Page 134 - Visions of the Future Chemistry and Life Science

Skeletal structure 123

(a)

(b)

(c)

Figure 7.6. When a force is applied to a bone of uniform structure (a), the structure
adapts by the feedback mechanism shown in Figure 7.5 and forms a nonuniform
structure to carry the load efficiently (b). The resulting structure resembles the
familiar design of bridges and other man-made trusses (c).

Mechanobiologic concepts have been applied to other skeletal tissues.
Differentiation of stem cells to form cartilage, fibrous tissue, and bone is
central to tissue growth and regeneration. Friedrich Pauwels proposed in
1941 that hydrostatic stresses stimulate differentiation to cartilage cells,
whereas distortion stimulates differentiation into fibrous cells (Figure 7.3).
Simulations based on Pauwels’s ideas have correlated patterns of mechan-
ical stimuli with skeletal tissue type during fracture healing. These models
suggest that we will soon be able to simulate skeletal growth, adaptation,
and degeneration over an individual’s lifetime.