LASSS muscle repair study finds stronger signal in aging-related pathway

A new LASSS muscle repair study from Kyushu University reports that a sulfur-based compound strengthened a protein signal involved in rebuilding damaged skeletal muscle. The finding could help researchers develop ways to preserve muscle repair as aging, bed rest or inactivity weaken the body’s ability to recover.

The work, led by Professor Ryuichi Tatsumi of Kyushu University’s Faculty of Agriculture, was published July 24, 2026, in Scientific Reports. The study focused on lipoic acid trisulfide, or LASSS, and its interaction with hepatocyte growth factor, known as HGF.

How could LASSS help muscle repair?

HGF is a protein that helps start skeletal muscle repair. Under ordinary conditions, it sits inactive in the structural network around muscle fibers; after injury or mechanical stimulation, it is released and binds to c-met receptors on satellite cells, the stem cells that maintain and repair muscle.

That binding signal prompts satellite cells to leave their resting state, multiply, mature and contribute to rebuilding muscle fibers, according to Kyushu University. The researchers said aging can interfere with the system because HGF can be chemically altered through nitration, which adds a nitro group at two sites, called Y198 and Y250.

Those two sites sit in the region HGF uses to connect with c-met. Tatsumi’s team previously reported that nitrated HGF loses its ability to attach effectively to the receptor, a change the researchers link to weaker regeneration and muscle wasting in older adults.

What the researchers tested

The Kyushu University team examined two trisulfide compounds with antioxidant properties: glutathione trisulfide, or GSSSG, and LASSS. Trisulfides contain three sulfur atoms in a chain and are being studied in pharmaceutical research because of their sulfur chemistry and role in redox reactions.

In early experiments, both compounds reduced nitration at the Y198 and Y250 sites on HGF. Neither fully restored HGF’s receptor binding at the first tested ratio, so the researchers raised the amount of trisulfide relative to HGF from 1:4000 to 1:8000.

At the higher concentration, LASSS produced a result not seen with GSSSG. HGF mixed with LASSS bound to c-met at more than twice the level of untreated HGF and was more resistant to nitration-related loss of function, especially at the Y198 site, according to the study.

The researchers said the result suggests LASSS may do more than neutralize reactive molecules. Their interpretation is that LASSS may interact directly with HGF and cause a subtle structural change, producing a more active form of the protein with stronger receptor affinity and better resistance to nitration.

Mouse results and next steps

To test whether the effect could appear in living tissue, the team used a mouse model of muscle atrophy caused by tail suspension. Mice treated with LASSS before the procedure had significantly lower nitration levels than untreated mice, while GSSSG did not show measurable protection, Kyushu University reported.

The study does not establish LASSS as a treatment for age-related muscle loss. The researchers said further studies in aging animals are needed to assess safety and effectiveness in vivo.

Kyushu University said the findings may support future approaches to maintaining muscle repair during aging, long periods of inactivity and extended bed rest. The team also said the effect could potentially apply across species, including humans and companion animals such as cats and dogs, but that remains a future research question.

Journal reference: Kahona Zushi and colleagues, “Enhanced HGF with increased receptor affinity and nitration-dysfunction resistance through interaction with lipoic acid trisulfide,” Scientific Reports, 2026, DOI: 10.1038/s41598-026-60835-w.

This story draws on original reporting from ScienceDaily.