Science & Technology



Meet the Penn engineer who delivers mRNA inside human cells

Tom Avril, The Philadelphia Inquirer on

Published in Science & Technology News

PHILADELPHIA -- Messenger RNA became a household term when it was used as the backbone of the first COVID-19 vaccines, especially after the Nobel Prize was awarded to two mRNA pioneers at the University of Pennsylvania.

But the fragile genetic molecules would be useless for vaccines and other emerging treatments if they could not be delivered inside the body.

That’s where Michael J. Mitchell comes in.

An associate professor of bioengineering at Penn, Mitchell is an expert in lipid nanoparticles, the tiny, fatty droplets that are used to carry mRNA inside human cells.

The vaccines used lipid nanoparticles to deliver mRNA to immune cells in the arm. That’s just the beginning of the potential applications in medicine. Mitchell is now tweaking the chemistry of these lipids to deliver cutting-edge treatments against cancer and other diseases to hard-to-reach organs such as the lungs and brain.

In an interview with The Inquirer, Mitchell described how the nanoparticles are made, how he is designing them to target various organs, and what steps he is taking to improve their efficiency.


This conversation has been edited for length and clarity.

Who came up with the idea of lipid nanoparticles?

The idea of using lipids to encapsulate various types of drugs for delivery has been around for several decades. In the context of mRNA delivery, in the early 2000s, the major discovery was creating what is known as the ionizable lipid nanoparticle [meaning it changes its electric charge in order to release its medicinal cargo].

Part of the reason they go into cells so well is because cell membranes are made of lipids. Lipid nanoparticles (LNPs) have an affinity for fusing with those membranes.


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