuronal cortical cultures and analyzed neuronal death twenty-four hours following administration of NMDA (a model of NMDAR excitotoxicity) or oxygen-glucose deprivation (a model of ischemic injury).

Neuronal gap junction coupling as the primary determinant of the extent of glutamate-mediated excitotoxicity.

In the mammalian central nervous system (CNS), coupling of neurons by gap junctions (electrical synapses) increases during early postnatal development, then decreases, but increases in the mature CNS following neuronal injury, such as ischemia, traumatic brain injury and epilepsy. Glutamate-dependent neuronal death also occurs in the CNS during development and neuronal injury, i.e.

Neuronal gap junctions: making and breaking connections during development and injury.

In the mammalian central nervous system (CNS), coupling of neurons by gap junctions (i.e., electrical synapses) and the expression of the neuronal gap junction protein, connexin 36 (Cx36), transiently increase during early postnatal development.

The regulation and role of neuronal gap junctions during neuronal injury.

In the mammalian CNS, excessive release of glutamate and overactivation of glutamate receptors are responsible for the secondary (delayed) neuronal death following neuronal injury, including ischemia, traumatic brain injury (TBI) and epilepsy. The coupling of neurons by gap junctions (electrical synapses) increases during neuronal injury. In a recent study with the use of in vivo and in vitro models of cortical ischemia in mice, we have demonstrated that the ischemic increase in neuronal gap junction coupling is regulated by glutamate via group II metabotropic glutamate receptors (mGluR).

Neuronal gap junctions play a role in the secondary neuronal death following controlled cortical impact.

In the mammalian CNS, excessive release of glutamate and overactivation of glutamate receptors are responsible for the secondary (delayed) neuronal death following neuronal injury, including ischemia, traumatic brain injury (TBI) and epilepsy. Recent studies in mice showed a critical role for neuronal gap junctions in NMDA receptor-mediated excitotoxicity and ischemia-mediated neuronal death. Here, using controlled cortical impact (CCI) in adult mice, as a model of TBI, and Fluoro-Jade B staining for analysis of neuronal death, we set to determine whether neuronal gap junctions play a role in the CCI-mediated secondary neuronal death.

Novel model for the mechanisms of glutamate-dependent excitotoxicity: role of neuronal gap junctions.

In the mammalian central nervous system (CNS), coupling of neurons by gap junctions (electrical synapses) increases during early post-natal development, then decreases, but increases in the mature CNS following neuronal injury, such as ischemia, traumatic brain injury and epilepsy. Glutamate-dependent neuronal death also occurs in the CNS during development and neuronal injury, i.e.

Regulation of connexin 36 expression during development.

In the mammalian CNS, the expression of neuronal gap junction protein, connexin 36 (Cx36), increases during the first 2 weeks of postnatal development and then decreases during the following 2 weeks. Recently we showed that the developmental increase in Cx36 expression is augmented by chronic (2 weeks) activation of group II metabotropic glutamate receptors (mGluR), prevented by chronic receptor inactivation, and the receptor-dependent increase in Cx36 expression is regulated via transcriptional control of the Cx36 gene activity. We demonstrate here that acute (60 min) activation of group II mGluRs in developing cortical neuronal cultures causes transient increase in Cx36 protein expression with decrease during the following 24h.

Neuronal gap junction coupling is regulated by glutamate and plays critical role in cell death during neuronal injury.

In the mammalian CNS, excessive release of glutamate and overactivation of glutamate receptors are responsible for the secondary (delayed) neuronal death following neuronal injury, including ischemia, traumatic brain injury (TBI), and epilepsy. The coupling of neurons by gap junctions (electrical synapses) increases during neuronal injury. We report here that the ischemic increase in neuronal gap junction coupling is regulated by glutamate via group II metabotropic glutamate receptors (mGluRs).

The regulation and role of neuronal gap junctions during development.

Coupling of neurons by electrical synapses (gap junctions) transiently increases in the mammalian CNS during development and plays a role in a number of developmental events, including neuronal death. The coupling subsequently decreases and remains low in the adult, confined to specific subsets of neurons. In a recent study we have demonstrated that the developmental increase in neuronal gap junction coupling is regulated by the balance between the activity of two neurotransmitter receptors, group II metabotropic glutamate receptors (mGluR) and GABA(A) receptors.

Deletion of neuronal gap junction protein connexin 36 impairs hippocampal LTP.

In the mammalian CNS, deletion of neuronal gap junction protein, connexin 36 (Cx36), causes deficiencies in learning and memory. Here we tested whether Cx36 deletion affects the hippocampal long-term potentiation (LTP), which is considered as a cellular model of learning and memory mechanisms. We report that in acute slices of the hippocampal CA1 area, LTP is reduced in Cx36 knockout mice as compared to wild-type mice.

Interplay of chemical neurotransmitters regulates developmental increase in electrical synapses.

Coupling of neurons by electrical synapses (gap junctions) transiently increases in the mammalian CNS during development. We report here that the developmental increase in neuronal gap junction coupling and expression of connexin 36 (Cx36; neuronal gap junction protein) are regulated by an interplay between the activity of group II metabotropic glutamate receptors (mGluRs) and GABA(A) receptors. Specifically, using dye coupling, electrotonic coupling, Western blots and small interfering RNA in the rat and mouse hypothalamus and cortex in vivo and in vitro, we demonstrate that activation of group II mGluRs augments, and inactivation prevents, the developmental increase in neuronal gap junction coupling and Cx36 expression.

Neuronal gap junctions are required for NMDA receptor-mediated excitotoxicity: implications in ischemic stroke.

N-methyl-D-aspartate receptors (NMDARs) play an important role in cell survival versus cell death decisions during neuronal development, ischemia, trauma, and epilepsy. Coupling of neurons by electrical synapses (gap junctions) is high or increases in neuronal networks during all these conditions. In the developing CNS, neuronal gap junctions are critical for two different types of NMDAR-dependent cell death.

Transgenic expression of Glud1 (glutamate dehydrogenase 1) in neurons: in vivo model of enhanced glutamate release, altered synaptic plasticity, and selective neuronal vulnerability.

The effects of lifelong, moderate excess release of glutamate (Glu) in the CNS have not been previously characterized. We created a transgenic (Tg) mouse model of lifelong excess synaptic Glu release in the CNS by introducing the gene for glutamate dehydrogenase 1 (Glud1) under the control of the neuron-specific enolase promoter. Glud1 is, potentially, an important enzyme in the pathway of Glu synthesis in nerve terminals.