Lecture 15 - Stem Cells: Basic Concepts Flashcards
Develpoment from blastocyst involves a series of fate choices, what does the epiblast give rise to?
The 3 germ layers:
Endoderm
mesoderm
ectoderm
Determination and differentiation results not from changes in genes, but…
changes in gene expression (exception being immune system and gametes)
What makes this change in gene expression?
alterations in chromatin structure and transcription factor expression
Often quite permanent and heritable through many cell divisions
Determination occurs prior to overt…
differentiation - heritable change in a cell’s developmental potential -operationally defined
cells don’t LOOK like the cells they will become, but have made the decision to do so
What is differentiation?
results of the change in gene expression
cells acquires correct shape polarity, orientation with respect to neighbour, appropriate organelles and proteins which enable it to carry out metabolic signalling, transport or contractile signalling, transport or contractile functions required in a partilcular tissue3
What is transdifferentiation?
cell normally committed to one lineage is switched to a different lineage pathway
Many known examples from disease states - intetinal metaplasis of the esophagus
May be induced experimentally by ectopic expression of master regulator transcription factors
Describe Intestinal metaplasia, and how it is caused?
What can it lead to?
Damage to esophageal epithelium through acid reflux from the stomach leads to conversion of squamous epithelium into intestine
The condition is a precurosor to esophageal adenocarcinoma
Define a multipotent cell
cell that can give rise to several types of mature cells - not that many, limited.
Define a pluripotent cell
Cell that can give rise to ALL types of adult tissue cells plus extraembryonic tissue: cells which support embryonic development
Define a totipotent cell
cell that can give rise to a new individual given appropriate maternal support - Restricted to the blastomeres; the early cells of the embryo
What are the different types of adult tissue, with respect to renewal?
continuously renewing - bone marrow, skin, gut
Conditionally renewing - liver, kidney
Non renewing - cardiac muscle
We lose __ billion cells per day
20 billion
The lining of the intestineis replaced every 4 days
every 4 weeks a completely new epidermis is generated
some tissues turn over slowly, e.g?
hepatocytes live for 300 days, cardiomyocytes 0.5% annually
One blood stem cell gives rise to…
red cells, white cells and platelets
Stem cells may give rise to transit amplifying cell compartment, what is this?
group of commited cells with limited division capacity
Stem cells are often lacking in ____ _____
specialised organelles, and show high nucleus/cytoplasm ration