Pancreas from hydrogel

The "smart gel" will replace electronics and inject the right dose of insulin for diabetes by itself

Anna Kaznadzei, N+1

Japanese scientists have created a system for automatic delivery of insulin into the blood without electronic control. It is made on the basis of a synthetic polymer with boronic acid residues, which changes the permeability depending on the glucose level in the medium. Diabetic patients with such a system will not have to adjust insulin doses themselves, since the system will inject them into the blood automatically. The article with the description was published in Science Advances (Matsumoto et al., Synthetic “smart gel” provides glucose-responsive insulin delivery in diabetic mice).

Diabetes mellitus is a very common disease in which glucose uptake is disrupted due to absolute or partial insufficiency of the hormone insulin. Insulin is produced by the pancreas and is necessary to maintain a certain level of glucose in the blood. With its lack, glucose levels grow uncontrollably, which in severe diabetes can lead to hyperglycemic coma and death. As of 2016, 422 million people with diabetes of varying severity were registered in the world. On average, 8.5 percent of adults have diabetes.

There are systems for automatic delivery of insulin. At the moment, the most common system of this kind is an electronic "open" system that determines the level of glucose, with which a person himself controls the supply of insulin to the blood. However, such a method, on the one hand, is often associated with inaccuracies in dose calculations, and on the other hand, it turns out to be too complicated for some patients (for example, for the elderly or, conversely, for young children).

The technology developed by Akira Matsumoto and his colleagues is based on the work of a "smart gel". This gel is sensitive to the level of glucose in the blood and independently delivers the necessary dose of insulin into the blood through a catheter. This happens as follows: when there is a lot of glucose in the blood, the gel becomes more permeable, and more insulin enters the blood through it. When the glucose level drops, the gel, on the contrary, becomes impenetrable, like skin, and the supply of insulin to the blood stops.

The use of hydrogels to determine glucose levels is not a new idea, but technologies that have been tested before (for example, gels based on glucose oxidase and lectins) turned out to be too unstable and, often, cytotoxic (caused pathological changes in cells). In this case, scientists have created a synthetic non-protein polymer structure. Its action is based on the sensitivity to glucose of boronic acid (HB(OH)2). By binding to glucose, the residue of this acid changes the permeability of the entire polymer, and the shell that "holds back" the flow of insulin into the blood in the catheter becomes more permeable.

The principle of operation of the gel with the remnants of boronic acid

The system was tested first in vitro, on fibroblasts, and then in vivo, on mice with different types of diabetes and a control group of mice. Her work was observed for three weeks and achieved positive results: after eating in mice with diabetes, in which the right amount of insulin is not produced in the body, the glucose level first increased, the gel became more permeable, after which the right amount of insulin entered the blood. The glucose level in the blood decreased to normal values after 15 minutes.

The scheme of operation of the catheter with insulin

Scientists note that in comparison with electronic mechanisms, such a device is much cheaper, easier to operate and has a large margin of safety.

And you can read about the treatment of diabetes using the effects of signaling molecules on brain cells here.

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