As with other in vivo tissues, stem cell niches are an hypoxic environment and exhibit oxygen levels that are notably lower than the ambient environment. Indeed, in most tissues, physiological normoxia ranges from <1-9% oxygen, and stem cell niches are no different. Hypoxia chambers can help to emulate these environments.
Cell migration is an essential process involved in important physiological processes such as embryogenesis, angiogenesis, wound healing and the immune response. Cells migrate in different modes depending on the type and function of the cells. Leukocytes, for example, migrate the majority of their life span as single cells within virtually any tissue in the body. Many other cell types only move at specific situations to place, shape or repair tissue. Most of these cells move in groups that are loosely or closely associated. This type of migration is called collective cell migration. In this article, different modes of both single cell migration and collective cell migration are discussed.
The wound-healing assay is a convenient and economical method to investigate collective cell migration under different experimental conditions. As collective cell migration is linked to many physiological and pathological processes related to embryogenesis, wound repair and cancer metastasis, the wound healing assay is broadly applicable. We discuss how to set up an experiment and several options to analyze imaging data.
Although colony formation assays are more widely known as a cancer biology assay, they do have applications in the field of stem cell biology where the self renewal potential of stem cells and their progenitors is assessed. Colony forming assays that are used in this context are not end-point based and rely on live cell imaging. The assay enables selection of desired colonies for further culturing and experimentation. Assessing colony formation is most commonly used for hematopoietic stem cells (HSCs), in the form of a colony formation unit (CFU) assay.