Magnetic Nanoparticles Target Tumors and Get Cells to Commit Suicide

magnetic nanoparticles
Magnetic nanoparticles were equipped with a tumor-specific promoter gene and a “suicide” gene to target liver cancer cells and kill them, according to a new study reported in the journal Nanotechnology. This is an example of gene therapy and magnetic hyperthermia methodology combined to treat cancer.

Gene therapy has been difficult to perfect because it has been hard to find the proper vehicle for genes that are intended to be placed into cells. Viruses have been used as vehicles because they naturally insert themselves into cells, however, they provoke an immune response and are hard to direct without errors. Nanoparticles were used in this study as a substitute for viruses as gene vehicles.

Researchers from the Jiangsu Key Laboratory for Biomaterials and Devices at Southeast University in China manufactured magnetic nanoparticles to target liver cancer cells. The magnetic nanoparticles were coated with a positive charge. The positively charged nanoparticles were then bound to negatively charged DNA molecules, which allowed the attachment of genes to the nanoparticles. In the experiment, a cell suicide gene was bound to the nanoparticles along with a tumor-specific promoter gene chosen to target liver cancer cells. When injected into the body, the liver tumor promoter gene “drives” the nanoparticle to the liver cancer cells and then the suicide gene causes the cancer cells to commit suicide. These nanoparticles were about 20 nm wide, do not provoke an immune system response and they can be produced on a large scale.

The magnetic nanoparticles that carried the two genes that killed the liver cancer cells were tested on human cells in vitro (that means in dishes) and also in vivo in female mice. When the magnetic nanoparticles were injected and found the target tumor cells, alternating magnetic energy was applied and this energy was then converted to heat so that the tumor cells committed suicide but the surrounding healthy cells remained unaffected. This methodology is called magnetic hyperthermia.

This type of treatment for cancer is highly desirable because it is targeted rather than systemic and is less likely to produce unwanted side effects. Chemotherapy and radiation therapy have systemic effects and the immune system is compromised. With magnetic nanoparticle therapy, the immune system is not compromised.

Another study was reported recently that used similar technology but employed magnetic bacteria rather than magnetic nanoparticles. Researchers at the University of Granada in Spain created digestible magnetic bacteria that targeted stomach cancer cells. These magnetic bacteria contained iron particles that were then delivered to the cancer cells. Hyperthermia was then employed to kill the cancer cells. A patient with stomach cancer would just need to eat yoghurt containing the modified bacteria as the first step of the treatment. The magnetic bacteria would then find their way to the tumor and do the work of killing the cancer cells.

Magnetic hyperthermia has the potential to cure many types of cancer in many areas of the body. The trick is to engineer appropriate methods to target the cancer cells and deliver either a suicide gene or molecule such as iron or gold to the cell. The advantage of any of these types of methods to treat cancer is the unwanted systemic side effects can be avoided. Combining gene therapy, magnetic hyperthermia and nanotechnology is an exciting arena of research that holds great promise for treating cancer patients.

By Margaret Lutze

Medical Physics Web

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