Nano-engineered mesenchymal stem cells as a platform for targeted and biologically regulated drug delivery in ocular surface inflammation.

Transplantation of human mesenchymal stem cells (hMSCs) has demonstrated safety and efficacy in the treatment of the inflamed and damaged ocular surface in patients with limbal stem cell deficiency (LSCD). However, this strategy alone is often insufficient to fully resolve clinical signs such as corneal opacity, neovascularization, ulceration, chronic inflammation, vision loss, and pain. The aim of this work was to nano-engineer hMSCs with fluorometholone-loaded nanostructured lipid carriers (FML-NLCs) to develop a combined cell-based drug delivery strategy capable of achieving sustained drug release, enhanced in situ anti-inflammatory activity, and promoting corneal repair. FML-NLCs were characterized in terms of particle size, polydispersity index, zeta potential, morphology, encapsulation efficiency, and drug release profile. The impact of hMSC nano-engineering with FML-NLCs on cell functionality was evaluated, including viability, nanoparticle uptake, immunophenotype, differentiation potential, migration capacity, extracellular drug release profile, and anti-inflammatory activity in vitro. The results demonstrated that nano-engineered hMSCs remained viable and preserved their characteristic immunophenotype and multilineage differentiation potential. Although a modest reduction in migratory capacity was observed, FML-NLC-loaded hMSCs provided sustained extracellular drug release and exerted a potent anti-inflammatory effect on inflamed corneal epithelium. Overall, these findings demonstrate that nano-engineered hMSCs with FML-NLCs act as an effective intermediate pharmacokinetic compartment that generates a biologically regulated extracellular drug release profile and represent a promising platform for the targeted treatment of inflammatory ocular surface diseases. These findings provide the basis for future in vivo proof-of-concept studies and support the subsequent clinical translation of this strategy for the treatment of LSCD.