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Oral Insulin Delivery: Can the Tortoise Win the Race?

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Turtle shape compared to capsule shape
Caption: The African leopard tortoise’s shape inspired a new insulin-injecting “pill” (right). Credit: Alex Abramson

People with diabetes often must inject insulin multiple times a day to keep their blood glucose levels under control. So, I was intrigued to learn that NIH-funded bioengineers have designed a new kind of “pill” that may someday reduce the need for those uncomfortable shots. The inspiration for their design? A tortoise!

The new “pill”—actually, a swallowable device containing a tiny injection system—is shaped like the shell of an African leopard tortoise. In much the same way that the animal’s highly curved shell enables it to quickly right itself when flipped on its back, the shape of the new device is intended to help it land in the right position to inject insulin or other medicines into the stomach wall.

The hunt for a means to deliver insulin in pill form has been on ever since insulin injections first were introduced, nearly a century ago. The challenge in oral delivery of insulin and other “biologic” drugs—including therapeutic proteins, peptides, or nucleic acids—is how to get these large biomolecules through the highly acidic stomach and duodenum, where multiple powerful digestive enzymes reside, and into the bloodstream unscathed. Past efforts to address this challenge have met with only limited success.

In a study published in the journal Science, a team, led by Robert Langer at Massachusetts Institute of Technology, Cambridge, and Giovanni Traverso, Brigham and Women’s Hospital, Harvard Medical School, Boston, took a new approach to the problem by developing a tiny, ingestible injection system [1]. They call their pea-sized device SOMA, short for “self-orienting millimeter-scale applicator.”

In designing SOMA, the researchers knew they had to come up with a design that would orient the injection apparatus correctly. So they looked to the African leopard tortoise. They knew that, much like a child’s “weeble-wobble” toy, this tortoise can easily right its body if tipped over due to its low center of gravity and highly curved shell. With the shape of the tortoise shell as a starting point, the researchers used computer modeling to perfect their design. The final result features a partially hollowed-out, polymer-and-steel capsule that houses a tiny, spring-loaded needle tipped with compressed, freeze-dried insulin. There is also a dissolvable sugar disk to hold the needle in place until the time is right.

Here’s how it works: once a SOMA is swallowed and reaches the stomach, it quickly orients itself in a way that its needle-side rests against the stomach wall. After the protective sugar disk dissolves in stomach acid, the spring-loaded needle tipped with insulin is released, injecting its load of insulin into the stomach wall, from which it enters the bloodstream. Meanwhile, the spent SOMA device passes on through the digestive system.

The researchers’ tests in pigs have shown that a single SOMA can successfully deliver insulin doses of up to 3 milligrams, comparable to the amount a human with diabetes might need to inject. The tests also showed that the device’s microinjection did not damage the animals’ stomach tissue or the muscles surrounding the stomach. Because the stomach is known for being insensitive to pain, researchers expect that people receiving insulin via SOMA wouldn’t feel a thing, but much more research is needed to confirm both the safety and efficacy of the new device for human use.

Meanwhile, this fascinating work serves as a reminder that when it comes to biomedical science, inspiration sometimes can come from the most unexpected places.

Reference:

[1] An ingestible self-orienting system for oral delivery of macromolecules. Abramson A, Caffarel-Salvador E, Khang M, Dellal D, Silverstein D, Gao Y, Frederiksen MR, Vegge A, Hubálek F, Water JJ, Friderichsen AV, Fels J, Kirk RK, Cleveland C, Collins J, Tamang S, Hayward A, Landh T, Buckley ST, Roxhed N, Rahbek U, Langer R, Traverso G. Science. 2019 Feb 8;363(6427):611-615.

Links:

Diabetes (National Institute of Diabetes and Digestive and Kidney Diseases/NIH)

Langer Lab (MIT, Cambridge)

Giovanni Traverso (Brigham and Women’s Hospital, Harvard Medical School, Boston)

NIH Support: National Institute of Biomedical Imaging and Bioengineering


The Actin Superhighway

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Actin Superhighway

Credit: Andrew Lombardo and David Warshaw, University of Vermont, Burlington

What looks like a traffic grid filled with roundabouts is nothing of the sort: It’s actually a peek inside a tiny microchamber that models a complex system operating in many of our cells. The system is a molecular transportation network made of the protein actin, and researchers have reconstructed it in the lab to study its rules of the road and, when things go wrong, how it can lead to molecular traffic accidents.

This 3D super-resolution image shows the model’s silicone beads (circles) positioned in a tiny microfluidic-chamber. Suspended from the beads are actin filaments that form some of the main cytoskeletal roadways in our cells. Interestingly, a single dye creates the photo’s beautiful colors, which arise from the different vertical dimensions of a microscopic image: 300 nanometers below the focus (red), at focus (green), and 300 nanometers above the focus (blue). When a component spans multiple dimensions—such as the spherical beads—all the colors of the rainbow are visible. The technique is called 3D stochastic optical reconstruction microscopy, or STORM [1].


Building a Smarter Bandage

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Smart Bandage

Credit: Tufts University, Medford, MA

Smartphones, smartwatches, and smart electrocardiograms. How about a smart bandage?

This image features a prototype of a smart bandage equipped with temperature and pH sensors (lower right) printed directly onto the surface of a thin, flexible medical tape. You also see the “brains” of the operation: a microprocessor (upper left). When the sensors prompt the microprocessor, it heats up a hydrogel heating element in the bandage, releasing drugs and/or other healing substances on demand. It can also wirelessly transmit messages directly to a smartphone to keep patients and doctors updated.

While the smart bandage might help mend everyday cuts and scrapes, it was designed with the intent of helping people with hard-to-heal chronic wounds, such as leg and foot ulcers. Chronic wounds affect millions of Americans, including many seniors [1]. Such wounds are often treated at home and, if managed incorrectly, can lead to infections and potentially serious health problems.


Does Gastric Bypass Reduce Cardiovascular Complications of Diabetes?

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Doctor with patient

Thinkstock/IPGGutenbergUKLtd

For obese people with diabetes, doctors have increasingly been offering gastric bypass surgery as a way to lose weight and control blood glucose levels. Short-term results are often impressive, but questions have remained about the long-term benefits of such operations. Now, a large, international study has some answers.

Soon after gastric bypass surgery, about 50 percent of folks not only lost weight but they also showed well-controlled blood glucose, cholesterol, and blood pressure. The good news is that five years later about half of those who originally showed those broad benefits of surgery maintained that healthy profile. The not-so-good news is that the other half, while they generally continued to sustain weight loss and better glucose control, began to show signs of increasing risk for cardiovascular complications.


Creative Minds: Designing Personalized Clinical Trials

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Karina Davidson

Karina Davidson/Jörg Meyer

It might have been 25 years ago, but Karina Davidson remembers that day like yesterday. She was an intern in clinical psychology, and two concerned parents walked into the hospital with their troubled, seven-year-old son. The boy was severely underweight at just 37 pounds and had been acting out violently toward himself and others. It seemed as though Ritalin, a drug commonly prescribed for Attention Deficit Disorder, might help. But would it?

To find out, the clinical team did something unconventional: they designed for the boy a clinical trial to test the benefit of Ritalin versus a placebo. The boy was randomly assigned to take either the drug or placebo each day for four weeks. As a controlled study, neither clinical staff nor the family knew whether he was taking the drug or placebo at any given time. The result: Ritalin wasn’t the answer. The boy was spared any side effects from long term administration of a medication that wouldn’t help him, and his doctors could turn to other potentially more beneficial approaches to his treatment.

Davidson, now an established clinical psychologist at the Columbia University Irving Medical Center, New York, wants to take the unconventional approach that helped this boy and make it more of the norm in medicine. With support from a 2017 NIH Director’s Transformative Research Award, she and her colleagues will develop three pilot computer applications—or digital platforms—to help doctors conduct one-person studies in their offices.


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