A new approach developed by researchers at University of California, Irvine, can vastly improve the targeting of chemotherapeutic drugs to specific cells and organs.
The findings of the study could pave the way to precisely targeted cancer treatments.
For the study, the researchers used liposomes, small spheres (less-than 100 nanometer in diameter) of naturally occurring lipid molecules, as "packages" for the cancer chemotherapeutic agent doxorubicin, and a small peptide molecule to "address" the package to the targeted tissue.
Using this technology, they showed that the doxorubicin was directed almost entirely to the targeted site with virtually no uptake by other organs, including lung, kidney and heart.
The new approach is based on the fact that a dense region of sugar-containing molecules called polysaccharides surrounds all tissues and organs, including all tumors.
Most importantly, the particular chemical composition of the polysaccharides is different in each tissue and organ of the body.
The chemical compositions of the polysaccharides of tumour regions are also different from normal tissue.
The scientists developed a nanocarrier system that can recognize specific types of polysaccharide, and has demonstrated effective, organ-specific delivery of nanocarriers, and their therapeutic contents, based upon this polysaccharide-targeting approach.
In their study, the researchers used a peptide derived from a protein found in the microorganism Plasmodium, which has an exceptional ability to exclusively target the polysaccharides of liver following entry into the bloodstream.
The drug doxorubicin is a chemotherapeutic agent commonly used as treatment for a variety of cancers. When administered in a chemotherapeutic regimen, doxorubicin distributes widely in the body, including the heart, rather than specifically in tumor regions.
The serious heart damage that results from systemic administration places limits on the dosage that a patient can receive.
By encapsulating doxorubicin into a liposome package and including a peptide targeting message on the carrier, the researchers showed that doxorubicin can be effectively delivered to the liver, and away from the heart, with a specificity of greater than 100:1.
The study has appeared online in the International Journal of Pharmaceutics.