Stem Cell Flashcards
Define totipotent
Undifferentiated cell that can form anyone of the different cell types needed for an entire new organism
Define Stem cell
Unspecialised cells that can divide by mitosis to produce daughter cells thta can become specialised for specific function
Define Pluripotent
An undifferentiated cell that can form most of the cell types needed for an entire new organism
Define multipotent
A cell that can form a very limited range of differentiated cells within a mature organism
Define Morula
An early embryo made up of a solid ball of 10-30 totipotent cell
Define Blasocyst
An early embryo consisting of a hollow ball of cells with an inner cell mass of pluripotent cells that will eventually forma new organism
What are embryonic stem cell
Stem cell found in very early embryos that are specialised and capable of differentitiating into any type of cells
Where can embryonic stem cell be collected from
Donor stem cells removed from embryos grwon in IVF (left overs)
Patients own stem cells remove the from the umbilical blood before birth
What are adult stem cell
Undifferentiat3d cells found among the normal differentiated cells in tissue or organs that can differentiate when needed to produce any one of the major cells type found in tha tparticular tissue or organs
Potential uses of stem cell
Treat disease
Used to repair damded tissue
Used in scientic genetic research
Growing organs for transplant
Stem cell therapy
First stage of development
Stage
Day
Description
Fertilisation
Day 0
Fusion of nuclei of the gamete
Second stage of development
Stage
Day
Description
Zygote forms
Day 1
Fertilised egg
Ability to differentiate into any cell type (totipotent)
Stage 3
Day
Description
Cleavage
Day 1-3
volves a special kind of mitosis where cells divide repeatly without normal interphase for growth between division
Stage 5
Day
Description
Morula
Day 3-5
A solid ball of 10-30 totipotent cell
Stage 6
Day
Description
Blascocyst
Day
A mass of identical and undifferentiated cells forming a hollow sphere, which are pluripotent
Where are pluripotent stem cell found
Embryonic and fetal stem cell
Multipotent stem cell found?
Bone marrow cells
Adult
Umbilical cord stem cells
Where is umbilical cord stem cells from
The blood that drains from the placenta and umbilical cord after birth is a rich source of pluripotent stem cells
Usage of umbilical cord stem cell and drawbacks
If this blood is frozen and stored, those stem cells will be available throughout the life of a child and be used, should the child need treatment
DRAWBACKS
Large space is needed for storing of -the blood
-genetic disorder are present in the stem cells
Adult stem cell
Exist in a form of undifferentiated cells among the normal differentiated cells in the tissue or organs- they differentiated only when needed
They are multipotent and give limited range of cells
These could be extracted from a patient and treated so that they develop into cells that the patient needs
Using patient adult own stem cell avois the risk of rejection of new tissue
Totipotent issues
Limited - no issues with rejection
May cause tumours
Pluripotent issues
More likely to be rejected by immune system
May cause tumours - risk of developing cancer
Ethical issues with the use of embryos as a source
Difficult to control differentiation into specific types of cell
Multipotent
Even more likely to by rejected by immune system
May cause tumours
Relatively hard to grow and extract
Differentiate into limited number of cells types
If an individual has a genetic. Problem it will be present in their own adult stem cells
What is therapeutic cloning
Experimental technique used to produce large quantities of healthy tissue hoping it can cure diseases
Procedure of therapeutic cloning
1) removing the nucleus from one of the normal body cells and transfer it to a human ovum which has it orginal nucleus removed
2) a mild electric shock is used to fuse with the nucleus with the new cell and trigger development
3) the nearly formed cell starts to development and divide by mitosis
—> collecton of identical cells with the same genetic information as the patient
4j stem cells are harvested and then cultured in a suitable environement so that they differentiate into required tissue
5) there tissue cells then be transferred to the patient where they can do their job without the risk of the immune system rejecting them
Totipotent pros
Easy to isolate and grow
Can differentiate into any cell type
Pluripotent pros
Easy to isolate and grow
Adult stem cell pros
Less ethical issues as no embryonic tissue involved
Less chance of immune rejection if taken from same patient
If an individual has a genetic problem it will be present in their own adult stem cell
Embryonic stem cell
The earliest embryonic stem cells are totipotent
The blastocyst stage, the inner cells of this ball are pluripotent.
Pluripotent cells become more specialised as the embryo develops
By around three month of pregnancu the cells have become sufficiently specialised that when they divide they inly form more of the same type of cell
Embryonic stem cells example
Form blood stem cells which give rise to blood cells or skin stem cells
Umbilical cord stem cell
The blood that drains from the placenta and umbilical cord after birth is a rich sorce of pluripotent stem cell.
If this blood is frozen and stored , those stem cells will be available throughout the life of a child and be used should the child need treatment.
Drawback include large space needed for storing of blood and genetic disorders are present in the stem cells
Adult stem cell
Adult stem cell exist in the form of undifferentiated cells found among the normal differentiated cells in a tissue or organ.
They differentiate when needed.
These somatic stem cells are multipotent because they can give a limited range of cells.
Adult stem cells have been found in many different organs and tissue.
Adult stem cell cons
Relatively hard to extract and difficult to grow in the laboratory
Induced pluripotent stem cells
Produced from adult somatic cells using appropriate protein transcription factors to overcome some of the ethical issues with using embryonic stem cells
The genes that were switch off to make the cell specialised must be switched back on
This is done using transcriptional factors
Parkinsons disease
Nerve cells in the brains that produce dopamine stop working and are lost.
—> uncontrollable tremors in their hands and body become rigid , cannot move
—> transplant stem cells that farms dopamin neurones (pluripotent stem cells is the best hope)
Type 1 diabetes
The glucose - sensitive —> beta cells, insulin secreting cells from islet of langerhans in the pancreas are destroyed or stop making insulin
—> use human embryonic stem cell
—> (developed) mature human glucose - sensitive insulin producing beta cells.
Damaged nerves
Permanetly damaged and dont regrows
Cause paralyzed below the location of the damage
Included brain cell
Potential risk of using stem cells
Stem cell could cause the development of cancers in the body
Not fully discoverinf the knowledge of stem cell so some unexpected condition might occur
Potential benefits of using stem cell
- stem cell therapy which no other cure could do
- avoid risk of rejection if using stem cell from own patient (compare to risk of rejection when using organ transplant)
No need to use immunosuppressive drug
Ethical concern
Respect for autonomy - respect for individual, by not perofrming procedures without consent
Beneficence - the aim of doing good, by giving medicine to relieve suffering , using proper method etc.
Non maleficence - doing no harm
Justice - treating everyone equally and sharing resource fairly to avoid discrmination
Development of an organism
These stem cells self-renew and differentiate to create the entire organism through the process of controlling gene expression (switching on and off the transcription of certain gene)
Epigenic in fetal haemoglobin vs adult haemoglobin
- fetal haemoglobin has a stronger affinity for oxygen than adult haemoglobin
- fetal hadmoglobin contain alpha globin and gamma globin
- adult haemoglobin contain alpha globin and beta globin
- globin production moves from yolk sac in the embryo to the liver in the fetus and then to spleen, at birth, genes in the bone marrow taken this function almost completly
Epigenetic control mechnism in human development
- histone acetylation appear to activate the gamma globin gene in the fetus
- DNA methlyation silencing the fetal gamma globin gene just before and after birth and switch to beta globin expression
- non coding RNAs associated
- number of transciption factors in the switch to the production of beta globin in the spleen and bone marrow as the fetus approaches full term and birth
Embryonic stem cell
The undifferentiated cells of the early human embryo with potential to develop into many different type of specialised cell
Umbilical cord stem cell
The blood drain from the placenta and umbilical cord after birth
Rich in pluripotent stem cell
Frozen and sotred , can be used to produce certain cell/tissue organ in the future
(Intheory , not wnough evidenec yet)
Adult stem cells
Found only in certain area eg bone marrow, skin, intestinal wall
Multipotent stem cell
Problems with using stem cells from donor
- you need to find suitable match which can be difficult
- risk of rejection
- risk of transmission of disease
- the recipient would have to take immunosupressant drugs to prevent their body from rejecting the stem cells makinf them vulnerable to opportunistic disease
- can cause cancer to develop
Problems with using stem cells from donors
- you need to find a suitable match which can be difficult
- risk of rejection
- risk of transmission of disease
- the recipient would have to take immunosupressant drugs to prevent their from rejecting the stem cells making them vulnerable to opportnistic disease
- can cause cancer to develop
The development of an organism
These stem cells self re-new and differentiate to create the entire organism throug the process of contorlling gene expression
Epigenetic in fetal haemoglobin vs adult haemoglobin
- fetal haemoglobin has a stronger afgnity for oxygen than adult haemoglobin
- fetal haemoglobin contain alpha globin and gamma globin
- adult haemoglobin contain alpha globin and beta globin
- globin peoduction moves from yolk sac in the embroyo to the liver in the fetus and then to spleen at birth genes in the bine marrow taken this function almost completely
Stage 1
Zygote - sperm fertilised with the egg
Stage 2
Zygote divide by mitosis -> embryo
Stage 3
Embryo divide until it becomes a hollow ball of cell - morula
Stage 4 day 5
Blastocyst
Benefits of using stem cells
Great potential to treat wide variety of diseases
Organs developed from a patient own stem cell reduce the risk of organ rejection and the wait for the organ
Painless technique
Disadvantages of uses stem cells
Harm or death to embryo
Embryo cannot consent
—> there is a risk of culturing stem cells accumulating mutation that can lead to them developing into cancer cells
Stem cell cultured in the lab could become infected with a virus which could be transmitted to be the patients
Low numbers of stem cell donors
Sources of stem cell
Bone marrow
Skin
Umbilical cord blood
Liver brain
Uses of stem cell
Repair damaged organs
Growing organs
Research
Social issues of stem cells
It is possible for embryonic stem cells to be collected before birth (from amniotic fluid) or after birth (umbilical cord blood) and stored by a clinic but this can be expensive and isn’t an option for everyone
Lack of peer review clinical evidence of stem cell treatment
Educating the public sufficiently about what stem cells can and cannot be used for
Ethical issues stem cells
Stem cells may be sourced form unused embryo produced in IVF treatment - is it right to use them
Is it right to create embryos through therapeutic clinging and then destroying them
Should an embryo be treated as a person with human rights or as a commmodity
Disadvantages of stem cells
(Embryonic stem cells )Embryo destroyed when cells removed
—> embryos have the right to live
(Embryonic stem cells) body recognises the cells as different and willl reject them without the use of drug
(All stem cells) may produce cancer cells instead of healthy cells
Adult stem cell difficult to find and extract from tissue
Adult stem cell - only produced a few types of cells
Advantages of umbilical cord blood
No ethical issues of embryo involvement
Reduced problems of rejection
Disadvantages of umbilical cord blood
Has to be stored( cost implications)
Carries genetic diseases
Discuss how regulartoey authorities control the use of embryonic stem cells in research
Monitoring research
Issue license
Monitoring sources of stem cells
Ensure that only early stage of embryo are used
Prevention of unethical use of stem cells
- human cloning
Genetic manipulation
Discuss how regulatory authorities control the use of embryonic stem cells in research
Monitor the research is necessary
Issue the license for stem cell research
Monitoring sources of stem cells
Ensure that only early stages embryos are used as sources of stem cell
Prevention of unethical of stem cells
Risk of stem cells
Risk of transmission of disease
Risk of rejection
Risk having to take immunosuppressant drug
Risk stem cell
Risk of rejection
Risk of transmission of disease
Risk when taking immunosuppressant drug
Suggest why research with embryonic stem cell is further advantaged than research with adult stem cell
Are easier to work with
Embryonic are undifferentiated whereas adult stem cell appear to be less
Embryonic stem cell have a wider range of clinical application
Against
Embryonic is taken unborn children
Lack of respect of the embryonic
Not enough funding
A lot of current stem cell treatment badly regulated encourage to create more spares embryo
Evaluate the benefits and the ethical issues associated with embryonic stem cell research
Offers prospect of treatment to many suffering
If we ban it it will still happen in other countries
adult stem cell is progressing slower than embryonic stem cell
An embryo is not a new human until it is viable
