Common and Deadly Brain Tumor Could be Treated with Herpes Stem Cells

The Harvard Stem Cell Institute found an interesting way to combat glioblastoma tumors in mice. Similar to the Mayo Clinic study that used high doses of the measles virus to defeat myeloma, the Harvard researchers used a different virus in their trial.

Glioblastoma multiforme is the most common brain tumor and the most difficult to treat in human adults. In the Harvard research, scientists sought to discover how to more effectively kill tumor cells through using mice with gliobastoma multiforme. The researchers loaded stem cells with the herpes virus and injected them into the mice.

The mesenchymal stem cells that were used give rise to bone marrow tissue, which is important because they trigger a minimal immune response and can carry oncolytic viruses (ones that infect and kill cancer cells). The oncolytic virus that these mesenchymal stem cells carried was herpes. They used imaging markers to watch the virus pass on from the stem cells and into the first layer of brain tumor cells.

They encapsulated the cells in biocompatible gels to ensure its security. While watching the cells, the researchers found that the gel actually helped the stem cells live longer, enabling the herpes to replicate and continue infiltrating the cancer cells. Lead researcher Khaldi Shah, MS, PhD, and faculty member at the Harvard Stem Cell Institute was happy to explain why the gel was so important.

"They survived because the virus doesn't get washed out by the cerebrospinal fluid that fills the cavity," Shah said in this Harvard news article. "Previous studies that have injected the virus directly into the resection cavity did not follow the fate of the virus in the cavity. However, our imaging and side-by-side comparison studies showed that the naked virus rarely infects the residual tumor cells. This could give us insight into why the results from clinical trials with oncolytic viruses alone were modest."

The study, "Stem Cells Loaded with Multimechanistic Oncolytic Herpes Simplex Virus Variants for Brain Tumor Therapy," was published in the Journal of the National Cancer Institute in March.

The scientists plan to further their preclinical research by using the herpes-injected mesenchymal stem cells to treat breast, lung, and skin cancers that metastasize the brain. Shah believes clinical trials are 2-3 years away.