02 April 2012

Cancer Vaccine Based on Cancer Stem Cell Being Developed

Human embryonic stem cells(hESCs) research has been around since its discovery 12 years ago. Since then, it has garnered publicity both good and bad due to the advancement it promises in medical research as well as the ethical concerns of harvesting them.

To date, much progress has been made in better understanding these cells and their capabilities. hESCs hold much promise not only for being cellular models of human development and function, but also for use in the field of regenerative medicine. However, due to ethical and application concerns, only recently have these cells made it to clinical trials.

Human Embryonic Stem Cells are taken from embryos about four or five days after fertilization. That stage of the embryo is called the late blastocyst stage. The blastocyst contains three distinct areas:

  • Trophoblast - surrounding outer layer that later becomes the placenta
  • Blastocoel - fluid-filled cavity within the blastocyst
  • Embryoblast - the inner cell mass which can become the embryo or fetus.

Embryonic stem cells can be created from cells taken from the inner cell mass Because these cells are taken from such an early stage in development, they have the ability to become cells of any tissue type (except for the whole embryo itself), making them pluripotent.

Cancer Stem Cells

Cancer stem cells on the other hand are different from human embryonic stem cells. Cancer stem cells (CSCs) are cancer cells that are similar in properties with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample. Because of this, cancer stem cells are tumorigenic (tumor-forming). These cells can be found within tumors or hematological cancers (cancer that affect blood, bone marrow, and lymph nodes).

CSCs may generate tumors through the stem cell processes of self-renewal and differentiation into multiple cell types. Such cells are proposed to persist in tumors as a distinct population and cause relapse and metastasis by giving rise to new tumors. Therefore, development of specific therapies targeted at CSCs holds hope for improvement of survival and quality of life of cancer patients, especially for sufferers of metastatic disease.

Using cancer stem cells as a vaccine against cancer

Scientists may have discovered a new paradigm for immunotherapy against cancer by priming antibodies and T cells with cancer stem cells, according to a study published in Cancer Research, a journal of the American Association for Cancer Research.

Video: Cancer Stem Cell Research

"This is a major breakthrough in immunotherapy research because we were able to use purified cancer stem cells to generate a vaccine, which strengthened the potency of antibodies and T cells that selectively targeted cancer stem cells," said Qiao Li, Ph.D., a research assistant professor in the department of surgery at the University of Michigan.

Cancer stem cells are tumor cells that remain present, and ultimately resistant, after chemotherapy or radiation treatment. Scientists disagree on whether these cells have unique properties, but those who support the uniqueness idea have argued that these cells regenerate the tumors that lead to relapse.

Despite the similar name, cancer stem cells are distinct from embryonic stem cells, and the two avenues of research are separate.

For the current study, Li and colleagues extracted cancer stem cells from two immunocompetent mouse models and used them to prepare the vaccine.

"We found that these enriched cancer stem cells were immunogenic and far more effective as an antigen source compared with the unselected tumor cells normally used in previous immunotherapy trials," said Li. "The mechanistic investigations found that when antibodies were primed with cancer stem cells, they were capable of targeting cancer stem cells and conferring antitumor immunity."

The researchers also found that cytotoxic T lymphocytes harvested from cancer stem cell-vaccinated hosts were capable of killing cancer stem cells in vitro.

About the AACR

Founded in 1907, the American Association for Cancer Research (AACR) is the world's first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR's membership includes 34,000 laboratory, translational and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 18,000 attendees. In addition, the AACR publishes seven peer-reviewed scientific journals and a magazine for cancer survivors, patients and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the Scientific Partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration and scientific oversight of individual and team science grants in cancer research that have the potential for patient benefit. The AACR actively communicates with legislators and policy makers about the value of cancer research and related biomedical science in saving lives from cancer.


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