Microspheres scar formation glaucoma filtration surgery area therapeutic effect-Based on rapamycin-chitosan-calcium alginate sustained-release

To study the efficacy of rapamycin (RAPA)-chitosan (CS)-calcium alginate (CA) sustained-release microspheres on scar formation in a rabbit model of glaucoma filtration surgery. Eighty New Zealand white rabbits were randomly divided into four groups and a glaucoma filtration model was established by scleral bite through the eyes. RAPA-CS-CA sustained-release microspheres were implanted in the right eye of 40 rabbits (Group A) and CS blank sustained-release microspheres were implanted in the left eye (Group B). Another 40 rabbits were treated with a 0.2 g·L-1 RAPA cotton sheet in the right eye (Group C) and the left eye underwent a simple sclerotomy (Group D). The intraocular pressure, filter bleb, anterior chamber inflammation, complications, and corneal endothelial cell density were observed after the operation. Rabbits were euthanized for pathological examination 7 days, 14 days, and 21 days after the operation. The drug loading rate of RAPA-CS-CA sustainedrelease microspheres was (34.58±1.47)% and the encapsulation rate was (56.23±1.55)%. The microsphere release in vitro was relatively stable. The release rate of the microspheres during the burst was only 16.54%. After 49 days, the cumulative release rate of the microspheres reached 94.07% and the sustained release effect was significant within 45 days. Group A maintained low-level intraocular pressure for the longest period of time, followed by Group C, and then Group B and D. The survival time of filter vesicles in Group A was longer than that in other groups. There were no postoperative complications in each group. The conjunctival epithelium of Group A had better integrity and fewer subconjunctival fibroblasts than other groups. There was no obvious inflammation or infiltration around the filtering mouth and there were fewer new collagen fibers. RAPA-CS-CA slow-release microspheres safely and effectively inhibited the proliferation of fibroblasts and neonatal collagen fibers in rabbit glaucoma filtration surgery and significantly improved the success rate of glaucoma filtration surgery.