Biomedical Engineering Reference
In-Depth Information
Keratinocytes
( skin grafts )
Skeletal muscle cells
( muscle damage/disease )
Cardiac muscle
( heart disease/attack )
Embryonic
stem cell
Pancreatic islet-like cells
( diabetes )
Neurons
( neurodegenerative disease )
Hepatocytes
( liver disease )
Chondrocytes
( cartilage defects )
Figure 14.18 Some cell types reported to have been produced via in vitro directed differentiation from
either mouse or human embryonic stem cells. Potential uses for such cell types in regenerative medicines are
listed in italics
14.10.2 Adult stem cells
The main focus of stem cell research over the last few decades has been directed to embryonic
stem cells. However, more recently, research upon and an understanding of various populations
of adult stem cells has gathered pace. Adult stem cells are undifferentiated cells found amongst
differentiated cells in a tissue or organ. These cells can renew themselves and can differentiate to
yield the major cell types characteristic of the tissue in which they reside. The main physiological
role of adult stem cells, therefore, appears to be to maintain and to repair (to a certain extent at
least) the tissue in which they reside.
For many years it was believed that adult stem cell populations were present in a very limited
number of tissue types, and that they could only differentiate into cells characteristic of the tissue
in which they reside. Recent research challenges both of these assertions. Adult stem cells are
being discovered in a growing number of tissues, including bone marrow, peripheral blood and
Culture as floating aggregrates
(embryoid bodies), forming
neuroepithelial cells
Human embryonic
stem cells
Culture to form midbrain
dopamine neurons
Commercial culture
media containing FGF-2
Culture media with various
supplements & grow in
adhesive culture dishes
Culture medium supplemented with FGF-8
and SHH, added at specific culture timepoints
Figure 14.19 Simplifi ed schematic overview of the directed differentiation of human embryonic stem cells
to form differentiated dopamine like neurons. The full pathway details are available in Yan, Y., Yang, D.,
Zarnowska, E.D., Du, Z., Werbel, B., Valliere, C., et al . 2005. Directed differentiation of dopaminergic neuronal
subtypes from human embryonic stem cells. Stem Cells 23 , 781-790. FGF: fi broblast growth factor; SHH: sonic
hedgehog (a regulatory protein)
 
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