Travel in space and your joints

A new study from the Henry Ford Hospital on mice on board a Russian space flight could pose an intriguing question to tomorrow's astronauts: could traveling in space be bad for your joints?

The researchers found early signs of cartilage rupture in mice, suggesting that the reduced biomechanical forces of space flight play on the musculoskeletal system.

Although it is premature to pass on this discovery to humans, this study, the first of its kind, adds to a growing body of research on the effects of spaceflight on the health of the system. musculoskeletal. Research has shown that living and working in space causes many changes in the human body, including the immune system, blood pressure and eye shape.

The study is published online in npg Microgravity, member of the Nature Partner Journals Publishing Group.

Jamie Fitzgerald, Ph.D., head of musculoskeletal genetics at the Henry Ford Orthopedic Surgery Department and lead author of the study, says that evidence of articular cartilage rupture in mice was "clearly established".

"We believe that this degradation is due to the joint unloading caused by the almost insufficient lack of gravity in the space," he said. "If it were to happen to the man, if he had enough time, it would cause major joint problems."

The researchers assume that because biomechanical forces in space are different from those on Earth, changes in the musculoskeletal system occur.

"We know that the tissues of the musculoskeletal system – bone, muscle, tendon, cartilage and ligament – are constantly being" loaded "all over the world," says Dr. Fitzgerald.

"This comes from daily activities like walking and lifting, and the action of gravity on the musculoskeletal system. When this loading is removed due to weightlessness and gravity almost nil in space, these tissues begin to degrade.The most striking example is the atrophy of muscles and bone demineralization during space flight.

"This loss of muscle and bone is reversed when astronauts return to Earth.What is interesting about cartilage is that it is a tissue that repairs very badly. important question of whether the cartilage is also degrading in the space. "

For the study, funded by a $ 100,000 NASA grant, Dr. Fitzgerald and his research team analyzed molecular changes in the cartilage of mice that spent 30 days in animal research enclosures aboard 'an unmanned Russian spacecraft Bion-M1 in 2013. They included stains and studies of gene expression on cartilage. The results were compared to mice observed on Earth during the same period.

Dr. Fitzgerald said the changes were consistent with those associated with osteoarthritis.

"Overall, we can say that after 30 days of microgravity, the process of cartilage degradation started," he said. "We found changes in the expression of genes consistent with cartilage degradation."

The video footage taken with the mice showed them floating in their pens during the day. At night, the footage showed that they were struggling to climb on it and hang on the grill inside the enclosure. "The mice suffered some load on the joints while they were trying to hook up to each other.This was not a complete unloading," says the Dr. Fitzgerald.

In comparison, mice on Earth showed no noticeable cartilage degradation.

"When there is no gravity on the cartilage, it is not able to maintain its structure, its integrity," says Dr. Fitzgerald. "On Earth, every time you step, you load that cartilage, and in space there is very little."

Mr Fitzgerald said that NASA wanted to better understand what is happening in the human body in space. More research is needed, he says, especially with a possible trip to Mars in the future.

"You may have payload specialists and experienced pilots already experiencing some degree of pre-symptomatic cartilage damage at the time of their flight," says Dr. Fitzgerald. "Because cartilage in humans does not repair easily, returning to Earth could lead to long-term health problems."