In cancer therapy, often only a small amount of the injected drugs actually reach the intended tumor site, leading to ineffective treatment. The blood vessel walls near a tumor serve as a leaky barrier to tumor cells and provide a pathway through which drugs can reach the tumor. However, the way in which the blood vessels leak is not well-understood. Since this porous filter remains the key to targeting cancer, the derivation of a mathematical understanding of the parameters governing entry will unlock the ability to optimize properties of drug delivery vehicles.
The cover image for the September 18th issue of Biophysical Journal is an artistic rendering of a close-up view of the dynamics occurring around pores within a tumor blood vessel. The image shows spheroidal nanoparticles of various shapes — rods (red), disks (beige), and spheres (orange) — on the verge of potentially extravasating through pores (grey), reaching the tumor cells where delivered drugs could have an effect.
The extravasation of nanoparticles is governed by a number of physical processes. First, the particles undergo tiny random movements (Brownian motion) due to their small size. The nanoparticles also move with the flow of blood, and are pushed in and out of pores due to differences in pressure across the pores. The combination of blood flow and the pressure differences results in the fluid flow illustrated in the image. Grey streamlines show the direction of fluid flow; some of the fluid is sucked into the pores, dragging nanoparticles with it, while the rest flows past them.
The cover image highlights the complexity of the drug delivery process to tumors. Both Brownian motion and fluid flow affect the extravasation process, and these processes are coupled in a nontrivial way to the size and shape of the nanoparticles.
Recent research done by Tiras Y. Lin can be found here, and recent research done by Professor Eric S.G. Shaqfeh’s group can be found here.
- Preyas N. Shah, Tiras Y. Lin, Ioana L. Aanei, Sarah H. Klass, Bryan Ronain Smith, and Eric S. G. Shaqfeh