The liver plays a vital role in human health, regulating metabolism and blood nutrient levels, filtering toxins, and synthesizing important proteins for blood clotting. It is also sensitive to changes in diet, behavior, and environmental factors, meaning it will also respond to changes in gravity. Despite considerable research into liver metabolism and function aboard the International Space Station (ISS), unanswered questions remain about how liver cells sense gravity and convert mechanical stress into metabolic responses.

While the research has suggested a strong link between microgravity and the accumulation of fatty cells in liver tissue, knowing how this process is triggered is key to developing mitigation strategies. To address this, a team of Chinese scientists investigated the effects of microgravity on two cultures of liver cells, one aboard the Tiangong space station and the other on Earth. Their results offer some potential solutions for monitoring and mitigating the effects of microgravity on the liver.

The team was led by Professor Mian Long from the Institute of Mechanics, Chinese Academy of Sciences. He was joined by researchers from the Center for Biomechanics and Bioengineering, the Beijing Key Laboratory of Engineered Construction and Mechanobiology, the Key Laboratory of Microgravity, the University of Chinese Academy of Sciences, and the Key Laboratory of Biorheological Science and Technology. Their work is detailed in a paper published in Science Bulletin.

Understanding the effects of microgravity on liver health is paramount for astronauts on future deep-space missions. Credit: Li, N. et al. (2026)

Research conducted aboard the ISS has consistently shown a link between microgravity and hepatic lipid metabolism, the process by which the liver regulates energy balance by synthesizing, breaking down, and transporting fats. This is characterized by neutral lipids accumulating within the primary tissue cells of the liver (hepatocytes), responsible for bile secretion, glucose regulation, lipid uptake, and urea production. Research has also shown that prolonged exposure to microgravity leads to an increased risk of metabolic dysfunction–associated steatotic liver disease (MASLD).

Increased lipid dysregulation and hepatic damage constitute major health risks for astronauts engaged in future deep-space exploration missions. To investigate the mechanics of spaceflight and liver function, the team cultured two hepatocyte samples in a Biomechanics Experiment Module (BMEM). One sample was sent to the Tiangong space station while the other remained on Earth. These samples were divided into three experimental groups based on culturing and exposure to shear flow stress.

This stress simulated the normal movement of fluid within the liver (i.e., blood flow), specifically in the area between hepatocytes and sinusoidal endothelial cells. The samples were then observed for nine days to monitor for any changes. The results showed that spaceflight promotes the synthesis of fatty acids and cholesterol by activating sterol regulatory element-binding proteins (SREBPs), effectively demonstrating that SREBPs could serve as gravity-sensitive regulators of lipid accumulation in hepatocytes.

The results further indicate that SREBPs have potential as therapeutic targets for maintaining liver health during long-duration space missions. In addition, analysis of the samples upon their return to Earth showed that shear flow exerted a protective effect, partially mitigating lipid dysregulation. In short, the tests demonstrated a means to monitor liver function in space while offering a mitigation strategy for future missions.

Further Reading: Science China Press, Science Bulletin

A longtime El Segundo resident was arrested earlier this month after installing unauthorized stop signs at a neighborhood intersection he says has become increasingly dangerous for children.

Joseph Brandlin, 44, who has lived in El Segundo more than four decades, said he took matters into his own hands after months of unsuccessful attempts to get city officials to address safety concerns about the intersection of Loma Vista Street and Acacia Avenue.

The intersection is currently a two-way stop and is located near Acacia Park, a children’s park that reopened after renovation in 2021.

“I care deeply about the safety of our neighborhood and the families that live here,” Brandlin said.

Brandlin raised concerns about the intersection last year. He and other residents submitted a petition with roughly 50 signatures requesting additional stop signs. The city later said it conducted a traffic evaluation, but residents were not notified when it took place and saw no visible evidence of it, according to Brandlin.

El Segundo resident Joseph Brandlin was arrested earlier this month after installing unauthorized stop signs and painting “STOP” at a neighborhood intersection.

(Joseph Brandlin)

The city ultimately determined the intersection did not meet the required traffic volume for additional stop signs, Brandlin said.

But residents say that the city’s standard doesn’t reflect reality.

“There’s a park right there, and it’s a magnet for children,” said Gary Sanders, 62, a resident in the neighborhood for more than 30 years. He noted that drivers traveling downhill toward the intersection often gain speed and may not anticipate pedestrians crossing.

On weekends and after school, the area becomes especially busy with families and parked cars, according to Sanders.

“A tragedy could occur,” he said. “I wonder if a tragedy does have to occur for the city to do something about it.”

A resident walks his dog toward the intersection of Loma Vista Street and west Acacia Avenue in El Segundo, where resident Joseph Brandlin installed two new stop signs and painted a “Stop” sign in white paint on the street.

(Gina Ferazzi / Los Angeles Times)

In the weeks leading up to his arrest, Brandlin said he witnessed several near-collisions, including incidents involving children.

He described a close call involving his son, who was nearly hit while on a bike due to limited visibility at the intersection.

“That was the last straw,” he said.

Brandlin spent approximately $1,000 of his own money on commercial-grade materials, including 30-inch reflective stop signs matching the other ones on the street. He began installing them himself to replace the yellow posted crosswalk signs on the intersection in the early morning of March 14, according to the El Segundo Police Department.

Police arrested him around 1:30 a.m. while he worked on the second direction of traffic. Brandlin said the arrest was excessive, saying he was cited with multiple charges, including felonies.

The charges include interfering with a traffic control device, grand theft, and vandalism exceeding $400, Sgt. Paul Saldana of the El Segundo Police Department said.

Joseph Brandlin said he attended many El Segundo City Council meetings asking the city to install stop signs but, the city ignored his concerns. So, he decided to take matters into his own hands.

(Gina Ferazzi/Los Angeles Times)

He was taken to a nearby jail and released later the morning of March 14, with a citation, according to police. His court date is scheduled for June.

Despite the legal consequences, several residents expressed support for Brandlin’s actions and expressed broader concerns about safety.

“I think it is a huge issue,” said Amanda Pruett, a local nanny and parent. “Our kids’ safety is very important.”

Pruett said she has frequently witnessed unsafe driving in the area and believes additional stop signs could help reduce risk.

Numerous residents told a Times reporter that they’ve seen dangerous driving through that intersection for years, and one said their cat was hit by a car.

Following Brandlin’s arrest, residents quickly organized. Brandlin gathered 73 letters in 24 hours from nearby households urging the city to take action.

On March 17, he presented the letters at a City Council meeting held days after his release.

“I’m asking the council for a straightforward action to install stop signs on intersection of Loma Vista Street and Acacia Avenue, or complete and transparent evaluation with the community,” Brandlin said.

The incident prompted debate about how cities respond to community safety concerns and what happens when residents feel ignored.

El Segundo resident Joseph Brandlin was arrested earlier this month after installing unauthorized stop signs at a neighborhood intersection he says has become increasingly dangerous for children.

(Joseph Brandlin)

Brandlin said he has reached out to city officials but has not received a response.

“The city just wasn’t listening,” he said.

El Segundo officials did not respond to a request for comment from The Times.

Brandlin’s case is not an isolated incident. Across Los Angeles, residents and activists have increasingly taken street safety into their own hands, often out of frustration with delays in city response.

In Sawtelle, community members painted crosswalks near Stoner Park after raising concerns about pedestrian safety in an area frequented by families, schools and day cares. The city initially removed the markings, citing accessibility requirements, before later reversing course and installing permanent crosswalks following public outcry.

Similar efforts have appeared in Koreatown, where a group of activists painted a crosswalk at an intersection where a 9-year-old boy was fatally struck by a vehicle. The action was part of a broader movement by residents who say safety improvements often take too long or never come at all.

Tensions between residents and city officials have led to arrests.

In Westwood, an activist with the group People’s Vision Zero was cited for vandalism while painting a crosswalk without a permit, highlighting the legal risks of unauthorized safety efforts.

As Brandlin’s case moves forward, the intersection remains unchanged, and residents continue to push for the installation of stop signs.