Stem cells and regenerative medicine Flashcards
what are the characteristics of stem cells
- Are primitive or undiffertaited
- Can divide indefinitely
- Are self-renewing
- Give rise to progeny that differentiate into specialised cells
what is the mulipotential capacity of
- totipotent
- pluripotent
- multipotent
- oligopotent
- unipotent
- totipotent - can differentiate into anything including the placenta
- Pluripotent – can differentiate into cells derived from any of the three germ layers – they can’t develop into the placenta – naturally occur within embryos
- Multipotent – can give rise to several specialised cells or tissues of an organism – often tissue specific
- Oligopotent – can generate a few cells types within a particular tissue
- Unipotent – can produce only one cell type but still capable of self-renewal
what are stem cells maintained by
- Stem cells are through to be maintained by the environment produced by surrounding differentiated cells
how does the niche environment regulate stem cells
- Secrete specific factors into the surrounding matrix
- Communicate with the stem cells via gap junctions
- Changes within the niche may induce a stem cell to die, divide or differentiate
what are the two methods of differentiate in stem cells
- symmetric cell division
- asymmetric cell division
what is symmetric cell division
- Stem cell + Stem Cell
- Differentiated cell + Differentiated cell
what is asymmetric cell division
Stem Cell + Differentiated Cell
what is an embryonic stem cell derived from
- ES cells lines are derived from individual ES cells
- Common source – IVF – embryos in excess of clinical need
what are the ways that embryonic stem cells can be identified from other cells
- stem cells have immortality
- clonaility - maintain a normal karyotype and have expression of telomerase
- undifferentiated - there are only marks that are found in undifferated stem cells Oct14 Nanog
- wide developmental potential - able to differentiated into a wide range of cell types in Vitor and in vivo
what are the challenges of using embryonic stem cells for transplantation therapies
Purity/production problems
Cancer problems
Immunology problems
Ethics problems
what are the potential solutions to immune rejection using embryonic stem cells
- large banks of ES cells
- manipulation of histocompatibility genes in ES cells
- replacement of hematopoietic tissue of patient with ES-derived cells prior to graft
- immunosuppressive drugs or antibodies
- therapeutic cloning
how does therapeutic cloning work
- Take somatic cell
- Pop out nucleus from the somatic cell
- Unfertilised egg remove the nucleus
- Combine nucleus and anulcear unfertilised egg
- Then diploid oocyste
- Shock
- Development
- Blastocyst
- Then this can create embryo stem cell line
what are the benefits of therapeutic cloning
- Ideal tissue for regenerative medicine because genetically identical to patient
- circumvents problem of tissue rejection
- model a patient’s specific disease
what are the challenges and controversies of therapeutic cloning
- Percentage of successful clones is low – long time-frame to generate
- Creating potential embryo (not fertilized) for research/treatment
- Practical - source of oocytes? Should women donate for such research/treatments?
- Slippery slope to reproductive cloning
describe how reproductive cloning works
- Same process
- Implant back into the surrogate mum
- Get cloned
- For example dolly the sheep
what is the ethical debate of embryos
- Are humans playing god
- Will embryo arms be around in the future
- Will healthcare costs skyrocket
- Is it morally right
- Are embryos alive
what is the regulation of experiments on embryos
- can only be legally used up to 14 days of development in some countries, in others this is only a guideline
what are adult stem cells
- Rare, undifferentiated cells found among differentiated cells in a tissue or organ
- Capable of differentiating to produce the major specialised cell types of the tissue
what is the primary role of adult stem cells
- Primary role: to maintain and repair the tissue in which they are found
what type of stem cells are adult stem cells
- Multipotent, not pluripotent
what are the advantages for using adult stem cells
• No legal or ethical concerns
• Using a patient’s own cells circumvents the problem of immunological rejection
• Injection of normal somatic stem cells has not lead to tumour formation
- By learning to manipulate endogenous adult stem cells in the body we may learn how to repair ourselves avoiding the problems of cell transplantation
what are the examples of bone marrow transplants
- Bone marrow transplants
- Skin grafts for burn victims
what is an example of stem cell success
- Repair and replace strategy
- Remove stem cells from a patients bone marrow
- Transfer a correct copy of the defective ADA gene
- Replace cells
- The therapy was tested on 18 children, the first of them 15 years ago, all are still alive
what is an induced pluripotent stem cell
Add certain genes to the cell and this sets the cell back to the inducted pluripotent stem cells this then behaves like an embryonic stem cell
