title: Exploring advantages/disadvantages and improvements in overcoming gene delivery barriers of amino acid modified trimethylated chitosan.
abstract: OBJECTIVE
  Present study aimed at exploring advantages/disadvantages of amino acid modified trimethylated chitosan in conquering multiple gene delivery obstacles and thus providing comprehensive understandings for improved transfection efficiency.
  
  
  METHODS
  Arginine, cysteine, and histidine modified trimethyl chitosan were synthesized and employed to self-assemble with plasmid DNA (pDNA) to form nanocomplexes, namely TRNC, TCNC, and THNC, respectively. They were assessed by structural stability, cellular uptake, endosomal escape, release behavior, nuclear localization, and in vitro and in vivo transfection efficiencies. Besides, sodium tripolyphosphate (TPP) was added into TRNC to compromise certain disadvantageous attributes for pDNA delivery.
  
  
  RESULTS
  Optimal endosomal escape ability failed to bring in satisfactory transfection efficiency of THNC due to drawbacks in structural stability, cellular uptake, pDNA liberation, and nuclear distribution. TCNC evoked the most potent gene expression owing to multiple advantages including sufficient stability, preferable uptake, efficient pDNA release, and high nucleic accumulation. Undesirable stability and insufficient pDNA release adversely affected TRNC-mediated gene transfer. However, incorporation of TPP could improve such disadvantages and consequently resulted in enhanced transfection efficiencies.
  
  
  CONCLUSIONS
  Coordination of multiple contributing effects to conquer all delivery obstacles was necessitated for improved transfection efficiency, which would provide insights into rational design of gene delivery vehicles.
authors.affiliation: State Key Laboratory of Genetic Engineering Department of Pharmaceutical Sciences, School of Life Sciences, Fudan University, Shanghai, 200433, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zheng
authors.forename: Cui
authors.initials: C
authors.lastname: Tang
authors.forename: Chunhua
authors.initials: C
authors.lastname: Yin
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D001120:Arginine; D048271:Chitosan / Q000031:analogs & derivatives / Q000138:chemical synthesis*; D003545:Cysteine; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D057809:HEK293 Cells; D006639:Histidine; D006801:Humans; D051379:Mice; D018482:Muscle, Skeletal / Q000378:metabolism; D053758:Nanoparticles; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism*; D011122:Polyphosphates / Q000737:chemistry; D013997:Time Factors; D014162:Transfection / Q000379:methods*
chemical_list: C118071:N-trimethyl chitosan chloride; D011122:Polyphosphates; D049452:Green Fluorescent Proteins; D006639:Histidine; D048271:Chitosan; D001120:Arginine; D003545:Cysteine; C005692:triphosphoric acid