DEPARTAMENTO DE CIÊNCIAS DA VIDA ... - Estudo Geral

3
I - Introduction
I.1 - Mesenchymal stem cells (MSCs)
Mesenchymal stem cells (MSCs), also referred to as mesenchymal stromal cells or
mesenchymal progenitor cells were identified for the first time in the bone marrow
(BM) and were described as a population of plastic-adherent, non-hematopoietic and
spindle-shaped mesenchymal precursor cells. Due to their ability to form colonies of
cells similar to fibroblasts, those colonies were called, colony-forming unit-fibroblast
(CFU-Fs) (Friedenstein et al., 1970). As the studies and years advanced, observations
over MSCs showed that those cells from the bone marrow were multipotent and could
differentiate into osteoblasts, chondroblasts, myoblasts and adipocytes (Prockop,
1997; Nardi and da Silva Meirelles, 2006).
Therefore, MSCs are currently defined as multipotent cells capable of self-renewal
that can differentiate into different mesenchymal cell phenotypes (da Silva Meirelles
et al., 2008).
I.1.1 - Sources of MSCs
Although MSCs were initially identified and characterized in the bone marrow
(BM), with the years and research they have also been isolated from adipose and other
human adult tissues (Friedenstein et al., 1974; Zuk et al., 2001).
As there is a great interest for cells with proliferation and differentiation
potential and also because in adult tissues with ageing there is a decrease of MSCs
frequency and their differentiation capacity, alternative sources have been explored.
In this way, MSCs have been identified in several fetal tissues (including BM, liver,
blood, lung and spleen) but their full potential for use in clinical trials has been
compromised by technical and ethical factors (Malgieri et al., 2010). Hence,
alternatives like other primitive sources, namely extra-embryonic tissues like the
umbilical cord blood (UCB), the umbilical cord matrix/Wharton’s jelly (UCM/WJ),
placenta and amniotic membrane have been studied and protocols for the extraction
of MSCs from those tissues have been developed.