Engineers at University of California in Los Angeles and University of Southern California developed tiny degradable capsules that can deliver cancer treatments directly to tumors, sparing healthy cells from damage. The team led by UCLA professor Yi Tang published its findings online in the journal Nano Today (paid subscription required).
Tang (pictured left) and colleagues built capsules about 100 nanometers in length, roughly half the size of the smallest bacteria, made of water-soluble polymers. The shells are made under mild physiological conditions, so they do not affect the chemistry of the therapeutic cargo or cause the cargo to clump, which would impair its effectiveness.
The shells contain apoptin, a protein complex with the ability to induce tumors to undergo apoptosis, or programmed self-destruction. Apoptin is derived from an anemia virus in birds. The protein cargo accumulates in the nucleus of cancer cells and signals to the cell to undergo apoptosis.
This approach using proteins has an advantage over gene therapy, says Tang, in that it does not present the risk of genetic mutation. In addition, the capsules degrade harmlessly in non-cancerous cells.
Tang and colleagues, some of whom are now at the joint biomedical engineering program at University of North Carolina and North Carolina State, tested the capsules with apoptin on human breast cancer lines in lab mice, and found the technique to successfully inhibit tumor growth. “It is a difficult problem to deliver the protein if we don’t use this vehicle,” says Tang. “This is a unique way to treat cancer cells and leave healthy cells untouched.”
“Delivering a large protein complex such as apoptin to the innermost compartment of tumor cells was a challenge,” says first author and graduate student Muxun Zhao, “but the reversible polymer encapsulation strategy was very effective in protecting and escorting the cargo in its functional form.”
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