Apoptosis of Difficult-to-Reach Spinal Tumors Using Magnetic Nanoparticles

Scientists from the University of Illinois at Chicago have shown that it is possible to use magnetic nanoparticles to carry chemotherapy drugs into the spinal cord to treat hard-to-reach spinal tumors in an animal model.

The distinctive delivery system is an innovative way to deliver chemotherapy drugs to spinal cancer cells, which are hard to reach as the drugs have to cross the blood-brain barrier.

Spinal cord tumors are difficult to treat since it is hard to surgically remove them as they are in the close vicinity of healthy spinal tissue and since chemotherapy drugs have to cross the blood-brain barrier to reach them. Intramedullary spinal cord tumors account for 8%–10% of all spinal cord tumors and are more prevalent among children and adolescents. Average survival for patients suffering from these tumors is 15.5 months.

Doxorubicin, a chemotherapy commonly used to treat spinal tumors, is administered intravenously and has an impact on the entire body with poor penetration to the spine. Radiation therapy is also difficult for these tumors since the radiation usually damages healthy adjacent spinal tissue and can have destructive effects, including paraplegia.

Getting chemotherapy drugs to spinal tumors has always been a problem,” stated 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 team, whose results have been reported in the Scientific Reports journal, employed a distinctive rat model with implanted human intramedullary spinal cord tumors to demonstrate that it is possible to successfully use magnetic nanoparticles to destroy tumor cells.

Initially, they developed nanoparticles formed of tiny, metallic magnets attached to particles of doxorubicin. Then, they implanted a magnet immediately under the skin covering the spinal vertebrae in the rat models. Subsequently, they injected the magnetic nanoparticles into the space surrounding the spinal cord where the tumor was observed.

The magnet implanted in the close vicinity of the tumor guided the nanoparticles to the tumor sites. The team could demonstrate that tumor cells absorbed the nanoparticles and experienced apoptosis—or, they were effectively killed. Mehta stated that the effect of the nanoparticles on adjacent healthy cells was very minimal.

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. We will continue to investigate the potential of this therapy and hope to enter human trials if it continues to show promise.

Dr Ankit Mehta

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 of the paper.

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

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