No abstract

Biodegradable polyurethane films display the proper mechanical properties for an easy transscleral-driven subretinal implantation and can be considered as biocompatible supports for a functional ARPE-19 monolayer.

The aim of this study was to synthesize and characterize the biodegradable intraocular implants based on poly (D,L-lactide-co-glycolide) (PLGA 75:25) with Cyclosporine-A (CyA) and to evaluate their in vitro drug delivery profile. Thermal analysis was conducted by using Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Phase analysis and crystallinity of the polymer-CyA samples were assessed through X ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Finally, microstructure and morphology of the systems were investigated by Scanning Electron Microscopy (SEM). The results showed that CyA was successfully incorporated into PLGA network with drug loading of approximately 31.6%. Also, based on FTIR and thermal analyses (TGA/DSC) no significant physical-chemical interaction was detected at the micro-nanoscale level between polymer/drug. SEM micrographs have indicated a uniform drug distribution in PLGA matrix. XRD patterns have showed that the incorporated semi-crystalline structure of CyA has not significantly altered the polymeric mainly amorphous network. In addition, the results have confirmed the chemical and biological drug stability, the drug distribution into the polymeric matrix and the possibility of cyclosporine prolonged delivery system profile.

Dexamethasone-PUD implanted in the anterior suprachoroidal space may be of interest in the treatment of intraocular inflammation.

No abstract

Following a single intravitreal injection, the median concentration of triamcinolone acetonide is significantly higher in the TA-BA compared to the TA-PF group at 7 days post-injection. No toxic reactions in the retina were observed in either group.

The subretinal transplantation of retinal pigment epithelial cells (RPE cells) grown on polymeric supports may have interest in retinal diseases affecting RPE cells. In this study, montmorillonite based polyurethane nanocomposite (PU-NC) was investigated as substrate for human RPE cell growth (ARPE-19 cells). The ARPE-19 cells were seeded on the PU-NC, and cell viability, proliferation and differentiation were investigated. The results indicated that ARPE-19 cells attached, proliferated onto the PU-NC, and expressed occludin. The in vivo ocular biocompatibility of the PU-NC was assessed by using the HET-CAM; and through its implantation under the retina. The direct application of the nanocomposite onto the CAM did not compromise the vascular tissue in the CAM surface, suggesting no ocular irritancy of the PU-NC film. The nanocomposite did not elicit any inflammatory response when implanted into the eye of rats. The PU-NC may have potential application as a substrate for RPE cell transplantation.

An HPLC method was developed and validated aiming to quantify the cyclosporine-A incorporated into intraocular implants, released from them; and in direct contact with the degradation products of PLGA. The separation was carried out in isocratic mode using acetonitrile/water (70:30) as mobile phase, a C18 column at 80 ºC and UV detection at 210 nm. The method provided selectivity based on resolution among peaks. It was linear over the range of 2.5-40.0 µg/mL. The quantitation and detection limits were 0.8 and 1.2 µg/mL, respectively. The recovery was 101.8% and intra-day and inter-day precision was close to 2%