Non-Viral Gene Therapy for the Treatment of Retinal Degeneration.
pigmentosa (RP) is the most common neurodegenerative disorder that leads to blindness
and affects approximately 1 in 4000 individuals world wide. There is currently no
curative therapeutic option for patients suffering from RP. Because of the chronic
nature of RP and many other ocular diseases, gene therapy may offer an ideal form of
treatment. We have shown that a novel ... read moresynthetic peptide POD, or "protein for ocular
delivery," is able to deliver small molecules to the retina in vivo. Generation of a
POD-GFP fusion protein demonstrated that POD was able to deliver macromolecules to the
retinal pigment epithelium (RPE) and photoreceptors after subretinal delivery, and to
the retinal ganglion calls after intravitreal delivery. POD was also shown to
efficiently compact DNA and deliver it to cells in vitro. This observation prompted us
to develop use of POD as a non-viral vector in vivo. When conjugated with polyethylene
glycol (PEG-POD), PEG-POD can compact plasmid DNA into 136 nm that can penetrate and
transduce the retinal pigment epithelium (RPE) of adult murine retina in vivo. PEG-POD
significantly increased expression of plasmid DNA 215-fold relative to DNA alone.
PEG-POD can protect plasmid DNA from DNaseI digestion, resulting in significant
transfection of the lung following intravenous injection. To observe the therapeutic
implications of PEG-POD mediated transduction, nanoparticles containing an expression
cassette for Glial Cell Line-Derived Neurotrophic Factor (PEG-POD~GDNF) were
investigated for their ability to slow or inhibit blue light-induced photoreceptor
apoptosis. Animals injected with PEG-POD~GDNF showed a significant decrease in apoptosis
photoreceptor survival relative to control-injected animals. PEG-POD~GDNF injected eyes
showed a 27-39% increase in their functional response relative to controls, as measured
by electroretinogram. Taken together, PEG-POD was found to significantly increase gene
delivery relative to both DNA alone and other PEGylated peptides. This is one of only
two studies demonstrating both histological and functional rescue of a mouse model of
retinal degeneration following non-viral administration of a therapeutic transgene into
adult retina. Although rescue is short lived for clinical application, this study
represents an important step in the development of non-viral gene therapy for retinal
Thesis (Ph.D.)--Tufts University, 2012.
Submitted to the Dept. of Genetics.
Advisor: Rajendra Kumar-Singh.
Committee: Janis Lem, Gavin Schnitzler, Michael Rosenblatt, Naomi Rosenberg, and John Castellot.
Keywords: Genetics, and Ophthalmology.read less