In situ deformation measurement of 3D printed scaffold and mechano-regulation in tissue engineering

Three-dimensional (3D) mechanical microenvironments, such as 3D strain fields in tissue engineering scaffolds have a crucial impact on the interactions between scaffold architecture, mechanical stimuli, and tissue differenti-ation. However, the discontinuity induced by the pores poses a challenge to the measurement of the 3D strains of the scaffolds. Herein, we present a tissue engineering scaffold optical coherence elastography (TES-OCE) method to visualize the full-field 3D strain fields of the tissue engineering scaffolds when cells are cultured on them and to explore the relationship between mechanical stimulation and cell differentiation. A semi-continuous digital volume correlation (SC-DVC) method based on a material component identification algorithm was proposed to automatically extract the scaffold architecture information and obtain the 3D strain fields with high accuracy. The non-uniform deformation field of a 3D printed tissue engineering scaffold with various water contents under loading in vitro was measured by the TES-OCE method, based on the tissue shear strain field obtained above, the area of cell differentiation phenotype on tissue engineering scaffolds was accurately predicted. Experimental results show that the loads and water absorption of the scaffold significantly affects the 3D tissue shear strain field in the tissue engineering scaffold. Thus, the cell differentiation fate can be modulated by loading culture and scaffold pore structure. The TES-OCE provides a new experimental method to delineate the interrelationship between tissue engineering scaffolds, the mechanical microenvironment, and cell proliferation and differentia-tion. It may be further developed as an effective tool to guide the design and development of superior tissue engineering scaffolds.