Stem Cell Notes

IB Biology HL 1Mrs. PetersFall 2014

What we know…

•Organisms can be unicellular (bacteria) or multicellular (plants and animals)

•Cells can function on their own or together forming tissue, organs, organ systems and organisms.

U6. Differentiation

•The process of becoming a specialized cell

•Muscle Cells

•Nerve Cells

•Liver Cells

•The process can not be reversed; specialized cells can’t become unspecialized.

•All cells can differentiate to form the different types of cells in an organism, all have the same DNA, just certain genes are turned on to designate specific function

U4. Emergent Properties

•Cell differentiation allows for emergent properties in multicellular organisms

•Different cell types interact to allow more complex functions to take place.

•Ex: Nerve cells interact with muscle cells to stimulate movement.

U7. What are Stem Cells?

•Stem cells: cells which have not differentiated

•They have not been assigned a specific job in the organism.

www.nas-sites.org

U7. What are Stem Cells?

•Stem Cell Characteristics:• Unspecialized

• Divide repeatedly to make large numbers of new cells

• Have a large nucleus relative to the volume of the cytoplasm

www.nas-sites.org

U7. Stages of Stem Cells

•Totipotent: (total) able to make any body cell or placenta (only from very early cells of embryo, up to 3 days)

www.patentbaristas.com

U7. Stages of Stem Cells

•Pluripotent: able to make any body cell (from day 3 to 14 of an embryo)

• Also referred to as Embryonic Stem Cells

www.patentbaristas.com

U7. Stages of Stem Cells

•Multipotent: able to make a range of cells within a particular tissue type (after day 14 of an embryo)

• Differentiation determined by age of the cell

www.patentbaristas.com

A4. Where are Stem Cells found?

•Embryonic: from donated fertilized eggs (IVF) or donated eggs fertilized by researchers; or products of somatic cell nuclear transfer (genetically identical to donor nucleus)

www.en.wikipedia.org

A4. Where are Stem Cells found?

•Embryonic:

• pluripotent cells

• can become most cells and tissues of the body

• easier to culture in lab

• great potential for developing future therapies to cure diseases

• potentially ethically problematic

www.en.wikipedia.org

A4. Where are Stem Cells found?

•Adult: often from tissues or organs; can be from cord blood or bone marrow

•

multipotent cells

•

hard to culture in lab

•

Not as ethically problematic

www.stemcells.nih.gov

A4. Therapeutic Uses of Stem Cells

www.en.wikipedia.org

A4. Therapeutic Uses of Stem Cells

www.stemcellsforhope.com

How do we get stem cells?

•In Vitro Fertilization (IVF)

•Therapeutic Cloning

•Bone Marrow Transplant

•Umbilical Cord Blood

A 4. Theraputic Uses: Stargardt’s Disease

Stargardt’s Disease: an eye condition that leads to blindness

• Found by Karl Stargardt in 1901

•an inherited condition which starts in childhood leads to macular degeneration

• A gradual destruction of the cells in the center of the retina and eventually causes blindness

• Retina: a layer of photoreceptor cells

• function: to receive light focused from the lens, converts it to neural signals and sends signals to the brain;

The Eye

A 4. Theraputic Uses: Stargardt’s Disease

Retinal cells can be made from embryonic stem cells

2012: the first patient was given a retinal cell transplant

•Cells were injected directly into the retina

• the cells survived and increased in number over a 3 month time period.

•The cells developed visual pigments and the patient noticed improvements in vision

A 4. Ethical Issues involved

• Stem cell investigations and cloning began in the 1980’s

• Early research focused on embryonic stem cells which were acquired from discarded IVF clinics

• Debates around the moral implications of destroying embryos for science

• Is it justified if the contribution to science and the treatment of disease is significant to human survival?

Adult stem cells are less contriversial because the cells are obtained from bone marrow or other tissues which are donated

A 4. Ethical Issues involved

Adult stem cells are less controversial

•the cells are obtained from bone marrow or other tissues which are donated

•Cells can be harvested and grown without destruction of a person.

A 4. Internationalism Aspects of Stem Cell Research

European Union: research using human embryos is permitted in some countries

•It is illegal in Germany, Ireland, Italy, Portugal, and Austria

Australia: permits research

New Zealand: restricts research

US: depends on the state, some ban research on stem cells

BIG Picture

• Stem Cells have the capacity to divide (and remain undifferentiated)

• Stem Cells have the ability to differentiate along different pathways