China Exclusive: Are human space babies conceivable? Tianzhou-1 experiment may give clue
Source: Xinhua|
2017-04-21 10:44:11|
Editor: Xiang Bo
By Xinhua writer Yu Fei
BEIJING, April 21 (Xinhua) -- As astronauts continue to break records for time spent in space and manned Mars exploration is under discussion, scientists in China have begun a groundbreaking study to determine if humans can reproduce in space.
Scientists will for the first time conduct an experiment to induce the differentiation of human embryonic stem cells into germ cells on China's first cargo spacecraft, Tianzhou-1.
The experiment aims to study the effects of the space environment on human reproduction, beginning with the study of microgravity on human stem cells and germ cells, says Kehkooi Kee, lead researcher on the project.
Kee, a Malaysia Chinese professor at China's prestigious Tsinghua University, says the unprecedented experiment will study the basic development and maturation of germ cells in the micro-gravity environment, and the developmental potential of human embryonic stem cells.
The research is expected to provide a theoretical basis and technical support to solve the possible problems of human reproduction caused by the space environment, Kee said.
"It's an important experiment because it is the first step towards directly understanding human reproduction during space exploration," he says.
What kind of difficulties could people face by having children in space?
Experts say that in the known space environment, micro-gravity, radiation and magnetic fields could have a great impact on human reproduction. Among these factors, micro-gravity could be the largest challenge.
At the cellular level, micro-gravity might affect cell division or polarity. The cells of living organisms contain many organic molecules. These molecules and cells are evolved to function under the earth gravitational force. But scientists are still not clear how micro-gravity could affect the physical force governing the molecular interactions and developments of the cells, says Kee.
The
United States,
Russia and Europe have conducted many space experiments to examine if micro-gravity is harmful to astronauts, especially the effects on the muscle and bones. However, microgravity effect on human reproductive capacity has been rarely studied.
Previous research in this area mainly focused on monitoring the reproductive hormone levels of astronauts. Due to the ethical and physical constraints, it has been very difficult to directly obtain and study their germ cells.
"If we aim to directly study human reproductive biology in space, we need to build an in-vitro platform to study the germ cells. So we chose to use human embryonic stem cells to differentiate into germ cells," says Kee.
In 2009, he and his colleagues used human embryonic stem cells to create human primordial germ cells and sperm-like cells for the first time. They published their research in the academic journal Nature.
Currently, the team has successfully obtained egg-like cells from human embryonic stem cells and will be publishing this novel finding soon.
Human embryonic stem cells can be induced into primordial germ cells and further differentiate into sperm-like or egg-like cells. But differentiating embryonic stem cells into sperm-like or egg-like cells is very difficult because they require more developmental steps and more cellular factors, says Kee.
Although other scientists have conducted similar experiments, none has made human germ cells differentiate into such a mature state as Kee's team has.
"We have compared the in-vitro cultured cells with in-vivo cells, and found they have many similar characteristics. But we can only call the in-vitro ones sperm-like cells or egg-like cells, because we still can't prove they are exactly the same until we conduct functional experiments," Kee says.
So far, all such experiments have been conducted on the ground, so scientists do not know whether micro-gravity will affect the differentiation of human embryonic stem cells and the formation of germ cells.
"In the experiments on the ground, it usually takes six days to culture and obtain primordial germ cells, and about two weeks to form sperm-like or egg-like cells," says Kee.
"The experiment on Tianzhou-1 will last 30 days. To what extent the human embryonic stem cell can differentiate in space is still unknown. Will the process be delayed? If so, by how much?" asks Kee, adding they expect to see at least the first stage of the primordial germ cells appear.
Scientists on the ground will remotely control the research equipment to change the cell-culture medium to induce the human embryonic stem cells to differentiate into germ cells. Images of the cells under the microscope will be transmitted to earth.
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China Exclusive: Scientists to test medicine for bone loss on Tianzhou-1
Source: Xinhua|
2017-04-21 11:09:15|
Editor: Xiang Bo
By Xinhua writer Yu Fei
BEIJING, April 21 (Xinhua) -- Scientists will test a medicine to treat bone loss during the maiden voyage of China's first cargo spacecraft Tianzhou-1. The medicine has been specially developed for astronauts, but they hope it will benefit ordinary people too.
The main mission of Tianzhou-1 launched on Thursday is to test propellant refueling technology, which is crucial for the construction and operation of China's planned space station. But each voyage is a precious opportunity to conduct space experiments.
Chinese scientists will use the micro-gravity environment to test the effect of 3-hydroxybutyric acid (3HB) in preventing osteoporosis, said research leader Chen Guoqiang ,who is also director of the Center for Synthetic and Systems Biology at Tsinghua University.
Normally, the solid structure of bone tissue is stimulated and maintained by gravity and physical exercise. But the micro-gravity environment in space eases the load on bones, causing rapid bone loss and osteoporosis, Chen said.
"One day of bone loss in space is equivalent to a year on earth," he said.
Research shows astronauts suffer average monthly bone loss of 0.5 percent to 2 percent in space, especially in weight-bearing bones such as the tibia, femur and vertebrae.
Back on earth, they can take double or triple the time of their flight period to recover. Sometimes bone loss is permanent.
Micro-gravity mainly inhibits the differentiation of osteoblasts (bone-forming cells), which is accompanied by the mass growth of osteoclasts (bone-resorbing cells), causing bone structure to change, said Chen.
Standard drug treatments for osteoporosis have a range of side effects, including tumors or cardiovascular diseases. The medicines are also relatively ineffective for treating osteoporosis caused by micro-gravity.
Chen said 3HB is one of the main components of ketone bodies, which occur naturally in mammals. It had been used to treat epilepsy for many years.
"We found that 3HB can promote bone formation," said Chen.
In an experiment simulating the micro-gravity environment, the effect was obvious.
Unlike the chemical synthetic 3HB for treating epilepsy, Chen's team use microbial fermentation to produce 3HB, which has entirely the same structure as the 3HB naturally existing in the human body. So it's safer than chemical synthetic drugs, Chen said.
Experiments simulating the micro-gravity environment have been conducted on the ground. Scientists hung up mice by their hind legs, and found that those given 3HB had normal bones, while those without suffered serious bone loss.
"We hope to test the effect of the medicine in a real space micro-gravity environment," Chen said.
Since Tianzhou-1 cannot carry animals, scientists will compare the osteoblast cell samples treated and not treated with 3HB. Microscope images of the samples will be transmitted to earth.
Although China has conducted many experiments on the
Shenzhou series spacecraft and the Tiangong-1 and Tiangong-2 space labs, opportunities for space experiments are still rare.
"After more than a decade of research we have one chance to conduct an experiment in space. We cherish the chance. We hope Chinese scientists will have more opportunities to conduct experiments in China's space station in future," Chen said.
Scientists believe the science and technologies developed in space exploration can benefit ordinary people. For instance, modern baby diapers were originally developed for astronauts on extended space walks. And the intensive care unit (ICU) system was first developed to monitor astronauts preparing to go to the moon in the 1970s.
The medicine for treating bone loss could also be used by ordinary people.
Osteoporosis is the seventh most common disease in the world. Each year it causes 8.9 million cases of fractures worldwide.
China has 90 million osteoporosis sufferers. The morbidity of osteoporosis among Chinese over 60 years old is 56 percent, while the rate among postmenopausal women is between 60 percent and 70 percent.
With China's aging population, osteoporosis cases will continue to rise. Experts estimate the number of patients in China will reach 200 million in 2050, accounting for 13.2 percent of the total population.
"We hope to solve this global problem," Chen said.
Long March long exposure: Launch of Tianzhou-1 via Long March 7 from Wenchang on April 20, 2017. (Photo: CASC)
) with a payload of 1500 kg, requiring the heavy-lift Long March 5 to take it to nearly 36,000 km above the Earth.
