MIT scientists, working with the Broad Institute, have found a new way to give aging immune systems a temporary boost. Instead of trying to fix the worn-out thymus—the organ that normally helps your body make new T cells—they found a workaround. They taught the liver, which still works well even as we get older, to step in and pick up the slack.
Here’s the problem
With age, our immune system changes it’s not the same what it used to be. The thymus gland, train T cells to fight infections and cancer cells, shrinks and basically shuts down. That means less new T cells, weaker defenses, and inferior responses to vaccines or cancer treatments.
The MIT scientists team choose not to struggle with nature by trying to regrow the thymus. Instead, they used mRNA technology (the same kind used in COVID vaccines) to send new instructions straight to the liver. They picked the liver because it’s good at making proteins, easy to reach with modern drug delivery methods, and it naturally interacts with blood and immune cells.
Here’s how it works
The researchers figured out that three key signals—DLL1, FLT-3, and IL-7—are missing in older people because the thymus isn’t making them anymore. So, they packaged the genetic blueprints for these signals into tiny mRNA-filled lipid nanoparticles. When inserted, these elements head directly to the liver, where liver cells start thrusting out the missing immune-boosting features. Suddenly, the liver acts like a temporary backup for the thymus, sending out signals that help build a stronger, more diverse T cell army.
In tests with older mice (roughly comparable to middle-aged humans), several rounds of the mRNA treatment over a month made a real difference. The mice produced more T cells, and those cells were better at responding to vaccines. The treatment also made cancer immunotherapy more effective—mice with tumors lived longer when they got both the mRNA boost and standard cancer drugs, compared to mice that didn’t.
Of course, we’re not there yet for humans. The MIT scientist team still needs to test this method in bigger animals, finding out if other features could help even more, and understand how it moves other important immune cells like B cells. But if it works, this strategy might one day help older adults respond better to vaccines, fight off infections, and make cancer treatments hit harder—something we’ll need more and more as the world’s population ages.
All in all
MIT’s creative use of mRNA to reprogram the liver is opening up new possibilities in the fight against immune aging. By pacing in when the thymus drops the ball, this method could help humans to keep our immune systems strong and healthy as we grow older. It’s a glimmer of hope for healthier aging and better disease protection down the road.