Precious Cargo: Scientists Hijack Red Blood Cells to Serve as Potential Therapeutic Delivery System

A unique property of red blood cells is now being harnessed to help deliver microscopic cargo to sites throughout the body, according to research published today in the Proceedings of the National Academy of Sciences.

There are anywhere from 3 to 6 million red blood cells in the human body at any given time, and they are tasked with one main job: transport oxygen throughout the body. But researchers, led by Drs. Harvey Lodish and Hidde Ploegh from the Whitehead Institute, wondered if these cells could transport other important molecules. As Lodish explained in today’s news release:

“We wanted to create high-value red blood cells that do more than simply carry oxygen. Here we’ve laid out the technology to make mouse and human red blood cells that…can potentially be used for therapeutic purposes.”

Red blood cells are unusual in that, once mature, they ditch their nucleus—and the DNA housed within. This is an attractive characteristic for a potential therapy: without any genetic material, there is no risk that manipulating the DNA could result in later tumor formation.

So Lodish, an expert in the biology of red blood cells, and his team used this characteristic to their advantage. They introduced a set of genes into early stage red blood cells, called ‘progenitors,’ that still had their nucleus. These genes, when activated instructed the cell to produce a particular type of protein that latched itself to the surface of the cell. Then, when the cells matured and jettisoned their nuclei, the proteins remained on the cells’ surface.

And while this method, called ‘sortagging,’ here involved a protein sticking to the cellular surface, the researchers argue that the same method could be applied to stick virtually any type of molecule to the cell. As Ploegh explained:

“Because the modified human red blood cells can circulate in the body for up to four months, one could envision a scenario in which the cells are used to introduce antibodies that neutralize a toxin. The result would be long-lasting reserves of antitoxin antibodies.”

The research team envisions this approach being useful for everything from carrying proteins to break up blood clots to those that alleviate chronic inflammation. One of the most exciting possibilities, according to Ploegh, would be using this method to suppress the body’s unwanted immune response after being treated with protein-based therapies.

The possibilities, it would seem, are endless.

Anne Holden