Biomedical Engineering Reference
In-Depth Information
Mechanical stimulation
Single cell mechanics
Mechanotransduction
Shear
stress
Ion channel
Membrane tensions
Cytoskeleton connected
Mechanical lever
Applied
forces
Compression
Stretching
Adhesion
Extra-cellular matrix
Figure 7.1
Schematic illustration of mechanical stimulation on bone cells.
force microscopy (AFM). Recently, research on mechanical stimulation on cells
using magnetic micro- and nanoparticles has increased. This is partly due to
the advancement made in nanoparticle technology and the various biological
techniques such as electrophysiology and microscopy. In the second half, we
discuss the possibility of using magnetic particles in cell stimulation and their
potential application in bone regeneration.
7.2
Mechanical Stimulation on Cells
7.2.1
Various Mechanical Stimulations
There has been a long debate regarding the types of forces, that is, tension,
compression, or shear force, that play the most important role in bone remod-
eling and formation. Similar questions have been asked by bioscientists. Which
force among strain, stress, and strain rate, plays the most important role in
bone growth and remodeling? Although it still needs detailed studies to answer
these questions more accurately, animal studies have shown that strain rate
is more important than strain amplitude to induce bone formation [4]. Some
other recent studies, however, show that both strain and loading frequency are
important for bone adaptation [5, 6]. For example, Turner
et al
. showed that
the bone formation had increased more than 10-fold when the frequency of
loading applied on rat forelimbs had been increased from 1 to 10Hz [6]. The
most common frequency applied for stimulating bone regeneration is around
1-10Hz [2], which is close to walking pace, while the optimal strain for bone
growth is around a few hundreds to thousands microstrain [7]. It is worth
pointing out that the
in vivo
strains for osteoblasts are between 0 and 4000
microstrain. Nonetheless, the optimal microstrain and frequency are somewhat
cross-related.
