Research Study Update: Ensuring That Emerging Stem Cell Treatments Do Not Activate or Exacerbate Cancer in Dogs

AKC Canine Health Foundation Grant 1876
Principal Investigator: Dr. Douglas H Thamm, VMD; Colorado State University

Study supports the recommendation that thorough screening for cancer be undertaken prior to stem cell therapy

Treatment with adult stem cells is showing promise for a variety of immune, inflammatory and degenerative diseases in dogs and humans. However, there is accumulating evidence that stem cells may promote tumor growth through direct stimulation of tumor cell proliferation, migration and invasion and suppression of programmed cell death (apoptosis), as well as indirectly through stimulation of blood vessel growth and suppression of the immune system. Cancer is generally a disease of older dogs, the same population of patients likely to receive stem cell therapy for other diseases. In this pilot study, Dr. Thamm proposed to investigate the effects of canine stem cell factors on proliferation, apoptosis, invasion and migration in a large panel of canine tumor and blood vessel cell lines. The knowledge of whether stem cells can promote tumor growth will address a key safety concern regarding the application of stem cell-based therapies in dogs with known or suspected cancer, and will inform decision making regarding stem cell use in an aged dog population at risk for tumor development.

Dr. Thamm evaluated the effects of stem cells derived from canine bone marrow on the growth and migration of a panel cell lines derived from canine tumors. Compared with control medium, the stem cells significantly promoted tumor proliferation in 11-18 of 29 evaluated cell lines (38-62%), and proliferation was significantly inhibited in 4-7 of 29 (14-24%) cell lines, depending on the individual dog used for stem cell generation. Sarcomas were more likely to be stimulated and blood-derived tumors more likely to be suppressed by these stem cells. The stem cells significantly stimulated tumor cell migration in two of the four evaluated cell lines (osteosarcoma and hemangiosarcoma). Demonstration that these stem cells can exert pro-tumorigenic effects in vitro (in test tubes) addresses a key safety concern regarding the application of stem cell based therapies in dogs with known or suspected cancer, and should inform decision making regarding using stem cell therapies in an aged dog population at risk for tumor development. At minimum, it supports the recommendation that thorough screening for cancer be undertaken prior to MSC therapy.