January 30, 2006
Nanoparticles Improve Biodistribution of Promising
Indocyanine green (ICG), an FDA-approved dye used in a variety of diagnostic applications, has shown promise as a light-activated anticancer agent, but the human body eliminates this molecule so rapidly that little of it accumulates in tumors. To solve this problem, a group of investigators at St. John’s University in New York have created a polymeric nanoparticle formulation of ICG that appears to increase dramatically the amount of dye that remains in the body long enough to accumulate in tissues.
Reporting their work in the International Journal of Pharmaceutics, Jun Shao, Ph.D., and his colleagues first describe the methods, based on fluorescence spectroscopy, that they developed to recover nanoparticle-bound ICG from biological samples. Such methods are critical for determining how effective this new delivery system is at enabling drug to reach its target and to optimize the nanoparticle to achieve maximum drug concentrations in tumors. The investigators note that the procedure they developed should be applicable to analyzing biodistribution properties for many types of nanoparticle-based drug formulations.
With this technique in hand, the researchers were then able to compare the biodistribution characteristics of nanoparticle-entrapped ICG and the free dye in healthy mice. Their data showed that ICG concentrations in blood were 5 to 10 times higher when delivered using nanoparticles. Levels remained elevated for four hours. ICG levels in organs were also between 2 and 8 times higher using the nanoparticle formulation. The investigators are now conducting more detailed studies in tumor-bearing animals.
This work is detailed in a paper titled, “Polymeric nanoparticulate delivery system for Indocyanine green: Biodistribution in healthy mice.” An abstract is available through PubMed.
The investigators’ initial work developing the ICG-nanoparticle formulation was reported in an earlier paper titled, “Enhanced photo-stability, thermal-stability and aqueous-stability of Indocyanine green in polymeric nanoparticulate systems.” An abstract of this paper, which was also published in the International Journal of Pharmaceutics, is available through PubMed.