Using a self-assembling DNA nanostructure, biomedical engineers at the University of North Carolina have developed a novel method for delivering drugs directly to cancer cells. While DNA-based drug delivery platforms have been tested before, this marks a breakthrough in medicine release; the chemotherapeutic agent erupts from its capsule only within the tumour microenvironment.
Doxorubicin, the drug used in this study, is potentially harmful. Typically it is deployed to fight the tumour only after several other methods have proved ineffective, and delivery is invasive: it is given either intravenously, where it notoriously leaks out of blood vessels, or directly into the chest, which is even more frightening considering its potential cardiac side effects. Other chemotherapy delivery systems involving DNA have been tested, but have thus far been restricted to passive drug delivery, which have catastrophic repercussions if the cytotoxic molecule is released within healthy cells.
Zhen Gu and his team have ingeniously tackled this problem with what they term “cocoon-like” balls of DNA that non-covalently incorporate the doxorubicin, keeping it sheathed until it reaches the appropriate molecular battlefield. These cocoons are further outfitted with folic acid, which targets the structure towards the folate receptors on tumour cells; and DNase, hidden within an acid-degradable capsule. When the cocoon reaches its objective, the cancer cell accepts the package within an acidic endosome, thereby releasing the DNase. This in turn digests the cocoon, sending the doxorubicin free on a guided path of destruction. Though at the moment this system can deliver only small quantities of medicine, and has not been tested in vivo, it yet holds promise for the development of similarly programmed drug delivery mechanisms.