Scientists at The Ohio State University have built tiny drug-delivery particles from the lipids of expired red blood cells, showing in mouse trials that the particles can avoid immune detection and reach cancer cells. The study was published in Advanced Healthcare Materials.
The particles are called engineered extracellular vesicles. Extracellular vesicles are naturally occurring particles that cells release to carry signals to other cells. The Ohio State team used the lipids from donated, expired red blood cells to construct their own version, with more control over what goes inside and how the particles are built.
The key to building the vesicles is a manufacturing process called microfluidics. It allows researchers to load therapeutic cargo into the particles as they form, rather than in a separate step afterward. That cargo can include genetic material, proteins, or whole viruses used in gene therapy.
"In terms of lipid composition, they basically match very closely with what the natural extracellular vesicles from red blood cells would have," said senior author Eduardo Reátegui, professor of chemical and biomolecular engineering at Ohio State. "We are keeping some of the great biological advantages that these particles have by themselves because they are very biocompatible."
In mouse trials, the engineered vesicles stayed in circulation and spread to multiple organs in patterns similar to naturally produced vesicles. There was notable accumulation in the lungs.
The red blood cells used as raw material come from the lab of co-author Andre Palmer, a professor of chemical and biomolecular engineering and an Ohio Eminent Scholar at Ohio State. His lab normally extracts hemoglobin from expired blood to make red blood cell substitutes. The leftover cell material now has a new use.
"We're always purifying hemoglobin from expired red blood cells," said Palmer. "The approach here is very sustainable because these expired red blood cells would otherwise be thrown out since they cannot be transfused into patients."
The team was clear about what they are claiming and what they are not. The goal was not to prove their process superior to existing methods but to demonstrate a higher degree of control over the final product.
"We're not saying our process is better. We're claiming that we have a lot more controllability in terms of what we want the composition of this engineered vesicle to look like," said Reátegui.
Reátegui is also a member of the Cancer Biology program at Ohio State. The researchers said the vesicles could eventually be used for tumor targeting, gene therapy delivery, and other medical treatments, though further research is needed before any clinical application.
