Biomedical Engineering Reference
In-Depth Information
Directions and Relevant Studies: We and Others
What is
“
stemness
” [
1
,
70
-
74
]?
Stemness
has so far been defi ned as both
phenotypically and functionally recognizable cell pattern capable of self-renewal,
proliferation and trans-differentiation through the phenomenon of plasticity [
1
,
74
].
One has to be aware of the fact that stem cell category, as an elementary term is
assuming the particular functionality. As the entity, or the state, it rationally presents
the cell which of its all possible functions possesses at the moment of stemness only
those that allow it to survive and sometimes divide: all other functions of this cell
are at the potential level. When those possible functions really come up into sce-
nario, that cell is not stem cell anymore. That is why the collections and clusters of
different antigens expressed all over the cells in different developmental stages of
different tissues (such as kit-receptor, CD117) cannot be the stem cell markers.
The “
stemness
” is the status in which only the oldest, the most primitive part of
the genome is activated “with the only purpose to save what is stored in the nucleus
of stem cell: genetic information”, e.g. potential [
1
]. The purpose of this event is to
save the cell of death and (if it comes to the stimulus for differentiation by asym-
metric division) from self-renewal [
1
]. In that way we are becoming aware that the
nature does create the standards that we should rather understand, instead of forcing
the nature into our simplifi ed concepts, some of which are very superfi cial.
Tremendous advance which has enabled enrichment of stem cells based upon selec-
tion using phenotype as a standard could be appreciated as the advance in this dis-
cipline. It has also enabled more direct approach to investigation of stem cells.
However, there are other explanations for this status and one of them was defi ned
by Dov Zipori [
70
-
72
]. According to him, this feature is not stem-cell specifi c,
given the fact that it is unaquired. Most importantly, according to Zipori, 'stemness'
is a
transient trait
and cannot be predicted on the basis of momentary gene-
expression patterns (Fig.
9.8
) [
73
].
Fig. 9.8
Stem cell
maturation according to
D. Zipori. Med Sci (Paris)
2011; 27: 303-301
