The article "The stiffness of living tissues and its implications for their engineering" by Carlos F. Guimarães, Luca Gasperini, Alexandra P. Marques, and Rui L. Reis discusses the importance of understanding tissue stiffness in the context of biomaterials, tissue engineering, and regenerative medicine. The authors highlight that the mechanical properties of biological tissues, from nanoscale to macroscale, are crucial for cellular behavior and tissue functionality. They emphasize that engineering tissues must integrate and approximate the mechanics of native tissues, both static and dynamic. The review covers the measurement of tissue stiffness, the role of extracellular matrix (ECM) components and single cells in tissue stiffness, and the challenges in engineering life-like tissues. It also discusses the viscoelastic properties of tissues and the impact of different loading conditions on tissue mechanics. The authors provide insights into the mechanical properties of various tissues, including neural tissues, abdominal organs, muscles, cartilage, tendons, ligaments, and bone, and explore the anisotropy and composite nature of biological tissues. They conclude by emphasizing the need for standardized techniques to measure tissue stiffness and the importance of considering the dimension and directionality of measurements.The article "The stiffness of living tissues and its implications for their engineering" by Carlos F. Guimarães, Luca Gasperini, Alexandra P. Marques, and Rui L. Reis discusses the importance of understanding tissue stiffness in the context of biomaterials, tissue engineering, and regenerative medicine. The authors highlight that the mechanical properties of biological tissues, from nanoscale to macroscale, are crucial for cellular behavior and tissue functionality. They emphasize that engineering tissues must integrate and approximate the mechanics of native tissues, both static and dynamic. The review covers the measurement of tissue stiffness, the role of extracellular matrix (ECM) components and single cells in tissue stiffness, and the challenges in engineering life-like tissues. It also discusses the viscoelastic properties of tissues and the impact of different loading conditions on tissue mechanics. The authors provide insights into the mechanical properties of various tissues, including neural tissues, abdominal organs, muscles, cartilage, tendons, ligaments, and bone, and explore the anisotropy and composite nature of biological tissues. They conclude by emphasizing the need for standardized techniques to measure tissue stiffness and the importance of considering the dimension and directionality of measurements.