Scientists from the Harvard Stem Cell Institute at the Massachusetts General Hospital have created a way to engineer stem cells to secrete toxins that can cure brain tumors.
The team of scientists is led by Khalid Shah, who recently showed the value of engineered stem cells that have been loaded with herpes viruses that can kill cancer.
The work of the scientists has been published in the Stem Cells journal, showing how the engineered stem cells can secrete toxins to kill remaining cancer cells in the brains of mice after the removal of the main tumor.
To place the stem cells at the site where they will do their work, the cells are enclosed inside a biodegradable gel. This process is different from the failed methods used by previous clinical studies that looked to introduce purified toxins that kill cancer into the brains of patients.
Shah and his team have now applied for approval from the FDA to bring their breakthrough process, along with other stem cell methods that the team developed, into clinical trials.
According to Shah, the toxins that kill cancer are very effective in dealing with several varieties of blood cancer. However, the toxins lose their effectiveness when dealing with solid tumors due to the fact that the cancer involved for those cases are not as accessible. The toxins do not have enough time to kill the cancer because they only have a short half-life.
Shah added that a few years ago, his team thought of using stem cells to be able to deliver the therapeutic toxins to the brains of patients to fight the tumors. However, the team needed to first genetically engineer the stem cells to be resistant to the toxins themselves, so that they wouldn't be killed by the toxins that they carry.
"Now, we have toxin-resistant stem cells that can make and release cancer-killing drugs," said Shah.
The toxins, known as cytotoxins, can prove to be fatal to all kinds of cells. However, since the late 90s, scientists have been modifying the toxins to have them seek out and invade only cancer cells and ignore healthy, normal cells.
Once the toxin is within the cancer cell, it causes a disruption on the ability of the cell to create proteins, resulting in the death of the cell within days.
The stem cells created by Shah have been engineered to prevent the toxin from disrupting its own protein-creating processes. The stem cells, in fact, even have an extra code that allows the cells to both make and release the toxins.
Shah said that testing the engineered stem cells in mice with brain cancer has proven to be successful. The tumors are first removed before the engineered stem cells are contained within the biodegradable gel and inserted in the spot where the tumor was removed.
