Transcript Cell Differentiation - Mounds Park Academy Blogs

Cell Differentiation
How cells specialize to become tissues and
organs
Current Research in Cell Differentiation
Anthony Atala –
researcher on growing
new organs.
Able to grow a bladder
Has a dot matrix
printer that prints out
a heart.
For simple, hollow organs such as the bladder and
trachea, researchers seed scaffolds with living cells and
then transplant the entire organ into patients
July 13, 2012, Hannah Warren, 2, poses with her parents
Lee Young-mi and Darryl Warren at Seoul National
University Hospital in Seoul, South Korea.
The stem cells used came from Hannah's bone marrow
through her hip bone. They were then seeded in a lab
onto a plastic scaffold, where it took a week for them to
multiply and make a new windpipe.
Dr. Doris Taylor
University of Minnesota
researcher.
You can use detergents
to remove all of the cells
from connective tissue.
She is holding a heart
that has had all of the
cells removed.
She has been able to
place cells on these
hearts and have the
cells grow and form a
new heart.
She has even been able
to make one that beats!
Liver Buds
Human skin stem cells, reprogrammed into an
embryonic state and mixed with 2 other cell types
formed miniature livers that kept mice alive for a few
months.
Researchers have also worked to create pure cultures of
functional cells in the laboratory, hoping that cells could
be infused into patients, where they would establish
themselves.
3 current Strategies:
1. Seed scaffolds with living cells and then
transplant entire organ
2. Create pure cultures of cells and infuse into patients.
3. Grow and combine cell types together and then
transplant.
spray on skin
Cells
Cells specialize and
organize themselves
into tissues.
These are the four
types of tissues found
in humans
What type of tissue
makes up the blood?
Tissues
Tissues organize
themselves into
organs
So, an organ is
different types of
tissues working
together to do a job.
In the case of the
heart, there is
muscular,
connective, nervous
and epithelial tissue
in the heart
working together to
pump blood to the
body.
How a cell decides what it will become
Some of the signals
that determine what a
cell becomes comes
from the cell itself.
Depending on where
the cell is certain genes
will be turned on and
others turned off.
This will help
determine the kind of
cell it becomes.
External Factors in Cell differentiation
Chemicals coming
from other cells can
influence what a cell
becomes.
These chemicals
usually come from
cells that are close
by
The chemicals
emitted turn on and
off certain genes.
Environmental Signals
Cells also get signals
from the
environment.
Temperature can be
a factor that affects
cells.
Heat Shock can
cause cells to
produce proteins
(HSP) to protect
them from heat.
Lack of oxygen, pH,
UV radiation are
other factors that
can affect what
genes are turned on
by a cell.
Stem Cells
This is a photo of a
human stem cell
growing on a culture
medium
This cell has the
potential to become
any cell in the human
body.
All of the specialized
cells have the same
DNA as the Stem Cell.
Fat cells
Nerve cells
Specialized cells of the retina
Macrophage
Fertilization and the Zygote
If a cell is taken from
the Morula stage it can
become a person.
The cell is totipotent
If the cell is taken from
the blastocyst stage it
can become any organ,
but it cannot become a
person.
Those cells are
pluripotent
Unipotent
Once a human cell
starts down a path to
become a specialized
cell it cannot go back.
For us the cell cannot
become anything else,
but that particular
specialized cell.
At this stage the cell is
unipotent.
Regeneration
There are some
creatures who have
cells that can go
backward.
That is they can go
from unipotent to
pluripotent
For the salamander
some of the cells in its
leg can dedifferentiate.
Those cells can become
stem cells and then
specialize into tissues
to form a new leg.
This Sea Star is regenerating it lost limbs
The salamander can regenerate the limb, heart,
tail, eye tissues, kidney, brain and spinal cord
through out life
The Zebra fish can regenerate heart tissue
Deer regenerate their antlers every year. For a
white tailed deer this can be 60 lbs.
The Snow shoe hare can regenerate parts of its
ears.
The Brown Bat can regenerate parts of its wings
Crayfish can regrow lost claws.
Sea squirts can regrow a whole new animal
Gecko’s can regenerate their tails.
One third of the human liver can regenerate into
a whole organ
This patient has received a liver transplant. It
will take up to 6 months for the liver to
regenerate completely
Internal Cues
The cells position in the blastula helps to determine what it
will become as the blastula turns into the gastrula.
Cells on the outside of the gastrula become what’s called
ectoderm.
Cells on the inside become what is called endoderm.
The middle germ layer is called the mesoderm.
General fates of the three germ layers
Gene Regulation
All cells start out with
the same # of
chromosomes and the
same # of genes.
For a stem cell to
become a smooth
muscle cell it must
turn on the smooth
muscle genes and turn
off the others.
Internal cues
Where the stem cells is
helps to determine
which genes are turned
on and off.
One of the internal cues
is transcription factors.
Transcription factors
are proteins, made in
the cell, that turn genes
on.
So where the cell is can
cause particular
proteins to be made that
help to turn genes on.
Male and Female
Up to 5 weeks in
development the male and
female fetuses look the
same.
At that point the testes start
producing a transcription
factor.
This protein, called the SRY
factor is produced in the
testes.
It flows from cell to cell and
turns on The SRY gene in
the Y chromosomes of the
males.
This gene causes a fetus to
develop as a male.
So, until about 6 weeks in
development we are all
females!
Heat Shock Factor- External cues
When a cell is too
hot it produces
heat shock factor
(HSF).
This protein goes to
the nucleus.
It turns on certain
genes to produce
compounds that
will make the cell
membrane
resistant to heat.
Other external factors
Similar shock factors
have been discovered
for lack of oxygen
(hypoxia).
So cells have a
number of fates.
They are affected by
their location, the
cells next to them
and external factors
like heat and oxygen.
These whitefish cells
are in the morula
stage.
What is their
potency?