Biomedical Engineering Reference
In-Depth Information
1 Introduction
Obesity occurs with increased adipose tissue formation. This originates from
increased adipocyte number growth and the hypertrophy of adipocytes. A
recruitment of new adipocytes from mesenchymal stem cell (MSC) sources is one
of the main causes of adipocyte number growth and thus obesity. Therefore, how
to control MSC fate decision into adipogenesis may be a critical factor to deal with
obesity. Mesenchymal stem cell differentiation, or any stem cell differentiation for
that matter, involves a multitude of factors that affect the fate of the stem cells. The
human body contains many different types of cells that begin as stem cells and
commit and differentiate into cells with specified phenotype and function.
Understanding as much as possible behind this commitment and differentiation is
incredibly important because the more knowledge that can be gathered regarding
stem cell fate decision, the more that can be done in treating diseases related to
stem cell commitment and differentiation (such as obesity that has a relevance to
stem cell adipogenesis).
Mesenchymal stem cells have the multipotent ability (or so-called plasticity) to
become cells to form bone, cartilage, fat, and connective tissue. Identifying the
factors that inhibit or promote MSCs in differentiating into fat cells (adipogenesis)
is of particular interest recalling the theme of this topic, obesity. In the literature,
however, there are not many studies on MSC fate direction dedicated solely to
adipogenesis. On the other hand, differentiation to musculoskeletal lineages by
MSCs has been targeted in many studies for the goal of tissue engineering and
regenerative medicine. Studies have proposed a potential of MSC fate selection
among various differentiation lineages, one terminal lineage over the other,
depending on extracellular factors. Specifically, it has been suggested that MSC
osteogenesis and adipogenesis may be regulated in a mutually antagonistic manner
by external signals, that is, under culture conditions in which MSC osteogenesis is
enhanced MSC adipogenesis is decreased, and vice versa. Studies on such com-
parison of MSC adipogenesis with osteogenesis are included in this chapter.
The stem cell lineage commitment and differentiation are unsurprisingly
affected by soluble factors surrounding the cells. The cell culture medium has been
optimized (in the name of induction or differentiation medium) to effectively direct
stem cell's fate. Much research has been completed regarding the biochemical
factors affecting MSC fate and what can be added or removed to the growth
medium to help control the commitment and differentiation of MSCs. As a
promising new factor for controlling MSC fate, recent studies have exploited how
mechanical stimulations affect MSC differentiation. These factors include cell
stretching, cell compression, shear stress from fluid flow, etc. Studies have actually
demonstrated a potential that various ways of manipulating these mechanical
factors can influence MSC fate decision. This includes the manipulation of MSC
fate either towards or away from adipogenesis or osteogenesis. Each of these types
of mechanical stimuli affects MSC differentiation in some manner, even though
there are variations in effects among different types of mechanical stimulations and
Search WWH ::
Custom Search