Bioengineers from ETH Zurich’s Department of Biosystems Science and Engineering in Basel have created a prototype implantable molecular device which regulates the blood pH levels through a closed loop pH sensing and insulin production mechanism.
Normal metabolic function requires acid levels in the body to be tightly regulated. If the pH level of the blood strays too far from a narrow band of healthy values there are severe consequences in the form of impaired organ function, seizures, shock, and possibly death.
pH regulation is particularly problematic in people with type 1 diabetes. As their bodies do not produce their own insulin, their cells metabolize fat reserves. This in turn produces beta-hydroxybutyrate in the liver, an acid which serves as an energy source when blood glucose is low. If the liver produces too much beta-hydroxybutyrate the blood’s pH value can drop to dangerous levels, a condition known as acidosis.
The molecular device was designed from various genes and proteins and comprises a pH sensing element and a gene feedback mechanism which produces insulin. The pH sensor monitors the blood’s acidity with a high degree of precision and reacts to minor deviations from the ideal pH value. If the pH value dips below 7.35, a critically low value for people with type 1 diabetes, the pH sensor triggers insulin production. The insulin causes the cells to metabolise glucose instead of fat reserves and returns the blood pH to a healthy level.
To date the researchers have tested their device in mice with type 1 diabetes and related acidosis. Effective insulin production was observed in mice with the implanted capsules, having hormone levels comparable to that of healthy mice. The implant was able to successfully counteract the effects of significant changes in blood sugar levels.
While the present system is an initial proof of concept, the team have recognized possible applications for human implants, though it would require significant time and resources to take to market. The system design and test results have been published in the journal Molecular Cell.
Study abstract: A Synthetic Multifunctional Mammalian pH Sensor and CO2 Transgene-Control Device
Press release: Sensitive acid sensor controls insulin production