Ultrasound-Controlled Nano-Oxygen Delivery Modulates Endothelial Cells to Enhance Tumor Perfusion

The concept of vascular normalization represents a promising strategy for antitumor therapy. However, clinical translation of antiangiogenic agents to induce and sustain tumor vascular normalization remains hampered by acquired drug tolerance and dose-limiting systemic toxicities. Here, we demonstrate that focused ultrasound-stimulating oxygen nanobubbles (ONB_FUS) can effectively alleviate tumor hypoxia and drive vascular normalization, evidenced by improved intratumoral perfusion, reduced microvascular density, and increased pericyte coverage. During this normalization window, key proangiogenic signaling pathways, including VEGFA and ANGPT2, were significantly downregulated. Single-cell RNA sequencing of tumor endothelial cells (TECs) identified capillary endothelial cells (CapECs) as the primary responsive population, with selective depletion of the proangiogenic CapEC_Spp1⁺ subset. Clinical tumor samples corroborated these findings, showing elevated CapEC abundance and heightened ANGPT/VEGF pathway activity, specifically in high-proliferation CapECs. Functionally, ONB_FUS-mediated vascular repriming significantly enhanced intratumoral drug delivery and potentiated chemotherapy efficacy. Collectively, ONB_FUS offers a spatiotemporally controllable approach to vascular remodeling that complements standard-of-care therapeutics. Moreover, the identification of functionally distinct TEC subpopulations reveals mechanistically guided targets for precision antiangiogenic intervention.