WASHINGTONThe blood of the human umbilical cord, although often discarded after childbirth, is a "very rich source" of lymphocytes potentially capable of killing cancer cells, according to Shantaram Joshi, PhD, professor of genetics, cell biology, and anatomy, University of Nebraska Medical Center, Omaha.
Natural killer cells and cytotoxic T lymphocytes from cord blood have the advantage of being "naïve cells" that "you can activate to recognize and kill tumor cells," Dr. Joshi said at the Susan G. Komen Breast Cancer Foundation 5th Annual Conference on Innovations in Quality Care.
He reported on the use of cytokines and antigen-presenting dendritic cells as a means of activating cord blood lymphocytes to kill cancer cells. Both techniques have proven effective, and the latter one permits targeting of lymphocytes against specific breast cancer cells expressing the HER-2/neu oncogene protein.
In the first activation approach, natural killer lymphocytes from cord blood were exposed to the cytokines inter-leukin-2, interleukin-15, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in various combinations. Lymphocytes activated with all three cytokines proved more effective at eliminating breast cancer cells than those exposed to only one or none of the cyto-kines. Various types of tumor cells, including breast cancer, were destroyed by the activated lymphocytes.
In the second approach, cytotoxic T lymphocytes from cord blood were activated using antigen-presenting dendritic cells primed with the breast-cancer-specific HER-2/neu peptide. Lymphocytes activated in this manner destroyed only breast tumor cells expressing HER-2/neu antigen.
Studies in SCID Mice
Early studies in severe combined immunodeficient (SCID) mice, Dr. Joshi said, show that use of activated cord blood cells "not only increases survival, but actively prevents metastasis." [See Figure.] Thus, he said, cord blood lymphocytes’ potential as cancer therapy deserves continued investigation.