title: Effect of serum on transfection by polyethylenimine/virus-like particle hybrid gene delivery vectors.
abstract: OBJECTIVE
  Murine leukemia virus-like particles (M-VLP) complexed with polymers to promote cellular uptake and endosomal escape represent a new class of effective gene delivery vectors. Building upon recent studies of viral-synthetic hybrid vectors, we report the effects of serum on the formation, activity and stability of PEI/M-VLP complexes.
  
  
  METHODS
  M-VLP were produced by cells grown in serum-supplemented media (M-VLP-S), serum-free media (M-VLP-SF) or serum-free Opti-MEM® I (M-VLP-OM). PEI/M-VLP stoichiometry was varied to investigate complex formation and optimal transfection conditions. The effects of prolonged storage, freeze-thaw cycles, and ultracentrifugation of M-VLP on the stability of vector transduction efficiency were also observed.
  
  
  RESULTS
  M-VLP-S required more PEI to form infective complexes than M-VLP-SF and M-VLP-OM. The stoichiometry of PEI/M-VLP-S was dependent on total PEI concentration (7-8 μg/100 μL M-VLP supernatant), while optimal infectivity of PEI/M-VLP-SF and PEI/M-VLP-OM depended on PEI/M-VLP ratios (12-17 μg and 10-14 μg PEI/10(9) M-VLP, respectively). PEI/M-VLP-SF and PEI/M-VLP-OM complexes were significantly more efficient than PEI/M-VLP-S. Stability of the hybrid vectors was not significantly affected by serum.
  
  
  CONCLUSIONS
  PEI/M-VLP complexes exhibiting increased efficiency were constructed by producing M-VLP in serum-free media. M-VLP could be stored by freezing or refrigeration and concentrated by ultracentrifugation without unacceptable loss of infectivity.
authors: Department of Chemical and Biomolecular Engineering, University of Illinois, Box C-3, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
authors: David M
authors: DM
authors: Drake
authors: Rahul K
authors: RK
authors: Keswani
authors: Daniel W
authors: DW
authors: Pack
mesh_terms: D001769:Blood; D004337:Drug Carriers; D011094:Polyethyleneimine; D014162:Transfection
chemical_list: D004337:Drug Carriers; D011094:Polyethyleneimine