|Nanodiamond particles bound to chemotherapeutic agents can be used to treat a broad range of tumor models. The nanodiamond-drug hybrids are capable of markedly improving the efficacy and safety of cancer treatment.
Illustration: Courtesy of Dr. Dean Ho.
The research was a collaboration between Dean Ho, PhD, of the UCLA School of Dentistry, and colleagues from the Lurie Children’s Hospital of Chicago and Northwestern University’s Feinberg School of Medicine.
Glioblastoma is the most common and lethal type of brain tumor, with median survival time less than one-and-a-half years. The tumors are notoriously difficult to treat; chemotherapy drugs injected alone often are unable to penetrate the system of protective blood vessels that surround the brain, known as the blood-brain barrier, and those drugs that do cross the barrier do not stay concentrated in the tumor tissue long enough to be effective.
Doxorubicin, a common chemotherapy agent, has served as a model drug for the treatment of brain tumors when injected directly into the tumor. Dr. Ho’s team originally developed a strategy for strongly attaching doxorubicin molecules to nanodiamond surfaces, creating a combined substance called ND-DOX.
Nanodiamonds are multi-faceted carbon-based particles roughly four-to-five nanometers in diameter that can carry a broad range of drug compounds. And while tumor-cell proteins are able to eject most anticancer drugs that are injected into the cell before those drugs have time to work, they can’t get rid of the nanodiamonds. Thus, drug-nanodiamond combinations remain in the cells much longer without affecting the tissue surrounding the tumor.
The researchers found that ND-DOX levels in glioblastoma tumors were retained far longer than doxorubicin alone. In addition, ND-DOX was also found to increase apoptosis — programmed cancercell death — and to decrease cell viability in brain-cancer cell lines. The results also demonstrated for the first time that the ND-DOX delivery limited the amount of doxorubicin that was distributed outside the tumor. This reduced toxic side effects and kept more of the drug in the tumor longer, increasing the drug’s tumor-killing efficiency without affecting the surrounding tissue. Survival time increased significantly in rats treated with ND-DOX, compared with those given only unmodified doxorubicin.
“Nanomaterials are promising vehicles for treating different types of cancer,” Dr. Ho says. “We’re looking for the drugs and situations where nanotechnology actually helps chemotherapy function better, making it easier on the patient and harder on the cancer.”
“Convection-enhanced delivery of nanodiamond drug delivery platforms for intracranial tumor treatment,” Nanomedicine: Nanotechnology, Biology and Medicine, August 5, 2013