Shu Takayama – Biomedical Engineering at the University of Michigan

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“Kidney on a chip” could lead to safer drug dosing

From: Gabe Cherry
Michigan Engineering

University of Michigan researchers have used a “kidney on a chip” device to mimic the flow of medication through human kidneys and measure its effect on kidney cells. The new technique could lead to more precise dosing of drugs, including some potentially toxic medicines often delivered in intensive care units.

Precise dosing in intensive care units is critical, as up to two-thirds of patients in the ICU experience serious kidney injury. Medications contribute to this injury in more than 20 percent of cases, largely because many intensive care drugs are potentially dangerous to the kidneys.

Determining a safe dosage, however, can be surprisingly difficult. Today, doctors and drug developers rely mainly on animal testing to measure the toxicity of drugs and determine safe doses. But animals process medications more quickly than humans, making it difficult to interpret test results and sometimes leading researchers to underestimate toxicity.

The new technique offers a more accurate way to test medications, closely replicating the environment inside a human kidney. It uses a microfluidic chip device to deliver a precise flow of medication across cultured kidney cells. This is believed to be the first time such a device has been used to study how a medication behaves in the body over time, called its “pharmacokinetic profile.”

“When you administer a drug, its concentration goes up quickly and it’s gradually filtered out as it flows through the kidneys,” said University of Michigan Biomedical Engineering professor Shuichi Takayama, an author on the paper. “A kidney on a chip enables us to simulate that filtering process, providing a much more accurate way to study how medications behave in the body.”

Takayama said the use of an artificial device provides the opportunity to run test after test in a controlled environment. It also enables researchers to alter the flow through the device to simulate varying levels of kidney function.

“Even the same dose of the same drug can have very different effects on the kidneys and other organs, depending on how it’s administered,” said Sejoong Kim, an associate professor at Korea’s Seoul national University Budang Hospital, former U-M researcher and author on the paper. “This device provides a uniform, inexpensive way to capture data that more accurately reflects actual human patients.”

In the study, the team tested their approach by comparing two different dosing regimens for gentamicin, an antibiotic that’s commonly used in intensive care units. They used a microfluidic device that sandwiches a thin, permeable polyester membrane and a layer of cultured kidney cells between top and bottom compartments.

Ryan Oliver, Post-Doctorate Researcher, demonstrates use of a special microchip that can simulate different organs and parts of the body. Photo by: Joseph Xu

They then pumped a gentamicin solution into the top compartment, where it gradually filtered through the cells and the membrane, simulating the flow of medication through a human kidney. One test started with a high concentration that quickly tapered off, mimicking a once-daily drug dose. The other test simulated a slow infusion of the drug, using a lower concentration that stayed constant. Takayama’s team then measured damage to the kidney cells inside the device.

They found that a once-daily dose of the medication is significantly less harmful than a continuous infusion—even though both cases ultimately delivered the same dose of medication. The results of the test could help doctors better optimize dosing regimens for gentamicin in the future. Perhaps most importantly, they showed that a kidney on a chip device can be used to study the flow of medication through human organs.

“We were able to get results that better relate to human physiology, at least in terms of dosing effects, than what’s currently possible to obtain from common animal tests,” Takayama said. “The goal for the future is to improve these devices to the point where we’re able to see exactly how a medication affects the body from moment to moment, in real time.”

Takayama said the techniques used in the study should be generalizable to a wide variety of other organs and medications, enabling researchers to gather detailed information on how medications affect the heart, liver and other organs. In addition to helping researchers fine-tune drug dosing regimens, he believes the technique could also help drug makers test drugs more efficiently, bringing new medications to market faster.

Within a few years, Takayama envisions the creation of integrated devices that can quickly test multiple medication regimens and deliver a wide variety of information on how they affect human organs. PHASIQ, an Ann Arbor-based spinoff company founded by Takayama is commercializing the biomarker readout aspect of this type of technology in conjunction with the University of Michigan Office of Technology Transfer, where Takayama serves as a Faculty Innovation Ambassador.

University of Michigan researchers used a “kidney on a chip” to mimic the flow of medication through human kidneys. This enabled them to study the dosing regimen for a common intensive care drug.

The paper, published in the journal Biofabrication, is titled “Pharmacokinetic profile that reduces nephrotoxicity of gentamicin in a perfused kidney-on-a-chip.” Funding and assistance for the project was provided by the National Institutes of Health (grant number GM096040), the University of Michigan Center for Integrative Research in Critical Care (MCIRCC), the University of Michigan Biointerfaces Institute, the National Research Foundation of Korea and the Korean Association of Internal Medicine Research Grant 2015.

The sweet smell of science: A failed candy recipe solves a sticky problem in the lab

By Gabe Cherry
Michigan Engineering

Anyone who has made Jello knows how difficult it can be to spring the wobbly treat from its mold intact. Now, imagine trying to dislodge something 10 times softer than gelatin, while keeping every detail unscathed down to a microscopic level. That was the problem faced by University of Michigan postdoctoral researcher Chris Moraes.

Moraes’s team, led by biomedical engineering professor Shu Takayama, was studying how scar tissue forms inside the body, specifically in the soft-celled lungs and liver. To do that, they were working with a type of silicone called Sylgard 527. It’s so soft that just a few cells can squeeze it out of shape.

“Soft silicone structures are useful for studying human cells outside the body,” Takayama said. “We can use them to measure the very small squeezing effect that cells generate during wound healing. This enables us to test the effects of drugs using very small samples of human cells, instead of testing on actual patients.”

Moraes wanted to mold the Sylgard into tiny pillars less than a millimeter wide, then position the cells around them in a donut shape. He could then apply different treatments to the cells and measure how much their expansion and contraction squeezed the pillars out of shape.

Molding those pillars, however, turned out not to be so simple. The team was using hard epoxy molds, and there was no way to remove the silicone pillars without turning them into useless lumps of goo.

The solution came when Moraes was at home in his kitchen. An avid cook, he was trying a new recipe for homemade cotton candy.

“The cotton candy was a total failure,” he said. “I ended up with nothing but a huge blob of sugar syrup. I gave up and left it to cool in the pan.”

But when he took the hardened mass out of the pan, he noticed something surprising: The sugar retained every detail of the pan it came out of. It got him thinking: why not use hardened sugar as a mold for super-soft silicone? They could pour in the silicone, wait for it to cure, then dissolve the mold in water, leaving perfectly cast pillars of soft silicone.

The next day, Moraes was in the lab, perfecting a recipe for sacrificial sugar molds. The recipe was simple: sugar, water and corn syrup, cooked in the microwave to just the right consistency.

“It smelled great,” said biomedical engineering doctoral student Joe Labuz, who also works on the project. “The trick is to caramelize the sugar, hardening it enough so that it doesn’t deform as the silicone cures. Eventually, we got it just right and also drew a crowd of our colleagues who wondered where the great smell was coming from.”

The sugar molds turn out perfect soft silicone pillars every time.

Joseph Labuz, BME PhD Student, puts sugar molds in a water bath for the casting of soft silicone pillars in the NCRC. Photo by: Joseph Xu

The pillar-making process begins with a hard epoxy “negative mold” – a mirror image of the sugar mold used to cast the final pillars. The researchers pour in hard silicone to create an initial plastic mold. Next, the molten sugar mixture is poured into this initial plastic mold and left to cool, hardening into what looks a lot like a piece of hard candy. The hardened sugar is popped out of the initial plastic mold and the sugar is then used as a mold for the silicone. The researchers pour the silicone into the sugar mold and cure the concoction in an oven. Finally, the silicone and sugar mold are put into a water bath. The sugar dissolves, while the water-repellent silicone stays intact.

The team is using the new process to better understand how scar tissue forms inside the body. Internal scarring is a common occurrence in diseases like cancer and diabetes, where the body tries to repair organ damage done by the disease. The formation of scar tissue can cause further problems by preventing organs from working properly.

“Scarring happens when the body’s healing process goes too far,” Takayama said. “If we can prevent it from happening or even reverse it, we could reduce the impact of a lot of diseases and create better outcomes for patients.”

The candy molding process is detailed in a paper published in the journal Lab on a Chip. Labuz says it can also be used other researchers to create virtually any type of soft silicone structure. In the meantime, they’re in the lab enjoying the sweet smell of science.

The paper is titled “Supersoft lithography: candy-based fabrication of soft silicone microstructures.” The work was supported by the National Science Foundation, National Institute of Health (grant numbers CA 170198 and AI116482) and the Natural Sciences and Engineering Research Council of Canada.

In vitro pregnancy rates improve with new device that mimics motions in the body

By Nicole Casal Moore
Michigan News

ANN ARBOR, Mich.—Gently rocking embryos while they grow during in vitro fertilization (IVF) improves pregnancy rates in mice by 22 percent, new University of Michigan research shows. The procedure could one day lead to significantly higher IVF success rates in humans.
Researchers built a device that imitates the motion that embryos experience in the body as they make their way down a mammal’s oviduct (a woman’s Fallopian tube) to the uterus. Currently in IVF, eggs are fertilized with sperm and left to grow for several days in a culture dish that remains still. Then the embryos are transferred to the uterus.

“By making the cells feel more at home, we get better cells, which is key to having better infertility treatment,” said Shu Takayama, an associate professor in the Department of Biomedical Engineering and in macromolecular science and engineering.

Takayama and Gary Smith, associate professor in the Department of Obstetrics and Gynecology at the U-M Medical Center, are co-authors of a paper detailing the findings published online in the journal Human Reproduction.

Their device holds early-stage embryos, which are about half the size of the period at the end of this sentence, in a thimble-sized funnel. The bottom of the funnel is lined with microscopic channels that allow fresh nutrient-rich fluid to flow in and waste products out. The funnel sits on rows of Braille pins that are programmed to pulse up and down, pushing the fluids in and out of the channels.

The current the Braille pins generate simulates flows that occurs in the body due to muscle contractions and the motion of hair-like projections called cilia that line the oviducts. In the body, these motions help to push fertilized eggs to the uterus and flush out eggs’ waste products.

Compared with mouse embryos grown in a static dish, those incubated in the new dynamic device were healthier and more robust after four days. Those grown in static dishes contained an average of 67 cells. Those grown in the new device had an average of 109. Control embryos that had matured in the bodies of mice for the same amount of time had an average of 144 cells.

Approximately 77 percent of the rocked mouse embryos led to ongoing pregnancies, compared with 55 percent of the statically-grown embryos. In a control group of mouse embryos conceived naturally and grown within the oviduct, 83 percent led to ongoing pregnancies.

“One of our goals for years now has been to modify how we grow embryos in the lab to be more like how they grow in the human body, because we know that the human body grows them most efficiently,” Smith said.

Infertility affects one in six couples, Smith said. Many of them turn to IVF, which can cost $15,000 per cycle and is often not covered by insurance. Currently, it has a success rate of about 35 percent.

“If we could increase that, even just to 45 percent, that’s significant,” Smith said. “We’re making healthier embryos, which not only can improve pregnancy rates, but also could allow us to transfer fewer embryos per cycle and reduce the incidence of twins and triplets.”

Through the company Takayama and Smith founded, Incept Biosystems, human clinical trials have begun.

Smith is also an associate professor in the departments of Molecular and Integrative Physiology and Urology, as well as director of the Reproductive Sciences Program.

The paper is called “Dynamic Microfunnel Culture Enhances Embryo Development and Pregnancy Rates.” The research is funded by the National Institutes of Health, the U.S. Department of Agriculture, the Michigan Economic Development Corp., the U.S. Army Research Laboratory and the Coulter Foundation.