Findings suggest that malignant tissue consisting of these cells used in the lab for drug testing could lead to false results.
Researchers found that bone marrow stem cells attracted to the site of a cancerous growth frequently take on the outward appearance of the malignant cells but don’t actually seed cancer.
If there are bone marrow cells in malignant tissue grown in the laboratory for experiments, “these cells may actually contaminate our cancer studies and could make a difference as to whether or not investigational drugs we’re testing work or don’t work,” notes Chris Cogle, M.D., an assistant professor of medicine at the University of Florida’s (UF) College of Medicine Program in Stem Cell Biology and Regenerative Medicine. “The significance of this is new treatments may work in the culture dish but may not translate to the clinic or the hospital room.”
In their study, UF scientists evaluated women who underwent bone marrow transplantation. Two of them subsequently developed colonic adenomas, four got skin cancer, and one developed lung cancer. Each patient received infusions of bone marrow cells from a brother or an unrelated male donor. That enabled the physicians to track the transplanted cells by screening for the Y male chromosome.
They found that the cancers were mostly of female origin, but the malignant tissue often contained small areas of male marrow cells.
The investigators then studied mice who underwent bone marrow transplant and developed the same cancers as the women. When they viewed the cancerous tissues under the microscope, they found marrow cells shared outward features of the cancer cells.
“Our results indicate these cells act as developmental mimics; they come in and look like the surrounding neoplastic tissue but they aren’t actually the seed of cancer,” explains Dr. Cogle. “At the worst, these cells could help support cancerous tissue by providing it with growth factors or proteins that help the cancer grow and survive. At the very least, these marrow cells are just being tricked into coming into the cancerous environment and then made to walk and talk like they don’t usually do.”
The results are published online in Stem Cells.