CELLULAR DIVISION Stem Cells What Are Stem Cells

CELLULAR DIVISION Stem Cells

What Are Stem Cells? �Stem cells are the source, or “stem”, for all of the specialized cells that form our organs and tissues. �Your body contains over 200 types of cells �blood cells carry oxygen �muscle cells contract so that you can move �nerve cells transmit chemical signals �The job of a stem cell is to make new cells.

HOW? �It does this by undergoing an amazing process differentiating, or changing into another type of cell. �Each time a stem cell divides, one of the new cells might remain a stem cell while the other turns into a heart, blood, brain, or other type of cell. �In fact, stem cells are able to divide to replenish themselves and other cells without any apparent limit.

Stem Cell History �Scientists discovered ways to derive embryonic stem cells from early mouse embryos more than 30 years ago, in 1981. �In 1998 the detailed study of the biology of mouse stem cells led to the discovery of a method to derive stem cells from human embryos and grow the cells in the laboratory.

Stem Cells

Types of Stem Cells �There are many kinds of stem cells, but two types have made frequent appearances in the news: �embryonic stem cells (ES) �somatic stem cells (adult stem cells)

Embryonic Stem Cells �present in very early—and very tiny— embryos �produce the first cells of the heart, brain, and other organs. �have the potential to form just about any other cell in the body.

Zygote - (fertilization took place)

Early Cell Division Source: Florida Institute for Reproductive Science and Technologies

Four-cell stage 2 days after fertilization Source: Florida Institute for Reproductive Science and Technologies

Eight-cell stage 3 days after fertilization Courtesy: RWJMS IVF Program Source: Florida Institute for Reproductive Science and Technologies

Morula (ball of cells) 4 days after fertilization 16 cells Source: Florida Institute for Reproductive Science and Technologies

Blastula (earliest stage of embryo) 5 days after fertilization Source: Florida Institute for Reproductive Science and Technologies Courtesy: RWJMS IVF Program

Blastula (Blastocyst) (hollow ball of cells making embryo) This image has been released into the public domain.

Adult Stem Cells �Adult stem cells can replenish some tissues lost through normal wear and tear or injury. �However, adult stem cells are only able to generate a few specific cell types. �adult stem cells in bone marrow, for example, make new blood cells, �adult stem cells in the skin make the cells that replenish layers of the skin.

Types of Stem Cells

�Totipotent stem cells �one of the most important stem cells types because they have the potential to develop into any cell found in the human body �“whole” �Pluripotent stem cells �which can go on to specialize further but can't ever produce an entire organism. �“many”

�Multipotent Stem Cells �Develop multiple, organ specific cell types. �“several” �Unipotent stem cells �a cell that can differentiate along only one lineage. �the word 'uni' itself is derived from the Latin word 'unus, ' meaning one. �found in adult tissues �has the capacity to differentiate into only one type of cell or tissue

Induced Pluripotent Stem Cells �Induced pluripotent stem (i. PS) cells are created artificially in the lab by "reprogramming" a patient's own cells. �i. PS cells can be made from readily available cells including fat, skin, and fibroblasts (cells that produce connective tissue).

• Since i. PS cells can be made from a patient's own cells, there is no danger that their immune system will reject them. • i. PS cells are much less expensive to create than ES • However, because the "reprogramming" process introduces genetic modifications, the safety of using i. PS cells in patients is uncertain.

Stem Cells: Cells With Potential

Where are Stem Cells Located? �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 � testis.

Cord blood �Once discarded as medical waste, cord blood is the small volume of blood that’s left in the umbilical cord after birth. �rich sources of stem cells in the body, due to the type of stem cells it contains �has long been used in the treatment of many blood diseases, including anemia, leukemia, myelodysplasia, and lymphoma. �$3000 upfront $150/year

Teeth �In the early 2000 s, around 20 years after they were discovered in umbilical cord blood, stem cells were found in our teeth.

Save a Tooth Upfront Cost Annual Cost Store – A - Tooth $1, 749 $120 The Tooth Bank $475 $115 Stem Save $630 $120

Why Important �Stem cells represent an exciting area in medicine because of their potential to regenerate and repair damaged tissue. �Some current therapies, such as bone marrow transplantation, already make use of stem cells and their potential for regeneration of damaged tissues.

Potential Treatments Include: �regenerating bone using cells derived from bone marrow stroma �developing insulin-producing cells for type 1 diabetes �repairing damaged heart muscle following a heart attack with cardiac muscle cells.

Stem Cell Story Stem Cell Medicine Stem Cell Heart

Stem Cell Quiz

Stem Cells �Private Funding �Public Funding

Parents have babies by means of in vitro fertilization. �After the fertilized eggs were examined, the best ones were implanted and the babies were born. �What should become of the other fertilized eggs. �Annual cost to “keep the others frozen” is $500 annually.

Ethics �Until recently, the only way to get pluripotent stem cells for research was to remove the inner cell mass of an embryo and put it in a dish. The thought of destroying a human embryo can be unsettling, even if it is only five days old.

Ethics �Stem cell research thus raised difficult questions: �Does life begin at fertilization, in the womb, or at birth? �Is a human embryo equivalent to a human child? �Does a human embryo have any rights? �Might the destruction of a single embryo be justified if it provides a cure for a countless number of patients? �Since ES cells can grow indefinitely in a dish and can, in theory, still grow into a human being, is the embryo really destroyed?

One Families Dilemma