One of the most promising near-term applications of current nanotechnology is in targeted drug delivery to treat cancer. Despite the fact that a number of approaches based on very different areas of nanoscience have shown promise in delivering a wide variety of agents in different animal models of cancer, a number of challenges remain, principally involving the stability of the nanoparticles in the circulatory system, getting them into cancer cells, releasing the cargo to kill the cells, and the fact that cancer cells often have defenses against anti-cancer drugs. A core-shell nanoparticle has been cleverly adapted to deliver a particularly effective agent to where it is needed. A hat tip to ScienceDaily for reprinting this UCLA news release “Tiny capsule effectively kills cancer cells“:
Devising a method for more precise and less invasive treatment of cancer tumors, a team led by researchers from the UCLA Henry Samueli School of Engineering and Applied Science has developed a degradable nanoscale shell to carry proteins to cancer cells and stunt the growth of tumors without damaging healthy cells.
In a new study, published online Feb. 1 in the peer-reviewed journal Nano Today [abstract], a group led by Yi Tang, a professor of chemical and biomolecular engineering and a member of the California NanoSystems Institute at UCLA, reports developing tiny shells composed of a water-soluble polymer that safely deliver a protein complex to the nucleus of cancer cells to induce their death. The shells, which at about 100 nanometers are roughly half the size of the smallest bacterium, degrade harmlessly in non-cancerous cells.
The process does not present the risk of genetic mutation posed by gene therapies for cancer, or the risk to healthy cells caused by chemotherapy, which does not effectively discriminate between healthy and cancerous cells, Tang said.
“This approach is potentially a new way to treat cancer,” said Tang. “It is a difficult problem to deliver the protein if we don’t use this vehicle. This is a unique way to treat cancer cells and leave healthy cells untouched.”
The cell-destroying material, apoptin, is a protein complex derived from an anemia virus in birds. This protein cargo accumulates in the nucleus of cancer cells and signals to the cell to undergo programmed self-destruction.
The polymer shells are developed under mild physiological conditions so as not to alter the chemical structure of the proteins or cause them to clump, preserving their effectiveness on the cancer cells.
Tests done on human breast cancer cell lines in laboratory mice showed significant reduction in tumor growth.
“Delivering a large protein complex such as apoptin to the innermost compartment of tumor cells was a challenge, but the reversible polymer encapsulation strategy was very effective in protecting and escorting the cargo in its functional form,” said Muxun Zhao, lead author of the research and a graduate student in chemical and biomolecular engineering at UCLA.
Tang’s group continues to research ways of more precisely targeting tumors, prolonging the circulation time of the capsules and delivering other highly sought-after proteins to cancer cells.
There is nothing very interesting here from the standpoint of the eventual development of atomically precise manufacturing, but this work presents an excellent case for making the most of the current tools of nanotechnology and employing a deep knowledge of biotechnology and using imaging technology to see what happens inside of cells to develop a promising solution to a set of difficult and important problems.
—James Lewis, PhD