OSTEOSARCOMA Osteosarcoma

Osteosarcoma (bone cancer)

Hypothetical Testing

The hypothesis of cancer stem cells suggests that within a heterogeneous tumor is a small subpopulation of cells called cancer stem cells (CSC) "that are responsible for the formation of most of the tumor. Are similar to stem cells and may arise from the transformation of stem cells or de-differentiation of stem cells did not. They are at rest and capable of self-renewal and differentiation into all cells of a tumor.

The first evidence of the existence of CSC was based on studies of hematologic malignancies. In 1994, Lapidot and colleagues showed evidence that only a small percentage of acute myeloid leukemia (AML) cells were capable of initiating leukemia in mice. They found that at least 250,000 cells from peripheral blood of patients with AML graft is required for leukemia in severe combined immunodeficiency (SCID) mice, suggesting that there was only one cell per 250,000 cells capable of engraftment. Classification using fluorescence activated cell sorting (FACS), leukemic stem cells were isolated from a subpopulation of less than 0.2% of total leukemic cells in patients with AML with similar cell surface markers (CD34 + CD38-) to normal hematopoietic stem cells. Interestingly, only the stem cell population CD34 + CD38-leukemic, but not the CD34 + CD38 + or CD34 in the population was able to form AML in SCID mice.

After the success in hematological malignancies, FACS and cell sorting by magnetic activated (MACS) for markers of stem cell surface as CD34, CD138, CD20, CD90, CD133, CD44 and have been widely used to identify CSC in a number cancers]). However, the use of markers of tissue-specific stem cells to identify CSC is limited by the lack of knowledge of these markers for each type of tissue. Other methods to isolate CSC are based on common characteristics of normal stem cells. These include cell growth in serum-free, non-stick field trials, trials serial colony-forming unit, the classification of the cells of the aldehyde dehydrogenase (ALDH) activity, and qualifying for the side population (SP) to cells. Although these functional tests are a great tool to determine if a population has normal stem cells when stem cell surface markers are unknown, one pitfall is that these essays more than anything to enrich the CSC, so they really offer a mixed population of cells for the study. The best evidence that the cells isolated using these methods are true cancer stem cells derived ...