Vaccinating Against Cancer with Stem Cells

Researchers at the University of Connecticut Stem Cell Institute have developed a technique whereby mice have become relatively resistant to colon cancer after being given a vaccine derived from human embryonic stem cells (hESCs). The mice developed a consistent immune response against colon cancer cells and when injected with these cells they showed a significantly smaller amount of tumor growth compared to controls (Li, et al, 2009). These results have been echoed by scientists at the University of Minnesota where all of the mice treated with cancer-killing immune cells derived from hESCs became completely free of cancerous tumors (Woll, et al, 2009). The same study used human umbilical cord blood cells and found that the immune cells resulting from these stem cells eliminated cancer in five out of thirteen mice. The embryonic stem cells were cultured to create Natural Killer (NK) cells which are potent antitumor agents and the researchers are hopeful that the in vivo successes with animals will translate into positive results in human patients, although clinical trials using such techniques have not yet been approved by the FDA.

Stem Cells Fight Cancer Cells

Trials of stem cell treatments using mesenchymal stem cells may soon be underway however as researchers in Massachusetts recently demonstrated that genetically modified stem cells were effective at inducing apoptosis (cell death) in cancer cells in the brains of laboratory mice (Sassportas, et al, 2009). The mesenchymal stem cells (MSCs) used in this study were human MSCs and researchers observed that these were resistant to the cytokine tumor necrosis factor apoptosis ligand (TRAIL) which could eliminate gliomas in the brain. The MSCs were then engineered to express secreted recombinant TRAIL which induced caspase-mediated apoptosis in existing glioma cell lines as well as CD133-positive primary glioma cells. What this means, sans jargon, is that the researchers developed a technique where stem cells which can be taken from the fat of adult humans, or indeed the bone marrow, skin, and other areas of the body can be programmed to seek cancer cells in the brain and kickstart a process where these cancer cells die. Stem-cell therapies may, as a result of this study and those mentioned previously, be designed to treat a variety of cancers based on the factors that induce apoptosis in those specific tumor cells.

References

Sasportas LS, Kasmieh R, Wakimoto H, Hingtgen S, van de Water JA, Mohapatra G, Figueiredo JL, Martuza RL, Weissleder R,Shah K., Assessment of therapeutic efficacy and fate of engineered human mesenchymal stem cells for cancer therapy, Proc Natl Acad Sci U S A. 2009 Mar 24;106(12):4822-7. Epub 2009 Mar 5.

Li.Y, Hui.Z, Ren-He.X, Bei.L, Z.Li “Vaccination with Human Pluripotent Stem Cells Generates A Broad Spectrum of Immunological And Clinical Response Against Colon Cancer”, STEM CELLS, 2009, DOI: 10.1002/stem.234

Woll, P.S., Grzywacz, B., et al, 2009, Human embryonic stem cells differentiate into a homogeneous population of natural killer cells with potent in vivo antitumor activity, Published online before print April 13, 2009, doi: 10.1182/blood-2008-06-165225