title: Feasibility of lactadherin-bearing clinically available microbubbles as ultrasound contrast agent for angiogenesis.
abstract: OBJECTIVE
  Phagocytosis of apoptotic cells is carried out through bridging of phosphatidylserine (PS)-expressing apoptotic cells and integrin αvβ3-expressing phagocytes with lactadherin. The objective of this study was to examine whether microbubbles targeted to integrin αvβ3 could be produced by conjugating a PS-containing clinically available ultrasound contrast agent with lactadherin.
  
  
  METHODS
  PS-containing perfluorobutane-filled microbubbles were incubated with R-phycoerythrin (PE)-labeled lactadherin, and the presence of PE-positive bubbles was examined by FACS analysis. Secondly, the attachment of lactadherin to integrin αvβ3-expressing cells (human umbilical vein endothelial cells (HUVEC)) was also examined by FACS analysis. Finally, the adhesion of PS-containing bubbles to HUVEC was examined using a parallel plate flow chamber. The number of adherent bubbles with or without the intermediation of lactadherin was compared.
  
  
  RESULTS
  The more lactadherin was added to the bubble suspension, the more PE-positive bubbles were detected. The size of bubbles was not increased even after conjugation with lactadherin (2.90 ± 0.04 vs. 2.81 ± 0.02 μm). Binding between lactadherin and HUVEC was also confirmed by FACS analysis. The parallel plate flow chamber study revealed that the number of PS-containing bubbles adherent to HUVEC was increased about five times by the intermediation of lactadherin (12.1 ± 6.0 to 58.7 ± 33.1 bubbles).
  
  
  CONCLUSIONS
  Because integrin αvβ3 is well-known to play a key role in angiogenesis, the complex of PS-containing bubbles and lactadherin has feasibility as a clinically translatable targeted ultrasound contrast agent for angiogenesis.
authors.affiliation: Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan, otani@ri.ncvc.go.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Otani
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamahara
mesh_terms: D000162:Acoustics; D000954:Antigens, Surface / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D003287:Contrast Media; D005240:Feasibility Studies; D005290:Ferric Compounds; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D007501:Iron; D045423:Microbubbles; D008894:Milk Proteins / Q000494:pharmacology*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010087:Oxides; D010316:Particle Size; D014465:Ultrasonics
chemical_list: D000954:Antigens, Surface; D003287:Contrast Media; D005290:Ferric Compounds; D039302:Integrin alphaVbeta3; C098942:MFGE8 protein, human; D008894:Milk Proteins; D010087:Oxides; C069727:Sonazoid; D007501:Iron
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