Don’t let the name
scare you, these cells start as any cell type and are forced to become embryonic
stem cell like cells. A starting cell type such as a skin fibroblast (tissue
cell) is given a few genes to reprogram them and give them the properties of an
embryonic stem cell which are self-renewal (immortality) and pluripotency (can
differentiate into any body cell). The main advantage of this cell type is the improved
ethics when compared to embryonic stem cells as no embryo is destroyed during
their production. Ideally the iPSC will resemble an embryonic stem cell very
closely and stay that way however this is easier said than done.
Four main genes are used to reprogram the starting cell types
which are SOX2, Oct4, c-Myc and Klf4. These genes are delivered in any
different ways such as using viruses, microinjection or chemical transformation
(using chemicals to induce uptake of surrounding DNA). These genes can also
have negative effects; c-Myc in particular increases cell proliferation (growth
and division) and therefore gives a cell cancer like characteristics.
Additionally the reprogramming process requires heavy manipulation and growth
outside the body (in vitro) which
changes the cell overtime to make it less stable and more likely to have deleterious
mutations.
The reprogramming process is continually being refined and
improved so iPSCs have great potential in the future however currently the most
effective method uses viruses and therefore these cannot be given to humans due
to possible pathogen transmission and immune rejection. iPSCs may replace
embryonic stem cells and be capable of treating many diseases and regrow
damaged or defective tissues.
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