Multi-functional nanosonosensitizer-engineered bacteria to overcome tumor hypoxia for enhanced sonodynamic therapy

Background

Ultrasound-triggered sonodynamic therapy (SDT), with high safety and acceptance, has become a promising tumor treatment. However, the dense stroma, hypoxic microenvironment of tumor, and the unpredictable treatment timing limit the effectiveness of sonosensitizers and the antitumor therapeutic effect. Thus, it is crucial to develop an imaging-guided sensitization strategy for hypoxic tumor sonosensitization to improve the efficacy of SDT.

Methods

In this study, we developed a biohybrid system CB@HPP, which genetically engineered bacteria to express catalase (CB) and modified nanosonosensitizers (HPP) to the surface of these bacteria. Tumor hypoxia relief, tumor targeting, biocompatibility, and antitumor efficacy were evaluated through in vitro and in vivo experiments. In addition, the photoacoustic (PA), ultrasound (US), and fluorescence (FL) imaging effects of CB@HPP were evaluated in vivo and in vitro.

Results

After intravenous injection, CB@HPP was able to target tumor tissue. CB@HPP possessed efficient catalase activity and successfully degraded hydrogen peroxide to produce oxygen. Increased oxygen levels relief intratumoral hypoxia, thereby enhancing CB@HPP-mediated. In addition, CB@HPP showed FL/PA/US multimodal imaging capabilities, which reflects the aggregation effect of CB@HPP in the tumor and suggest the timing of treatment.

Conclusion

The biohybrid system CB@HPP significantly alleviates tumor hypoxia, and multimodal imaging-mediated oxygen-producing SDT effectively suppresses tumors. This integrated imaging and therapeutic biohybrid system provides a more efficient and attractive cancer treatment strategy for SDT.

Statement of significance

This study developed a sensitizing SDT strategy for imaging-guided drug-targeted delivery and in situ oxygen production. We designed a biohybrid system CB@HPP, which was hybridized by the engineered bacteria with catalytic oxygen production and nanosonosensitizer with multimodal imaging capability. CB@HPP significantly alleviates tumor hypoxia, and multimodal imaging-mediated oxygen-producing SDT effectively suppresses tumors. This integrated imaging and therapeutic biohybrid system provides a more efficient and attractive cancer treatment strategy for SDT.