Cancer Stem Cells

Different tissue-specific cancer stem cells ( CSCs) have been isolated from both big killers and rare cancers. Four properties are adopted to define CSC: 1) expression of a distinctive repertoire of cell surface markers for isolation and purification;2) formation of tumorspheres in suspension culture;3) tumorigenic capacity in immunocompromised mice;4) generation of a heterogeneous cancer tissue closely resembling the original tumor. CSCs constitute a minority of the cells within a tumor but this population is critical for tumor propagation. It is reasonable that CSC can initiate a metastatic lesionand than thrive in a tumor-hostile microenvironment. CSCs actively contribute to tumor vascularization by serving as vascular progenitors. CSCs are in the order of 0,1% in primary tumors. Given the long experience gained with the development of MRI and PET, these technologies have more possibilities to be adopted in the clinic with the specific aim of monitoring the CSCs pool.