Endocrine Abstracts

Cell therapy with Embryonic, Adult or iPSs Stem cells? As knowledge and scientific data start to increase the answer to that question seems still far away. Although all of them have in common their pluripotenciality and their infinite growth in vitro, the physiological regulation of stem cells in vivo is not really defined. Embryonic stem cells isolated from different steps from the initial embryonic development present in culture some different properties. New studies need to be performed to clarify the importance and deepness of that heterogeneity.

We know that adult stem cells remain organized in a delicate structure called the stem cell niche. The concept of niche includes aside from the stem cells organized in a characteristic way, vascular, neural and stromal support. There are known a few niches in the body but not all have been described with similar characteristics. The niche is an essential part in the recruitment of the stem cells and also can be affected by disease. Thus it is important to study in detail the biology and physiological regulation of the niche. Recently, the role of oxygen in the regulation of the stem cell niche has been highlighted. It is also under discussion if the asymmetric division of stem cells is a rule or if they usually divide symmetrically either as stem cells or getting differentiated into progenitors.

In the endocrine organs, the pituitary and the testes present a well localized niche that seems to share some characteristics. Among them the organized expression of the RET/GFRa receptors and its ligands. We do not know if they could be markers of ectodermic stemness or be common to all stem cells. But they are useful for technical isolation of the stem cells.