Pluripotency: These are the cells that can generate into any of the three Germ layers which imply Endodermal, Mesodermal, and Ectodermal cells except tissues like the placenta.
According to Latin terms, Pluripotentia means the ability for many things.
We can generate Induced Pluripotent cells by using the Induced pluripotency technique by triggering or expressing the genes or the transcription factors of the normal somatic cells. They are abbreviated as iPSC or IPS. We can forcefully express the transcription factors like
Oct4,
Sox2,
Klf4, and c-
Myc of a non-pluripotent cell and convert them into a stem cell. This procedure is first studied in a Mouse fibroblast cell in 2006 and followed the same instructions in developing a Human pluripotent cell from a Human epidermal fibroblast cell. The technique is called Regeneration.
Though the iPSC has similar properties to embryonic stem cells they were never approved for clinical stage research because they are highly Tumerogenic, having low replication rates and early senescence.
There are two distinctive phases called Naïve and Primed conditions of pluripotency in epiblasts. We call it pre and post-implementation. The pre-implemented epiblast is referred to as embryonic stem cells which can generate into an entire fetus.
On the other hand, the Post-implemented epiblasts show several marked differences from pre-implemented epiblasts like the difference in morphology (showing morphological differences like developing a cup-like shape called “egg cylinder” after implementation) and taking part in X-inactivation.
Cell potency is a
cell's ability to
differentiate into other cell types.
The more cell types a cell can differentiate into, the greater its potency. Potency is also described as the gene activation potential within a cell, which like a continuum, begins with
totipotency to designate a cell with the most differentiation potential,
pluripotency,
multipotency,
oligopotency, and finally
unipotency.
Totipotency
Totipotency (Lat. ''totipotentia,'' "ability for all
hings) is the ability of a single
cell to divide and produce all of the differentiated cells in an
organism.
Spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s and
zygotes are examples of totipotent cells.
In the spectrum of cell potency, totipotency represents the cell with the greatest
differentiation potential, being able to differentiate into any
embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
nic cell, as well as any extraembryonic cell. In contrast, pluripotent cells can only differentiate into embryonic cells.
A fully differentiated cell can return to a state of totipotency. The conversion to totipotency is complex and not fully understood. In 2011, research revealed that cells may differentiate not into a fully totipotent cell, but instead into a "complex cellular variation" of totipotency. Stem cells resembling totipotent
blastomeres from 2-cell stage embryos can arise spontaneously in mouse embryonic stem cell cultures and also can be induced to arise more frequently ''
in vitro'' through down-regulation of the
chromatin
Chromatin is a complex of DNA and protein found in eukaryote, eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important ...
assembly activity of
CAF-1
Chromatin assembly factor-1 (CAF-1) is a protein complex — including Chaf1a (p150), Chaf1b (p60), and p48 subunits in humans, or Cac1, Cac2, and Cac3, respectively, in yeast— that assembles histone tetramers onto replicating DNA during the ...
.
The human development model can be used to describe how totipotent cells arise. Human development begins when a
sperm
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...
fertilizes an egg and the resulting fertilized egg creates a single totipotent cell, a
zygote. In the first hours after fertilization, this zygote divides into identical totipotent cells, which can later develop into any of the three germ layers of a human (
endoderm
Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gast ...
,
mesoderm
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical E ...
, or
ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...
), or into cells of the
placenta (
cytotrophoblast
"Cytotrophoblast" is the name given to both the inner layer of the trophoblast (also called layer of Langhans) or the cells that live there. It is interior to the syncytiotrophoblast and external to the wall of the blastocyst in a developing embryo ...
or
syncytiotrophoblast
Syncytiotrophoblast (from the Greek 'syn'- "together"; 'cytio'- "of cells"; 'tropho'- "nutrition"; 'blast'- "bud") is the epithelial covering of the highly vascular embryonic placental villi, which invades the wall of the uterus to establish nut ...
). After reaching a 16-cell stage, the totipotent cells of the
morula differentiate into cells that will eventually become either the
blastocyst
The blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the ''embryoblast'' which subsequently forms the embryo, and an outer layer of trophoblast cells called the t ...
's
Inner cell mass
The inner cell mass (ICM) or embryoblast (known as the pluriblast in marsupials) is a structure in the early development of an embryo. It is the mass of cells inside the blastocyst that will eventually give rise to the definitive structures of ...
or the outer
trophoblasts. Approximately four days after fertilization and after several cycles of cell division, these totipotent cells begin to specialize. The inner cell mass, the source of
embryonic stem cells, becomes pluripotent.
Research on ''
Caenorhabditis elegans
''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (ro ...
'' suggests that multiple mechanisms including
RNA regulation may play a role in maintaining totipotency at different stages of development in some species.
Work with
zebrafish and mammals suggest a further interplay between
miRNA and
RNA-binding proteins (RBPs) in determining development differences.
Primordial germ cells
In mouse primordial
germ cells,
genome-wide reprogramming leading to totipotency involves erasure of
epigenetic
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...
imprints. Reprogramming is facilitated by active
DNA demethylation involving the DNA
base excision repair enzymatic pathway.
This pathway entails erasure of
CpG CpG can be:
* CpG site - methylated sequences of DNA significant in gene regulation
* CpG Oligodeoxynucleotide - unmethylated sequences of DNA that have immunostimulatory properties
*CpG island
The CpG sites or CG sites are regions of DNA wher ...
methylation (5mC) in primordial germ cells via the initial conversion of 5mC to
5-hydroxymethylcytosine (5hmC), a reaction driven by high levels of the ten-eleven dioxygenase enzymes
TET-1 and
TET-2.
Pluripotency

In cell biology, ''
pluripotency'' (Lat. ''pluripotentia'', "ability for many
hings)
refers to a stem cell that has the potential to
differentiate into any of the three
germ layers:
endoderm
Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gast ...
(gut, lungs, yolk sac),
mesoderm
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical E ...
(muscle, skeleton, blood vascular, urogenital, dermis), or
ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...
(nervous, sensory, epidermis), but not into extra-embryonic tissues like the placenta.
However, cell pluripotency is a continuum, ranging from the completely pluripotent cell that can form every cell of the embryo proper, e.g., embryonic stem cells and iPSCs, to the incompletely or partially pluripotent cell that can form cells of all three germ layers but that may not exhibit all the characteristics of completely pluripotent cells.
Induced pluripotency
Induced pluripotent stem cells, commonly abbreviated as iPS cells or iPSCs, are a type of pluripotent
stem cell
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type o ...
artificially derived from a non-pluripotent cell, typically an adult
somatic cell
A somatic cell (from Ancient Greek σῶμα ''sôma'', meaning "body"), or vegetal cell, is any biological cell forming the body of a multicellular organism other than a gamete, germ cell, gametocyte or undifferentiated stem cell. Such cells compo ...
, by inducing a "forced" expression of certain
genes and
transcription factors.
These transcription factors play a key role in determining the state of these cells and also highlights the fact that these somatic cells do preserve the same genetic information as early embryonic cells.
The ability to induce cells into a pluripotent state was initially pioneered in 2006 using mouse
fibroblast
A fibroblast is a type of cell (biology), biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and plays a critical role in wound ...
s and four transcription factors,
Oct4,
Sox2,
Klf4 and c-
Myc;
this technique, called
reprogramming, later earned
Shinya Yamanaka and
John Gurdon the Nobel Prize in Physiology or Medicine. This was then followed in 2007 by the successful induction of human iPSCs derived from human dermal fibroblasts using methods similar to those used for the induction of mouse cells. These induced cells exhibit similar traits to those of embryonic stem cells (ESCs) but do not require