STEM CELLSLeah Yang

DEFINITION

• Stem cell: A cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues

RELEVANCE• Stem cells have the ability to

differentiate into other cell/tissue types, which allows them to replace cells that have died.

• They have been used to replace defective cells/tissues in patients who have certain diseases or defects.

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 approves stem cell research • 2004 - Harvard researchers grow stem cells from embryos using private

funding• 2004 - Ballot measure for $3 Billion bond for stem cells

CHARACTERISTICS• 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)

EMBRYONIC STEM CELLS• derived from extra blastocysts

that would otherwise be discarded following IVF

• from five to six-day-old embryos• can also be grown in lab by cell

culture (see next slide)• can proliferate for a year or more

in the laboratory without differentiating

ADULT STEM CELLS• undifferentiated cells found among

specialized or differentiated cells in a tissue or organ after birth

• they have a more restricted ability to produce different cell types and to self-renew (see next slide)

• can be found in many organs and tissues, including the brain and the heart

KINDS

PLURIPOTENT STEM CELLS• pluripotent stem cells have

more potential to become any type of cell

MULTIPOTENT STEM CELLS• multipotent stem cells are more limited in what

they can become

INDUCED PLURIPOTENT STEM CELLS

• IPSCs are adult cells that have been genetically reprogrammed to an embryonic stem cell–like state

APPLICATIONS• tissue repair -nerve, heart,

muscle, organ, skin• cancers• autoimmune diseases• diabetes• rheumatoid arthritis• MS

TISSUES• stem cells can be used to

regenerate spinal cord, heart tissue or any other major tissue in the body

BONE MARROW• adult stem cells help with jumpstarting

repair of eroded cartilage, and can replace damaged/destroyed bone marrow with healthy bone marrow stem cells

HEART DISEASE• adult bone marrow stem cells

injected into the hearts are believed to improve cardiac function in victims of heart failure or heart attack

RISKS• because stem cells injected into a patient are

permanent, long term side effects may not be fully understood for years

• injection of embryonic stem cells may result in minor miscalculations – side effects are endless

• about 20% of rats injected with embryonic stem cells later die from some form of cancerous tumor

IMPORTANCE OF STEM CELL RESEARCH• stem cells can replace diseased or

damaged cells • stem cells can be used to test

different substances (drugs and chemicals)

• scientists can use stem cells to screen new drugs, and develop systems to study growth/identify the causes of birth defects

• stem cells allow us to study development and genetics