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Microscale Mimic Of Human Ingestion

Microfluidics: A novel device simulates the journey that food and oral medications take through the body

by Rajendrani Mukhopadhyay
December 2, 2010 | A version of this story appeared in Volume 88, Issue 49

Credit: Anal. Chem.
Microfluidic channels connect microscale versions of organs to mimic human ingestion.
Credit: Anal. Chem.
Microfluidic channels connect microscale versions of organs to mimic human ingestion.

Next time you pop a pill, consider the route the medicine follows: from your mouth, through your digestive tract and liver, and to the organ where the chemical exerts its effects. Bioanalytical chemist Kiichi Sato and colleagues at the University of Tokyo have now developed a microfluidic device that mimics that journey (Anal. Chem., DOI 10.1021/ac100806x). They say it could be useful for applications such as drug screening and risk assessment of chemicals.

To understand the fate of chemicals that people ingest, scientists usually rely on animal models or cultured cells. But animal experiments are expensive, can be difficult to perform, and raise ethical issues. Meanwhile, because cell cultures contain only one cell type, they force scientists to ignore the chemical's effects on multiple cell types in an organ or on other organs in the body.

Microfluidic techniques have helped researchers develop tests that better reflect the complexities of the human body. These devices can simulate single organs, such as livers and lungs, with multiple cell types surrounded by channels that transport molecules, just as blood carries molecules around the body. Microfluidics needs only small amounts of reagents and cells, which keeps costs down.

But organs don't exist in isolation. Sato and colleagues wanted to watch what happened to a chemical in food or medicine as it traveled to several model organs one by one, just as it would in a human. They designed a three-stop organ journey in which a micro-intestine and micro-liver absorb and metabolize the chemical before passing it to breast cancer cells—the target tissue. The researchers bundled cells of those three organs onto a glass-and-plastic microfluidic chip that measured 7.5 by 2.5 cm. Samples entered the device through an inlet that led sequentially to the three chambers. At the final stop, the researchers could measure how the chemical affected the breast cancer cells.

Sato and his colleagues evaluated the device's performance using well-studied hormones, drugs, and nutrients. For example, the device's micro-intestine blocked intravenous drugs known to be held up by human intestines. Drugs with liver metabolites known to kill breast cancer cells also elicited the same effect in the model.

The device is an advance because it is a better representation than current microfluidic models of what happens to oral medicines and food in human bodies, says bioengineer Shuichi Takayama at the University of Michigan, Ann Arbor. He commends the researchers for the technical skill it took to incorporate several organ systems into a single microfluidic device.



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