Artificial Scaffolds and Mesenchymal Stem Cells for Hard Tissues - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 162

Fig. 3 The differentiation potential of MSCs. In accordance with HSCs, more committed
progenitor cells are discussed, but they have not yet been defined. MSCs have the potential to
differentiate into multiple mesenchymal-derived lineages. Adipogenesis leads to adipocytes and
osteogenesis to osteocytes. Similar, chondrogenesis will end with chondrocytes. Myogenesis will
generate cardiac, smooth, and skeletal muscle cells and neurogenesis will lead to astrocytes,
oligodendrocytes, and neurons. After tendogenesis and ligamentogenesis, fibroblasts are

produced

the hematopoietic stem cell (HSC). But the isolation procedure from bone marrow
is painful and the yield of cells which can be obtained is low, and thus various
other tissues have been investigated as sources of MSCs, with umbilical cord and
fat being the most prominent [ 62 - 67 ].
Fat tissue-derived MSCs are especially attractive as a basic cell source for
allografts, since they can be obtained from healthy and young donors with long
telomers and thus an extended lifespan [ 68 , 69 ]. They have eliminated some of the
key challenges in potential tissue repair: the lack of sufficient base material and the
risk of putative cell rejection by the immune defense system of the recipient,
because these cells can be also isolated in abundance from the patient's own
liposuction material and differentiated towards the desired cell type.
MSCs have the ability to differentiate into several different cell lineages, such
as chondrocytes, astrocytes, myocytes, adipocytes, or osteoblasts (see Fig. 3 ),
when cultivated under appropriate conditions using specific hormonal inducers
and/or growth factors [ 3 , 61 , 66 , 67 , 70 - 74 ]. There are controversies about the
limitation of the differentiation potential of MSCs. Several studies have shown
differentiation of MSCs into cell types belonging to a germ layer other than
mesoderm. Examples are differentiation into neuron-like cells [ 75 ], islet-like cells
[ 76 , 77 ] or hepatocytes [ 78 ]. They also posses the capacity to differentiate into
cardiomyocytes [ 79 ] and endothelial cells [ 79 , 80 ]. This might be due to the fact
that the mesenchyme does not completely originate from the mesoderm, but partly
stems from both of the other germ layers as well. A different hypothesis explains
the potential of MSCs to differentiate into endodermal or exodermal cell types by