Role of Mechanical Stimulation in Stem Cell Differentiation

Mechanical forces are known to play a role in cell behavior and adaptation within their environment. In recent years, special attention has been paid to how these forces interact with various stem cell sources to direct stem cell differentiation. Embryonic, induced pluripotent, and adult or progenitor stem cells have all used in research involving mechanical stimulation. These various cell types have been exposed to numerous types of stimulation, such as tensile or compressive strain, fluid shear stress, or oscillatory vibration. Interestingly, despite the wide range of stem cell sources and types of mechanical stimulation used, the pathways activated under mechanical stimulation are very similar. Mechanical stimulation can impact numerous pathways, including TGF-β, Wnt, and MAPK. Forces can also affect cytoskeletal structure, osmolality of the cytoplasm, or affect nuclear pore size and permeability. This collective knowledge has provided great evidence for the field to use mechanical stimulation alone, or combined with biochemical stimulation, to promote differentiation towards various phenotypes. This differentiation is often associated with increased production of extracellular matrix proteins, such as collagens and glycosaminoglycans, which can greatly impact the mechanical properties of a tissue-engineered construct. Ultimately, the role of mechanical stimulation in stem cell differentiation and behavior is, and will continue to be, a vital component in countless tissue engineering applications.