Regulation of the Ocular Cell/Tissue Response by Implantable Biomaterials and Drug Delivery Systems

Abstract

Therapeutic advancements in the treatment of various ocular diseases is often linked to the development of efficient drug delivery systems (DDSs), which would allow a sustained release while maintaining therapeutic drug levels in the target tissues. In this way, ocular tissue/cell response can be properly modulated and designed in order to produce a therapeutic effect. An ideal ocular DDS should encapsulate and release the appropriate drug concentration to the target tissue (therapeutic but non-toxic level) while preserving drug functionality. Furthermore, a constant release is usually preferred, keeping the initial burst to a minimum. Different materials are used, modified, and combined in order to achieve a sustained drug release in both the anterior and posterior segments of the eye. After giving a picture of the different strategies adopted for ocular drug release, this review article provides an overview of the biomaterials that are used as drug carriers in the eye, including micro- and nanospheres, liposomes, hydrogels, and multi-material implants; the advantages and limitations of these DDSs are discussed in reference to the major ocular applications.

Current Therapeutics and Future Perspectives to Ocular Melanocytic Neoplasms in Dogs and Cats

“…Further studies show encouraging potential to treat ocular melanomas in humans and animals. Regarding these, the use of implantable biomaterials and drug delivery systems present as therapeutic advancements for various ocular diseases [ 133 ].…”

Considerations for Polymers Used in Ocular Drug Delivery

“…Implementation of PLGA for ocular drug delivery vehicles is aimed at controlling the release of therapeutic through tunable polymer properties and improving biocompatibility and bioavailability. Altering the ratios of PGA and PLA also allows for optimization of degradation time, degrees of crystallinity, and hydrophobicity (44). Incorporation of a hydrophobic polymer can allow for selective permeation across mucus membranes if applied topically, or, if administered intravitreally, can work to minimize diffusion of therapeutic away from the target region and slow release.…”

“…These degradation characteristics make PLGA one of the most common biomaterials found in approved polymeric ocular drug delivery vehicles. However, there have been challenges with some PLGA-based systems due to acidic degradation byproducts (44,45). Ozurdex R is an FDA approved PLGA-based intravitreal implant used for extended release of dexamethasone in treatment of retinal vein occlusion, noninfectious posterior uveitis, and DME.…”

“…Within the field of micro-and nanotechnology, there are a variety of drug delivery vehicles such as microparticles, nanoparticles, micelles, and liposomes. These drug delivery vehicles show significant promise in the eye due to their less invasive application approaches topically as well as ease of injection through small gauge needles (44,142). These have also been explored for incorporation into drug-eluting contact lenses to facilitate topical delivery (143).…”

Research Progress of Bioactive Glass and Its Application in Orthopedics

“…[95] In recent years, MBGs have been widely studied because of their good carrier loading and release ability. Through the sol-gel method, metal ions with antibacterial properties such as silver (Ag + ), Zn 2+ , Cu + and Cu 2+ , [74] cerium (Ce 3+ and Ce 4+ ), and Ga 3+ have been introduced into the MBGs structure, and can effectively control the release and inhibit the growth and reproduction of bacteria. Ag + has been used as an antimicrobial since ancient times and is more effective against gramnegative bacteria than gram-positive bacteria.…”