STEM STEM CELLSCELLS

By: Harsukh B, Ritu P, Yuchi W, Faiza J, Jathuson J By: Harsukh B, Ritu P, Yuchi W, Faiza J, Jathuson J

Biological Background Technology Used in the Process Ethical and Social Issues Political Issues Economic Issues Current Medical Use Future Vision for this Technology

Can divide indefinitely Undifferentiated cells Can transform into any type of body cell Contain the enzyme telomerase—which

allows cells to grow and proliferate There are two types of stem cells:

Human Embryonic Stem CellsAdult Embryonic Stem Cells

Able to continue dividing indefinitely without losing their genetic structure

Can be manipulated without losing cell function

Cells are pluripotent: able to differentiate into all the 220 cell types in the adult body.

In the In vitro fertilization the embryos not used for fertilization are frozen and are used for this research

Come from embryos that are in blatocyst stage A stage where a pair of stem cells are grouped

together which later differentiate to form the human.

Are derived from the epiblast tissue of the inner cell mass (ICM) of a blastocyst

Scientist can then form cell lines: a stock of living embryonic stem cells without always having to obtain them from a human embryo because they reproduce into identical daughter cells under ideal conditions

Scientists remove the pluripotent cells using a pipette and transfer them into a Petri dish in a lab

Human Embryonic Stem cells are grown on a feeder layer of mouse embryonic fibroblasts and require the presence of basic Fibroblast Growth Factor

Scientists add various chemicals to direct the growth of the cellsEmbryonic Stem cells, being pluripotent

cells, require specific signals for correct differentiation or they differentiate into all the different types of body cells

IssuesIssues If injected directly into another body, Embryonic Stem

cells will differentiate into many different types of cells, causing a teratoma.

Every time Embryonic Stem cells are transplanted they have a different genetic background than the patient- can lead to rejection of the cells

Bacteria Infested CellBacteria Infested Cell

Properties of Adult Stem Properties of Adult Stem CellsCellsAKA Somatic Stem CellsAKA Somatic Stem Cells

Undifferentiated cells found among differentiated cells in a tissue Role: to maintain and repair the tissue in which

they are found May remain undifferentiated until needed Not many of them in a tissue Different types: hematopetic stem cells(give rise to blood cells) and mesenchymal stem cells(give rise to bone, cartilage, fat cells)

ReproductionReproduction Can make identical copies of themselves as

long as the person is alive Produce a intermediary cell called a

precursor cell which matures into the copy of the Adult Embryonic stem Cell

Research suggests that these cells do not particularly differentiate into the organ they are set, they can divide into many other types of cells this process is known as plasticity Ex. Bone stem cells can differentiate into liver

cell

BenefitsBenefits They avoid the rejection of stem cells from

transplantation because they are generated from the same individuals body

Successful in treating leukemia and related bone/blood cancers through bone marrow transplants

Used in veterinary medicine to treat tendon and ligament injuries in horses

IssuesIssues Harder for scientists to manipulate them with

different chemicals Hard to find one undifferentiated stem cell

amongst billions of differentiated cells Grow slowly and have a limited life span

when grown in an in vitro in a lab

How do How do ALLALL the stem cells the stem cells differentiate?differentiate? Internal signals which are controlled by cell

genes External signals:

Chemicals secreted by other cells Physical contact with neighboring cells

Technology Used in the Technology Used in the ProcessProcess