OTX2 stimulates adult retinal ganglion cell regeneration.

Retinal ganglion cell (RGC) axons provide the only link between the light sensitive and photon transducing neural retina and visual centers of the brain. RGC axon degeneration occurs in a number of blinding diseases and the ability to stimulate axon regeneration from surviving ganglion cells could provide the anatomic substrate for restoration of vision. OTX2 is a homeoprotein transcription factor expressed in the retina and previous studies showed that, in response to stress, exogenous OTX2 increases the in vitro and in vivo survival of RGCs. Here we examined and quantified the effects of OTX2 on adult RGC axon regeneration in vitro and in vivo. The results show that exogenous OTX2 stimulates the regrowth of axons from RGCs in cultures of dissociated adult retinal cells and from explants of adult retinal tissue and that RGCs respond directly to OTX2 as regrowth is observed in cultures of purified adult rat RGCs. Importantly, after nerve crush in vivo, we observed a positive effect of OTX2 on the number of regenerating axons up to the optic chiasm within 14 days post crush and a very modest level of acuity absent in control mice. The effect of OTX2 on RGC survival and regeneration is of potential interest for degenerative diseases affecting this cell type. All animal procedures were approved by the local "Comié d'éιthique en expérimentation animale n°59" and authorization n° 00702.01 delivered March 28, 2014 by the French "Ministére de l'enseignement supérieur et de la recherche".

Anionic polyethyleneglycol lipids added to cationic lipoplexes increase their plasmatic circulation time.

Cationic liposomes have been widely sensed as good DNA compacting delivery agents. Although their use generally met with encouraging results in vitro, the results in vivo were rather disappointing, as they strongly interact with the blood components before they can reach the therapeutic target. Polyethyleneglycol (PEG) shielding has been proposed as a way to alleviate this effect, but was still found unsatisfactory in most instances for systemic administration. We demonstrate here that the insertion of anionic functions between the lipid part and the PEG, at a correct distance to favor electrostatic interactions with the outer cationic layer of the lipoplexes, provides not only a decrease in the mean peripheral charge of the lipoplex (zeta potential), but also a greater colloidal stability of the particles in the presence of serum. Transfection in the lung is also decreased with negatively charged PEG shielding, although no significant changes are observed in the tumor. This encouraging new approach should consequently be combined with active extra-cellular receptor targeting to achieve the desired delivery of the therapeutic DNA to tumor tissues.