8th February 2013

Nano-sized capsule kills cancer cells without harming healthy cells

A tiny capsule invented at a UCLA lab could go a long way toward improving cancer treatment.

Devising a method for more precise and less invasive treatment of cancer tumours, 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. This can stunt the growth of tumours without damaging healthy cells.

In a study published online in the peer-reviewed journal Nano Today, a group led by Professor Yi Tang reports developing tiny shells composed of a water-soluble polymer. These can safely deliver a protein complex to the nucleus of cancer cells to induce their death. The shells – which are just 100 nanometres in size, 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.

"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 tumour growth.

Muxun Zhao, lead author of the research and a graduate student in chemical and biomolecular engineering at UCLA: "Delivering a large protein complex such as apoptin to the innermost compartment of tumour cells was a challenge, but the reversible polymer encapsulation strategy was very effective in protecting and escorting the cargo in its functional form."

Tang's group continues to research ways of more precisely targeting tumours, prolonging the circulation time of the capsules and delivering other highly sought-after proteins to cancer cells.

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