stem cells
- cells found in most multicellular organisms
- characterised by ability to renew themselves through mitotic cell division and
differentiating into a diverse range of specialised cell types
Ernest A. McCulloch and James E. Till grew findings of stem cells in 1960s.
2 broad types of mammalian stem cells:
1. Embryonic stem cells (ESC): located in inner cell mass of blastocysts
2. Adult stem cells: found in adult tissues
The difference between these two types is that ESC can become any cell type,
while adult stem cells do not have that option. Limitation called plasticity.
- in developing embryo, stems cells differentiate into all of specialised embryonic
tissues.
- in adult organisms, stem cells and progenitor cells act as a repair system for body,
replenishing specialised ells, but also maintain normal turnover of regenerative
organs, such as blood, skin or intestinal tissues
1998 = human embryonic stem cells isolated for the first time
Types of stem cells
Have 2 common qualities:
• ability to regenerate tissue (divide and renew themselves)
• unspecialised cells that have ability to differentiate into other specialised cells
e.g. stem cells can be used to produce muscle tissue or insulin producing cells
Controversy over embryonic stem cell research
- ESC can only be obtained from 3-5 day old embryo
- embryo destroyed in process
- primitive stage - no heart, brain or limbs
- ESC hold much hope as can be used for damaged organs and transplantation
- can lead to embryos being cloned:
• devalues life
• richer people freeze embryos to create own cells they may need
• pro life argue embryos still alive - qualifies as murder
- in fertilisation clinics, many eggs produced for in vitro fertilisation (IVF)
- many not used and and some believed that instead of being discarded, they
should be used for research to discover potential treatments for illnesses
New hope
- hard to isolate and cultivate adult stem cells
- this limits their usefulness
- cells found in most multicellular organisms
- characterised by ability to renew themselves through mitotic cell division and
differentiating into a diverse range of specialised cell types
Ernest A. McCulloch and James E. Till grew findings of stem cells in 1960s.
2 broad types of mammalian stem cells:
1. Embryonic stem cells (ESC): located in inner cell mass of blastocysts
2. Adult stem cells: found in adult tissues
The difference between these two types is that ESC can become any cell type,
while adult stem cells do not have that option. Limitation called plasticity.
- in developing embryo, stems cells differentiate into all of specialised embryonic
tissues.
- in adult organisms, stem cells and progenitor cells act as a repair system for body,
replenishing specialised ells, but also maintain normal turnover of regenerative
organs, such as blood, skin or intestinal tissues
1998 = human embryonic stem cells isolated for the first time
Types of stem cells
Have 2 common qualities:
• ability to regenerate tissue (divide and renew themselves)
• unspecialised cells that have ability to differentiate into other specialised cells
e.g. stem cells can be used to produce muscle tissue or insulin producing cells
Controversy over embryonic stem cell research
- ESC can only be obtained from 3-5 day old embryo
- embryo destroyed in process
- primitive stage - no heart, brain or limbs
- ESC hold much hope as can be used for damaged organs and transplantation
- can lead to embryos being cloned:
• devalues life
• richer people freeze embryos to create own cells they may need
• pro life argue embryos still alive - qualifies as murder
- in fertilisation clinics, many eggs produced for in vitro fertilisation (IVF)
- many not used and and some believed that instead of being discarded, they
should be used for research to discover potential treatments for illnesses
New hope
- hard to isolate and cultivate adult stem cells
- this limits their usefulness
