Stem Cells The process of cell differentiation A

Stem Cells The process of cell differentiation A primary goal of research on embryonic stem cells is to learn how undifferentiated stem cells turn into differentiated stem cells that form specific tissues and organs. Researchers are also interested in figuring out how to control this process of differentiation.

What is a Stem Cell? • A cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues • 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.

Stem Cell Applications • Tissue repair § nerve, heart, muscle, organ, skin § Regenerate spinal cord, heart tissue or any other major tissue in the body. • Cancers § Studies show leukemia patients treated with stem cells emerge free of disease § Injections of stem cells have also reduces pancreatic cancers in some patients. • Autoimmune diseases § diabetes, rheumatoid arthritis, MS

Kinds of Stem Cells Stem cell type Totipotent Pluripotent Multipotent Description Each cell can develop into a new individual Examples Cells from early (13 days) embryos Some cells of Cells can form any (over blastocyst (5 to 14 200) cell types days) Cells differentiated, but Fetal tissue, cord can form a number of blood, and adult other tissues stem cells

Embryonic Stem cells are obtained from In-Vitro Fertilization embryos that were not used - http: //www. news. wisc. edu/packages/stemcells/illustration. html Illustration by Matt Bohan, 2007

This cell Can form the Embryo and placenta This cell Can just form the embryo Totipotent Pluripotent Fully mature

Adult Stem Cells An undifferentiated cells found among specialized or differentiated cells in a tissue or organ after birth • • • Skin Fat Cells Bone marrow Brain Many other organs & tissues

STEM CELLS HAVE ALSO BEEN FOUND IN “MATURE” ORGANS Illustration by Matt Bohan, 2007

Differences between embryonic stem cells and adult/somatic stem cells • They have different self-renewal capabilities – Embryonic stem cells: near indefinite self-renewal – Adult stem cells: limited self-renewal • They have differentiation potentials –. Embryonic stem cells: differentiate into all cell types in an organism – Adult stem cells: differentiate into restricted cells types. • They differ in how they respond to external stimuli – Embryonic stem cells are readily to change upon stimulation – Adult cells emphasize on stability and need to be activated by cues, e. g. injuries.

PROS AND CONS OF EACH TYPE • EMBRYONIC – CELL LINES LAST AND LAST – Pluripotent and totipotent in an early embryonic stage – EASY TO FIND – ETHICAL ISSUES • ADULT – CELL LINES DO NOT LAST – MULTIPOTENT – HARD TO LOCATE – NO ETHICAL ISSUES

Why the Controversy Over Stem cells? • • Embryonic Stem cells are derived from extra blastocysts that would otherwise be discarded following IVF( in vitro fertilisation) Extracting stem cells destroys the developing blastocyst (embryo). -Questions for Consideration. Is an embryo a person? Is it morally acceptable to use embryos for research?

Current medical application of human stem cell research -Grow new cells in a laboratory to replace damaged organs or tissues -Correct parts of organs that don’t work properly -Research causes of genetic defects in cells -Research how diseases occur or why certain cells develop into cancer cells -Test new drugs for safety and effectiveness - Bone marrow transplantation

Cord blood stem cells and amniotic fluid stem cells Cord blood stem cells are harvested from the umbilical cord after childbirth. They can be frozen in cell banks for use in the future. These cells have been successfully used to treat children with blood cancers, such as leukemia, and certain genetic blood disorders.

Dolly the Sheep. Dolly (July 5, 1996 - February 14, 2003), a ewe, was the first mammal to have been successfully cloned from an adult cell. She was cloned at the. Roslin Institute in Midlothian, Scotland, and lived there until her death when she was six years old