Appendicitis.

Anti-angiogenic therapies targeting the vascular endothelial growth factor (VEGF) axis have achieved transient benefits, as tumors rapidly activate compensatory vascular programs. Here, we present a bioinspired nanoplatform that reproduces the anti-angiogenic signaling of mesenchymal-stromal-cell-derived extracellular vesicles (EVs) by delivering the endogenous metalloproteinase inhibitor tissue inhibitor of metalloproteinases-1 (TIMP-1). Poly(methyl methacrylate) nanoparticles (NP_TIMP1) were engineered to retain TIMP-1 bioactivity, inhibit matrix metalloproteinase activity, and efficiently interact with endothelial cells. In vitro, NP_TIMP1 suppressed endothelial sprouting and tip-cell formation in 2-dimensional and 3-dimensional microfluidic systems. In zebrafish patient-derived xenografts of Ewing sarcoma, NP_TIMP1 localized to tumor-associated vessels and substantially reduced vascular infiltration, reproducing the efficacy of TIMP-1-enriched EVs. In contrast, soluble TIMP-1 failed to elicit these effects, indicating that nanoparticle-mediated delivery enhances protein stability and spatial engagement with the endothelium. This study establishes TIMP-1 as a key stromal regulator of angiogenesis and demonstrates that EV-mimetic nanoparticles can recapitulate its therapeutic potential, providing a scalable bioengineering approach to overcome the limitations of natural vesicles and develop next-generation anti-angiogenic nanotherapeutics.