CSB329H1 Lecture Notes - Lecture 1: Degenerative Disease, Hepatocyte, Flow Cytometry
9 May 2018
School
Department
Course
Professor
Mouse Interfollicular Epidermis
Lecture 1(b): Introduction to Stem Cells
Question:
• Stem cells are present at very low levels; how can we separate them from other cells?
Florescence-Activated Cell Sorting (FACS):
• Specialized form of flow cytometry that enables us to separated
cells from a mixed population based on fluorescent labeling
(even for cells present in low levels, i.e. stem cells)
o Fluorescently labeling cells that express a specific
marker will allow us to separate them from other cells
that do not express that marker
Experiment:
• Mixed population of cells: some cells express CFP and some express GFP
o Therefore, certain cells will have specific and unique markers on their cell surface
• Mass of cells will move through an instrument and are individually interrogated by a laser light
o Cells will be separated into individual droplets by a vibrating mechanism and given
an electronic charge DEPENDING on the fluorescence of the cell
§ Separates cells with different fluorescence but also separates defective cells
Stem Cell Niche:
• Stem cells are not specified, undifferentiated and can remain quiescent until they are recruited
o Can be found in very distinctive locations
i.e. Intestinal Stem Cells
• For stem cells to maintain their niche viability they are required to maintain in
association with their extracellular matrix
o Basal lamina (form of specialized ECM) is found wherever we see an
epithelial sheet that contains stem cell populations
§ Basal surface of the epithelia is always in contact with the basal lamina
ð IF basal lamina is removed; the stem cell will no longer contain epithelial character
o Microenvironments play an essential role to stem cells
§ Stem cells cannot retain their stem-like prosperities without communication
with their extracellular matrix molecules
i.e. Epidermal Stem Cells
• Epidermal stem cells have a basal layer which
is in direct contact with the basal lamina
o Depending on the complexity of the
epidermis, stem cells will undergo
differentiation and begin to move up to
form new epidermal cells
ð A differentiated epidermal (skin) cell was reprogrammed to become embryonic-like stem cell
o Took them “back in time” in terms of potency to be used in tissue regeneration
Document Summary
Separates cells with different fluorescence but also separates defective cells. Basal surface of the epithelia is always in contact with the basal lamina. If basal lamina is removed; the stem cell will no longer contain epithelial character: microenvironments play an essential role to stem cells. A differentiated epidermal (skin) cell was reprogrammed to become embryonic-like stem cell: took them back in time in terms of potency to be used in tissue regeneration, human epidermal layer are different than mice. Consists of more layers | molecular design contains some similarities. Mouse skin can be used as a model for wound repair and can be translated to human stem cells. Cell transmembrane receptors that bind to skin extra cellular molecules are integrins. Human interfollicular epidermis: stem cell population can be identified by having integrin subunits; as integrins are a complex family made up alpha and beta subunits.
