In silico quantification of the stiffness perceived by cells inside porous collagen-based scaffolds

Stiffness is a pivotal property of the insoluble matrix surrounding cells, and a known regulator of multiple cell phenotypes. Yet, no universal metric to quantify the stiffness perceived by cells in 3D matrices exists. This manuscript presents a direct metric and efficient in silico method to quantify cell-perceived stiffness within lattice-like microporous biomaterials, focusing on freeze-dried porous collagen-based scaffolds (PCS) and 3D-printed scaffolds. Simulations show that cells inside microporous biomaterials perceived variable matrix stiffness due to the stochastic nature of cell-matrix adhesion and lattice loading. In PCS, cells sense a softer matrix with increased contractility, opposing the stress-stiffening response observed in most biological specimens. Furthermore, cell-perceived stiffness in PCS is significantly affected by neighbouring cell contractility, suggesting cell–cell communication through matrix stiffness alterations. These force-dependent effects, arising from the large deformations of PCS struts, may influence cell mechanoresponsive pathways and explain reported downregulation of wound contraction during skin regeneration in PCS. In contrast, cells in 3D-printed scaffolds perceive stiffness three orders of magnitude higher, which is insensitive to cell contractility. The methodology offers novel insights on the mechanical environment perceived by cells within microporous biomaterials, supporting biomaterial design, comparison, interpretation of complex cell-biomaterial interactions observed in vitro or in vivo.