biotechnology

2. DEFINITION
• A cell that has the ability to continuously divide and
differentiate (develop) into various other kind(s) of
cells/tissues.
• the body is made up of about 200 different kinds of
specialised cells such as muscle cells, nerve cells, fat cells
and skin cells.
• all cells in the body come from stem cells.
• a stem cell is a cell that is not yet specialised.
• the process of specialisation is called differentiation.
• once the differentiation pathway of a stem cell has been
decided, it can no longer become another type of cell on its
own.

3. STEM CELL HISTORY
1998 - Researchers first extract stem cells from human embryos
1999 - First Successful human transplant of insulin-making cells
from cadavers
2001 - President Bush restricts federal funding for embryonic
stem-cell research
2002 - Juvenile Diabetes Research Foundation International
creates $20 million fund-raising effort to support stem-cell
research
2002 - California stem cell research
2004 - Harvard researchers grow stem cells from embryos using
private funding
2004 - Ballot measure for $3 Billion bond for stem cells

4. STEM CELL CHARACTERISTICS
 ‘Blank cells’ (unspecialized)
 Capable of dividing and renewing themselves for long
periods of time (proliferation and renewal)
 Have the potential to give rise to specialized cell types
(differentiation)

6. TYPES OF STEM CELL
Stem cell
type Description Examples
Totipotent
Each cell can develop into
a new individual
Cells from early (1-3
days) embryos
Pluripotent
Cells can form any (over
200) cell types
Some cells of
blastocyst (5 to 14
days)
Multipotent
Cells differentiated, but
can form a number of
other tissues
Fetal tissue, cord
blood, and adult
stem cells

7. KINDS OF STEM CELL
1. Embryonic stem cells come from a five to six-day-old embryo. They
have the ability to form virtually any type of cell found in the
human body.
2. Embryonic germ cells are derived from the part of a human
embryo or foetus that will ultimately produce eggs or sperm
(gametes).
3. Adult stem cells are undifferentiated cells found among specialised
or differentiated cells in a tissue or organ after birth. Based on
current research they appear to have a more restricted ability to
produce different cell types and to self-renew.

8. STEM CELL DIFFERENTIATION

9. WHY ARE STEM CELLS SPECIAL?
 Stem cells can:
1. self-renew to make more stem cells.
2. differentiate into a specialised cell type.
Embryonic stem cells (pluripotent)
Stem cells that can become
many types of cells in the
body are called pluripotent
Tissue stem cells (multipotent)
Stem cells that can
become only a few types
of cells are called
multipotent

10. TISSUE STEM CELLS
• often known as adult stem cells
• also includes stem cells isolated from fetal and cord
blood
• reside in most tissues of the body where they are
involved in repair and replacement
• generally very difficult to isolate
• already used to treat patients (haematological
malignancies, diseases of the immune system)
Bone marrow Kidney Lung

11. 8-cell blastocystfertilised
egg
2-cellegg
Day 0 Day 1 Day 2 Day 3 Day 6
• Donated excess IVF embryos
Images from www.advancedfertility.com
Where do embryonic stem cells
come from?
Inner cell mass

12. Embryonic stem cells
• derived from donated IVF
embryos
• can be grown indefinitely
in the laboratory in an
unspecialised state
• retain ability to specialise
into many different tissue
types – know as
pluripotent
• can restore function in
animal models following
transplantation
Human embryonic stem cells can become any
cell in the body including these beating heart
cells
human embryonic
stem cells

13. INDUCED PLURIPOTENT STEM CELLS
• derived from adult cells in
2007 - very recent discovery!
• can be grown indefinitely in
culture in an undifferentiated
state
• similar properties to
embryonic stem cells as can
differentiate into many
different tissue types –
pluripotent
• can create stem cells directly
from a patient for research
Induced change in
gene expression
pluripotent
stem cells
Starting cells from
donor tissue
iPS Cells

14. WHAT MAKES STEM CELLS SO VALUABLE?
Cell Therapy
Research
New Drugs
Pluripotent
stem cells
Tissue stem
cells
No one stem cell type fits all applications.
Research must continue using all types of stem cells.

17. APPLICATIONS
 Disease
• Diabetes, Spinal cord
injury, Parkinson’s
disease, heart
disease
 Genetic based Disease
• Cystic fibrosis,
Huntington’s

18. CHALLENGES TO STEM CELL/CLONING
RESEARCH
1. Stem cells need to be differentiated to the
appropriate cell type(s) before they can be
used clinically.
2. Recently, abnormalities in chromosome
number and structure were found in three
human ESC lines.
3. Stem cell development or proliferation
must be controlled once placed into
patients.
4. Possibility of rejection of stem cell
transplants as foreign tissues is very high.
5. Contamination by viruses, bacteria, fungi, and
Mycoplasma possible.
6. The use of mouse “feeder” cells to grow ESC
could result in problems due to
xenotransplantation.

19. UNKNOWNS IN STEM CELL/CLONING RESEARCH
• It is uncertain that human embryonic stem
cells in vitro can give rise to all the different
cell types of the adult body.
• It is unknown if stem cells cultured in vitro
(apart from the embryo) will function as the
cells do when they are part of the developing
embryo

20. REFERENCES
 www.stemcellcentre.edu.au
 www.stemcellchannel.com.au