Strategies for the identification and isolation of cancer stem cells and non-cancerous stem cells

The present invention, in some embodiments, describes methods for selecting and enriching specific types of stem cells and/or progenitor cells from a sample containing at least two different types of stem cells and/or progenitor cells. In one embodiment, the method involves selecting and enriching cancer stem cells and/or cancer progenitor cells. In other embodiments, the invention involves improved methods for purging cancer cells from autologous or allogenic transplants prior to reinjection into a patient. In other embodiments, the invention describes improved methods to screen for the efficacy of drug candidate for affecting the function and/or viability of a specific type of stem cell or progenitor cell, for example a cancer stem cell. In this context, the inventive method can involve screening the effectiveness of chemotherapeutic agents in completely eliminating all cancer cells (i.e. mature cancer cells and cancer stem/progenitor cells). In yet other embodiments, the invention provides methods for the identification of a particular type or sub-population of stem cells or progenitor cells from a mixed cell-type population. In one embodiment of such a method, the invention describes a method for the early detection of metastatic cancer from simple tests on blood or bone marrow. Stem cell culture methods are also disclosed which utilize cell lysates to preferentially induce either asymmetric or symmetric division of the stem cells. The invention also provides, in some embodiments, novel stem cell suspensions that include, in some instances enriched suspensions of particular types or sub-populations of stem cells or progenitor cells, for example cancer stem cells. In other embodiments, the invention provides a suspension of stem cells that is substantially free of all stem cells of a particular type or sub-population and, optionally, also substantially free of all mature cells. In one example of such an embodiment, the invention provides a suspension of stem cells that is substantially free of all cancer cells (i.e. mature cancer cells as well as cancer stem cells and cancer progenitor cells).