Lecture 7 - Cloning & regenerative medicine Flashcards
What is a technique that is evidence that ‘terminal differentiation’ can be reversed?
Nuclear transfer
What 2 types of cells from 2 different organisms were combined to demonstrate that ‘terminal differentiation’ can be reversed?
A human liver cell & a mouse muscle cell were fused to which the human nucleus responded by not producing liver proteins and produced muscle proteins. This may be because muscle have a lot of nuclei.
Other than the introduction of Yamanaka factors, what is another process that can induce the reprogramming of cells?
Damage
What is an physiological example of damage inducing the reprogramming of cells?
Iris cells transdifferentiate into lens cells to regenerate the missing tissue - in newts
- not due to stem cells but dedifferentiation and redifferentiation
What can control gene expression?
cytoplasmic factors
Can tissue loss be sensed in some animals?
yes
What is meant by clonal cells?
a group of identical cells that share a common ancestry, meaning they are derived from the same cell - they are genetically identical
What were the first animal to be cloned in a lab?
frogs (tadpoles - using adult skin cells)
What is the name given to the method by which clones are created using the transfer of a nuclei?
somatic cell nuclear transfer
What type of cell nuclei is more successful in the production of clones that adult stem cells?
Blastula nuclei
Describe the steps by which the first mammal was cloned?
- Mammary epithelial cells removed from donor.
- An oocyte removed from host and nucleus is removed.
- The nucleus from the mammary epithelial cell are out into host oocyte.
- Pulse of electricity causes the fusion of the nuclear membrane (fusion is induced by an electric current)
- After fusion, a diploid nucleus is present inside the egg. This is then cultured to ensure that an embryo is being developed
- After an embryo starts to develop, it is transplanted into the uterus of a foster mother.
Why should stem cells used in regenerative medicine be taken from the patient?
to avoid rejection
What are the 2 types of regenerative medicine?
- stem cells
- drugs or genetic methods
Describe the stem cell approach (in vitro) approach to regenerative medicine
- stem cells can be differentiated into cell type (and the tissue) that is needed. The tissue can then be implanted/transplanted into the required area.
- at times the tissue is more complicated than just a layer of cells (scaffolds)
Describe the drugs & genetic methods (in vivo) approach to regenerative medicine.
drugs or genetic methods are used to signal to normal tissue that it should replace the defective tissue
Describe the process by which somatic cell transplant can lead to the creation of insulin producing cells
Transfection of adult stem cells using Yamanaka factors can lead to pluripotency. This pluripotent cells can then be used to produce pancreas cells.
What gene regulates pancreas differentiation?
PDX1
What will occur if liver cells (in mice & frogs) are transfected with PDX1?
the cells will become insulin secreting cells?
What is meant by ‘transfer’ in the creation of a transgene?
to introduce a modified gene into cells or an animal (to make a transgene)
What 3 factors are important to consider when differentiating a cell?
- different mix of ligand
- timing
- concentration
(markers can be used to track progress)
(ligands may be important more than once)
What is the scaffold used when multiple cell types are needed to be regenerated in a damaged tissue?
scaffolds are fabricated out of biodegradable materials to support 3D growth of cells
What are the positive applications of stem cell therapies based upon IPS cells?
- correcting genetic defects (like junctional epidermolysis bullosa - JEB - skin falls off)
- replacing simple tissue or single cell types (bladder retinal cells)
- testing how your cells will respond to different pharmaceuticals (personal medicine)
What are the limitations of stem cell therapies based upon IPS cells?
- transplantation could be difficult (e.g. personalised medicine)
- organogenesis is very complex - tissue engineering scaffolds have had limited success - e.g. hard to create heart.
How did Wilson suggest that harnessing the innate power of cells to self- organise?
Wilson dissociated sponges by putting them through a fine sieve then watched as the cells reorganised into intact sponges.
- adhesion molecules & cell signaling play roles in this process
What is required for organoids to form by stem cells?
special media in which they are cultured in.
