Reader Comments

Post a new comment on this article

A real vision of niche-determned fate of pluripotent cells

Posted by Truth_coming on 16 Sep 2009 at 09:45 GMT

Viczian et al.'s work captured a vivid part of this differentiation-based and niche-guided organ development from some fate-doomed "pluripotent" cells, eye field transcription factors (EFTFs)-expressing multipotent cells. By demonstrating the formation of a critical part of an organ (complete retina and some nerves of an eye) with some functions such as light-sensing from "animal caps" cells (collected at stage 9 and transplanted back at stag 15) whose developmental fates were already doomed earlier (at the 2-cell stage) with injection of capped RNAs coding for the EFTFs, these researchers not only further delineated the factors and processes involved in the light-sensing organ formation but also showed the very importance of correct differentiation and normal niche in guiding organ development from multipotent stem cells.
Currently, cell therapy-aimed cloning research has been focuses on finding "fully" pluripotent stem cells. However, in this study, it is reported that "YFP-expressing pluripotent cells grafted in place of the eye field never formed eyes" and "Control, YFP-only expressing pluripotent cells never generated mosaic retinas". This means that pluripotent stem cells passing their differentiation time windows are not suitable for direct use in organ regeneration even if they are placed into a right niche at its later developmental time. These fate-unspecified pluripotent stem cells may even yield some unexpected tissues. As a matter of fact, as reported in this study and even pointed out in the Author Summary, "If left untreated [referring to the EFTF-induction which causes a differentiation from pluripotent to multipotent state of the animal caps], transplanted pluripotent cells only form the epidermal layer of the skin".
Thus, the above observations should serve as a warning against any blind direct use of pluripotent stem cells in cell therapy. The value of generating "fully pluripotent" is also questionable as extra differentiation must be performed prior to any well-guided formation of any specific organ.
Some recent studies have hazard a view that niche is not necessary for organogenesis. But careful review on these studies suggests that that view is unjustified and even some misunderstanding of the observations. We are happy to see that some observations reported in this study seem to argue that niche is un-dispensable for complete organ development, at least in this "visible" case of eye formation.

No competing interests declared.