Figure 4.

ECM dynamics in maintenance of the stem cell niche and cell differentiation. Together with hormones, oxygen, and Ca²⁺, the ECM may play multiple roles in maintaining stem cell properties. The ECM anchors stem cells in the niche, and thus allows them to be exposed to paracrine (1) and cell–cell contact signals (not depicted) that are essential for maintaining stem cell properties. Anchorage is also important for orienting the mitotic spindle and makes it possible for stem cells to undergo asymmetric cell division (2), which is essential for stem cell self-renewal and generation of daughter cells that are destined to undergo cell differentiation. The exact mechanism whereby ECM anchorage controls asymmetric cell division remains unclear, although one possibility is to allow cytoplasmic cell-fate determinants to be differentially distributed between the daughter cells. The ECM may also maintain stem cell properties via its many other features including biochemical signaling potentials and, as has become increasingly clear, its biomechanical properties including ECM stiffness, which may play a major role in cell-fate determination (3).