A rapid screening platform to coculture bacteria within tumor spheroids

Area of Science:

• Microbiology
• Cancer Biology
• Synthetic Biology

Background:

• Living microbial cancer therapies are emerging, driven by tumor-colonizing bacteria and synthetic biology advancements.
• Engineering bacteria to produce therapeutics within tumors necessitates high-throughput screening platforms to assess bacterial candidates and their interactions with cancer cells.

Purpose of the Study:

• To describe a novel protocol for selectively growing bacteria within tumor spheroids for continuous, parallel profiling.
• To establish a robust platform for studying bacteria-tumor interactions and accelerating the development of engineered microbial therapies.

Main Methods:

• A bacteria spheroid coculture (BSCC) system was developed using 96-well low-adhesion plates.
• The protocol involves incubating tumor spheroids with bacteria, followed by washing and antibiotic selection to confine bacterial growth to the spheroid core.
• The system is compatible with time-lapse microscopy, staining assays, and histology for analyzing growth kinetics, viability, and spatial distribution.

Main Results:

• The BSCC system demonstrated stability for over 2 weeks under physiologically relevant conditions.
• The protocol is adaptable to various tumor cell types and bacterial species, with validation in animal models.
• The platform enables continuous monitoring and analysis of bacteria-tumor interactions.

Conclusions:

• The BSCC platform provides a simple, equipment-independent method for studying engineered bacteria in a tumor microenvironment.
• This system facilitates the rapid development and characterization of novel microbial cancer therapies.
• The BSCC platform is crucial for advancing the field of precision oncology with microbial interventions.