Exam 4: Stem Cells

How tissues maintain organization

cell communication (what is going on around me?)

selective cell-cell adhesion (who are my neighbors?)

Cell memory (who am I? what is my job? who do I turn into?)

Characteristics of stem cells

They can turn into whatever they want

infinite replication

can be used in therapeutic treatments

low abundance

undifferentiated

slow growing

more motile than other cell types

what signals stem cell transitions into differentiated cells

soluble signals (hormones)

Matrix (what am I sitting on?)

induce genetic reprogramming

multipotent stem cells

can make some (maybe even many) cell types but not all

pluripotent stem cells

can make any cell type within the embryo itself

totipotent stem cells

can make all cells in a developing embryo and extra-embryonic tissue

example of multipotent stem cells

hemopoietic stem cells; they can make any cell type found in blood: T and B lymphocytes, red blood cells, and white blood cells

when did researchers learn how to grow mouse embryonic stem cells? Human?

1981 mice; 1998 human

pros and cons of cloned embryonic stem cells

pros: can make anything, no transplant rejection because they come from host, species diversity (resurrecting extinct species), replace damaged tissue

Cons: ethics, environmental influence still matters in the growth of clones, stem cells can create tumors, shorter telomeres

inductible pluripotent stem cells (iPSCs)

addition of stem cell forming genes to change an adult cell into a stem cell; transcription factors intended on maintaining embryonic state (activates the programming)

pros and cons of iPSCs

pros: no human embryo distruction, still have all possible cell types, can study rare diseases

Cons: tumor potential, affects of genetic modification, “off targeting”- manipulating DNA may not always go to the place you intended