In vivo Uptake of Nanoparticulate Drug Delivery Systems by Ocular Surface Structures

Abstract

Purpose: : Our group has previously developed different nanoparticulate drug delivery systems and has tested them in vitro and in vivo. The purpose of this work was to evaluate the in vivo uptake of these new systems by ocular surface tissues and whether it causes an alteration in these tissues.

Methods: : Three different nanoparticulate colloidal systems carrying a marker molecule (bovine serum albumin conjugated with FITC) were prepared by ionotropic gelation, followed by freeze drying in the presence of 5.0 % trehalose: chitosan–based nanoparticles (CH–NPs), hyaluronic acid–based nanoparticles (HA–NPs) and lipids–chitosan nanoparticle complexes (LNPs). In vivo uptake of any of the three formulations (0.5 mg/ml in PBS plus 0.27% glucose, pH 7.4) by ocular surface structures was studied in 17 female albino rabbits (n = 5 for each group + 2 sham control animals). Each formulation was instilled in OD every 30 minutes, for a total of 13 times, leaving OS untouched as a control. Eyeballs and lid tissues were removed, fixed, embedded in paraffin and sectioned. Paraffin was removed from 4–µm tissue sections, mounted with anti–fade fluorescence mounting media and evaluated by epi–fluorescence microscopy. Experiments were performed in a masked fashion.

Results: : Ocular surface epithelia and lid tissues were not altered or damaged in any way after exposure to any of the nanoparticles and complexes studied. Formulations were observed inside conjunctival and corneal epithelial cells with a different localization pattern, fluoresce distribution and intensity depending on each particular formulation. Florescent signal was also observed in conjunctiva but not cornea stromal cells.

Conclusions: : Tested CH–NPs, HA–NPs and LNPs were uptaken by ocular surface epithelial cells in vivo and these tissues remained histologically normal. These results add further support to the potential use these nanoparticulate systems as drug carriers to topically treat ocular surface disorders.

Keywords: conjunctiva • cornea: epithelium • cornea: tears/tear film/dry eye