2
1 Introduction
mechanobiology as the study of the biological response of cells to mechanical
stimuli (Ambrosi et al. 2019). 1
According to these definitions, lung inflation, muscle contraction, and bone
fracture are problems in biomechanics. How the lungs, muscles, and bones adapt
to changing loads through growth and remodeling are problems in mechanobiology.
This response is called functional adaptation.
Some problems have aspects in both camps. For example, the mechanism by
which cells crawl is biomechanics, but how they sense substrate stiffness to guide
the direction in which they crawl is mechanobiology. How a muscle tears is
biomechanics, but the way it heals is mechanobiology. Blood flow is a problem
in biomechanics, but how the heart and arteries adapt to changing hemodynamic
loads through growth and remodeling is a problem in mechanobiology.
Mechanobiology plays a major role in embryonic development. Abnormal loads
can cause congenital defects, and increasing numbers of researchers now recognize
the need to consider mechanobiology in the related fields of tissue engineering and
regenerative medicine. Mechanobiology also is an important factor in diseases such
as cancer, atherosclerosis, and osteoporosis.
1.2 Origins of Mechanobiology
Interest in biomechanics goes back many centuries, at least as far back as Leonardo
da Vinci and Galileo Galilei, who used mechanical principles to try to understand
biological structure and function (Ascenzi 1993; Fung 1993; Humphrey 2002).
More than 2000 years ago, Aristotle studied the kinematics of animal motion
(Nussbaum 1985). However, biomechanics did not become a widespread scientific
discipline until Y.C. Fung entered the field during the 1960s with pioneering studies
of blood flow and the mechanical properties of living tissues (Fung 1993, 1997).
Many consider Fung the father of modern biomechanics.
Perhaps the first mechanobiologists were Julius Wolff and Wilhelm Roux, who
in the late 1800s proposed Wolff’s Law of trabecular bone architecture and the
concept of functional adaptation, respectively (Roux 1885; Cowin 2001). Motivated
by an earlier mathematical analysis showing that principal stress trajectories for a
curved bar resemble the structural pattern of trabecular bone in the human femur
(Koch 1917), Wolff (1986) suggested that trabeculae reorient in response to altered
loading conditions. Although the analysis was later shown to be incorrect (Cowin
2001), it demonstrated the potential power of mathematical modeling in uncovering
fundamental principles of biology.
In 1917, D’arcy Thompson published the first edition of his classic monograph
entitled On Growth and Form, in which he argues that physical laws are a primary
determinant of biological form (Thompson 1942). Following this important contri1 In fact, my own definition of mechanobiology has evolved over the years (Taber 2016).
1 Introduction
mechanobiology as the study of the biological response of cells to mechanical
stimuli (Ambrosi et al. 2019). 1
According to these definitions, lung inflation, muscle contraction, and bone
fracture are problems in biomechanics. How the lungs, muscles, and bones adapt
to changing loads through growth and remodeling are problems in mechanobiology.
This response is called functional adaptation.
Some problems have aspects in both camps. For example, the mechanism by
which cells crawl is biomechanics, but how they sense substrate stiffness to guide
the direction in which they crawl is mechanobiology. How a muscle tears is
biomechanics, but the way it heals is mechanobiology. Blood flow is a problem
in biomechanics, but how the heart and arteries adapt to changing hemodynamic
loads through growth and remodeling is a problem in mechanobiology.
Mechanobiology plays a major role in embryonic development. Abnormal loads
can cause congenital defects, and increasing numbers of researchers now recognize
the need to consider mechanobiology in the related fields of tissue engineering and
regenerative medicine. Mechanobiology also is an important factor in diseases such
as cancer, atherosclerosis, and osteoporosis.
1.2 Origins of Mechanobiology
Interest in biomechanics goes back many centuries, at least as far back as Leonardo
da Vinci and Galileo Galilei, who used mechanical principles to try to understand
biological structure and function (Ascenzi 1993; Fung 1993; Humphrey 2002).
More than 2000 years ago, Aristotle studied the kinematics of animal motion
(Nussbaum 1985). However, biomechanics did not become a widespread scientific
discipline until Y.C. Fung entered the field during the 1960s with pioneering studies
of blood flow and the mechanical properties of living tissues (Fung 1993, 1997).
Many consider Fung the father of modern biomechanics.
Perhaps the first mechanobiologists were Julius Wolff and Wilhelm Roux, who
in the late 1800s proposed Wolff’s Law of trabecular bone architecture and the
concept of functional adaptation, respectively (Roux 1885; Cowin 2001). Motivated
by an earlier mathematical analysis showing that principal stress trajectories for a
curved bar resemble the structural pattern of trabecular bone in the human femur
(Koch 1917), Wolff (1986) suggested that trabeculae reorient in response to altered
loading conditions. Although the analysis was later shown to be incorrect (Cowin
2001), it demonstrated the potential power of mathematical modeling in uncovering
fundamental principles of biology.
In 1917, D’arcy Thompson published the first edition of his classic monograph
entitled On Growth and Form, in which he argues that physical laws are a primary
determinant of biological form (Thompson 1942). Following this important contri1 In fact, my own definition of mechanobiology has evolved over the years (Taber 2016).