Here’s what you’ll learn when you read this story:The immune system function declines with age, but a team of MIT researchers may have found a way to rejuvenate it. When older mice were injected with mRNA that coded for the creation of protein-signaling pathways involved in immune response, they experienced drastic improvement. This treatment has not yet been tested in humans, but could one day mitigate effects of aging. Immune function declines over time because the production of T-cells decreases, but there might soon be a way to reverse that dropoff. The mRNA was carried there by lipid nanoparticles, and once these particles accumulated in the liver, hepatocytes (liver cells) began to create them.