Stem Cells Flashcards
Self renewal
ability to copy itself
Potency
ability to change into other types of cells
normal self-renewal
cells can divide a limited number of times
immorality
the ability to self-renew indefinitely
totipotent
can become all cell types including extraembryonic membranes
pluripotent
can become all cells in the adult body
multipotent
can become multiple cell types. Usually from only one germ layer
Differentiation
a change from one cell type to another.
Potency of children
generally decreases as cells differentiate. More developed organisms generally have more differentiated cells.
Stem cell applications
study of developmental processes, tissue engineering
study of developmental processes
zygote is first stem cell. Reveals how cells in body develop
Tissue engineering
formation of engineered tissues. Stem cells can be used to make new tissues. Tissues can be used to replace organs
Embryonic Stem Cells (ESC)
cells are removed from inner cell mass. Kills the blastocyst. Often “extra” embryos from IVF are used. Immortal, pluripotent
Immortality + pluripotency
provides an unlimited cell source, potential therapies for unlimited patients. Provided any cell potential in the body, potential therapies for any part in the body.
Fetal Stem Cells
Sometimes improperly refers to fetal cells that are not stem cells.
Fetal Proper Stem Cells (FpSC)
tissue from fetus proper. Generally obtained after an abortion. References to fetal stem cells that are accurate usually refer to these. Not immortal, but high level of division. Multipotent.
Extrafetal Stem Cells (eFSC)
extraembryonic membranes (umbilical cord, placenta, amniotic fluid, etc.) Often not distinguished from adult stems cells, usually acquired soon after birth, tissue is thrown away, abundant untapped cell source. High level of cell division, pluripotent.
Adult Stem Cells
tissue and fluids from adults or earlier; generally obtained after birth. Not immortal, multipotent.
Induced pluripotent stem cells (iPSC)
a cell from the body that has been “reprogrammed”. Immortal, pluripotent
Advantages of iPSC
All adult cell types, early developmental models, wide support
What definitely produces all adult cell types?
ESCs, iPSCs. Have been directly shown to contribute to all tissues of an organism, confirmed through tetraploid complementation assays
What probably produces all adult cell types?
eFSCs. Can create cells of all three major tissue types. Possess pluripotency markers.
What probably doesn’t produce all adult cell types?
ASCs, FpSCs. May be “pluripotent” as a population. It may be possible to get any cell type if the correct stem cell is used. Individual cells are multipotent. Not all cell types are obtained from a single source.
CIRM
$3,000,000,000 (billion) California tax dollars. Designed to fund embryonic stem cell research.
Early developmental models
some cells can be used to investigate how the body grows/develops before birth. Useful in developmental models: ESCs, FpSCs, eFSs, iPSCs. Can provide cells from relatively early developmental stages. Not useful in developmental models:ASCs.
Wide Support
some people may reject treatments that they have ethical objections to. Are treatments that half of the population would be unconfortable using prudent? Wide support: eFSCs, ASCs, iPSCs. Challenged: ESCs, FpSCs
Significant disadvantages
tumors, immune rejection, pluripotency
tumors
some stem cells form tumors when implanted into the body. Pluripotency is linked to tumor formation.
tumor formation
ESCs, PfSCs, iPSCs. FpSCs from tumors despite multipotency.
no tumors
eFSCs, ASCs. eFSCs avoid tumor creation despite pluripotency.
Immune Rejection
the body attacks non-native cells. Treatments that don’t use the body’s own cells require suppression of the immune system.
Immune rejection
ESCs, FpSCs. Cells must come from a non-native source.
No immune rejection
eFSCs, ASCs, iPSCs. Cells can be taken from patient that they are used to treat. eFSCs and ASCs may not be rejected even if used from a non-native source.
cloning
direct reprogramming is superior to cloning for the purposes of creating patient matched cells. He is abandoning cloning and focusing on direct reprogramming.
problems with pluripotency
makes it difficult to obtain the exact cell type needed. Not all cells in a population differentiate uniformly. Undifferentiated or improperly differentiated cells can create tissues other than the desired type.
Geron
Funded first human embryonic stem cell isolation. Leader in the embryonic stem cell field.
Treatments
what has already helped some patients
Clinical trials
treatments being tested for safety/efficacy
research papers
what has a chance of working in the future. What is being investigated for future applications.
