Nanocarriers for Treatment of Ocular Neovascularization in the Back of the Eye: New Vehicles for Ophthalmic Drug Delivery

Abstract

Pathologic neovascularization of the retina is a major cause of substantial and irreversible loss of vision. Drugs are difficult to deliver to the lesions in the back of the eye and this is a major obstacle for the therapeutics. Current pharmacological approach involves an intravitreal injection of anti-VEGF agents to prevent aberrant growth of blood vessels, but it has limitations including therapeutic efficacy and side-effects associated with systemic exposure and invasive surgery. Nanotechnology provides novel opportunities to overcome the limitations of conventional delivery system to reach the back of the eye through fabrication of nanostructures capable of encapsulating and delivering small molecules. This review article introduces various forms of nanocarrier that can be adopted by ocular drug delivery systems to improve current therapy. The application of nanotechnology in medicine brings new hope for ocular drug delivery in the back of the eye to manage the major causes of blindness associated with ocular neovascularization.

Polysaccharides in Ocular Drug Delivery

“…Even though intravitreal injections are generally safe, the monthly and bimonthly requirements for these injections in long-term treatment may cause problems such as infection and reduced patient compliance [128][129][130][131][132]. For these reasons, intravitreal drug delivery systems are needed that will maintain therapeutic drug concentrations for an extended time, prolong the drug effect, and reduce the required number of applications [128,130,131,[133][134][135]. Obviously, the systems must also be safe and ideally they must be biodegradable, as biodegradable drug delivery systems do not require subsequent surgery to remove them from the eye [133].…”

Extrinsic and Intrinsic Mechanisms by Which Mesenchymal Stem Cells Suppress the Immune System

“…This emphasizes the need for in-depth studies regarding the delivery method 115,116 and the need/efficacy of gene manipulation of MSCs prior to treatment.…”

Nrf2 Is an Attractive Therapeutic Target for Retinal Diseases

“…Because continuing oxidative stress damages the retina over time and activation of Nrf2 is not expected to reverse cellular death, preventing the progress of dry AMD might be a more promising target, as in the case of the AREDS study. Systemic adverse events are still a big concern of triterpenoids; therefore, administering them via eye drops or intraocular implants would be a promising approach for lowering these risks [55, 56]. …”