Quantitative analysis of tissue distribution of the B16BL6-derived exosomes using a streptavidin-lactadherin fusion protein and iodine-125-labeled biotin derivative after intravenous injection in mice

J Pharm Sci. 2015 Feb;104(2):705-13. doi: 10.1002/jps.24251. Epub 2014 Nov 12.


We previously succeeded in the visualization of tissue distribution of B16BL6 cells-derived exosomes by labeling with Gaussia luciferase (gLuc)-LA, a fusion protein of gLuc (a reporter protein) and lactadherin (LA; an exosome-tropic protein). However, total amount of B16BL6-derived exosomes delivered to each organ could not be evaluated because of the reduction of luminescent signal from gLuc-LA. The aim of the present study was to quantitatively evaluate the tissue distribution of B16BL6-derived exosomes. To this end, we labeled B16BL6-derived exosomes with iodine-125 ((125) I) based on streptavidin (SAV)-biotin system. A plasmid vector encoding fusion protein, SAV-LA, was constructed, and B16BL6 cells were transfected with the plasmid to obtain SAV-LA-coupled exosomes. SAV-LA-coupled exosomes were incubated with (3-(125) I-iodobenzoyl) norbiotinamide ((125) I-IBB) to obtain (125) I-labeled B16BL6 exosomes. After intravenous injection of (125) I-labeled B16BL6 exosomes into mice, radioactivity quickly disappeared from the blood circulation. At 4 h, 28%, 1.6%, and 7% of the injected radioactivity/organ was detected in the liver, spleen, and lung, respectively. These results indicate that (125) I-labeling of exosomes using SAV-biotin system is a useful method to quantitatively evaluate the amount of exogenously administered exosomes delivered to each organ and that the liver is the major organ in the clearance of exogenously administered B16BL6-derived exosomes.

Keywords: biomaterials; clearance; exosome; lactadherin; nanoparticles; pharmacokinetics; phospholipids; quantitative analysis; radioisotope; streptavidin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biotin / administration & dosage
  • Biotin / analysis
  • Biotin / metabolism*
  • Exosomes / metabolism*
  • Injections, Intravenous
  • Iodine Radioisotopes / administration & dosage
  • Iodine Radioisotopes / analysis
  • Iodine Radioisotopes / metabolism*
  • Male
  • Melanoma, Experimental
  • Mice
  • Mice, Inbred BALB C
  • Protein Binding
  • Recombinant Fusion Proteins / administration & dosage
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / metabolism*
  • Streptavidin / analysis
  • Streptavidin / metabolism*
  • Tissue Distribution / drug effects
  • Tissue Distribution / physiology


  • Iodine Radioisotopes
  • Recombinant Fusion Proteins
  • Biotin
  • Streptavidin