Chapter 4: Mesenchymal stem cell isolation and expansion methodology. In: Stem Cells And Cancer Stem Cells: Therapeutic Applications in Disease and Injury
Mesenchymal stem cells (MSCs) are adult
non-hematopoietic stem cells originally isolated from
bone marrow (BM) (Prockop, 1997), but they are virtually
present and can be isolated from almost every
tissue of the body (Da Silva et al., 2006), including
peripheral blood (Roufosse et al., 2004). This
evidence suggests that MSCs could be part of a
mesenchymal-stromal cell system diffused throughout
the body. The real in vivo counterpart of cultureexpanded
MSCs is still unknown; however, different
Authors suggested that MSCs are a subgroup of
vessel-lining pericytes that may contribute to vessel
homeostasis by reacting to tissue damage with regenerative
processes, locally modulating the inflammatory
reaction, and entering systemic circulation to migrate
according to cytokine gradients (Crisan et al., 2008).
The International Society of Cellular Therapy (ISCT)
stated the following three criteria for the definition
of MSCs after in vitro expansion (Dominici et al.,
2006): (1) the adherence to plastic under standard tissue
culture conditions; (2) the expression of a specific
combination of cell surface markers; (3) the capability
of multilineage differentiation under appropriate
in vitro conditions. These criteria are necessary to
overcome the problems due to the absence of MSCspecific
cell surface markers, the high heterogeneity
in terms of differentiation potential, and the similarities
to fibroblasts displayed by isolated and expanded
MSCs. Consequently, ISTC suggested to define MSCs as \u201cMultipotent Mesenchymal Stromal Cells\u201d instead
of \u201cMesenchymal Stem Cells\u201d. In this Chapter, MSC
isolation, expansion and functional characterization
will be discussed in details