@phdthesis{discovery1335834,
            year = {2011},
           month = {December},
           title = {Derivation of photoreceptor precursors from human M{\"u}ller stem cells and their application in experimental photoreceptor replacement},
          school = {UCL (University College London)},
            note = {Permission for digitisation not received},
          author = {Jayaram, H.},
             url = {https://discovery.ucl.ac.uk/id/eprint/1335834/},
        abstract = {The adult human retina has a population of M{\"u}ller glia that exhibit stem cell
characteristics. The study investigated the feasibility of obtaining M{\"u}ller stem
cells from small samples of human, rat, rabbit and nonhuman primate retinae in
order to provide proof of concept for the development of patient specific
therapies. It also explored the role of human M{\"u}ller stem cells in providing a
source of rod photoreceptor precursors that may be applied to experimental
photoreceptor replacement. M{\"u}ller glia with stem cell characteristics were readily
obtained from small samples of fresh cadaveric human retina and retinae from
rats and non-human primates. However derivation of cells from human
retinectomy specimens was not possible, with the marked inflammatory
environment likely to be inhibiting proliferation of these cells in vitro.
As determined by quantitative PCR and immunocytochemistry, in vitro culture of
M{\"u}ller stem cells in the presence of FGF2, taurine, retinoic acid and IGF-1 led to
increased expression of the photoreceptor markers CRX, NR2E3 and rhodopsin,
associated with increased gene expression of components of the
phototransduction cascade. The expression of NRL was not modified,
suggesting that the differentiation of adult human M{\"u}ller stem cells towards
photoreceptors may occur through a pathway independent of this transcription
factor. In vitro functional analysis suggested an increased responsiveness of
differentiated cells to cGMP analogues and light stimulation as judged by
calcium imaging and patch clamp techniques.
Following subretinal transplantation into rodent models of photoreceptor
degeneration, M{\"u}ller stem cell derived photoreceptor precursors migrated and
integrated into the outer nuclear of degenerate rodent retina, demonstrating
expression of photoreceptor markers and local synapse formation. Grafting of
photoreceptor differentiated but not undifferentiated cells led to a significant
increase in rod photoreceptor function as shown by the scotopic
electroretinogram (ERG). The present observations show that human M{\"u}ller stem cells have the capacity
to differentiate into photoreceptor precursors and that these have the potential to
be used in the development of therapies for human photoreceptor disease.}
}