Different populations and sources of human mesenchymal stem cells (MSC): A comparison of adult and neonatal tissue-derived MSC

These functions underlie the important physiological roles of MSC and underscore a significant potential for the clinical use of distinct populations from the various tissues. MSC derived from different adult (adipose tissue, peripheral blood, bone marrow) and neonatal tissues (particular parts of the placenta and umbilical cord) are therefore compared in this mini-review with respect to their cell biological properties, surface marker expression and proliferative capacities. In addition, several MSC functions including in vitro and in vivo differentiation capacities within a variety of lineages and immune-modulatory properties are highlighted. Differences in the extracellular milieu such as the presence of interacting neighbouring cell populations, exposure to proteases or a hypoxic microenvironment contribute to functional developments within MSC populations originating from different tissues, and intracellular conditions such as the expression levels of certain micro RNAs can additionally balance MSC function and fate.During the last few years isolations of adult mesenchymal stem cells from different sources have been reported. Bone marrow derived stem cells first described by Friedenstein et al. are still the most frequently investigated cell type and often designated as the gold standard [1]. Mesenchymal stem cells derived from adipose tissue [2], peripheral blood [3], the lung [4] or the heart [5] however have also shown promising potential for proliferation and differentiation into different cell types. In this section we focus on the comparison of adult mesenchymal stem cells derived from bone marrow (BM), adipose tissue (AT) and peripheral blood (PB) (Figure 1).BM-MSC are isolated from bone marrow aspirate. This invasive procedure is painful for the patient and is accompanied by a risk of infection. The commonly applied preparation method for the generation of MSC from bone marrow is density gradient centrifugation [6]. The collected fraction containing mon