stem cell
What is a stem cell? A web research project
stem cell
SELF-RENEWAL(copying)
specialized celle.g. muscle cell, nerve cell
DIFFERENTIATION(specializing)
What can a stem cell do?
Identical stem cells
Stem cell
SELF-RENEWAL(copying)
Stem cell
Specialized cells
DIFFERENTIATION(specializing)
1) Describe the following stages of development:a) Zygote: right after an egg is fertilized. The zygote begins a two-week period of rapid cell division
FYI blastula: hollow ball right after morula but before inner mast cells form.
Blastocyst: A hollow ball that has a cluster of cells called the inner cell mass. These cells could become an embryo. These cells are used as embryonic stem cells. The outer layer of cells gives rise to the placenta.
http://www.medterms.com/script/main/art.asp?articlekey=18258
gastrula• the single-layered
blastula is reorganized into a trilaminar ("three-layered") structure known as the gastrula. These three germ layers are known as the ectoderm, mesoderm, and endoderm.
• Look back at your differentiation w.s.!
• http://www.hhmi.org/biointeractive/human-embryonic-development
#2) Explain type of SC, when & how harvestedPotency: A measure of how many types of specialized cell a stem cell can make
Totipotent: Can make any kind of cell. Unable/difficult to harvest due to small size.
Pluripotent: Can make all types of specialized cells in the body. Embryonic stem cells are pluripotent. Harvest from the bastocyst
Multipotent: Can make multiple types of specialized cells, but not all types (have some “programming”. Tissue (adult) stem cells are multipotent. Harvest from fetus or mature tissues (baby to elderly)
http://www.hhmi.org/biointeractive/cultured-human-embryonic-stem-cells
b) pluripotent: meaning they can divide into more stem cells or they can specialize and become any type of body cell. Because of this versatility, embryonic stem cells have the highest potential for use to regenerate or repair diseased tissue and organs in people.
http://www.mayoclinic.com/health/stem-cells/CA00081
Harvesting ES cells from human blastocysts is controversial because it destroys the embryo, which could have been implanted to produce another baby (but often was simply going to be discarded).
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Stem_Cells.html
multipotant: These are true stem cells but can only differentiate into a limited number of types.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Stem_Cells.html
adult stem cells are present in miniscule quantities and this can present difficulty for identifying and isolating them in numbers great enough to use therapeutically. Their self-renewal is also not as successful as embryonic stem cells and as such, they do not proliferate to the same degree
http://www.explorestemcells.co.uk/AdultStemCells.html
3) At what stage can embryonic stem cells be taken?
These stem cells come from bastocyst that are four to five days old. At this stage the cell consists of about 150 cells.
It is called an embryo once implanted into the uterus. Before that it can be called an early stage embryo.
• http://www.mayoclinic.com/health/stem-cells/CA00081
4) What are the two essential characteristics of stem cells?
First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity.
Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues. In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions.
http://stemcells.nih.gov/info/basics/basics1.asp
#5S.C. Type Definitio
nDescribe/ diagram
Advantage
Disadvantage
Political/ ethical issues?
Embryonic Taken from early stage of development
Embryos created from invitro are donated. The membrane around them is dissolved and the mast cells are used as embryonic stem cells
They can be turned into almost any type of cell
They are controversial b/c the embryo is destroyed
Definition of life is a moral dilemma that becomes political
Embryonic stem (ES) cells:Where we find them
blastocyst
outer layer of cells= ‘trophectoderm’
cells inside = ‘inner cell mass’
embryonic stem cells taken fromthe inner cell mass
culture in the labto grow more cells
fluid with nutrients
Embryonic stem (ES) cells:What they can do
embryonic stem cells
PLURIPOTENT
all possible types of specialized cells
differentiation
neuronsgrow under conditions B
Embryonic stem (ES) cells:Challenges
embryonic stem cells
skin
grow under conditions A
blood
grow under conditions C
liver
grow under conditions D
?
Adult/ tissue
Taken from differentiated tissues
Isolated from the different tissues know to have stem cells.
Could match exact DNA, doesn’t destroy potential life
Difficult to harvest, don’t self renew as well
none
IPSC Reverted from any cell back to s.c.
Regular body cells reverted to stem cells
Could match exact dna. The capacity to develop into almost all kinds of cells, like embryonic stem cells do
Cancer formation, inefficient process
none
Tissue stem cells:Where we find them
muscles
skin
surface of the eye brain
breast
intestines (gut)
bone marrow
testicles
Tissue stem cells:What they can do
MULTIPOTENT
blood stem cell
found in bone marrow
differentiation
only specialized types of blood cell:red blood cells, white blood cells,
platelets
Induced pluripotent stem cells (iPS cells)
cell from the body
‘genetic reprogramming’= add certain genes to the cell
induced pluripotent stem (iPS) cellbehaves like an embryonic stem cell
Advantage: no need for embryos! all possible types ofspecialized cells
culture iPS cells in the lab
differentiation
Induced pluripotent stem cells (iPS cells)
cell from the body (skin)
genetic reprogramming
pluripotent stem cell(iPS)
differentiation
6) How are adult stem cells different from embryonic stem cells?
They are multipotent, hard to harvest, might have mutations BUT they do have some potential and are not likely to be rejected
• Where are stem cells found in the adult body?Skin, Bone marrow, Brain, blood vessels, Liver, Skeletal
muscle http://www.explorestemcells.co.uk/AdultStemCells.html
• 7) What advantages do embryonic stem cells have over adult stem cells for medical research?
• No mutation, blank slate (pluripotent), easy to harvest
• Reieneke’s brain
• 8. what is a stem cell line?Embryonic stem cells that have been cultured in
a artificial environment that allows for multiple divisions (mitosis) without differentiation form months to years.
http://www.hhmi.org/biointeractive/creating-embryonic-stem-cell-lines
CloningThere are two VERY different types of cloning:
Reproductive cloning
Use to make two identical individuals
Very difficult to do
Illegal to do on humans
Molecular cloning
Use to study what a gene does
Routine in the biology labs
gene 1
gene 2
Reproductive cloning
remove nucleus and take the
rest of the cell
egg
take the nucleus (containing DNA)
cell from the body
Cloneidentical to the individual
that gave the nucleus
Dolly the sheep
Molecular cloning: Principles
gene 1
gene 2
2) Make a new piece of DNA
gene 1
gene 2
1) Take DNA out of the nucleus
cell 1 cell 2
gene 1 gene 2
3) Put new DNA into a test cell and grow copies
gene 1
cell divides
Daughter cells contain same DNA:
Genes 1 and 2 have
been cloned
gene 2
insert new DNA
10) Watch the following: http://www.hhmi.org/biointeractive/stemcells/animations.html
(Somatic Cell Nuclear Transfer Animation )a) Somatic cell nuclear transfer would allow researchers to create a large supply of diseased cells if they used nuclei from patients with disease. Why would that be advantageous for medical researchers?
Then you could test the diseased cells instead of the whole patient!
Stemcells.nih.gov
Molecular cloning: Applications
Normal mouseembryo
gene A missing
remove a gene to see if anything works differently
Loss of function
gene is involved ingiving the eye its colour
eye
Reporter geneadd a gene that shows
us when another gene is working
gene is active in blue areas only
Lineage tracingmark a group of cells to
see where their daughter cells end up
gene is passed on to cells all over the body
• http://media.hhmi.org/biointeractive/click/Stem_Cell_Therapies/13.html
• http://youtu.be/szxLvG4Vy-Q using stem cells to treat disease
• More review and more applications http://www.youtube.com/watch?v=evH0I7Coc54
• Making body parts http://www.teachersdomain.org/resource/nsn11.sci.life.stru.bodyparts/
11) Why is researching how animals are able to regenerate important to stem cell research?
If we can understand how regeneration (with stem cells ) allows animals to rte create limbs etc then we may be able to do the same for humans.
• Hhmi.com
12) watch the following video...it's about 15 minutes long & about 5 years old. http://www.pbs.org/wgbh/nova/body/stem-cells-research.html
• Summarize the argument that embryonic stem cell research should not be done.Basically comes down to the idea that you have to destroy embryos. Pro-life people believe that life begins at conception thus if you are destroying an embryo you are destroying a human life. Basically murder in the name of science. Other people believe it is just a ball of cells, thus have no issue. Others believe that it’s not a life until it is viable outside the mothers body (which is about 25/40 weeks of pregnancy).
• Why is using adult stem cells much less controversial?Because an adult can consent to having their stem cells
harvested.