Figure 1.

Schematic representation of generic adult stem cells (ASCs) niche features, including ASCs, their progenitor cells, neighbour cells, the vasculature and the extracellular matrix. Adult stem cells sense and respond to their surrounding extracellular matrix via integrin-mediated adhesion, depicted as α- and β-integrin chains, together with cytoskeletal intermediate filaments and intercellular spot desmosomes. Paracrine signals and growth factors are secreted by the vasculature and proximal progenitor or neighbouring cells, overall influencing ASC fate. The overarching biochemical, biophysical and biomechanical features discussed and referenced in this review have been distilled down to a list of conditions reported to promote ASC expansion in the four tissue-specific niches of interest. Elements within the boxes comprise general recommendations for oxygen levels (blue), ECM components (green), biochemical factors (orange) and stiffness module (yellow) to be used in specific ASC cultures. This figure was prepared using elements from Servier Medical Art.