Abstract
Purpose :
In topical treatment, only a few percent of the active ingredient reaches the inside of the eye. The reasons for this include washout through blinking, tear fluid, and the structural properties of the ocular surface. The same challenge also applies to dry eye disease for which long-lasting lubrication is needed. Supercharged unfolded polypeptides (SUPs) represent a possible solution for improved absorption, adhesion, and lubrication. SUPs have an elastin-like pentase sequence, which is positively overloaded with lysine at every 5th position. Electrostatic interaction with the negatively charged mucin layer of the cornea thus enables prolonged adhesion. In this project two different SUPs were tested for their potential as drug delivery systems.
Methods :
The adhesion, penetration, and biocompatibility of the SUPs were tested ex vivo on porcine eyes and in vivo on rats. To this end, SUPs were applied to the corneas and incubated for different time points. The tear film was simulated in the pig eyes with a buffer solution. The localization and adhesion of the SUPs were evaluated histologically and via antibody staining against mucin-1 and galectin-3. The fluorescence signal of the SUPs was measured with a Fluorotron™ Master Fluorophotometer to quantitatively determine the adhesion time and penetration depth of the particles. To verify the high biocompatibility of the SUPs, cryosections were analyzed using TUNEL-staining and HE-staining. Lastly, specific adhesion to primary porcine corneal cells was evaluated compared to primary porcine Müller and the MIO-M1-cell line.
Results :
The adhesion of the SUPs to the cornea of ex vivo porcine eyes was successfully demonstrated over 24 hours. The specific adhesion of SUPs to the mucin layer was confirmed by antibody staining against mucin-1 and galectin-3. Quantification by fluorophotometer showed that 96% of the two SUPs tested adhered to the cornea after 24 hours. Both SUPs showed no significant difference in adhesion. Moreover, excellent biocompatibility was shown. In vivo, the SUPs were still present on the corneal surface for up to four hours. In vitro studies with different cells (lines) proved specific adhesion to corneal cells.
Conclusions :
The specific long-time adhesion of SUPs to the mucin layer of corneal epithelial cells was demonstrated. Thus, SUPs offer a promising approach as periocular drug carriers or/and for long-term lubrication in dry eye disease.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.