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Evaluation of cell and matrix mechanics using fluorescence excitation spectroscopy: Feasibility study in collagen gels containing fibroblasts

Collagen gels containing cells are commonly used in tissue engineering, wound healing, and cancer research to investigate the interplay between cells and the extracellular matrix (ECM), as changes in the density and stiffness of the microenvironment are known to play a role in many diseases or pathological conditions. In these gels, the stiffness is regularly determined using destructive methods, such as indentation and tensile tests. Certain molecules native to cells and the ECM display fluorescence upon irradiation with ultraviolet light. The objective of the present study was to investigate the feasibility of using the endogenous, or innate, fluorescence of collagen gels containing fibroblasts as an optical marker to evaluate changes in the mechanical properties of the ECM.