Experimental Treatment Kept Muscle on ‘Mighty Mice’ in Space

 

Scientists say an experimental treatment helped "mighty¹ mice" keep healthy muscle mass during a recent stay in space of one month.

The treatment might one day prevent muscle and bone loss in astronauts during long periods in space. It could also be used to treat people suffering muscle or bone loss on Earth.

Astronauts in space live in an environment of microgravity, or weightlessness. This environment can cause muscles and bones to weaken and lose mass over time.

The U.S. space agency NASA has developed specialized² exercise programs for astronauts living on the International Space Station. The goal of the exercises is to limit muscle and bone loss.

But such programs are likely to be ineffective during very long space missions planned by NASA for the future, such as extended stays on the moon or Mars. The "Mighty Mice in Space" experiment was created to test a possible preventive treatment for muscle and bone loss during long space missions.

The project involved 40 female mice that were launched into space on a SpaceX rocket last December. The animals lived on the International Space Station for 33 days before returning to Earth in January.

Sixteen mice were given the experimental treatment, which involved a genetic⁴ engineering method. Researchers removed a gene³ responsible for producing myostatin, a protein that controls and can limit the growth of muscles and bone.

The mice that lacked the myostatin gene – the so-called mighty mice – showed muscle growth during the experiment.

Eight of these mice had at least twice the muscle mass of the untreated mice before being sent to space. The researchers said during their stay on the space station, these mice kept their muscle mass. Their muscles appeared very similar to the other mighty mice kept back on Earth at NASA's Kennedy Space Center.

The 24 mice that did not get the treatment lost a lot of muscle and bone mass in space, the researchers reported. Those mice lost between eight and 18 percent of weight in individual muscles compared to the mice on Earth. They also lost up to 11 percent of bone mineral density⁵ - a measure of bone strength.

Eight of the mice received another compound from astronauts on the space station. That compound has been found to block a protein that limits muscle and bone growth. The mice given this treatment in space gained 27 percent lean body weight, compared to 18 percent in mice on the ground. The mice receiving the compound – both in space and on the ground – also had increases in bone mineral density, the researchers found.

Some of the untreated mice were given the treatments after returning to earth. They quickly built up more muscle than untreated mice in the laboratory, the researchers reported.

The research was led by a team from the Jackson Laboratory, a nonprofit biomedical research center based in Bar Harbor, Maine. Results recently appeared in a study published in Proceedings⁶ of the National Academy of Sciences.

Jackson Laboratory's Dr. Se-Jin Lee was the lead writer of the study. He told The Associated Press the experiment identified additional molecules⁷ and signaling pathways relating to muscle and bone loss that could use more investigating. He said he would also like to send more "mighty mice" to the space station for additional study.

Lee's wife, Emily Germain-Lee of Connecticut Children's Medical Center, also took part in the study. While excited by the findings, she told the AP much more work is needed before the treatment can be tested on humans to build up muscle and bone.

"We're years away. But that's how everything is when you go from mouse to human studies," Germain-Lee said.

I'm Bryan Lynn.

Words in This Story

mighty – adj. very large, powerful or important

mission – n. an important task, usually involving travel somewhere

lean – adj. thin and healthy

1 mighty   

adj.强有力的；巨大的

参考例句：

• A mighty force was about to break loose.一股巨大的力量即将迸发而出。
• The mighty iceberg came into view.巨大的冰山出现在眼前。

2 specialized   

adj.专门的，专业化的

参考例句：

• There are many specialized agencies in the United Nations.联合国有许多专门机构。
• These tools are very specialized.这些是专用工具。

3 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

4 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

5 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

6 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

7 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。