“Dr. Shinya Yamanaka of the Center for iPS Cell Research and Application (CiRA) of Kyoto University has received the Nobel Prize for Physiology or Medicine. Gas did play an important role in this world class discovery.

iPS utilizes the cells of human cells. First of all these are frozen, preserved, and then stored in a cell bank. Liquid nitrogen is used for the freezing and preservation. When they are used for experiments, they are warmed in a water bath at a temperature of 37℃, to thaw them out. These iPS cells are sowed in a flask containing a culture medium, and are then cultivated in a CO2 incubator.

A liquid nitrogen dewar is used as the cell bank. When the cells are frozen, they are frozen in stages in a program freezer. A small amount of liquid nitrogen is used here too to prevent cell destruction.

Not only for iPS cell research, the CO2 incubator is also a required item for biotechnology research using human and animal cells. For this, cells are cultivated while maintained at set temperature and inside a carbon dioxide atmosphere, but exactly what is the role of the carbon dioxide? This is indeed a complicated question.

A large amount of sodium hydrogen carbonate is in the buffer included in the culture medium made from the blood serum of bovine calves. If this is left inside the incubator, components of carbon dioxide are emitted from the medium, and end up becoming sodium carbonate. When this happens, the PH value in the culture medium rises from 7.1 to 7.4　which is the optimum for cultivation. The role here is to maintain a carbon dioxide density of 5% inside the incubator constantly, and to keep the PH value at a set level.

Little gas is consumed for this. Around 2-4 cylinders of carbon dioxide are required per annum for one carbon dioxide incubator. This is just to add additional carbon dioxide to replace that which is emitted when the incubator is opened. What is quite certain, however, is that it plays a very important role.”