4. 1998 - Researchers first extract stem cells from human
1999 - First Successful human transplant of insulin-making cells
2001 - President Bush restricts federal funding for embryonic
2002 - Juvenile Diabetes Research Foundation International
creates $20 million fund-raising effort to support stem-cell
2002 - California ok stem cell research
2004 - Harvard researchers grow stem cells from embryos
using private funding
2004 - Ballot measure for $3 Billion bond for stem cells
Stem Cell HistoryStem Cell History
5. Stem Cell – DefinitionStem Cell – Definition
• A cell that has the ability to
continuously divide and
differentiate (develop) into various
other kind(s) of cells/tissues
6. Stem Cell CharacteristicsStem 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
7. Kinds of Stem CellsKinds of Stem Cells
Embryonic stEm cElls
• five to six-day-old embryo
They have the ability to form virtually any type of
cell found in the human body.
Adult stEm cElls
• undifferentiated cells found among specialized or
differentiated cells in a tissue or organ after birth
• appear to have a more restricted ability to produce
different cell types and to self-renew.
8. Kinds of Stem CellsKinds of Stem Cells
Stem cellStem cell
typetype DescriptionDescription ExamplesExamples
Each cell can developEach cell can develop
into a new individualinto a new individual
Cells from early (1-Cells from early (1-
3 days) embryos3 days) embryos
Cells can form any (overCells can form any (over
200) cell types200) cell types
Some cells ofSome cells of
blastocyst (5 to 7blastocyst (5 to 7
15. Type I DiabetesType I Diabetes
• Pancreatic cells do not produce
• Embryonic Stems Cells might be
trained to become pancreatic islets
cells needed to secrete insulin.
16. • Skin
• Fat Cells
• Bone marrow
• Many other organs
Adult Stem CellsAdult Stem Cells
An undifferentiated cells found among
specialized or differentiated cells in a tissue
or organ after birth
19. Bone MarrowBone Marrow
• Found in spongy bone where blood cells form
• Used to replace damaged or destroyed bone marrow with
healthy bone marrow stem cells.
• treat patients diagnosed with leukemia, aplastic anemia, and
• Need a greater histological immunocompatibility
20. Umbilical cord stem cellsUmbilical cord stem cells
• Also Known as Wharton’s Jelly
• Adult stem cells of infant origin
• Less invasive than bone marrow
• Greater compatibility
• Less expensive
21. Umbilical cord stem cellsUmbilical cord stem cells
>Three important functions:
1.Plasticity: Potential to change
into other cell types like nerve cells
2.Homing: To travel to the site of
3.EngraftmEnt: To unite with
25. Heart DiseaseHeart Disease
• Adult bone marrow stem cells
injected into the hearts are believed
to improve cardiac function in
victims of heart failure or heart
27. Leukemia and CancerLeukemia and Cancer
• Studies show leukemia patients
treated with stem cells emerge free
• Injections of stem cells have also
reduces pancreatic cancers in some
Proliferation of white cells
32. Many important questions about adult stem cells remain to be
How many kinds of adult stem cells exist, and in which tissues
do they exist?
Why do stem cells remain in an undifferentiated state when all
the cells around them have differentiated?
What are the factors that stimulate stem cells to relocate to
sites of injury or damage, and how can this process be
enhanced for better healing?
33. Why is Stem Cell Research SoWhy is Stem Cell Research So
Important to All of Us?Important to All of Us?
Stem cells can replace diseased or
Stem cells allow us to study
development and genetics
Stem cells can be used to test different
substances (drugs and chemicals)
34. Why the Controversy Over StemWhy the Controversy Over Stem
• Embryonic Stem cells are derived from extra
blastocysts that would otherwise be discarded
• Extracting stem cells destroys the developing
-Questions for Consideration-
• Is an embryo a person?
• Is it morally acceptable to use embryos for
• When do we become “human beings?”
Stem cells are different from other cells of the body in that they have the ability to differentiate into other cell/tissue types. This ability allows them to replace cells that have died. With this ability, they have been used to replace defective cells/tissues in patients who have certain diseases or defects.
Common variants, called polymorphisms, occur at greater than 1% frequency
I have given some examples of how exposure induced risk is modified in various ways
Typically the effects are modest in magnitude.
We are interested in how genetics modifies Exposure and exposure-related diseases Because…..
Stem cells can be classified into three broad categories, based on their ability to differentiate. Totipotent stem cells are found only in early embryos. Each cell can form a complete organism (e.g., identical twins). Pluripotent stem cells exist in the undifferentiated inner cell mass of the blastocyst and can form any of the over 200 different cell types found in the body. Multipotent stem cells are derived from fetal tissue, cord blood and adult stem cells. Although their ability to differentiate is more limited than pluripotent stem cells, they already have a track record of success in cell-based therapies. Here is a current list of the sources of stem cells:
Embryonic stem cells - are harvested from the inner cell mass of the blastocyst seven to ten days after fertilization.
Fetal stem cells - are taken from the germline tissues that will make up the gonads of aborted fetuses.
Umbilical cord stem cells - Umbilical cord blood contains stem cells similar to those found in bone marrow.
Placenta derived stem cells - up to ten times as many stem cells can be harvested from a placenta as from cord blood.
Adult stem cells - Many adult tissues contain stem cells that can be isolated.
Every cell contains a complete copy of “the blueprint of life”
DNA consists of two strands of nucleotides - 4 bases (A,G,T,C)
23 pairs of chromosomes
If unwound and tied together, human DNA in one cell would stretch ~ 5 feet, but would be only 50 trillionths of an inch wide!
Genes are specific sequences of DNA, each of which “codes” for a protein with a specific function
Genes are copied each time a cell divides, passing on the blueprint
1990s that scientists agreed that the adult brain does contain stem cells that are able to generate the brain&apos;s three major cell types—astrocytes and oligodendrocytes, which are non-neuronal cells, and neurons, or nerve cells.
A. Where are adult stem cells found, and what do they normally do?
Adult stem cells have been identified in many organs and tissues, including brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, teeth, heart, gut, liver, ovarian epithelium, and testis. They are thought to reside in a specific area of each tissue (called a &quot;stem cell niche&quot;). In many tissues, current evidence suggests that some types of stem cells are pericytes, cells that compose the outermost layer of small blood vessels. Stem cells may remain quiescent (non-dividing) for long periods of time until they are activated by a normal need for more cells to maintain tissues, or by disease or tissue injury.
Typically, there is a very small number of stem cells in each tissue, and once removed from the body, their capacity to divide is limited, making generation of large quantities of stem cells difficult. Scientists in many laboratories are trying to find better ways to grow large quantities of adult stem cells in cell culture and to manipulate them to generate specific cell types so they can be used to treat injury or disease. Some examples of potential treatments include regenerating bone using cells derived from bone marrow stroma, developing insulin-producing cells for type 1 diabetes, and repairing damaged heart muscle following a heart attack with cardiac muscle cells.
B. What tests are used for identifying adult stem cells?
Scientists often use one or more of the following methods to identify adult stem cells: (1) label the cells in a living tissue with molecular markers and then determine the specialized cell types they generate; (2) remove the cells from a living animal, label them in cell culture, and transplant them back into another animal to determine whether the cells replace (or &quot;repopulate&quot;) their tissue of origin.
Importantly, it must be demonstrated that a single adult stem cell can generate a line of genetically identical cells that then gives rise to all the appropriate differentiated cell types of the tissue. To confirm experimentally that a putative adult stem cell is indeed a stem cell, scientists tend to show either that the cell can give rise to these genetically identical cells in culture, and/or that a purified population of these candidate stem cells can repopulate or reform the tissue after transplant into an animal.
Adult stem cells are found all over your body. Here are a few examples of places in the body with stem cells.
Who here has been told that brain cells never regenerate? (hands) Whoever told you that was misinformed! Relatively recently scientists discovered that in two specific parts of your brain, neural stem cells divide and differentiate to become neurons and glial cells, which support the growth of neurons. Without neural stem cells in the hippocampus, you would probably not be able to learn or remember.
The top right picture is a cross-section of the rat hippocampus, and neural stem cells are the blue dots, which divide and differentiate to form mature neurons (green) and astrocytes (red).
The bottom right picture is of cultured neural stem cells (just plain blue dots), and derived from those stem cells, neurons (blue dots surrounded by red) and oligodendrocytes (blue dots surrounded by green).