Delivery of DNA octahedra enhanced by focused ultrasound with microbubbles for glioma therapy.

DNA nanostructures, with good biosafety, highly programmable assembly, flexible modification, and precise control, are tailored as drug carriers to deliver therapeutic agents for cancer therapy. However, they face considerable challenges regarding their delivery into the brain, mainly due to the blood-brain barrier (BBB). By controlling the acoustic parameters, focused ultrasound combined with microbubbles (FUS/MB) can temporarily, noninvasively, and reproducibly open the BBB in a localized region. We investigated the delivery outcome of pH-responsive DNA octahedra loading Epirubicin (Epr@DNA-Octa) via FUS/MB and its therapeutic efficiency in a mouse model bearing intracranial glioma xenograft. Using FUS/MB to locally disrupt the BBB or the blood-tumor barrier (BTB) and systemic administration of Epr@DNA-Octa (Epr@DNA-Octa + FUS/MB) (2 mg/kg of loaded Epr), we achieved an Epr concentration of 292.3 ± 10.1 ng/g tissue in glioma, a 4.4-fold increase compared to unsonicated animals (p < 0.001). The in vitro findings indicated that Epr released from DNA strands accumulated in lysosomes and induced enhanced cytotoxicity compared to free Epr. Further two-photon intravital imaging of spatiotemporal patterns of the DNA-Octa leakage revealed that the FUS/MB treatment enhanced DNA-Octa delivery across several physiological barriers at microscopic level, including the first extravasation across the BBB/BTB and then deep penetration into the glioma center and engulfment of DNA-Octa into the tumor cell body. Longitudinal in vivo bioluminescence imaging and histological analysis indicated that the intracranial glioma progression in nude mice treated with Epr@DNA-Octa + FUS/MB was effectively retarded compared to other groups. The beneficial effect on survival was most significant in the Epr@DNA-Octa + FUS/MB group, with a 50% increase in median survival and a 73% increase in the maximum survival compared to control animals. Our work demonstrates the potential viability of FUS/MB as an alternative strategy for glioma delivery of anticancer drugs using DNA nanostructures as the drug delivery platform for brain cancer therapy.