A Novel Decorin and SAHA Combination Therapy to Treat Bleb Fibrosis in Vivo in Rabbits

Abstract

Purpose : Successful glaucoma filtration surgery (GFS) requires incomplete healing of scleral wound and complete healing of epithelial and conjunctival wound. Mitomycin-C (MMC), current standard-of-care antifibrotic agent, can lead to nonspecific tissue toxicity and raise the risk of sight-threatening complications. This study evaluated therapeutic potential of AAV-decorin (DCN) and SAHA combination therapy to safely and effectively modulate tissue-specific ocular fibrosis after GFS using an in vivo rabbit model.

Methods : Thirty New Zealand White rabbits were divided into 5 groups: No GFS (surgery-naïve control), GFS +BSS (negative control), GFS +MMC (positive control), GFS +AAV-DCN (test-1), and GFS +AAV-DCN +SAHA (test-2). A fornix-based trabeculectomy was performed by one surgeon. BSS, MMC and AAV-DCN were administered by subconjunctival injection pre-operatively, and SAHA was administered topically BID for 5 days post-operatively. Slit-lamp exams, tonometry, corneal pachymetry and confocal microscopy were performed pre-operatively and on post-operative day-1, -3, -7, -14 and -21. Stereomicroscope was used to measure bleb size and vascularity. Ocular tissues were collected on day-7 and -21 to be snap frozen and subjected to gene expression and protein analyses using qRT-PCR, H&E, immunofluorescence and/or western blotting.

Results : Pre-operatively, all 5 groups had similar clinical findings including intraocular pressure (IOP), pachymetry, endothelial cell counts (ECC) and appearance of ocular surface. By postoperative day-3, complete scleral fibrosis, conjunctival hyperemia and flattening of filtering bleb was seen in BSS group, and cystic thin bleb with poor conjunctival and corneal epithelial healing was seen in MMC group. Lack of scleral fibrosis while maintaining complete conjunctival and corneal wound healing was seen in both AAV-DCN and AAV-DCN +SAHA groups, although early hyperencapsulation was evident on day-21 in AAV-DCN group only. IOP, pachymetry and ECC remained physiologic and stable in all 5 groups postoperatively, and there were no sight-threatening complications, including bleb leak, hypotony, retinal detachment and endophthalmitis. The results of H&E, qRT-PCR and immunofluorescence are pending and will be reported at the meeting.

Conclusions : AAV-DCN and SAHA combination therapy has potential to improve outcome of GFS by inhibiting scleral fibrosis without surrounding tissue toxicity.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.