Magnetic nanoparticles deliver chemotherapy to difficult-to-reach spinal tumors

Spinal cord tumors are a challenge to treat because they are difficult to surgically remove due to their proximity to healthy spinal tissue and because chemotherapy drugs must cross the blood-brain barrier in order to reach them. Intramedullary spinal cord tumors account for 8 percent to 10 percent of all spinal cord tumors and are common among children and adolescents. Average survival for patients with these tumors is 15.5 months.

Doxorubicin, a commonly used chemotherapy to treat spinal tumors, is delivered intravenously and affects the whole body with poor penetration to the spine. Radiation therapy is also problematic for these tumors because the radiation often damages healthy nearby spinal tissue and can have devastating effects, including paraplegia.

"Getting chemotherapy drugs to spinal tumors has always been a problem," said Dr. Ankit Mehta, assistant professor of neurosurgery and director of spinal oncology in the UIC College of Medicine and corresponding author on the paper. "But we can precisely guide chemotherapy to cancer cells into the spinal cord using magnetic nanoparticles."

The researchers, whose results are published in the journal Scientific Reports, used a unique rat model with implanted human intramedullary spinal cord tumors to show that magnetic nanoparticles could successfully be used to kill tumor cells.

First, they created nanoparticles made up of tiny, metallic magnets bound to particles of doxorubicin. Next, they implanted a magnet just under the skin covering the spinal vertebrae in the rat models. Then they injected the magnetic nanoparticles into the space around the spinal cord where the tumor was located.

The magnet implanted in close proximity to the tumor guided the nanoparticles to the tumor sites. The researchers were able to show that tumor cells took up the nanoparticles and underwent apoptosis -- in other words, they were effectively destroyed. The impact of the nanoparticles on nearby healthy cells was very minimal, Mehta said.

"This proof-of-concept study shows that magnetic nanoparticles are an effective way to deliver chemotherapy to an area of the body that has been difficult to reach with available treatments," he said. "We will continue to investigate the potential of this therapy and hope to enter human trials if it continues to show promise."

Pouyan Kheirkhan, Steven Denyer, Abhiraj Bhimani, Gregory Arnone, Darian Esfahani, Tania Aguilar, Jack Zakrzewski, Indu Venugopal, Nazia Habib, Andreas Linninger, and Dr. Fady Charbel of UIC, and Gary Gallia of Johns Hopkins University School of Medicine, are co-authors on the paper.

This research was supported in part by a Young Investigator Research Grant (G3895) from the AO Foundation, North America. Steven Denyer, a third-year medical student, was lead author on the study and receives research support from the Hispanic Center of Excellence at UIC.