Clusters of magnetic nanoparticles kill cancer with heat
Scientists are exploring all kinds of ways to improve cancer treatments, with some methods more tried-and-true and others at the experimental end of the spectrum. Using magnetism to heat up nanoparticles inside a tumor to destroy nearby cancer cells certainly falls among the latter, but scientists are now reporting an exciting advance in this area with some promising early results on mice.
Known as magnetic hyperthermia, this experimental cancer treatment has already been tested for safety and feasibility in clinical trials involving patients with prostate and brain cancer. The FDA has also granted special exemptions for devices that can help things along, but the technology as it stands has some limitations.
The current approach sees magnetic nanoparticles injected directly into an easily accessible tumor using a syringe. Here, amid the cancerous growth, these particles are exposed to an alternating magnetic field that heats them up to temperatures of around 100° F (38° C), which can cause the cancer cells to die off.
This is showing promise as a way of helping to treat certain types of cancers, but what about those beyond the reach of the humble syringe? Scientists at Oregon State University (OSU) have been working on a solution that would enable these magnetic particles to be delivered intravenously via the abdomen but still accumulate at the tumor, therefore bringing other cancer types into the range of magnetic hyperthermia.
"Our goal was to develop an effective nano-delivery system that could deliver magnetic nanoparticles so they could produce an effective temperature to the tumor after systemic administration," Olena Taratula, associate professor of pharmaceutical sciences and study author, explains to New Atlas.
Rather than relying on individual nanoparticles to do the job, Taratula and her colleagues set out to learn what happened when they grouped them together in clusters, along with a few other tweaks. The design they wound up with consists of clusters of hexagonal nanoparticles made with iron oxide, doped with cobalt and manganese and packed into biodgradeable nanocarriers. The team then tested them out on mice with ovarian tumors, delivering them via the abdomen.
"We injected these magnetic nanoparticles intravenously and the results suggest that the nanoclusters efficiently accumulated in the tumors via passive targeting, or the EPR effect," Taratula tells us. "We improved the delivery system and also the ability of the magnetic nanoparticles to produce heat by using a specific shape and doping it with other metals."
So there are a couple of things the scientists are trying to balance here. They need to get enough of the nanoparticles to the tumor site to generate the required levels of heat, but can only administer low levels of them at a time in the interests of patient safety. In their new nanoclusters, they believe they have found a sweet spot and the right tool for the job.
"We demonstrated that systemically delivered nanoclusters in mice elevate the intra-tumoral temperature up to 44° C (111° F) in the presence of a safe alternating magnetic field, and the required temperatures could be achieved after repeated injections of the nanoclusters," explains Taratula. "Finally, animal studies validated that the nanocluster-mediated hyperthermia significantly inhibited the growth of subcutaneous ovarian tumors."
The team will look to build on these promising results with further studies, testing out the nanoclusters in animal models where tumors are located deeper in the body (in this case they were grafted just beneath the skin of the mice). Further down the track, the team imagines that this kind of tech could come to complement existing cancer treatments such as chemotherapy and radiotherapy, or even be used to treat cancers on its own.
"There had been many attempts to develop nanoparticles that could be administered systemically in safe doses and still allow for hot enough temperatures inside the tumor," says Taratula. "Our new nanoplatform is a milestone for treating difficult-to-access tumors with magnetic hyperthermia. This is a proof of concept, and the nanoclusters could potentially be optimized for even greater heating efficiency."
The research was published in the journal ACS Nano.
Source: Oregon State University