The imbalance in the gut microbiome plays a vital role in the progression of many diseases, including cancer, due to increased inflammation in the body. Since gut microbiome-induced inflammation can serve as a novel therapeutic strategy, there is an increasing need to identify novel approaches to investigate the effect of inflammation instigated by gut microbiome on cancer cells. However, there are limited biomimetic co-culture systems that allow testing of the causal relationship of the microbiome on cancer cells. Here we developed a microfluidic chip that can simulate the interaction of the gut microbiome and cancer cells to investigate the effects of bacteria and inflammatory stress on cancer cells in vitro. To test the microfluidic chip, we used colorectal cancer cells, as an increased microbiome abundance has been associated with poor outcomes in colorectal cancer. We cultured colorectal cancer cells with Bacillus bacteria or lipopolysaccharide (LPS), a purified bacterial membrane that induces a significant inflammatory response, in the microfluidic device. Our results showed that both LPS and Bacillus significantly accelerated the growth of colorectal cancer cells, therefore supporting that the increased presence of certain bacteria promotes cancer cell growth. The microfluidic device included in this study may have significant implications in identifying new treatments for various cancer types in the future.

Background: Cancer is the second leading cause of death globally and ~39.5% of people will be diagnosed with cancer at some point during their lifetimes. Thus, there is an unmet need to identify novel strategies for early cancer detection and prevention. The emerging evidence suggests that the gut microbiome has a role in promoting cancer. This microbiome including bacteria plays a vital role in maintaining homeostasis in the body. An imbalance in bacterial composition may cause diseases including cancer. Here we developed a microfluidic chip that can accurately simulate the gut microbiome to test the effects of bacteria and therapies on cancer cells. Methods and Results: To test the causal effect of bacteria on cancer, we developed a new high-throughput microfluidic device for simulating the environment of the gut. Initially, we used the photolithography technique where we designed the chip in AutoCAD and fabricated using photoresist resins and Polydimethylsiloxane (PDMS). Next, we tested the effect of bacteria on the growth of colorectal cancer cells. For this, we cultured colorectal cancer cells (HCT-116) with lipopolysaccharide (LPS), which is found in the outer membrane of bacteria, as well as the Bacillus bacteria in our microfluidics. Our data show that both LPS and Bacillus significantly accelerate the growth of cancer cells 2.02 times (p value = 0.012) and 1.58 times (p value = 0.011), respectively, over a 4 day culture period. These results show that the increased presence of certain bacteria can promote cancer cell growth and that our chip can be used to test the specific correlation between bacteria and cancer cell growth. The previously described method was inefficient and time-consuming. To overcome this limitation, we designed a new chip that allows running 16 samples at once with improved efficiency and accuracy. The template of the device that had 16 microfluidic channels was printed by a 3D printer and used for PDMS replica molding. The PDMS device was attached to the modified multiwell plate to feed media to and collect waste from each channel in a high-throughput manner. In the initial design, the bacteria grew faster than cancer cells taking over the chips. Our new design has dual layered chambers to keep bacteria and cancer cells separated by a membrane, allowing only bacterial secretions to pass through the membrane to cancer cells, mimicking the human gut. The new design also allowed the chip to maintain continuous microfluidic flow and a hypoxic environment. Conclusion: Our research demonstrates that the new microfluidic device has broader implications including simulating other body organs such as the lung and liver, and testing the impact of viruses such as influenza and COVID-19 on human cells. This device can be used to test both the effect of bacteria and new treatment on clinical samples for the identification of personalized therapy, thus reducing the need for mouse model testing, which is a lengthy and expensive process. Citation Format: Ekansh Mittal, Young Bock Kang. Microfluidics: Simulating the gut microbiome for early cancer detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6031.

The gut microbiome has a role in the growth of many diseases such as cancer due to increased inflammation. There is an unmet need to identify novel strategies to investigate the effect of inflammation mediated by gut microbiome on cancer cells. However, there are limited biomimetic co-culture systems that allow to test causal relationship of microbiome on cancer cells. Here we developed a microfluidic chip that can simulate the interaction of the gut microbiome and cancer cells to test the effects of bacteria and inflammatory stress on cancer cells in vitro. To quantify the effect of bacteria on the growth of colorectal cancer cells, we cultured colorectal cancer cell line with Bacillus or lipopolysaccharide (LPS), which is a purified bacterial membrane and induce major inflammatory response, in the PDMS microfluidic device. We found that both LPS and Bacillus significantly accelerate the growth of colorectal cancer cells. These results show that the increased presence of certain bacteria can promote cancer cell growth and that these microfluidic chips can be used to test the specific correlation between bacteria and cancer cell growth. These microfluidic devices can have future implications for various cancer types and to identify treatment strategies.