Stem Cell Differentiation Depending on Different Surfaces - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 265

the differentiation of mesenchymal stem cells (MSC) has been studied in detail
[ 2 - 4 ]. Moreover, the application of human MSC (hMSC) has become more and
more attractive for tissue engineering [ 5 ], but also for clinical trails [ 6 ]. However,
the key parameter of the third approach seems to be the selection of the proper
biomaterial [ 7 ]. Presently, the physical characteristics which might control stem
cell fate have rarely been explored. This chapter will highlight an important
control mechanism of stem cell differentiation: the interaction of MSC with their
surrounding microenvironment.
2 Bone-Marrow-Derived Mesenchymal Stem Cells and Their
Alternatives
Today, hMSC isolated from bone marrow bm are considered as the ''gold
standard'' [ 8 ]. Among other criteria, they have the ability to differentiate into
several lineages, such as adipocytes, chondrocytes, and osteoblasts. Nevertheless,
bm as a source of MSC has several disadvantages, such as an invasive and painful
collection procedure with a high risk of infection, a low frequency of MSC, and a
differing quality depending on the donor's age [ 8 ]. Thus, MSC derived from other
sources, for example, adipose tissue [ 9 ], umbilical cord uc tissue [ 10 , 11 ], and uc
blood [ 12 ], represent an alternative and have shown promising results. Especially
MSC derived from postnatal tissues have gained the attention of several research
groups, since these tissues are easily accessible and can be processed directly after
birth. Furthermore, the frequency of MSC is much higher in postnatal tissues, and
the cells show a higher proliferation capacity compared with bm-derived MSC.
Summing up the increasing research activities over the last decade, uc MSC seem
to be a valuable cell source with a great potential for cell-based therapies which
initiate tissue repair [ 8 , 13 ].
3 Biomaterials as an Artificial Extracellular Matrix
Although it is well known that MSC and tissue cells grow best in a defined 3D
surrounding of macromolecules, most tissue engineering experiments are still
conducted on flat-bottom surfaces of culture vessels made of glass or plastic [ 14 ].
The first experiments to culture adherent cells on appropriate biomaterials were
performed during the mid-1980s [ 15 ]. Since then, research activity in the area of
biomaterials for tissue engineering has increased continuously (Fig. 1 ). Today, it is
known that an appropriate biomaterial mimics the extracellular matrix (ECM) in
vivo and a culture substrate in vitro. For tissue engineering applications the 3D
biomaterial should mimic the ECM properties of the specific tissue that needs to be
regenerated. In vitro these artificial matrices support cell proliferation, migration,