title: DNA complex-releasing system by injectable self-setting apatite cement.
abstract: BACKGROUND
  The therapeutic effect of plasmid DNA complexes is not satisfactory because of the short duration of their gene expression. However, an efficient DNA slow-release system has not been established owing to the low dispersion stability of the DNA/polycation (or cationic lipid) complexes. We have found that hyaluronan (HA) could deposit onto the DNA/polycation complexes, stabilize their dispersion and prepare very small particles. We have also reported that the injectable self-setting apatite cement has high biocompatibility and biodegradability. Thus, durable gene expression systems using injectable apatite cement, including DNA/polycation/HA complexes, were expected.
  
  
  METHODS
  Small DNA/polyethyleneimine (PEI)/HA complex particles were prepared by a lyophilizing and rehydration process, and the in vitro release ratio of DNA complex from the apatite cements by MLC-6 cells was examined. Apatite cement slurry with collagen including plasmid DNA (pDNA) complex [encoding granulocyte macrophage-colony stimulating factor (GM-CSF)] was injected close to the tumor subcutaneously inoculated into mice. The therapeutic effect and degradation ratio of the apatite cement were evaluated.
  
  
  RESULTS
  Very fine DNA/PEI/HA complex particles kept being dispersed in the apatite cement. The DNA complexes were continuously released from the apatite cement by MLC-6 cells. Single injection of the apatite cement-including pDNA-GM-CSF complex induced complete disappearance of tumor in 60% of mice. Smooth degradation of the apatite cement was observed in the mice in which a high therapeutic effect was seen.
  
  
  CONCLUSIONS
  Single injection of the apatite cement-including pDNA-GM-CSF complex showed a high therapeutic effect on solid tumor, and thus appears to be promising as a sustained gene expression device.
authors.affiliation: Musashino University, Research Institute of Pharmaceutical Sciences, Tokyo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ito
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Koyama
authors.forename: Makoto
authors.initials: M
authors.lastname: Otsuka
mesh_terms: D000818:Animals; D001031:Apatites / Q000008:administration & dosage / Q000737:chemistry*; D001843:Bone Cements / Q000737:chemistry*; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics; D007267:Injections; D051379:Mice; D011094:Polyethyleneimine / Q000737:chemistry; D014162:Transfection
chemical_list: D001031:Apatites; D001843:Bone Cements; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011094:Polyethyleneimine; D004247:DNA