In vitro and in vivo studies on bioactive hydroxyapatite-coated magnesium for glaucoma drainage implant

Given the alarmingly increasing rates of glaucoma worldwide and the lack of satisfactory treatments, there is a dire need to explore more feasible treatment options. Magnesium (Mg) is an essential element in maintaining the functional and structural integrity of vital ocular tissues, but Mg and its alloys are rarely mentioned in ophthalmic applications. Our previous research found that hydroxyapatite-coated Mg (Mg@HA) shows the best biocompatibility and bioactivity, and exhibits the effect of inhibiting fibrosis after filtration surgery in the rabbit model, which is expected to be a promising material for glaucoma drainage device. In this study, we further demonstrated the anti-fibrosis effect of Mg@HA from the molecular signal level and the efficacy of implantation in the rabbit filtration surgery model. In vitro experiments showed the surface modification of Mg affects the adhesion behavior and the reorganization of cytoskeleton of Human Western blot analysis and immunofluorescence found that Mg@HA regulates the adhesion and motility of human Tenon’s capsule fibroblasts mainly by down-regulating the phosphorylation of Smad2 and Smad3 in the canonical transforming growth factor-beta (TGF - β) signaling pathway. By observing and recording the condition of filtering blebs and intraocular pressure after surgery, the effectiveness of Mg@HA applied in the rabbit filtration surgery model was further evaluated. In conclusion, the application of hydroxyapatite-coated Mg in the eye has good biocompatibility and has the potential to resist postoperative glaucoma filtration fibrosis, which may be mediated by the regulation of the TGFβ/Smad signaling pathway.