UC Davis researchers are urging caution after discovering new evidence that shows a type of stem cell being considered for disease therapies is similar to cells that cause cancer.
In a new article in the journal Stem Cells and Development, the researchers say that although the stem cells, called induced pluripotent stem cells, show promise as a way to treat injuries, disease and chronic conditions, they could also cause malignant cancer.
“It means that much more study is required before iPSCs can be used clinically,” said Paul Knoepfler, associate professor of cell biology and human anatomy, and principal investigator of the study, in a UCD news release. “However, our study adds to a growing knowledge base that not only will help make stem cell therapies safer, but also provide us with new understandings about the cancer-causing process and more effective ways to fight the disease.”
The UCD study shows both iPSCs and embryonic stems cells showed “significant similarities” to malignant sarcoma cancer cells, according to the news release. The researchers found that genes that were not expressed in iPSCs were also not expressed in the cancer-generating cells and that both cell types showed evidence of similar metabolic activities.
Like embryonic stem cells, iPSCs can become any cell type — making them appealing because they sidestep the controversy over the use embryonic stem cells. The iPSCs can be taken from a patient’s skin and can be induced to produce needed tissues, eliminating the need for a patient to take immunosuppressive drugs after receiving a donor transplant.
Knoepfler said that iPSCs should be used to create cells or tissues in the laboratory, rather than be transplanted directly into a patient, thereby reducing the risk of tumor development as a side effect. Even trace amounts of iPSCs could cause cancer, he warned.
The researchers did find differences between iPSCs and cancer cells that may pave the way for making iPSCs safer.
In fact, they were able to tranfsorm tumor-generating cells into cells similar to iPS by manipulating their genetic makeup — suggesting that cancer cells could be reprogrammed, turning tumors into normal stem cells, Knoepfler said.
Other study authors are John Riggs, Bonnie Barrilleaux, Natalia Varlakhanova, Kelly Bush and Vanessa Chan, all of the department of cell biology and human anatomy. The the California Institute for Regenerative Medicine and from the National Institutes of Health funded their work.