CSB329H1 Lecture Notes - Lecture 1: Fibroblast, Heterochromatin, Euchromatin
9 May 2018
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Lecture 1(a): Introduction to Stem Cells
Cell Potency:
• Potency is the number of possible fates available to a cell
o “Potent” = having the power to achieve a certain fate
§ Few cells (i.e. blood stem cells); their potency decreases with age
Fertilized Eggs:
• First few cells making up the zygote in the morula stage
o Cells are known to being totipotent
§ Capable of reproducing the entire organism
• During the blastocyst stage, within them are inner mass
cells which are the source of embryonic stem cells
o Cells are known to being pluripotent
§ Can no longer reproduce an entire organism
but are capable of producing various cell
types (i.e. cardiac, nervous, immune cells)
• Afterwards, specific cell types (i.e. skin cells) are known to being unipotent
o Have ‘cell-cell character’ and are very limited to what type of cells they can give rise to
ð Normal development and tissue homeostasis and regeneration are dependent on stem cells
o ‘aka’ the survival of multicellular organisms are dependent on stem cells
Degrees of Potency:
a) Totipotent:
o Capable of generating new embryos
§ Zygote in mammals; remain totipotent until the morula stage (16 cell stage)
§ In mice, both cells of a two stage embryo are NOT totipotent
b) Pluripotent:
o Completely undifferentiated master cells that can make any tissue/cell in the body
i. Inner Cell Mass (ICM) of Blastocyst:
§ Regenerate the embryo - can make cells for all three basic layers, but
not the placenta; (greater than 200 different cell types)
ii. Induced Pluripotent Stem Cells (iPSCs)
§ Derived from a non-pluripotent stem cells; typically derived from an adult
somatic cell – reprogramed to acquire stem-like properties
c) Multipotent:
o More limited than pluripotent stem cells
i. Hematopoietic Stem Cells (HSCs):
§ Multipotent – give rise to all blood and immune cells
ii. Mesenchymal Stem Cells:
§ Multipotent – give rise to bone, cartilage and other connective tissue
Document Summary
Lecture 1(a): introduction to stem cells: potency is the number of possible fates available to a cell, potent = having the power to achieve a certain fate. Few cells (i. e. blood stem cells); their potency decreases with age. Fertilized eggs: first few cells making up the zygote in the morula stage, cells are known to being totipotent. Capable of reproducing the entire organism: during the blastocyst stage, within them are inner mass cells which are the source of embryonic stem cells, cells are known to being pluripotent. Normal development and tissue homeostasis and regeneration are dependent on stem cells. Aka" the survival of multicellular organisms are dependent on stem cells. Degrees of potency: totipotent, capable of generating new embryos. Zygote in mammals; remain totipotent until the morula stage (16 cell stage) In mice, both cells of a two stage embryo are not totipotent: pluripotent, completely undifferentiated master cells that can make any tissue/cell in the body.
