Targeted Delivery of CD34 Aptamer-Coupled Tocilizumab Microspheres for Effective Treatment of Thyroid-Associated Ophthalmopathy.

PURPOSE: Thyroid-associated ophthalmopathy (TAO) is a debilitating autoimmune disorder linked to Graves' disease (GD) that is characterized by inflammation and remodeling of orbital tissues. This study focuses on the use of poly(lactic-co-glycolic) acid (PLGA)-based microspheres (MS) coupled with CD34-specific aptamers to enhance the targeted delivery of Tocilizumab (Toc), an IL-6 receptor monoclonal antibody, to CD34+ orbital fibroblasts, which is a critical cell type implicated in TAO. METHODS: The flow cytometry and aptamer-mediated pull-down assays were applied to detect the affinity of CD34 aptamers (Apts) for CD34+ orbital fibroblasts. The CD34 Apt-modified Toc-loaded MS (Toc-MS-CD34 Apt) were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and agarose gel electrophoresis. The CCK-8 assay kit was used to examine cell viability. The EdU assay was used to assess cell proliferation. The scratch wound healing assay was applied to detect cell migration. RESULTS: The affinity of CD34 aptamers for CD34+ orbital fibroblasts was confirmed, demonstrating high specificity and binding strength. The Toc-MS-CD34 Apt exhibited size uniformity and successful aptamer conjugation. In vitro, studies showed that Toc-MS-CD34 Apt effectively inhibited the viability, proliferation and cell activation, extracellular matrix (ECM) protein expression, and migration of TGF-β1-stimulated CD34+ orbital fibroblasts. In vivo, a TAO mouse model treated with anti-mouse IL-6R microspheres (anti-mmu-IL-6R-MS) and CD34 aptamer-modified anti-mmu-IL-6R microspheres (anti-mmu-IL-6R-MS-CD34 Apt) demonstrated significant reductions in tissue inflammation, fibrosis, and ECM protein levels, with notable inhibition of the STAT3 signaling pathway. CONCLUSIONS: These findings highlight the potential of CD34 aptamer-coupled Toc microspheres as a targeted therapy for TAO, providing a comprehensive strategy that addresses local manifestations of the disease.