Artificial blood developed in Japan: can be stored for one year, suitable for any blood type

We often see scenes in film and television dramas where patients with heavy bleeding need blood transfusions and blood banks are in a hurry. How good it would be if blood could be artificially manufactured like normal saline, regardless of blood type, and did not require strict storage conditions. Not long ago, according to Japan's "Asahi Shimbun", a Japanese research team based on the Japan Defense Medical University announced that they have successfully developed an artificial blood that can save many lives, which can be stored at room temperature for more than 1 year, without considering the problem of different blood types. At present, this artificial blood has been successfully experimented with experimental rabbits.

Artificial blood is not the whole blood of the human body, what is artificial blood?

Artificial blood can be achieved in two ways: the best-selling species refers to the biosynthesis of red blood cells, white blood cells and platelets with complete biological functions; The other is synthetic substitutes with the main function of red blood cells or platelets.

Zhou Jiaxi, a researcher at the Institute of Hematology of the Chinese Academy of Medical Sciences and the State Key Laboratory of Experimental Hematology of the Hospital of Hematology, pointed out that human whole blood is very complex, and artificial whole blood is almost impossible. The artificial blood currently studied is artificial blood with certain components of artificial blood, more commonly artificial red blood cells and platelets.

The artificial blood developed by the Japanese research team is mainly composed of artificial platelets and artificial red blood cells, and is made of a very tiny "bag" of a cell membrane component called liposome, and then filled with hemostatic components and components that can transport oxygen.

With the development of cell biology and in vitro culture technology, the use of stem cells in vitro culture to expand patient-specific blood cells (red blood cells, white blood cells and platelets) has become the mainstream research direction of artificial blood. Zhou Jiaxi introduced that in 2007, Japanese scientist Shinya Yamanaka and American scientist Thomson respectively transformed fibroblasts taken from the human oral epithelium or the skin behind the ear into pluripotent stem cells. That is to say, the cells that have differentiated and matured return to a more primitive state and regain the function of differentiating into different mature cells. From pluripotent stem cells, the ancestor cells of platelets, megakaryocytes, can be differentiated, and megakaryocytes can continuously provide the "mother" of platelets. Similarly, pluripotent stem cells can also be multiplified and differentiated into any cell in the blood, such as red blood cells. This artificial blood is not a synthetic blood substitute, but the real "blood" of the human body, and the safety is more guaranteed.

In addition to alleviating the lack of blood sources, what are the benefits of artificial blood?

"The ideal artificial blood has the function of corresponding components of blood, does not produce transfusion-related complications, and is not limited by blood type, which is low cost and convenient to preserve." Zhou Jiaxi said.

Zhou Xueli, director of the blood transfusion department of the Institute of Hematology and Hematology Hospital of the Chinese Academy of Medical Sciences, explained that blood type refers to the type of antigen on the surface of blood components (including red blood cells, white blood cells, and platelets). People have antigens and antibodies in their blood, and if the red blood cell antigens and antibodies are not compatible, hemolysis will occur when they are injected into the human body. Therefore, except in emergency situations, transfusions of blood products containing red blood cells require antibody screening and crossmatching.

Artificial blood can be "genetically modified", using gene knockout methods to knock out the antigens on the surface of blood cells, so that blood transfusion can be retyped. This can not only save the trouble of blood group testing, but also solve the blood transfusion problem of rare blood type patients such as "panda blood".

"After leaving the human body, different blood components have different storage conditions and expiration dates." Zhou Xueli said that the component with a longer preservation time in whole blood is red blood cells, which can be stored for 42 days under the condition of 4 ° C ± 2 ° C, depending on the preservation solution. Platelets need to be stored by shock at 22 °C ± 2 °C, and the storage period varies from 24 hours to 5 days depending on the difference in preservation bags, because platelets have a short shelf life, which brings difficulties to emergency large supply.

Some synthetic substitutes with a certain blood function are not limited by these storage conditions, and can generally be stored at room temperature for more than one year. In addition, the use of artificial blood can also effectively avoid the risk of contracting infectious diseases such as AIDS and hepatitis during blood transfusion.

There are still three hurdles to go before clinical application

At present, artificial blood with so many benefits is still a long way from widespread clinical application. Zhou Jiaxi said frankly that artificial blood must meet three important conditions if it is to be applied to the clinic.

The first priority is security. Zhou Jiaxi said that at present, many artificial blood research is still only in the stage of animal experiments, and has not really entered clinical trials. Japan, which is moving faster, has only just begun to apply for clinical trials.

The second is to achieve mass production. Taking the pluripotent stem cell preparation of platelets by the Japanese team as an example, the whole process took 26 days, which was difficult to solve the emergency clinical blood needs. Moreover, clinical blood transfusion needs to reach a certain amount to be effective, and the current laboratory capacity to produce artificial blood is equivalent to the level of home workshops, and there is still a long way to go from large-scale production in factories.

The third is to reduce costs. At present, the cost of platelets prepared from pluripotent stem cells is much higher than that of donated platelets, and even tens of thousands of times higher than the cost of donating platelets. "If a bag of platelets costs 100,000 yuan for a transfusion, then this artificial blood is meaningless." Zhou Jiaxi said.

　　Although the road is long, with the emergence of pluripotent stem cell technology,

it is believed that with the continuous development of science and technology, in the

near future, artificial blood will definitely be able to achieve low-cost mass production

like normal saline, solve the problem of tight blood supply, and play an important role

in the treatment of various blood diseases.