Stem Cells (SCs) are undifferentiated cells, capable to self-renewal and that can virtually give origin to every tissues or organs [1]. By taking in consideration the new knowledge arisen from molecular biology techniques, a lot of new opportunities and strategies have been developed and established with SCs. SCs are pigeonholed as: (i) Embryonic Stem Cells (ESCs), (ii) Cord Blood Stem Cells (CB-SCs) and (iii) Adult Stem Cells (ASCs). Each one of these cellular populations has been characterized and further divided in sub-populations by using genotyping assays and phenotypical expression of markers [2]. SCs can be characterized by the presence of specific cellular markers such as CD34, CD44, CD105 and CD133 [3]. ESCs are narrowed as clonogenic and self-revamping progenitor cells that can generate all specialized cell types [4]. The main criteria currently used to characterize and identify these cells is their capacity to differentiate in every tissues of endodermal, mesodermal and ectodermal origin [4]. ESCs proceed from the starting embryonic mitosis and are considered a perfect instance of totipotent SCs; the Inner Cell Mass (ICM) of human blastocyst, at 5-6 days, is a flawless source of pluripotent ESCs. The intermediate SCs that are restricted to the lineage of a particular organ are called multipotent SCs [4]. Clinical research on ESCs is lust curbed by law enacted, but recently, new ongoing guidelines have been released by NIH [5]. CB-SCs are collected from the Umbilical Cord Blood (UCB) at birth. CB-SCs are self-renewable multipotent progenitor cells obtained from UCB that have the potential to differentiate into various lineages such as the potential to differentiate into chondrogenic, adypogenic, osteogenic and bone marrow tissues as well blood components [6; 7]. Compared to ASCs, CB-SCs have shown the advantages, when use for transplantation in an allogeneic setting, of quick availability and less risk of graft versus host disease (GvHD) due to their higher immaturity. Therefore, CB-SCs are endowed with a higher trafficking capacity to injured tissues and immunomodulatory property [8; 9; 10; 11; 12]. ASCs are undifferentiated multipotent cells virtually restrained in every specific adult tissues and organs; the main criteria currently used to characterize and identify these cells are the capacity for self-renewal and differentiation in specific tissue and organs whose belong to [13; 14; 15].
