CSB329H1 Lecture Notes - Lecture 8: Oct-4, Embryoid Body, Arizona Transition Zone
9 May 2018
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Lecture 8(a): Human ESCs & Induced Pluripotency
Human Embryonic Stem Cells (hESCs):
• First lines were made trying to use similar culture practices to mouse ES cells, however it was
unsuccessful due to the major differences between them
o (1) mouse feeder cells (2) bovine serum used in the media
ð Ideally, hESCs must be derived without the use of animal products and in a clean facility to
prevent contamination with pathogens
o Culturing hESCs (or iPSCs) are prone to genetic alterations – therefore, only a subset
will have the potential to reprogram as they acquire mutations through repeated
passages in culture => difficult to recapitulate what occurs naturally in reproduction
hESCs Therapies:
1. Retinitis Pigmentosa:
o Directly causes the destruction of photoreceptor cells
§ Patient retinal progenitor cells are grown in large quantities in the lab and
injected into the eye, hopefully replacing the lost photoreceptor cells or
prevent further photoreceptor cell loss
2. Macular Degeneration:
o Layer of retinal pigment epithelial (RPE) cell that supports photoreceptors is destroyed
§ Embryonic stem cells are differentiated to RPE cells in culture and are grow
in sheets on a scaffold and surgically implanted to the back of the eye
Cell Therapy Types:
a) Autologous:
o Cells and/or tissues are obtained from the same individual receiving the treatment
b) Allogenic:
o Genetically distinct cells and/or tissues are obtained from the same
species
:
§ Cells will be antigenically distinct – can be recognized as foreign
o Rejection possibility is higher: immunosuppressive drugs are used to avoid rejection
c) Xenogenic:
o Cells and/or tissues are obtained from a different species
(i.e. human cancer cells into immunocompromised mice)
Nuclear Reprogramming:
• Mature cells (i.e. somatic cells) are capable of
being reprogrammed to become pluripotent
o Induced pluripotent stem cells (iPSCs)
Document Summary
Embryonic stem cells are differentiated to rpe cells in culture and are grow in sheets on a scaffold and surgically implanted to the back of the eye. Cell therapy types: autologous, cells and/or tissues are obtained from the same individual receiving the treatment, allogenic, genetically distinct cells and/or tissues are obtained from the same species: Nuclear reprogramming: mature cells (i. e. somatic cells) are capable of being reprogrammed to become pluripotent, induced pluripotent stem cells (ipscs) First demonstration that somatic cells can be reprogrammed by transferring their nuclear contents into an enucleated oocyte; totipotent capable of generating an entire frog. Induced pluripotent stem cells (ipscs): 24 factors (mostly tf) were suspected in maintaining pluripotency generated vectors, constructed a mouse line that expressed drug resistance gene only in pluripotent cells. Internal ribosome entry site (ires) allows dicistronic expression allows the translation of both proteins (genes) from one mrna.
