Engineering inducible anhydrides for irreversible Red Blood Cell enzyme decoration

Many therapeutics drugs are cleared from the body in a matter of hours, so that people need to take the drug regularly to maintain the benefit. Red blood cells circulate around the bloodstream for 4 months. Therefore, binding to a red blood cell could allow drugs to be effective for much longer. Red blood cells are also important therapeutic vehicles because they move through all the blood vessels of the body, being involved in some of the most important diseases, namely heart attack, stroke and cancer growth. Our team has previously made advances enabling the production of red blood cells outside the body. We have also been able to remove many blood group markers from red blood cells, towards more universal cells for blood transfusion. The conventional way to bind protein drugs on the surface of red blood cells is through regular protein interactions like antibodies, which can fall off the red blood cell in hours. Through harnessing bacterial protein chemistry, we have identified a way to attach to specific cell-surface proteins and form an irreversible bond. This reaction is rapid and activated by calcium, providing gentle conditions for coupling to cells. Here we will use structure-based design and evolution to increase the speed, efficiency and general applicability of this irreversible protein reaction. We will then optimise the irreversible decoration of red blood cells with enzymes related to metabolic diseases or dissolving clots. Through this engineering of a new approach in protein chemistry, we can help red blood cells reach their potential as a cost-effective and long-lasting therapy.