Everyone has a liver, so why do we need an artificial liver? Does an artificial liver grow just like a normal liver? Can an artificial liver completely replace a liver? Many readers may have such questions in their minds. The liver is the chemical factory of the human body. Everyone has a liver, and the liver is the largest substantial organ in the human body, accounting for about 2% of the weight of the adult liver. The liver plays a role in nutrient metabolism and biotransformation at every moment, and is the most dedicated chemical plant in the human body. We all know that cars run on fuel and household appliances are powered by electricity, but where does the energy needed for human activity come from? The energy for human activities comes from the heat generated by aerobic or anaerobic respiration of glucose in cells, and the liver plays a very important role in the metabolism of glucose. Glucose taken in by the body through intestinal digestion and absorption is transported through the blood circulation to the liver where it is stored in the form of glycogen. The liver plays the role of a storage depot and when the body’s blood sugar drops, the liver can break down the stored glycogen into glucose and release it back into the bloodstream to supply energy. In addition to glucose, the liver is also involved in the anabolic metabolism of proteins and fats, and many of the proteins and clotting factors needed by the body are synthesized by the liver. In addition to nutrient metabolism, the liver also plays a role in converting many non-nutritive substances from outside the body, such as various drugs and poisons, as well as certain metabolites in the body, such as bilirubin. After drinking alcohol, it is absorbed into the body through the digestive tract and converted into acetaldehyde by the action of ethanol dehydrogenase in the liver, and then into acetic acid, which is finally broken down into carbon dioxide and water and excreted from the body. Similarly, many drugs absorbed into the body do not work directly, but need to be transformed by enzymes in the liver into an active form before they can work, and many poisons need to be detoxified by the liver before being excreted through the kidneys and other organs. Without the liver, the body would not be able to survive. What is an artificial liver? An artificial liver is called an artificial liver support system and is not placed in a person’s stomach. The artificial liver looks nothing like the red liver of the human body, but is a cold machine with various pipelines. In terms of mechanism of action, artificial liver can be divided into three categories: non-biological artificial liver, biological artificial liver and hybrid artificial liver. Non-biological artificial liver is more like a water purifier, which detoxifies the patient through physical, mechanical or chemical methods. The most used method is plasma exchange, which replaces normal human plasma with the patient’s plasma to clean the patient’s body of toxins and replenish essential substances. In addition, there are also methods such as solid adsorbent materials and semi-permeable membrane filtration to filter the toxins from the patient’s plasma and then return the plasma to the patient. Biological artificial liver is similar to the T800 robot played by Schwarzenegger in “The Terminator”, which has both a metal skeleton and human skin. The core technology of the biologic liver is artificially grown human or animal liver cells, which are stored in an in vitro bioreactor that mimics the human body temperature and other microenvironments to allow the liver cells to function at their maximum capacity. In the process of use, the patient’s plasma is first fed into the reactor, where it comes into contact with the hepatocytes and performs the physiological functions of the hepatocytes, carrying out the corresponding nutritional metabolism and detoxification, before the plasma is returned to the patient. The hybrid artificial liver, on the other hand, is a combination of the above two types of artificial livers, which can be used both physically, mechanically or chemically, as well as biologically by hepatocytes, in a two-pronged way, to better perform the role of liver replacement. Academician Lanjuan Li’s team has been the first in China to successfully develop a hybrid artificial liver for the benefit of patients with liver failure in China. What is meant by liver failure? The liver itself functions with a strong reserve capacity. A normal liver is like an energetic athlete, the amount of daily activity does not cause it any fatigue, and most of the time, most of the liver cells are not running at full speed. In liver surgery, 70% of the normal liver is removed, and the remaining 30% can still proliferate to its original size in a relatively short period of time, while the liver’s function is not greatly affected. Although the normal liver has a strong compensatory capacity, “the greater the capacity, the greater the responsibility”, and the liver is susceptible to attack by various diseases while performing its functions. For example, hepatitis virus, drugs, alcohol, and toxins can cause liver inflammation, which are called viral hepatitis, drug hepatitis, alcohol hepatitis, and toxic liver damage, respectively. In severe cases, all these hepatitis may lead to degeneration and necrosis of a large number of liver cells, and when the remaining liver cells are not sufficient to maintain the body’s vital needs, many clinical manifestations appear. For example, damage to the liver’s bilirubin metabolism function may lead to an increase in bilirubin in the blood, followed by yellowing of the skin and sclera, which is called jaundice in medical science; insufficient synthesis of clotting factors by the liver and clotting dysfunction may lead to nosebleeds and bleeding of the skin and mucous membranes; decreased synthesis of albumin by the liver may lead to ascites and pleural fluid; decreased metabolism of ammonia ions in the blood by the liver may lead to The decrease of the liver’s ability to metabolize ammonia ions in the blood can lead to various kinds of consciousness disorders and even coma, which is called hepatic encephalopathy. A group of syndromes including these clinical symptoms is called liver failure or liver insufficiency in medical science. Liver failure can further lead to serious metabolic disorders and accumulation of harmful substances in the body, which in turn can further inhibit the regeneration of liver cells, forming a vicious circle, and most of the current clinical drugs cannot completely correct the above problems, and eventually liver failure induces multiple complications or multi-organ failure and death. What kind of patients need artificial liver support? Artificial liver is mainly for patients with acute and chronic liver failure as mentioned before. By simulating the detoxification function of the liver, it can replace the failed liver to remove the toxic substances accumulated in the organism, replenish the substances needed by the body, create conditions for liver function recovery, or buy time for patients waiting for liver transplantation. China is a large country of liver disease, nearly one tenth of our people are chronic hepatitis B patients or hepatitis B carriers, other alcoholic liver disease, immune hepatitis patients are also many, about 8 million people each year new onset of liver disease. Due to untimely treatment and other reasons, many patients with chronic liver disease progress to liver failure, cirrhosis or even liver cancer, and liver disease has become an important disease that threatens the life and health of our nationals. According to incomplete statistics, nearly 500,000 people die from liver failure each year in China, and artificial liver support plays a crucial role in the treatment of this group of patients. Although artificial liver can replace some of the functions of the liver, the human being as the most exquisite design of the Creator, the functions of the human body’s own liver cannot yet be completely replaced. Non-biological artificial livers are primarily detoxifying and do not have the ability to synthesize clotting factors or metabolize bilirubin, and scientists are now turning their research toward biologic artificial livers. Although biologic artificial liver is closest to the function of human hepatocytes, it is still under continuous research and refinement to perform large scale cell culture with high activity in vitro and to keep the cultured hepatocytes functional for a long time. The application of artificial liver has effectively solved the problem of liver function support for patients with liver failure and reduced the risk of death for patients with acute and chronic liver failure, but at present the artificial liver cannot completely replace the function of the human body’s own liver, and there is still a long way to go in the development of artificial liver.