GROUP 4 PROJECT- STEM CELL

RESEARCH By: Jeet Mehta, Chelsea Bodoe, Jayneel Limbachia and Davina Sran.

WHAT ARE STEM CELLS?

Stem cells are basically cells found in every multi-cellular organism.

The difference between them and other cells is their ability to renew themselves.

While renewing, they can differentiate (specialize or transform) into many different cell types.

Stem-cell research started during the early 1960’s.

SCIENTIFIC DEFINITION

Stem cells are mainly defined by 2 important properties:

1. Self-Renewal: It is their ability to complete many cell division cycles while maintaining the same state.

2. Potency: It is their capacity to specialize into many different cell types. Potency describes the cell’s potential to differentiate into different cell types (differentiation potential).

SELF-RENEWAL

Self-Renewal also has two main mechanisms, and these exist so the cell’s population can maintain a certain state.

1. Obligatory Asymmetric Replication: The stem cell divides into 1 identical daughter

cell and 1 differentiated (transformed) daughter cell.

2. Stochastic Differentiation: One Stem cell divides into 2 transformed

daughter cells and another stem cell divides into 2 identical daughter cells.

POTENCY

As mentioned earlier, potency of a cell describes its potential to specialize or differentiate.

There are 5 types of cell potency:1. Totipotent: Totipotent cells can differentiate into embryonic

and extra- embryonic (located outside the embryonic body) cell types

They can construct a complete functioning organism.

Produced from the fusion of a egg and sperm cell

Totipotent cells can also be produced from the early divisions of a fertilized egg.

POTENCY CONT…

2. Pluripotent: Pluripotent stem cells come from totipotent

cells. They can differentiate into almost all cell

types. They can create fetal and adult cells but

cannot develop into the fetus or animal itself because they do not contribute towards non-embryonic tissue.

Pluripotent cells can also be forcefully create from non-pluripotent cells, usually somatic cells.

POTENCY CONT…

3. Multi-Potent: Multi-potent stem cells can transform into many

different cells, as long as they are in the same “family” of cells (originate from the same organ)

4. Oligopotent: Oligiopotent cells can specialize into only a few

cells5. Unipotent: Unipotent stem cells can only produce their own

cell types The only difference between them and normal

cells is their ability of self-renewal.

PRACTICAL DEFINITION

The definition of stem cells practially is this:Stem Cells – a cell that can regenerate tissue

and sustain it over a lifetime.This definition can be applied in many medical

uses of stem cells such as bone-marrow operations, hematopoietic cells etc.

There are two main types of stem cells:1. Embryonic 2. Adult (Somatic)

EMBRYONIC STEM CELLS

Embryonic stem cells are pluripotent cells They are found in the inner cell mass of the

blastocyst (structures inside an early stage embryo)

Embryo’s reach blastyocst stage 4-5 days after egg fertilization

The problem with embryonic stem cells is that isolating the inner cell mass to obtain these cells kills the embryo, thus creating many ethical issues.

WHERE DO THEY COME FROM?

Formation of Embryonic Stem Cells and the types of organs they can create

HUMAN EMBRYONIC STEM CELLS

ADULT STEM CELLS (SOMATIC CELLS)

They are Undifferentiated cells (cells that have not changed)

Found throughout the body after the embryo is developed

Somatic stem cells multiply through cell division

They are used to replenish or revive dying cells and tissues.

SOMATIC CELLS CONT…

They can be found in both juvenile and adult humans and animals.

The main property of somatic cells is that they can divide indefinitely and create cells of all types from the organ of their origin, possibly creating the whole organ.

They are not controversial because instead of deriving them from a dead embryo, they are found in normal adult muscle tissue.

HUMAN SOMATIC STEM CELLS

USES OF STEM CELLS

WHY IS STEM CELL RESEARCH DONE?

STEM CELLS Stem cells can be made into any kind of cell,

therefore, they are manipulated to do the job that another group of cells may lack

CANCER

Cancer is an example of manipulated stem cells

Stem cells leads to cancer as they are mutated

Normal mature cells do their assigned job

TO SUM UP…

Research is done to visualize how to create these other wanted cells

OTHER POTENTIAL USES

Research also leads to other potentials such as:

human cloning or whether these embryos are human life

CONTROVERSY

Research is the primary reason for controversy

Human cloning is a part of research and leads to many ethical arguments

Many humans argue that it not within a man’s preview to manufacture, manipulate or destroy human life

HOWEVER…

Research is needed to carry out the methods to create these other cells

Proper procedure and precautions must be taken

METHODS OF EXTRACTING STEM CELLS

USES FOR THE BODY

Sometimes useful in helping body replenish itself & repair disease Ex. Heart failure

Process of removal/re-admittance: Patient's stem cells extracted from the blood cultivated in a lab within 5 days into several tens

of millions of synergetic cells of the patient, then injected into the patient

USES FOR THE BODY CONT’D

Stem cells widely known for role in in-vitro fertilization extracted from ovaries

Stem cells can also be conceived as unborn fetus Hence reason research is a major ethical issue in

society Are humans really killing fetuses, even if they

are undeveloped?

AMNIOTIC STEM CELLS

amniotic sac fills with water after fertilization ‘liquid’ contains proteins, carbohydrates,

lipids and phospholipids, urea and electrolytes, all of which aid in the growth of the fetus

Amniocentesis = process to remove amniotic stem cells to check on fetus

AMNIOCENTESIS

Regular procedure Many amniotic stem cells can be removed

without harming the fetus Therefore, not as much controversy!

Process: Needle first inserted through mother's abdominal wall then through wall of the uterus, & finally into amniotic

sac.

ADVANTAGES/DISADVANTAGES OF STEM CELLS

ADVANTAGES OF STEM CELLS Form cells and tissues for medical therapies. Treat diseases as replacement cells.

Potentially reduce the illness and mortality for those awaiting transplant.

Diseases that could be cured by stem cells: Cardiovascular diseases Burn victims Type I diabetes Parkinson’s disease Arthritis

ADVANTAGES (CONT’D) A renewable source of replacement cells is

possible if the stem cells are differentiated into specialized cell types.

The ability to reverse diseases Ex: Replaced healthy new muscle cells for a

patient suffering from heart attack. New brain cells for damaged brain cells as a result

of Parkinson’s disease. treat genetic defects by introducing normal

healthy cells that do not have the defects. Burn victims’ suffering can be put to an end

by creating new and healthy tissues from stem cells.

ADVANTAGES (CONT’D) Stem cells are used to create specialized

blood cells for bone-marrow transplants. They are removed from a tissue and then are

differentiated outside the body before transplanting them back into the patient to replace damaged tissues.

usage in pharmacy: Stem cells can be used as testing grounds for

new drugs, avoiding animal and human testing.

ex: to test an anti-tumour drug, a cancer cell line could be created.

ADVANTAGES (CONT’D)

Organ donating problem can be avoided by extracting stem cells from a cloned embryo and use it to grow organs.

Results in a much lesser chance of tissue rejection as well.

Regarding the ethical implications of stem cells; it is important to mention that embryos are leftover from intro fertilisation and would be other wise be destroyed Thus, a better use fo the embryos includes

advancing human health.

DISADVANTAGES OF STEM CELL RESEARCHIncludes Ethical implications as well

DISADVANTAGES OF STEM CELLS Stem cells tend to divide indefinitely,

leading to a tumour The transplanted cells may differ from

the patient’s immune profile and thus get rejected by the immune system.

Unknown side effects and results from stem cell usage. Example: stem cell therapy may pass on

disease causing viruses or other microorganisms in an individual’s body.

DISADVANTAGES (CONT’D)

A patient receiving transplants is subject to drug intake that weaken the immune system, necessary for a successful transplant.

Clearly, if any diseases causing viruses are present in the transplanted cells, then the immune system would not be able to save the body.

The animal sources, used to provide nutrients to the stem cells may contain potential diseases which pass onto the individual receiving the therapy. Concern: Present diseases are not detected in

the screening of the stem cells

DISADVANTAGES (CONT’D) It is possible that the stem cells

differentiate into the wrong type of tissue Currently, scientists are uncertain about

how the differentiation of stem cells can be controlled. Ex: In 2001, scientists claimed to have

created cells that produced insulin, which later on was proved wrong because the cells had never produced insulin, rather had absorbed it from the environment.

DISADVANTAGES (CONT’D)

genetic dysfunctions are developed by the usage of older stem cells that have been approved for use. As they divide, a tumour is developed due to the

genetic disorders, putting the cells at risk. Thus the consequences may be very dangerous

in stem cell transplants.

ETHICAL IMPLICATIONS People believe that life begins at

conception and therefore research on human embryos is unethical. They believe that early-stage embryos,

known as blastocycts, have the potential to grow into a human being.

It is inhumane to kill one life in order to save another.

• Destroying the embryos signifies the minor value of human life over scientific research that de-values life.

ETHICAL IMPLICATIONS (CONT’D)

Additionally, animal testing is done in the process of preparing or experimenting stem cells.

Arguments against stem cell research include the idea that Embryos are divine creations. It is against the will of god to destroy an embryo,

and thus they are not to be created or destroyed by humans.

BIBLIOGRAPHY: Benefits of Stem Cells. In: Explore Stem Cells [discussion list on the Internet].

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Pecorino L.Stem Cells for Cell-Based Therapies. In: ActionBioscience - promoting bioscience literacy [discussion list on the Internet]. [American Institute of Biological Sciences]; 2010; [cited 2010 Dec. 24]. Available from: http://www.actionbioscience.org/biotech/pecorino2.html

Ethical Implications of Stem Cell Research. In: ISCID - International Society for Complexity Information and Design [discussion list on the Internet]. n.d.; [cited 2010 Dec. 24]. Available from: http://www.iscid.org/encyclopedia/Ethical_Implications_of_Stem_Cell_Research

Key Ethical Issues in Embryonic Stem Cell Research. In: Commonwealth of Australia [discussion list on the Internet]. 2002; [cited 2010 Dec. 23]. Available from: http://www.aph.gov.au/library/pubs/CIB/2002-03/03cib05.pdf

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