Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA.
Department of Biochemistry, Institute for Protein Design and Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA.
Nat Commun. 2022 Mar 24;13(1):1585. doi: 10.1038/s41467-022-29065-2.
Rapid advances in synthetic biology are driving the development of genetically engineered microbes as therapeutic agents for a multitude of human diseases, including cancer. The immunosuppressive microenvironment of solid tumors, in particular, creates a favorable niche for systemically administered bacteria to engraft and release therapeutic payloads. However, such payloads can be harmful if released outside the tumor in healthy tissues where the bacteria also engraft in smaller numbers. To address this limitation, we engineer therapeutic bacteria to be controlled by focused ultrasound, a form of energy that can be applied noninvasively to specific anatomical sites such as solid tumors. This control is provided by a temperature-actuated genetic state switch that produces lasting therapeutic output in response to briefly applied focused ultrasound hyperthermia. Using a combination of rational design and high-throughput screening we optimize the switching circuits of engineered cells and connect their activity to the release of immune checkpoint inhibitors. In a clinically relevant cancer model, ultrasound-activated therapeutic microbes successfully turn on in situ and induce a marked suppression of tumor growth. This technology provides a critical tool for the spatiotemporal targeting of potent bacterial therapeutics in a variety of biological and clinical scenarios.
合成生物学的快速发展推动了基因工程微生物作为治疗多种人类疾病（包括癌症）的治疗剂的发展。特别是，实体瘤的免疫抑制微环境为系统性给予的细菌定植和释放治疗有效载荷创造了有利的小生境。然而，如果在细菌定植数量较少的健康组织中释放这些有效载荷，它们可能会造成伤害。为了解决这个限制，我们设计了治疗性细菌，使其受到聚焦超声的控制，聚焦超声是一种可以非侵入性地应用于特定解剖部位（如实体瘤）的能量形式。这种控制是通过温度激活的遗传状态开关提供的，该开关在短暂应用聚焦超声热疗时产生持久的治疗输出。我们通过合理设计和高通量筛选相结合，优化了工程细胞的开关电路，并将其活性与免疫检查点抑制剂的释放联系起来。在一个临床相关的癌症模型中，超声激活的治疗性微生物成功地原位激活，并显著抑制肿瘤生长。这项技术为在各种生物学和临床情况下对强效细菌治疗剂进行时空靶向提供了一个关键工具。
