People with type 1 diabetes are particularly at risk of high acid levels. Their bodies produce no insulin, the hormone that regulates blood sugar levels, so their cells cannot absorb any glucose from the blood and have to tap into another energy source: fat reserves.
If the lack of insulin is not noticed or treated in time, people with type 1 diabetes can die from ketoacidosis metabolic shock resulting from an excess of beta-hydroxybutyrate, an acid which supplies the muscles and brain with energy via the bloodstream.
Bioengineers from ETH Zurich's Department of Biosystems Science and Engineering (D-BSSE) in Basel have now developed a new implantable molecular device composed of two modules: a sensor that constantly measures blood pH and a gene feedback mechanism that produces the necessary amount of insulin.
They constructed both modules from biological components, such as various genes and proteins, and incorporated them into cultivated renal cells.
Researchers then embedded millions of these customised cells in capsules which can be used as implants in the body.
The heart of the implantable molecular device is the pH sensor, which measures the blood's precise acidity and reacts sensitively to minor deviations from the ideal pH value.
If the pH values falls below 7.35, the sensor transmits a signal to trigger the production of insulin. Such a low pH value is specific for type 1 diabetes: although blood pH also drops due to alcohol abuse or exercise on account of the over-acidification of the muscles, it does not fall below 7.35.
The hormone insulin ensures that the normal cells in the body absorb glucose again and switch from fat to sugar as their energy source for metabolism, and the pH value rises again as a result.
Once blood pH returns to the ideal range, the sensor turns itself off and the reprogrammed cells stop producing insulin.
The researchers have already tested their invention on mice with type 1 diabetes and related acidosis.
The results look promising: mice with the capsules implanted produced the amount of insulin appropriate to their individual acid measurements.
The hormone level in the blood was comparable to that of healthy mice that regulated their insulin levels naturally. The implant also compensated for larger deviations in blood sugar.