Stem Cell Research

Types of Stem Cells Embryonic Stem Cells – from embryos (fertilized egg cell) Embryonic Stem Cells – from embryos (fertilized egg cell) Adult Stem Cells – from mature cells, don’t have to be from an adult; also called Somatic Stem Cells Adult Stem Cells – from mature cells, don’t have to be from an adult; also called Somatic Stem Cells Umbilical cord blood – not commonly used yet Umbilical cord blood – not commonly used yet

What are stem cells? Stem cells - cells that perform mitosis to create cells that can differentiate to become any type of cell within the body. differentiate – become specialized cells Most cells that divide create the same type of cell. (Liver cells produce liver cells, skin cells produce skin cells.) Stem cells are not specialized, so they can create a wide variety of cell types.

What are stem cells? What are stem cells? What are the three types of stem cells? What are the three types of stem cells? What does differentiate mean? What does differentiate mean?

Totipotent – have the ability to create all types of cells in the body, including the placenta

Pluripotent – have the ability to create almost any type of body cell (embryonic cells begin to lose this ability after a few days)

Multipotent - can produce several similar types of cells Multipotent - can produce several similar types of cells For example: hematopoetic stem cells can produce the different types of blood cells, but not skin cells Oligopotent – can produce only a few types of cells Oligopotent – can produce only a few types of cells

What does pluripotent mean? What does pluripotent mean? Why are embryonic stem cells easier to use than adult stem cells? Why are embryonic stem cells easier to use than adult stem cells?

What happens to the embryo? Removing stem cells from an embryo kills the embryo. (An embryo can’t survive when these cells are removed, but these cells can survive in a petri dish.)

Here is where the controversy begins: Essentially we are killing these embryos to use for research. Where do we get embryos to use for cells? Currently, these embryos are left over from fertility clinics; the embryos that aren’t used are saved, and eventually destroyed. Scientists instead use them for stem cell research. Currently, these embryos are left over from fertility clinics; the embryos that aren’t used are saved, and eventually destroyed. Scientists instead use them for stem cell research. Unfortunately, the left over embryos are often left over because they aren’t as strong as other embryos that are produced (not the best choice for treating diseases if they are weak to start out). Unfortunately, the left over embryos are often left over because they aren’t as strong as other embryos that are produced (not the best choice for treating diseases if they are weak to start out). There also aren’t enough left over embryonic stem cells to do all of the research that scientists want to do. There also aren’t enough left over embryonic stem cells to do all of the research that scientists want to do.

The solution to this problem is to create embryos to use for this process. The solution to this problem is to create embryos to use for this process. What problem do you see in this solution?

Why are embryonic stem cells controversial? (Remember, to be controversial, there must be a positive side and a negative side, otherwise no one would argue about it.) Why are embryonic stem cells controversial? (Remember, to be controversial, there must be a positive side and a negative side, otherwise no one would argue about it.)

Another problem Embryonic stem cells still have the ability to become nearly all types of cells. Researchers don’t know how to direct them perfectly. When implanted, they can continue to differentiate into different cell types creating a teratoma (tumor).

Adult Stem Cells Adult stem cells - found in various parts of the body; their job is to repair damaged tissue. New research: Scientists have found a way to make adult stem cells act like embryonic stem cells. These are called iPS cells – induced pluripotent stem cells. The most recent research has even created iPS cells from body cells.

Benefits Adult stem cells work almost as well as embryonic stem cells and can be harvested without harm. If you are given your own stem cells, the body is less likely to reject the cells. (Embryonic cells are foreign, the immune system may fight them like a disease.)

Problems The genes that are used to turn adult stem cells into embryonic stem cells are also oncogenes – they can cause cancer. It is more difficult to create iPS cells than embryonic stem cells. Scientists are only able to make these cells behave like embryos, they still have all of the errors in their DNA that adult cells have picked up as they have aged.