Biophysical Effects of a Novel Biodegradable Copolymer on the Repair of Damaged Neural Membranes

Abstract

The pathophysiology of Spinal cord injury (SCI) is involved primary mechanical injury followed by secondary delayed injury. Neural membrane is the most susceptible part of the cell and most of the time mechanical injury results in axolemma disruption and failure to function as an electrical and ionic barrier. This leads to blockage of nerve impulse conduction, deregulation of ionic gradients; free radical associated lipid peroxidation of membrane and increased influx of calcium ions that activates calpain and caspase-dependent cell death cascades. Thus immediate membrane repair can prevent various destructive processes, restoring of the physicochemical balance of the cytoplasm and ultimate functional recovery in neurons. Several degradable polymers and surfactants including PEG, Poloxamer 188, and poloxamine 1107 have shown to be effective in sealing and halting progressive permeabilization. Here, we applied ultrasound wave as mechanical insult to make transient breaches in membrane to simulate membrane damage in SCI and used a novel triblock copolymer of PEG-(fumaric-sebacic acids)-PEG to seal membrane breaches. Cell survival and membrane integrity were checked by MTT assay and Trypan blue exclusion test respectively. The results showed that this copolymer can be a promising candidate for membrane sealing. Now we are assessing the effects of this polymer on in vivo spinal cord evoked potential (SCEP).