Stem cell vesicles restore liver function in aging mice

As the liver ages, fat accumulates in liver cells. This can lead to non-alcoholic fatty liver disease (NAFLD), a condition rising sharply worldwide. A central part of the problem is autophagy (the process by which cells remove their own damaged components). Autophagy declines with age, causing fat droplets to build up. Researchers looked for a way to restore it using exosomes: small vesicles that cells secrete to exchange signals with other cells.

Exosomes from umbilical cord stem cells tested

The team used exosomes derived from mesenchymal stem cells taken from human umbilical cord tissue. These were injected into 18-month-old mice (a relatively advanced age for mice) and compared with young untreated mice and an untreated old control group.

According to the researchers, the treatment substantially improved liver markers. Four indicators of liver damage (ALT, AST, triglycerides, and total cholesterol) were markedly elevated in untreated old mice. After exosome treatment, those values declined, in some cases to near the levels seen in young mice. Lipid deposition in liver tissue also visibly decreased.

Autophagy partially restored, fat storage reduced

The researchers also observed changes in proteins that regulate fat storage and breakdown. SREBP1, a protein that promotes fat accumulation, was elevated in old mice but fell after treatment. PPARalpha, a protein that promotes fat breakdown, increased. This suggests the exosomes at least partially restored autophagy.

This is a mouse study, conducted exclusively in male animals. Whether this mechanism translates to humans is unknown. Exosome-based therapies are still at an early stage of development. Nevertheless, from a longevity perspective the results offer an intriguing pointer: restoring cellular autophagy via exosomes may have a role to play in slowing liver aging.

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