Biomedical Engineering Reference
In-Depth Information
7
Mechanical and Magnetic Stimulation on Cells for Bone
Regeneration
Humphrey Hak Ping Yiu and Kuo-Kang Liu
7.1
Introduction
Nature experiences the most amazing mechanical stimulations for its maintenance
and growth. Everyday, biological tissues or cells are under various mechanical
forces; for instances, human skeleton is mechanically stimulated by compression
forces during walking; cornea is constantly under mechanical stimulation by eyelid
sweeping; even blood vessels are under pulsatile pressure/forces that stem from
heartbeat. Hence, it is not surprising that mechanical stimulations have been
widely used in biomedical applications, such as tissue regeneration/engineering,
regenerative medicine, rehabilitation, and especially for enhancing bone tissue
growth.
In bone remodeling, it has been well recognized that mechanical forces have
profound and complex influences, which normally include osteoclastic resorption
and osteoblastic formation. For example, it has been found that mechanical stimu-
lation is essential for osteoblast cells to differentiate from their precursors. Through
analyzing osteoblast cell kinetic, the stage of differentiation and proliferation of
cells in response to elastic loading has been characterized [1]. It has been dis-
covered that increasing the mechanical loading (e.g., orthodontic force) has
been found to induce a shift in the cell nuclear volume, that is, shift from
less-differentiated precursor cells to preosteoblasts [2, 3]. Since bone consists of
75% organic and mineral component and 25% fluid, when it is subjected to
external loading, complex mechanical interplay will normally be involved in the
fluid-structure interactions within the bone. It is therefore highly challenging to
correlate mechanical stimulus with bone regeneration in a quantitative manner.
Recent endeavors in the advanced biomechanical measurement instruments open
a new vista for studying such ''mechanobiological'' issues in bone regeneration.
Figure 7.1 illustrates how mechanical stimulation influences bone regeneration,
which is addressed in detail later in this chapter.
In this chapter, we introduce several techniques that are used for cell stimulation.
The principles and their applications are discussed. In the first half, we focus
on the more commonly used techniques such as optical tweezers and atomic
