Page 124 - Visions of the Future Chemistry and Life Science

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Skeletal structure: synthesis of mechanics
and cell biology

1
Marjolein C. H. van der Meulen and Patrick
J. Prendergast 2
1 Sibley School of Mechanical and Aerospace Engineering, Cornell
University, Ithaca, NY 14853, USA
2 Department of Mechanical Engineering, Trinity College, Dublin 2, Ireland

7.1 Introduction and historical background
Vertebrate skeletons serve several important functions, including structu-
ral support; storage of ions, particularly calcium; production of red blood
cells; and protection of vital organs such as the heart and lungs. The struc-
tural role of the skeleton is particularly interesting to physicists and engi-
neers because bone is an adaptive, living tissue containing cells that
respond to their physical environment. Form follows function. Most of our
knowledge comes from treating bone as a conventional engineering
material, studying bone tissue and whole bones when placed under loads
in the laboratory. This approach does not consider that bone is a living
tissue or account for the influence of mechanical loading in regulating the
biological processes that occur to form the skeletal structure. Separating
the mechanics from the biology is impossible: mechano-biological cou-
pling begins during early development when the primordial cellular struc-
ture first experiences deformations and pressures and continues
throughout the growth, development and aging of the organism. The influ-
ence of biophysical stimuli on skeletal growth and adaptation is of great
interest in treating diseases such as osteoporosis and osteoarthritis.
The structural adaptation of the skeleton is one of the most fascinat-
ing problems in the history of science. Galileo observed in 1638 that longer
bones had to be thicker than shorter ones to have the same structural

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