Stem cell treatments Flashcards
Define stem cell
an unspecialised cell with ability to self-renew and the capability of differentiating into multiple cell types
2 types of stem cell
- embryonic (totipotent)
2. adult (or somatic, = mutlipotent)
Where are embryonic stem cells (ESCs) derived from?
- the ICM of the blastocyst
- in most mammals there are only a v small # of cells in the ICM and there is only a short period of time before they begin to differentiate
- need to be amplified for therapeutic benefit
How is the ICM amplified?
removed and cultured in conditions that keep them dividing but not differentiating, cells are passaged when confluent. Over a period of months, enough cells harvested to be of use. Cultures can be grown indefinitely as cells have a limitless capacity to self-renew and thus each ICM can lead to a new stem cell line. Cellls can be induced to differentiate by adding different gorwht facotrs and supplements to the media and/or encouraging cells to cluster in an embryoid body
Pros - ESCs
- generate vast #s cells with capacity to make any of 200+ cell types in body
Cons - ESCs
- takes long time to grow sufficient #s from individual embryo
- if implanted into lesion may differentiate into incorrect tissue or form a teratoma
Name clinical trials for humans with ESCs
- macular degeneration (partially differentiated ESCs injected into eye)
- diabetes (incorporating ESCs into medical device, it is semi-permeable, nutrients in/out, less vulnerable to attack by immune system)
What are adult stem cells?
- undifferentiated cells that can be found amongst differentiated cells in many (possibly all) adult tissues
- any SC found in a postnatal organ is classified as adult
- normal tissue they tend to be dormant (non-proliferating)
- often induced to proliferate upon injury
- don’t have infinite capacity to keep dividing (unlike ESCs)
- limited number of derivatives (most have only 2 derivatives, maybe 3/4 in culture)
Pros - adult stem cells
- cna harvest ‘own’ stem cells reducing the likelihood of rejection
- more limited capacity means you won’t be forming teratomas
- amplification is difficult as don’t proliferate fast/ indefinitely
- few ethical concerns
Cons - adult stem cells
- hard to get enough cells
- still don’t know how to generate all possible cell types
Function - adult stem cells
- replace worn out tissues
- replace damage tissues
examples - adult stem cell locaiton
- bone marrow (used to tx leukaemia)
Name 2 types of bone marrow stem cell
- ) Haematopoietic (forms all types of blood cell)
- ) Bone marrow stromal cells/ mesenchymal stem cells / skeletal stem cells = make up small % stromal cells in BM, can generate bone, cartilage and fat cells that support the formation of blood and fibrous CT
Where are adult stem cells found?
- bone marrow
- skin
- adipose tissue
- brain
- peripheral blood
- BVs
- skeletal mm
- teeth
- heart
- gut
- liver
- testes
- ovarian epithelium
Define iPSc
Induced pluripotent stem cells
- they are adult somatic cells (usually fibroblasts) that have been transfected with a viral vector carrying a stem cell gene
- once expressed, these instruct the cell to become ‘embryonic’ again
