Originally published 2019-08-31.
LIFNano is an experimental approach to multiple sclerosis (MS) developed by Cambridge immunologist Dr Su Metcalfe. It packs a natural repair protein called leukaemia inhibitory factor (LIF) inside tiny particles that dissolve in the body, so the protein survives long enough to reach the immune system and the brain. The idea is promising, and it has produced encouraging results in mice, but it has not been shown to cure MS in people. As far as published reports go, it is still a preclinical treatment.
The story spread widely in 2019 under headlines suggesting a cure was close. Below is what the research actually proposes, why the delivery method matters, what the animal studies found, and how to read news like this when you or someone you love lives with MS.
What multiple sclerosis does to the nervous system
MS is a long-term autoimmune disease. The immune system, which should only attack invaders, turns on myelin: the fatty coating that wraps nerve fibres in the brain and spinal cord and helps electrical signals travel quickly. Where myelin is stripped away, signals slow down or fail, and repeated attacks leave scar-like patches called plaques.
About 3.1 million people worldwide were living with MS in 2024. It usually begins between the ages of 20 and 40, and women are two to three times more likely to develop it than men. Around 85% of people start with the relapsing-remitting form, where flare-ups are followed by partial or full recovery. Others have a steadily progressive course from the beginning, or move into a progressive phase years later.
The exact cause is still unknown, but one risk factor stands out. A large study of US military personnel found that infection with the Epstein-Barr virus raised the risk of MS roughly 32-fold, while other common viruses did not.
The immune "switch" behind the LIFNano idea
Metcalfe developed her approach while working in the University of Cambridge's department of surgery, studying what stops the immune system from attacking healthy tissue. Her work focused on T lymphocytes, the white blood cells that direct many immune attacks. She described a kind of binary switch inside these cells that sets them either as protectors that keep the peace or as aggressors that damage tissue. In MS, the theory goes, too many cells are flipped into attack mode.
LIF is the molecule she linked to keeping that switch on the "friendly" setting. It is a small signalling protein belonging to the interleukin-6 family of cytokines, the chemical messengers cells use to talk to each other. Its name is historical: it was first identified because it pushed leukaemia cells in the lab to mature and stop dividing. Since then it has turned up in many roles, from embryo implantation to the development of nerve cells. Stem cell laboratories routinely add it to culture dishes because it helps embryonic stem cells keep renewing themselves.
In the nervous system, LIF is thought to protect nerve cells and support the cells that maintain myelin. That is why it is attractive for MS: in principle, one molecule could both calm the misguided immune response and help the brain repair itself. Metcalfe summed up the target in an interview: "The most urgent need is for a treatment that protects the brain."
Why LIF needs a nanoparticle carrier
The obvious problem is that LIF does not last. Injected on its own, the protein is broken down within minutes, far too fast to do useful work. Reports differ on the exact figure; the 2017 trade-press profile of the company put it at about ten minutes.
The solution was to hide LIF inside biodegradable nanoparticles. "Nano" simply refers to size: these particles are measured in billionths of a metre, small enough to interact with individual cells. They are made from the same kind of material used in dissolvable surgical stitches. As the particles slowly break down, they release their cargo over time, and the shell itself ends up as carbon dioxide and water.
The particles can also be steered. Later versions were coated so they latch onto CD4 T cells, a type of immune cell that can cross the blood-brain barrier. The researchers called this a "Trojan horse": the immune cell carries the hidden medicine into the brain, which is normally very hard for drugs to reach.
What the animal studies found
Metcalfe founded LIFNano as a University of Cambridge spin-out in 2013, with engineering work carried out alongside Yale University. By late 2017 the company said its first product had proved safe and effective in animal models of MS. It had won industry awards and funding from Merck and the UK government, and it hoped to begin human trials as early as 2020, a date Metcalfe herself called ambitious.
In 2021 the team published a preclinical proof-of-concept study in the journal Frontiers in Medical Technology. In healthy mice, a dye carried by the CD4-targeted particles was found in many tissues after six hours, but only in the brain after 24 hours. Particles loaded with human LIF raised LIF levels in the brain. In a mouse model that mimics progressive disease, treatment reversed some paralysis within four days and lowered an inflammatory signal called IL-6 in the brain. In a relapsing model, the treatment did not prevent relapses, but animals recovered from them faster at higher doses.
These are real, interesting results. They are also mouse results, from a study carried out by the company developing the therapy, and the reported trial dates have come and gone without published human data.
Common myths about this story
"A cure for MS has been found"
No. The Spanish fact-checking site Maldita.es rated the "scientists about to cure MS" headlines as false in 2019. The story grew out of a Cambridge business school article about a start-up seeking investors, which tabloids turned into cure headlines. Good News Network's August 2019 article, which this page originally drew on, repeated the hopeful framing, and its author later noted that human trials had not yet started.
"It works with no side effects"
Side effects can only be known after careful testing in people. Even in the 2021 mouse study, the two higher doses caused mild, short-lived effects in healthy animals; only the lowest dose did not.
"Existing treatments don't help"
There is no cure for MS, but that is not the same as having nothing. Disease-modifying therapies reduce relapses and slow progression for many people, steroids are used for severe attacks, and physiotherapy and other support help manage symptoms. What researchers like Metcalfe are chasing is the missing piece: a treatment that protects and repairs the brain rather than only holding the immune system back.
How to read MS research headlines
A few questions sort hopeful science from hype. Was the work done in cells, animals or people? Has it been published in a peer-reviewed journal, or only described in a press release or investor pitch? Who carried out the study, and has anyone independent repeated it? And is there a registered clinical trial with dates and results?
For LIFNano, the honest answers are: animals, partly published, company-led, and no human results yet. That still makes it a project worth following. It addresses a real gap, and the "Trojan horse" delivery idea could matter for other brain diseases too.
If you have MS and are curious about experimental treatments, talk to your neurologist or MS nurse. They can tell you which trials are recruiting and whether any might suit you.
Sources: Pharmaceutical Technology (30 November 2017): LIFNano, can nanotech flip the switch to cure multiple sclerosis?; Multiple Sclerosis News Today (20 May 2021): Early study supports nanoparticle delivery of LIF to the brain; Maldita.es fact-check (June 2019); Good News Network (August 2019), original report; Wikipedia: Leukemia inhibitory factor; Wikipedia: Multiple sclerosis.
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