Credit: PNAS
A new type of nanoparticle (NP) could aid the diagnosis and treatment of cancers, according to research published in Nature Communications.
Built on an easy-to-make polymer, these particles can be used as contrast agents to light up tumors for MRI and PET scans or to deliver chemotherapy and other treatments to cancer cells.
Furthermore, in vivo experiments showed the particles are biocompatible and elicit minimal side effects.
“These are amazingly useful particles,” said study author Yuanpei Li, PhD, of the UC Davis Comprehensive Cancer Center in Sacramento, California.
“As a contrast agent, they make tumors easier to see on MRI and other scans. We can also use them as vehicles to deliver chemotherapy directly to tumors, apply light to make the nanoparticles release singlet oxygen (photodynamic therapy), or use a laser to heat them (photothermal therapy)—all proven ways to destroy tumors.”
These NPs are built on a porphyrin/cholic acid polymer. Porphyrins are common organic compounds, and cholic acid is produced by the liver.
To further stabilize the particles, the researchers added the amino acid cysteine (creating CNPs), which prevents them from prematurely releasing their therapeutic payload when exposed to blood proteins and other barriers.
Therapeutic applications
The researchers tested the CNPs, both in vitro and in vivo, for a wide range of tasks. On the therapeutic side, the particles effectively transported anticancer drugs, such as doxorubicin.
CNPs carrying doxorubicin provided excellent cancer control in animals, with minimal side effects.
Even when kept in the blood for many hours, CNPs only released small amounts of the drug. However, when exposed to light or agents such as glutathione, they readily released their payloads.
The researchers showed that, when exposed to a single wavelength of light, the CNPs could generate heat or produce singlet oxygen to destroy tumor cells.
Imaging applications
CNPs offer a number of advantages to enhance imaging, according to the researchers. The particles readily chelate imaging agents and can remain in the body for long periods.
In animal studies, CNPs largely accumulated in tumors, rather than in normal tissue. So they dramatically enhanced tumor contrast for MRI and may also be promising for PET-MRI scans, the researchers said.
“These particles can combine imaging and therapeutics,” Dr Li noted. “We could potentially use them to simultaneously deliver treatment and monitor treatment efficacy.”
The researchers are now conducting additional preclinical studies with the CNPs. If all goes well, they will proceed to human trials. In the meantime, the team is excited about these capabilities.
“This is the first nanoparticle to perform so many different jobs,” Dr Li said. “From delivering chemo, photodynamic, and photothermal therapies, to enhancing diagnostic imaging, it’s the complete package.”
