By Kaitlyn Schaeffer
Dr. Mark Donowitz at Johns Hopkins School of Medicine is interested in ridding the world of diarrheal disease-related deaths. Every year, more than 800,000 children succumb to diseases such as cholera, rotavirus, and some strains of the bacteria E. coli.
“We’ve failed so far to find drugs to treat diarrhea using cell culture models and mouse intestine,” Donowitz explained. Mice guts are just not sufficiently similar to the human gut to provide guidance in solving these issues.

So Donowitz and his team of medical researchers have turned to a higher-tech solution: developing artificial human organs on microchips. These palm-sized creations are designed to mimic the functions of actual organs, so they can be used to help understand healthy and diseased organ functioning, as well as assist in the development of pharmaceuticals. The organs-on-a-chip are inch-long sheets of glass that host a tiny plastic microscope slide and a small cavity. Six cables protrude from the microchip.

“The reason we have so many tubes is we have a vacuum chamber that will cause the membrane to stretch, the way the intestine stretches as it moves food along,” explains postdoctoral researcher Jennifer Foulke-Abel.

The lab will extract human intestinal cells to implant into a chamber that surrounds the vacuum membrane; these cells will divide, grow, and organize the same way they would in a human gut. When fully functioning, the device will host as many as 50,000 cells.

So far, the organs-on-a-chip appear to be good models for getting a handle on human disease: in all three of the diseases mentioned by Dr. Donowitz, he and his team have been able to take the first steps to understanding the complex human processes associated with diarrheal problems.

However, organs-on-a-chip are still a working project: while artificial guts can produce digestive enzymes, hormones, and mucus, they are not yet capable of incorporating other important components of the human digestive system, such as blood vessels and nerve cells. “They all have to be incorporated if you want to move from a simple to a more complex system,” explains Dr. Donowitz, “which I think you need to do if you are going to reproduce intestinal biology.” His lab is working to realize these advancements, and once a complete system is artificially constructed, they believe it will be useful for determining which potential drugs could help combat the diseases being studied.

“We think this could be a real step forward in terms of reducing waste-of-time drug development,” explains Donowitz.

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