Immune cells with stem cell-like properties destroy tumors in mice
(4 July 2009: VIDYYA MEDICAL NEWS SERVICE) -- Researchers from NCI’s Center for Cancer Research have shown that a cell signaling network called the Wnt-ß-catenin pathway drives the development of a type of immune cell that may provide opportunities to enhance cancer immunotherapies. Immunotherapy techniques recruit the body’s immune system to attack cancer cells.
In a paper published online June 14 in Nature Medicine, the researchers found that when T cells—a type of white blood cell—were cultured with drugs that mimic components of the Wnt pathway, the T cells acquired stem-cell like properties. They were able to both regenerate themselves and produce daughter cells that differentiated into mature T cells, which can recognize and attack cancer cells.
These cells, called CD8+ memory stem cells, were tested as a treatment for large melanoma tumors (containing about one billion malignant cells) in mice. Relatively tiny numbers (about 40,000) of these T cells given in combination with a tumor vaccine and an immune system stimulant called interleukin 2 were able to trigger the destruction of the bulky tumors and improve survival. The memory stem cells that were transplanted multiplied 10 to 30 times more than other types of T cells tested in the mice.
“This new category of lymphocytes is superior to T cells used in earlier experiments because they have the enhanced ability to renew themselves, to proliferate, to differentiate and ultimately to kill tumor cells,” said lead author Dr. Nicholas Restifo in a statement.
Adoptive immunotherapy, the reinfusion of anti-tumor T cells after expansion outside the body, has shown promise as one of the few new therapies that may result in complete remission for patients with metastatic disease. This approach has previously relied on the transfer of large numbers of tumor-specific T cells generated and expanded in the laboratory, a time-consuming and expensive process. However, the use of smaller numbers of “stem-like” T cells may broaden the use of this treatment approach in patients with cancer, said Dr. Restifo. Further studies are needed to confirm the promising results from CD8+ memory stem cells in humans, concluded the authors.
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