Biomedical Engineering Reference
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also from different loading regimens. This chapter will review the findings on the
mechanical regulation of MSC fate decision focusing on adipogenesis. Note, while
there have been studies on the mechanical control of adipogenesis utilizing pre-
adipocytes (in most studies, 3T3-L1 cell line), this chapter will mostly focus on
MSCs and the control of their adipogenesis.
In addition to 'dynamic' mechanical cell stimulations (stretch, compression,
fluid flow, etc.), another potent factor affecting MSC differentiation may include
'static' mechanophysical signals from the substrate on which MSCs are cultured.
Cell interaction with biomaterial the cells are grown upon is one of the funda-
mental factors that influence the fate of the cells. Studies have shown that protein-
micropatterned surfaces, nanoscale biomaterials, and substrate rigidity affect the
differentiation of stem cells. The inside of the human body consists of extracellular
milieus with varying extracellular matrix (ECM) protein organizations, different
micro and nanotextures, and differential substrate rigidities. These all have a
potential to affect cell growth and differentiation. If MSCs are cultured outside the
body on biomimetic culture surfaces, this may effectively direct the cells to dif-
ferentiate into certain terminal lineages. This chapter will also cover the substrate
control of MSC fate including adipogenesis.
As noted above, many studies have examined MSC adipogenesis in comparison
with osteogenesis. Gaining a better understanding of the factors that promote MSC
osteogenesis while inhibiting adipogenesis may be meaningful to several parts of
the medical field. Generally, it is good to prevent an overload of adipogenesis,
especially in the arteries. An over-accumulation of fat in the body leads to obesity
which has many serious detrimental health effects inducing metabolic diseases.
Understanding what triggers MSC adipogenesis can help scientists find ways to
better prevent obesity. From a bone tissue engineering standpoint, understanding
what promotes MSC differentiation toward osteogenesis is important to better
design in vitro and in vivo bone tissue engineering protocols. Therefore, there are
many beneficial biomedical reasons to study the influences of extracellular cues,
including mechanical stimuli and certain types of substrates, on the MSC differ-
entiation process toward adipogenesis versus osteogenesis. Studies on this point
will be elucidated in this chapter.
2 Mechanical Control of Stem Cell Adipogenesis
2.1 Effects of Mechanical Stretch
Many cell types are exposed to stretching motion in vivo, and cells sensing and
response to stretch have been proposed to be a key process in maintaining healthy
tissue homeostasis for many tissue types. While relatively less understanding has
been available on the mechanical stretch effects on MSC adipogenesis, it has been
well established that stretching of MSCs has a positive effect on their osteogenesis.
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