Interaction of primary human trabecular meshwork cells with metal alloy candidates for micro-invasive glaucoma surgery

Background Microinvasive glaucoma surgery (MIGS) is a relatively new addition to the glaucoma treatment paradigm. Small metallic stents are inserted into the trabecular meshwork in order to increase aqueous humour drainage. MIGS procedures are rapidly being adopted due to a more favourable side effect profile when compared to traditional surgery. Remarkably, this rapid rate of utilization has occurred without any published studies on the effect of metal alloys used in these stents on human trabecular meshwork cells (HTMCs). Therefore, this study aimed to determine the effect of candidate metal alloys for micro-invasive glaucoma surgery on HTMC morphology, viability, and function. Methods HTMCs were cultured on the surfaces of titanium (polished and sandblasted), a titanium-nickel (nitinol) alloy, and glass (as control substratum). Fluorescence imaging was used to assess cell morphology and spreading. A lactate dehydrogenase cytotoxicity assay, cell death detection ELISA, MTT cell viability assay, BrdU cell proliferation assay, and fibronectin ELISA were also conducted. Results Cells cultured on sandblasted titanium exhibited significantly greater spreading than cells cultured on other substrata. In comparison, HTMCs cultured on nitinol displayed poor spreading. Significantly more cell death, by both necrosis and apoptosis, occurred on nitinol than on titanium and glass. Also, cell viability and proliferation were suppressed on nitinol compared to titanium or glass. Finally, HTMCs on both titanium and nitinol produced greater amounts of fibronectin than cells grown on glass. Conclusions Substratum topography and metal alloy composition were found to impact morphology, viability, and function of primary HTMC cultures.