November 6, 2014

A new study shows promising results for treating cancerous tumors with stem cells. Published in the journal Stem Cells, Harvard University’s Harvard Stem Cell Institute and Massachusetts General Hospital researchers used stem cells to create tumor-killing toxins without damaging healthy cells in the brain’s of mice.

The scientists genetically engineered stem cells to secrete a toxin that killed cancerous cells and showed no threat to normal, healthy cells. these modified stem cells were implanted in the voided space left after tumor removal with biodegradable gel and killed all remaining cancer cells.

The study authors explained that pseudomonas exotoxin-cytotoxins have been used against cancer in the past because they inhibit protein synthesis, but haven’t worked optimally with tumors because of their physical design and the short half-life of the toxins. Also, in the past, non-cancerous cells would also be affected by the toxin. Researchers combated this problem by manipulating “endogenous EF-2” in the stem cells to avoid collateral damage and designing the cells to directly spread PE-cytotoxins specifically targeted at glioblastomas – the most common and aggressive adult human brain tumor.

“Integrating stem cell-based engineering, multimodal imaging and delivery of PE-cytotoxins in a clinically-relevant GBM model represents a novel strategy and a potential advancement in GBM therapy,” the authors explained.
Promising results

Lead study author, Khalid Shah, Ph.D., who heads the Molecular Neurotherapy and Imaging Lab at Massachusetts General Hospital and Harvard Medical School, said that the researchers were able to measure the positive results of this experiment by using “molecular analysis and imaging to track the inhibition of protein synthesis within brain tumors.” They observed the toxins destroy the cancerous cells.

Nell Barrie, a science information manager for Cancer Research U.K. who wasn’t involved in the study, told the BBC that this “ingenious approach” was promising but a long way away from human use.

“We urgently need better treatments for brain tumors and this could help direct treatment to exactly where it’s needed,” she told the British news source. “But so far the technique has only been tested in mice and on cancer cells in the lab, so much more work will need to be done before we’ll know if it could help patients with brain tumors.”

Shah and his team are currently looking for approval from the U.S. Food and Drug Administration for clinical testing. Earlier in 2014, Harvard Stem Cell Institute scientists used a herpes virus against glioblastomas in a similar way.