A Twice-condensed Pdna Polyplex System Based On Small Molecular Weight Polyethylenimine For Peripheral Nerve Crush Injury

Peripheral nerve injury is a common clinical disease,leading to patients’ decreased motor and sensory functions.Patients receiving operations or those with minor injuries need to rely on nerve growth factors,several kinds of protein drugs,to promote nerve repair and regeneration.But,vascular endothelial growth factor(VEGF),with great treating effects,has an extremely short half-life in vivo,poor compliance because of frequent injections and high price.Thus,it is urgent to improve its formulation to solve these problems.Fortunately,Gene therapy can deliver vascular endothelial growth factor plasmid DNA(VEGF p DNA)into cells,enable those transfected cells to express VEGF and nourish injured nerves.However,the use of non-viral vectors is generally limited by their potential toxicity problems,relatively poor transfection abilities,serum stability,or complex construction processes of modified polyplexes.Thus,we develop an efficient and stable polyplex system by convenient construction methods.Here,polyethyleneimine(PEI)1.8 k Da and glutaraldehyde(GA)are used to construct a novel twice-condensed p DNA polyplex system using a one-pot construction method,including p H-responsive-C=N-linkages by which different PEI molecules on one single polyplex can link with each other.This system has good particle sizes and zeta potentials.In addition,serum stabilities are achieved without PEGylation or other chemical modifications using lyophobic segments,but via p H-responsive linkages that ensure the escape of nucleic acids.This polyplex system is used to deliver the p DNA of vascular endothelial growth factor(VEGF)whose half-life period in vivo is only around 30 minutes.Compared with polyplexes prepared using PEI 25 k Da,cells and rats treated with twice-condensed VEGF p DNA polyplexes express significantly more VEGF or myelin basic protein(MBP),and this new polyplex system showed fewer adverse effects in vitro and in vivo.In addition,revascularization and neurogenesis are also discovered in the rat sciatic nerve crush injury model.