Drug targeting with nanosize bioreactors

Delivering drugs to specific target cells within the body is a hot topic in pharmaceutical research. Anti-cancer treatments, for example, include powerful chemical agents which can easily damage healthy cells when ingested indiscriminately.

What if such therapeutic agents could be delivered to specific sites, and only then released to do their work? Researchers in Switzerland have developed nanoscale containers that may be able to do just this. The containers have membrane walls which become porous only when the acidity of their environment matches that inside cell structures called lysosomes, which break down foreign materials when they enter cells.

It is this pH-sensitivity that makes the bioreactors ‘smart’. In chemotherapy applications, the pores would become active only when the containers had reached the inside of target tumour cells, ensuring that the drug they contain is not released where it can do no good, or even damage healthy tissue.

Special polymers designed by chemist Wolfgang Meier from Basel University combine with bacterial proteins and self-assemble to form 200-nm wide containers, while enzymes that break down certain compounds are trapped inside the containers. The pores, which are open in most conditions, close in high acidity environments.

The research is led by Pavel Broz, a physician from University Hospital, Basel. With his colleagues, Broz is currently studying possible long-term toxicity and biodegradation of the container components. “We are very much looking forward to test our polymer vesicles in defined disease models in mice,” says Broz. “The hope is to create target-specific and highly potent novel therapies for diseases such as cancer or atherosclerosis. We are aware that the versatile properties of our polymer vesicles might be used for drug delivery, gene therapy or bioreactor applications.”

Recently published in the journal Nano Letters (subscription required), the research is still at an early stage, but Broz is open to new collaborations and industrial partnerships.