Transforming sutures from passive tools into active immunomodulatory platforms: Prolonging corneal graft survival using reloadable tacrolimus-eluting sutures

Corneal allograft rejection remains a major cause of transplant failure. To address the limitations of topical immunosuppressants—such as poor bioavailability and patient non-compliance—this study introduces a transformative strategy: engineering surgical sutures into active, reloadable immunomodulatory platforms. We developed a novel tacrolimus-eluting suture by modifying its surface with poly(dopamine) and anchoring a cyclodextrin-tacrolimus inclusion complex. This design enables sustained local drug release directly at the graft-host junction. Crucially, the system is reloadable; after initial depletion, the drug payload can be non-invasively replenished via cyclodextrin, allowing it to match the prolonged risk period of post-transplantation. In vitro studies confirmed sustained release over one week, and ex vivo corneal penetration models validated efficacy. By integrating long-term, localized immunosuppression into the standard-of-care suture, this platform offers a groundbreaking approach to prolong graft survival and personalize postoperative management.