Enhancing Rose Bengal photosensitized protein cross-linking in cornea

Session Details

Session Title: Cross-Linking

Session Date/Time: Tuesday 25/09/2018 | 14:00-16:00

Paper Time: 15:26

Venue: Room A3, Podium 3

First Author: : C.Wertheimer USA

Co Author(s): :    C. Elhardt   S. Kaminsky   S. Afshar   I. Kochevar           

Abstract Details

Purpose:

Potential medical applications of Rose Bengal (RB)-photosensitized protein crosslinking have been demonstrated in preclinical studies. In solution, RB photosensitization via the RB excited triplet state generally involves energy transfer to oxygen to form singlet oxygen and electron transfer to the RB triplet producing radical ions. This study identifies mechanistic pathways in cornea tissue for RB-photosensitized crosslinking in order to enhance the treatment efficiency.

Setting:

Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA

Methods:

Rabbit corneas ex vivo were stained with 1 mM RB and irradiated at 532 nm (0.22 W/cm2). The influences of oxygen, sodium azide, D2O, and arginine (an electron donor) on the rate of RB photodecomposition (by spectrophotometry, 18 corneas) and on cornea tensile strength (by linear tensiometry, 91 corneas) were evaluated. Controls were non-irradiated corneas without and with RB staining.

Results:

Photobleaching in air was partially inhibited by azide and enhanced by D2O, suggesting a partial singlet oxygen pathway. In the absence of oxygen, the absorption maximum decreased and shifted to 530 nm. With arginine present during irradiation, the maximum shifted to 555 nm in air and 510 nm without oxygen, suggesting that electron transfer initiates RB photodecomposition. Tensiometry results showed that in air RB-sensitized a tensile strength increase that was inhibited by azide and unaffected by D2O. Removing oxygen blocked the photosensitized tensile strength increase but addition of arginine augmented the increase to the level observed in air alone.

Conclusions:

These results suggest that in a solid tissue, cornea, both energy transfer/singlet oxygen and electron transfer mechanisms participate in RB-photosensitized tensile strength increase and that adding electron donors may increase the efficiency of this treatment.

Financial Disclosure:

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