In the last few decades, stem cell research has developed groundbreaking technologies
to both study and treat diseases. This research has proven fruitful for
the field of ophthalmology, especially in recent years. With its relative immune
privilege, the eye has proven an ideal testing ground for stem cell therapies.
This book describes just a few of these developing treatments. The authors of
this book describe a wide range of possible applications, from oculofacial plastic
surgery to the restoration of sight lost by degenerative disorders and glaucoma, to
cancer research. Indeed, stem cell research seems to have reached a critical mass in
ophthalmology. As recently as 2011, the FDA approved trials for stem cell-based
treatments for macular degeneration; other clinical trials may follow, as discussed
in the last chapter of this book.
These changes have not happened overnight. From a scientific standpoint,
several discoveries have made stem cells a viable treatment source for humans. In
1981, when embryonic stem cells were first synthesized in the laboratory, it became
possible to imagine generating graft tissues or animal models to test drugs from
stem cells. Fifteen years later, the Yamanaka research group discovered that mouse
skin samples could be reprogrammed through gene therapy into induced pluripotent
cells. Both ES and iPS cells are pluripotent, or reprogrammable. Moreover, iPS
cells are autologous, meaning they are derived from the subject’s own tissue. By
modifying cell culture media or performing gene therapy, researchers have been
able to generate many types of tissues using ES cells and iPS cells.
Autologous tissues can also be generated using the progenitor cells which
exist naturally inside the body. Unlike pluripotent stem cells, progenitor cells can
differentiate into a limited number of tissues. These “local” cells can be adapted to
replace and repair diseased tissue. Promising progenitor cells include: adipose
tissue stem cells, ciliary stem cells, mesenchymial stem cells, corneal stem cells,
and lens stem cells.