Discovery of 18-Digit Code Unlocks Exosome-Based Drug Delivery

Researchers at The Ottawa Hospital and the University of Ottawa have discovered an 18-digit code that allows proteins to attach themselves to exosomes - tiny pinched-off pieces of cells that travel around the body and deliver biochemical signals. The discovery, published in Science Advances, has major implications for the burgeoning field of exosome therapy, which seeks to harness exosomes to deliver drugs for various diseases.

"Proteins are the body's own home-made drugs, but they don't necessarily travel well around the body," said Dr. Michael Rudnicki, senior author of the study and Director of the Regenerative Medicine Program at The Ottawa Hospital and Professor at the University of Ottawa.

This discovery allows us to harness exosomes to deliver any protein throughout the body. It opens the door to a whole new field of drug development."

Dr. Michael Rudnicki, Senior Author and Director, Regenerative Medicine Program, The Ottawa Hospital

Dr. Rudnicki and his team discovered the exosome-targeting postal code or zip code within a protein called Wnt7a, which plays a critical role in development, growth, regeneration and cancer. First, they showed that Wnt7a can attach itself to exosomes. Then, they deleted various parts of the Wnt7a protein until they found the smallest part that was responsible for exosome-targeting. They called this part, which consists of 18 amino acids, the Exosome Binding Peptide (EBP). They then discovered that the EBP binds to proteins called Coatomers on exosomes, and that EBP could be used to target any protein to exosomes.

"Researchers have been trying for years to turn Wnt7a into a muscle regeneration drug, but it is very difficult to deliver Wnt7a throughout the body, since it is covered in fatty molecules that don't mix well with body fluid," said first author Dr. Uxia Gurriaran-Rodriguez, a former postdoctoral fellow in Dr. Michael Rudnicki's group, who is now working at the Center for Cooperative Research in Biosciences (CIC bioGUNE) in Spain. "Now that we know how Wnt7a attaches to exosomes, we have solved this problem and can now accelerate the development of drugs for devastating diseases such as Duchenne muscular dystrophy."

Exosomes have become a major area of research for both academic labs and biopharmaceutical companies, with DelveInsight predicting "tremendous" growth in the field. The Ottawa Hospital, together with the University of Ottawa and other partners, has become a leader in combining exosomes with proteins, RNA and other biomolecules to develop new therapies. The Ottawa Hospital's Biotherapeutics Manufacturing Centre will continue to play a key role in translating this promising part of the life science innovation ecosystem for the benefit of patients.