Researchers at Washington University, led by Karen Wooley, Ph. D., are developing
delivery vehicle to ferry doxorubicin to tumors in the brains of children,
where heavy chemotherapy can irreparably damage the developing bio-computer.
Though her group uses the same family of polymeric nanoparticles, the delivery
and effectiveness differs from UCSD's treatment.
Some of the properties of the nanoparticle important to Wooley's group are its
carrying capacity and the way it releases the cancer toxin into the body. Most
polymeric based nanoparticles have at best a three to four percent drug
capacity. Wooley's group's particles boast an up to 19 percent loading, five
times the typical delivery vehicle's capacity. While the large increase in
toxin is beneficial, not all of the toxin in these particles will be released.
Another difference is the rate at which the drug is released into the patient.
Most cancer-targeting nano and macroparticles verily explode a cancer cell in
one way or another. The WU group's particles are designed to release the toxin
more slowly over time. The group is working to tune these properties further,
allowing a tailored particle delivery vehicle.
One area yet to be refined by Wooley's team is the actual targeting method for
binding the particles to cancer cells. The typical approach has been to use a
ligand structure targeting protein expressions unique to cancerous cells. While
this is under development, another method, exploiting the “enhanced
permeability and retention effect” of tumors would rely on passive diffusion to
absorb the particles into a tumor where the doxorubicin could be released
directly into the mass.