Table 1.

Summary of studies (non-comprehensive) of single-cell systems relating Ca²⁺ oscillations and substrate stiffness for various cell types. E denotes Young's modulus of the substrates.

study	experimental system	main findings
Godbout et al. [27]	rat subcutaneous myofibroblasts (SCMFs) on silicon substrates (E = 5–50 kPa)	spontaneous Ca2+ oscillation period increases with decreasing substrate stiffness, decreasing spreading area and decreasing adhesion size
Kim et al. [28]	human mesenchymal stem cells on polyacrylamide gel (E = 1–8.5 kPa)	spontaneous Ca2+ oscillation magnitudes, frequencies and RhoA activities decrease with decreasing substrate stiffness
Zhang et al. [29]	mouse hippocampal neurons on PDMS substrates (E = 46–457 kPa)	spontaneous Ca2+ oscillation amplitude, frequency and synaptic connectivity increase with increasing substrate stiffness
Franz et al. [30]	human mesenchymal stem cells on collagen gel (E = 0.3–1.1 kPa)	spontaneous Ca2+ oscillation frequency and level of osteogenic gene markers increases with increasing substrate stiffness, suggesting the importance of intercellular calcium in the mechanical signal transduction of the extracellular matrix to the human mesenchymal stem cell differentiation