In a recent edition of Science Translational Medicine, researchers at the University of California, San Francisco published experimental findings which suggest that the use of nanodiamonds can be used as a novel and more effective drug delivery system for chemotherapeutic agents.
When a patient is diagnosed with cancer, it can be difficult to accept that many common cancers don’t respond well to treatment. Often, tumors can become drug-resistant, and standard therapies are almost completely useless against them.
At that point, cancer cells may become cross-resistant to a wide variety of drugs, further decreasing treatment options.
Doctors and scientists have been trying for years to get around this exact problem, and this new finding may open up a panorama of possibilities.
In the current study, researcher Edward Chow’s team used nanodiamond-bound doxorubicin, a standard chemotherapy drug, in mice models of liver and breast cancer.
That the treatment proved not only successful, but also non-toxic in the study is highly encouraging especially considering the difficulty of treating liver and breast cancers using standard therapies.
According to Dean Ho, the senior author of the paper, though the present findings are extremely exciting and promising, they are based on previous work with nanodiamonds.
“In our previously published study on nanodiamond-based DNA delivery [in individual cells], we observed a 70-fold increase in efficacy compared to a commercial standard with maintained non-toxicity,” Ho said. “This new study was done in mice, and showed that . . . the efficacy of treatment was even further enhanced.”
According to Ho, not only did the nanodiamond-doxorubicin complex decrease the size of the mice’s tumors, but it also decreased drug resistance, making the tumors easier to combat in the long run.
Additionally, the nanodiamond complex is still small enough that it can be cleared from tissues before its toxicity becomes too great and kills healthy cells as well as cancerous ones.
The carbon nanodiamonds Ho, et al. have been studying have many facets, just like their large-scale counterparts. Importantly, each facet of a nanodiamond contains functional groups which can be chemically bonded to drugs — like the drug doxorubicin Chow and colleagues used in the present study.
Nanodiamonds’ ability to carry a large variety of molecules as well as the nanodiamond-drug complex’s tiny size have caused scientists to consider nanodiamonds as a potentially useful drug delivery system — at least in theory. And now Ho and his team are showing that their potential may reach far beyond mere theory.
Perhaps the best feature of the nanodiamonds is that delivery of drugs to cancerous tissue with the nano gems increases the retention rate of chemotherapeutics not only within the target tissue, but also in the bloodstream.
This is likely because the nanodiamonds allow for an extended and prolonged release of the drug over time, which counteracts the high rates of drug efflux from tumor cells.
Tumor cells are abnormally good at staying alive, even in spite of toxic drug treatments, and they do this by utilizing specialized pumps in their outer membranes that can move unwanted chemicals out of cells almost as quickly as they are brought in.
According to Ho, however, a simple property of the drug-nanodiamond complex allows it to be kept within target tissues for a longer period of time: its relatively large size.
“Nanodiamond-drug complexes are challenging to eject when compared to the unmodified drug since the complexes are likely too large to efflux with the membrane transporters,” Ho said.
Rapid drug efflux is a major issue faced in many cases of drug resistance, and yet with the relatively simple nanodiamond delivery system, this problem is greatly reduced, if not eliminated.
Though nanodiamonds sound great on paper, the fact remains that good chemotherapies must meet a set of qualitative standards: they need to be able to be made readily available to the market at large, they have to work without causing undue damage and they can’t cost too much.
While nanodiamonds may bring to mind expensive bling, they actually fulfill most, if not all, of these requirements. They are relatively inexpensive to produce: the very same process Chow, et al. used in their research is readily scalable for larger-sized implementation. Additionally, nanodiamonds are highly
biocompatible, meaning that they haven’t yet caused any observable biological damage, not even to highly sensitive and crucial white blood cells.
All of these traits make nanodiamonds a potentially invaluable platform for future chemotherapy treatments. Even better, the researchers believe the possibilities aren’t limited to fighting cancer.
“These findings may make it possible to apply the nanodiamonds towards other diseases, such as inflammation and wound healing, or also towards regenerative medicine, particularly given the observations from our previous studies that nanodiamonds can carry a broad spectrum of therapeutics,” Ho said.
“Nanodiamonds are also applicable towards fundamental studies and may shed new light on how nanoparticles may enhance the efficacy of treatment towards other conditions.”
