Amphiphilic, tri-block copolymers provide potent membrane-targeted neuroprotection

Abstract

Excitatory amino acid receptor activation and reactive oxygen species production are important mediators of neuronal death following acute brain injury and can lead to loss of membrane integrity. Poloxamer 188 (P188) is an amphiphilic, polyethylene-polypropylene-polyethylene copolymer that restores plasma membrane integrity of nonneuronal cells following membrane injury. Here, we demonstrate that P188 provides profound protection of hippocampal and cerebellar neurons following severe excitotoxic and oxidative injury in vitro, through membranetargeted mechanisms. Widespread death of cultured hippocampal neurons observed 48 h after Nmethyl-D-aspartate (NMDA) exposure was prevented by incubation of neurons in P188 following NMDA. P188 provided similar neuroprotection from kainate, menadione, and tertbutyl-hydroperoxide, but not from staurosporine. P188 application did not alter either NMDA receptor function or NMDA-induced [Ca 2+ ] i increases. Whole-cell capacitance measurements revealed that P188 application increased cell surface area, consistent with its insertion into the plasma membrane. Following plasma membrane electroporation, P188 arrested loss of intracellular contents, which demonstrated direct restoration of plasma membrane integrity following physical disruption. Measurements of oxidized C11-BODIPY 581/591 fluorescence demonstrated that P188 blocked lipid peroxidation. These observations demonstrate that amphiphilic tri-block copolymers provide strong, membrane-targeted neuroprotection and represent a novel approach to the treatment of acute neuronal injury.Key words: poloxamer • N-methyl-D-aspartate • excitotoxicity • lipid peroxidation • electroporation • capacitance ctivation of receptors for glutamate plays a central role in neuronal death following hypoxia-ischemia/reperfusion, hypoglycemia, or trauma (1). Activation of the N-methyl-D-aspartate (NMDA) receptor subtype is an important mediator of neuronal death, and this mechanism depends on receptor-linked increases in free intracellular Ca 2+ concentration ([Ca 2+ ] i ) 2 . In addition to depleting ATP as a result of energy-requiring Ca 2+ extrusion 3 , NMDAinduced [Ca 2+ ] i influx increases production of reactive oxygen species (4, 5), inducing cellular damage via single-strand DNA breaks, protein oxidation, and lipid peroxidation (6). Lipid

Profiling plasma extracellular vesicle by pluronic block‐copolymer based enrichment method unveils features associated with breast cancer aggression, metastasis and invasion

“…Pluronic block copolymers F68 and related F127 have been reported to have broad utilities and biological properties: Copolymers with higher hydrophilic/lipophilic balance (HLB) (e.g. F-68, HLB0.80) were shown to be capable of being inserted into lipid bilayer membranes and able to restore the integrity of damaged membranes [10–13]; F68 was also shown to be capable of inhibiting protein aggregation [14]. These biological properties seem to be in large contrast to those from PEG, and offer the potential to increase the selectivity of EV precipitation when enriching from complex biofluids, such as plasma.…”

The Effect of Poloxamer-188 on Neuronal Cell Recovery from Mechanical Injury

“…Exposing electroporated cells to this surfactant effectively seals the damaged membranes; thereby, acutely arresting the leakage of intracellular components in vivo and in vitro (Hanning et al, 2000;Lee et al, 1992Lee et al, , 1994Merchant et al, 1998;Terry et al, 1999;Borgens et al, 2004). Recently, Marks et al (2001) reported that P188 is effective in restoring the integrity of injured membranes of electroporated neuronal cells. Since the mechanisms of P188 action are specifically directed at the plasma membrane, the use of this surfactant may provide an alternative approach to treat both acute and delayed post-traumatic injuries in neuronal cells.…”

Surfactant Copolymers Prevent Aggregation of Heat Denatured Lysozyme

“…26,31 Preliminary results showed that these polymers might be involved in the repair of proteins as well. 24 Towards our long term goal to learn about the effects of Poloxamers in the recovery of the cells and tissues, we plan to gain a fundamental understanding of the interaction of these polymers with different proteins in their denatured states.…”