Stem Cells
SC1. Features of Stem Cells
Undi erentiated and unspecialised cells
• Do not contain any tissue-speci c structures, no specialised functions
Able to di erentiate` into various specialised cell types with specialised functions
upon receiving speci c molecular signals
• Molecular signals will switch some genes on and others o (EG. Transcription
factors, growth factors, hormones)
• Genome of stem cell and specialised cell are the same, di erence is in gene
expression of speci c genes that result in synthesis of tissue-speci c structures
(regulation on the genetic level - DNA methylation, histone deacetylation, chromatin
remodelling complex)
• Regenerates cell lost due to cell death or injury
Capable of self-renewal and extensive proliferation via mitosis
• Symmetrical division: 2 daughter stem cells with the same developmental and
di erential potential as parent cell
• Asymmetrical division: 1 daughter stem cell identical to parent, 1 progenitor daughter
cell that increases or renews population of specialised cells in a speci c tissue
• Can produce telomerase to lengthen telomeres such that with each round of
replication, shortening of telomeres will not erode vital genetic information
Continuous lengthening of telomeres also ensures that telomeres will not reach a
critical length and apoptosis will not occur. Hence, stem cells can proliferate
continuously.
• Regenerates cell lost due to cell death or injury and maintains a constantly pool of
stem cells
SC2. Types of Stem Cells
Type of Cell Characteristics Examples
Totipotent Able to di erentiate into all cell types Zygotic stem cells produced
including the extra-embryonic tissue within the rst 3 divisions after
such as the placenta and can give rise the egg is fertilised
to an entire organism
Pluripotent Able to di erentiate into all cell types Embryonic stem cells from the
except the extra-embryonic tissue inner cell mass of the blastocyst
such as the placenta, unable to form
entire organism alone
Multipotent Able to di erent into several related Haematopoietic/blood stem
cell types but fewer types compared to cells found in the bone marrow,
pluripotent stem cells neural stem cells
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SC1. Features of Stem Cells
Undi erentiated and unspecialised cells
• Do not contain any tissue-speci c structures, no specialised functions
Able to di erentiate` into various specialised cell types with specialised functions
upon receiving speci c molecular signals
• Molecular signals will switch some genes on and others o (EG. Transcription
factors, growth factors, hormones)
• Genome of stem cell and specialised cell are the same, di erence is in gene
expression of speci c genes that result in synthesis of tissue-speci c structures
(regulation on the genetic level - DNA methylation, histone deacetylation, chromatin
remodelling complex)
• Regenerates cell lost due to cell death or injury
Capable of self-renewal and extensive proliferation via mitosis
• Symmetrical division: 2 daughter stem cells with the same developmental and
di erential potential as parent cell
• Asymmetrical division: 1 daughter stem cell identical to parent, 1 progenitor daughter
cell that increases or renews population of specialised cells in a speci c tissue
• Can produce telomerase to lengthen telomeres such that with each round of
replication, shortening of telomeres will not erode vital genetic information
Continuous lengthening of telomeres also ensures that telomeres will not reach a
critical length and apoptosis will not occur. Hence, stem cells can proliferate
continuously.
• Regenerates cell lost due to cell death or injury and maintains a constantly pool of
stem cells
SC2. Types of Stem Cells
Type of Cell Characteristics Examples
Totipotent Able to di erentiate into all cell types Zygotic stem cells produced
including the extra-embryonic tissue within the rst 3 divisions after
such as the placenta and can give rise the egg is fertilised
to an entire organism
Pluripotent Able to di erentiate into all cell types Embryonic stem cells from the
except the extra-embryonic tissue inner cell mass of the blastocyst
such as the placenta, unable to form
entire organism alone
Multipotent Able to di erent into several related Haematopoietic/blood stem
cell types but fewer types compared to cells found in the bone marrow,
pluripotent stem cells neural stem cells
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