The way of liver transplantation between relatives is feasible
A human body has a big liver
Location of liver:
The body is located in the right upper abdomen, hidden behind the ribs. Think of the liver when this part feels uncomfortable and painful. When impacted by external force, it is also the position that needs to be protected.
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Figure 1 The position, size and shape of the liver in the body
Features of liver:
The liver is the largest substantial organ in the body (on the contrary, gastrointestinal, lung, etc. are organs with cavities in the middle). It usually weighs three jin (1.5kg). Why does the liver have such a large volume and weight? In fact, it is determined by the important role of the liver in the body, because the liver is the organ with the most functions in the human body. At present, there are 6 major functions known:
one Manufacture and secretion of bile: The liver converts the heme in the hemoglobin in the aging red blood cells every day into bilirubin and secretes it into bile. Every day, about 600-1000ml of bile is continuously secreted from the liver and flows into the duodenum from the bile duct to help fat digestion and absorption of fat soluble vitamins A, D, E and K. Once bilirubin cannot be produced and discharged normally in the liver, it will accumulate in the blood, so the skin of the body will appear yellow, which is called "jaundice".
2 is metabolic function. We eat a lot of food every day. The protein, fat, sugar and vitamins in the food must be chemically treated in the liver to become the nutrients needed by the human body Necessary for life activities. Without the hard work of the liver, hundreds of large and small organs in the human body would "starve to death". The metabolism can be seen in 8 aspects:
(I) Liver and sugar metabolism: The rice, flour and other polysaccharides that you usually eat are broken down into monosaccharides (glucose) by amylase in the gastrointestinal tract and absorbed by the intestinal mucosa. When glucose enters the liver through the portal vein of the liver, the blood sugar rises, and the hepatocytes synthesize glycogen and are stored. When the hunger blood sugar of the human body decreases, the liver decomposes the synthetic stored glycogen into glucose, which is released into the blood for use by the whole body. Sugar generates heat. Therefore, the liver can regulate blood sugar. Don't you know, if you want to solve diabetes, you must start with the liver.
(II) Metabolism of liver and protein: people eat lean meat, eggs and other protein foods, which are processed by protease in the gastrointestinal tract. Decompose various proteins into amino acids. Because protein is a substance composed of many amino acids linked by peptide chains. Therefore, amino acid is the smallest unit of protein. Amino acid molecules are small and can absorb blood through gastrointestinal mucosa and enter the liver. Hepatocytes can re synthesize amino acids into various proteins and enzymes needed by the human body, such as albumin and prothrombin in the body. The liver has a strong ability to synthesize proteins. Except for immunoglobulin, almost all plasma proteins are produced by the liver. As long as there is no problem with the liver, the so-called "tonic, nutriment" of any protein is superfluous.
(III) Liver and fat metabolism: the liver absorbs fat and decomposes it into fatty acids and glycerol, and then re synthesizes the fat needed by the human body and stores it in adipose tissue. When the human body is hungry or suffering from diabetes, and blood sugar is largely lost from the urine (when the loss of sugar cannot produce the heat needed by the body), the body will mobilize the fat stored in the body to oxidize to generate heat for the needs of the body. The liver is an important organ for the synthesis of cholesterol in the body. About 60% - 80% of the cholesterol in the plasma comes from the synthesis of the liver. In order to reduce blood lipids, we must first ensure that the liver is normal.
(IV) Liver and bilirubin metabolism: the metabolism process of bilirubin in the liver includes the uptake of bilirubin in the blood by hepatocytes, the formation of conjugated bilirubin, and the discharge of conjugated bilirubin from hepatocytes into the biliary tract. Any obstacle in any process can lead to the accumulation of bilirubin in the blood and jaundice.
(V) Liver and hormone metabolism: sexual shock in human body, including female and male hormones and suprarenal corticosteroid hormones, is absorbed after being transported to the liver, excreted from the biliary tract through oxidation and reduction, combined with intestinal liver circulation, and finally excreted from urine and feces. So many "endocrine disorder" problems, in fact, root in the liver.
（6） Liver and collagen metabolism: Collagen is generally divided into five types, which are assembled into collagen fibers. Liver fibrosis is caused by accumulation of collagen in liver tissue. Elastin is the main component of elastic fiber, which increases with the increase of type I collagen. The matrix is an amorphous mucoid gel, which exists in the form of proteoglycans. Fibroblasts are involved in the synthesis and degradation of liver connective tissue. The essence of cirrhosis is whether the liver function is normal or not.
（7） Vitamin metabolism: The liver can store fat soluble vitamins. 95% of vitamin A in the body is stored in the liver. The liver is vitamin C D、E、K、B1、B6、B12、 It is a place where many vitamins such as nicotinic acid and folic acid are stored and metabolized. When your liver is defective, you must take vitamins to supplement it.
（8） The liver is involved in the generation of heat and the regulation of water and electrolyte balance. In quiet time, the body heat is mainly provided by the internal organs of the body. The main organ producing heat during labor and exercise is muscle. In various viscera, the liver is an organ with vigorous metabolism in the body. When it is quiet, the blood flow temperature of the liver is 0.4-0.8 ℃ higher than that of the aorta, indicating that it produces more heat. The liver is like a small heater in the body.
three It is a detoxification function. There are four main ways of liver detoxification: ⑴ Chemical methods: such as oxidation, reduction, decomposition, binding and deoxidation; ⑵ Secretion: some heavy metals, such as mercury, and bacteria from the intestine can be excreted with bile secretion; ⑶ Accumulation; ⑷ Phagocytosis. The liver is the main detoxification organ of the human body, which can protect the body from damage and make poisons non-toxic or highly soluble substances, which are discharged with bile or urine. This is an important function to maintain life. No matter food or drugs, they are inevitably toxic. Once the liver's detoxification ability declines, the consequences are unimaginable.
four Phagocytosis or immune function. The liver is the largest defense system in the human body. It has a strong team of "health guards" who can swallow, isolate and eliminate various invasive and endogenous pathogens to protect Poor health. This is the reason why people with poor liver function are easily associated with many diseases. In addition, there are physiological functions such as bile generation and excretion, blood coagulation, and regulation of water and salt metabolism. In short, life cannot be separated from the liver, and a healthy liver will lead to a prosperous life. The liver removes bacteria, pigments and other debris from the blood through the phagocytosis of Kupffer cells in the reticuloendothelial system. Any maintenance and improvement of immune ability must depend on normal liver function.
5 Coagulation function
If you cut your skin carelessly when shaving or peeling apples, your liver will make blood clots to stop the bleeding of the wound. The liver is the place where many clotting substances are synthesized or produced. In addition to the above synthesis of fibrinogen and prothrombin, coagulation factors 5, 7, 8, 9, 10, 11 and 12 are also produced. In addition, vitamin K stored in the liver is indispensable for the synthesis of prothrombin and coagulation factors 7, 9 and 10. It is conceivable what the consequences will be if the blood can not coagulate after the liver has a problem. This is also the reason why any medical treatment can not be carried out for patients with liver problems in the later stage (doctors dare not take any measures for fear of continuous bleeding).
six Regulate blood circulation: In normal conditions, the venous sinus in the liver can store a certain amount of blood. When the body loses blood, more blood is discharged from the venous sinus in the liver to compensate for the lack of peripheral blood circulation. Therefore, the liver is also a small blood bank of the human body.
Second liver transplantation has become the best choice for end-stage liver disease
Since the 1990s, liver transplantation has made rapid progress in the world and its effect is increasing day by day. It has become a routine operation in many large hospitals in advanced countries. In Asia, Japan, China's Taiwan and Hong Kong have carried out successively, and achieved good results. Domestic and foreign doctors are also eager to try. Especially the new generation of young and middle-aged doctors, some of whom have returned home from studying liver transplantation abroad, and some of whom have accumulated some experience as graduate students or research projects in China to engage in liver transplantation experiments, many of whom are enterprising. If the unit leaders pay attention to them and give material and financial support, they will have the main conditions to carry out liver transplantation. In the short 10 years since the beginning of this century, liver transplantation has developed rapidly, and there have been more than 20000 cases so far.
The main reasons for the development of liver transplantation in recent years are as follows: 1. Changes in indications: the early stage is mostly middle and late stage liver cancer, and now benign end-stage liver diseases, congenital and metabolic diseases are gradually increasing. 2. Technology tends to mature and experience is accumulated. 3. According to different patients, conditions and conditions, various new operations have been carried out, such as living relative partial liver transplantation, reduced volume liver transplantation, split liver transplantation and orthotopic auxiliary liver transplantation. 4. Application of new preservation solution. 5. Application of new generation immunosuppressants. 6. The increase of academic exchanges and technical cooperation.
In this way, liver transplantation has become the last line of defense for advanced liver disease, and can also be said to be the only radical treatment for various liver diseases in the end. From the current situation, liver transplantation has been applied to more than 60 diseases. It mainly includes liver parenchymal diseases, congenital metabolic disorders, cholestasis diseases, liver tumors, etc. In particular, it has gradually been found that children who receive living relative donor liver for liver transplantation can achieve ideal results in some liver failure that cannot be treated at present.
The regenerative ability of the three livers is unexpected
Because of the appearance of B ultrasound, CT and other examination means, people's understanding of the small size, shape and structure of the liver has become more convenient. Then the curious question came out: what will happen to the remaining half of a person's liver after half of it is removed? What a surprise! Three months later, only half of the original liver has almost become a complete liver! This means that the liver has doubled in a few months.
The reason why the liver regenerates is that the ability of liver cells to regenerate is extremely strong. The liver is composed of hepatocytes, which are too small to be seen with the naked eye and can only be seen through a microscope. There are about 200 billion hepatocytes in the human liver, which consists of about 500000 hepatic lobules. The left and right halves of the hepatic lobules (the right lobe accounts for 60% of the whole liver) are divided into five lobes (left lobe, left side middle lobe, caudate lobe, right side middle lobe, right lobe) and eight segments.
Normal human hepatocytes do not show strong regenerative capacity, but after liver damage, especially after partial hepatectomy, hepatocytes have amazing rapid proliferation capacity. Animal experiments have proved that when 70-80% of the liver is resected, there is no obvious physiological disorder. The residual liver can grow to its original size within 3-8 weeks. This indicates that the liver has regenerative function. After one half of the body is removed, the half liver can grow again in less than half a year. This is why now relatives can provide half of each other's liver for transplantation.
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Fig. 2 Normal human liver is composed of hepatic lobules composed of hepatocytes
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Figure 3 Two regenerated hepatocytes can be seen in the circle
When the liver is damaged or partially resected by physical and chemical factors, liver parenchymal cells can react quickly. The reaction speed of hepatocyte proliferation in different parts of hepatic lobule is different. Recent studies have found that bone marrow cells can differentiate into hepatocytes in the liver, which provides a new way for hepatocyte regeneration.
The liver is recognized as a preferential organ for immune tolerance
In the hundreds of millions of years of human evolution, the body has ingeniously formed a set of self-protection mechanisms, that is, any "outsider" cannot survive in its own body, and will be "eliminated", which is called transplantation rejection. The so-called "transplantation" is a method of replacing damaged or disabled tissues or organs with normal cells, tissues or organs.
The transplanted tissues or organs are called grafts, and the individuals providing grafts are called donors. The individual receiving the graft is called recipient.
The ancient people had fantasized about organ transplantation, but it was not until the 1950s that there was a real human organ transplantation. So far, the number of organ transplants in the world has reached more than 1 million. Moreover, various important human organs, such as heart, liver, lung, spleen, kidney, pancreas and bone marrow, can be transplanted. Strangely, in the transplantation of these many organs, people found that liver transplantation is different from other organ transplantation in that it is almost free of hyperacute rejection (Hyperacute rejection rejection, HAR)， Acute cell rejection, ACR) is easy to control, and even chronic rejection can be corrected. In short, the degree of reaction is light. Therefore, the liver is currently recognized as a preferential organ for immune tolerance. Before transplantation, donor and recipient only need to match ABO blood type, while HLA matching necessary for other organ transplantation is not strict. This phenomenon has to arouse the interest of researchers. The exact mechanism is not clear at present, and some factors may be related:
The liver is a "silent organ" without nerves. In fact, there is no peripheral nerve in the liver, so even if the liver is diseased, there is generally no pain, unlike the stomach, intestines, heart and other organs - once damaged, there will be severe pain. Therefore, the liver should "escape" from the recognition of the body in a non neural environment.
two Liver cells contain more than 2000 kinds of biological enzymes, which act as the medium of human chemical reaction and participate in all kinds of life activities of the human body. The reason why the liver is called "the comprehensive chemical plant of the human body". These more than 2000 enzymes should play a role in "helping" the liver "eliminate" recognition and rejection.
Donor hepatocytes secrete soluble HLA type I antigen, which may have immunosuppressive function.
There are powerful "clearing" cells in the liver, which phagocytize complement, immune complex and inhibit platelet aggregation to avoid rejection.
The unique dual blood supply system of the liver.
I believe that as the research goes deeper and deeper, the mystery will become less and less.
5. Congenital biliary atresia is an ideal approach for relative donor liver transplantation
Congenital biliary atresia is the main cause of long-term obstructive jaundice in neonates.
It is a kind of liver failure caused by obstruction of intrahepatic and extrahepatic bile ducts and cholestatic cirrhosis, with an average survival time of 12 months. In other words, once discovered, it can only survive for one year.
In general, children will have yellowing of their eyes and skin of the whole body 1-2 weeks after birth, and it will become increasingly serious. At the same time, their stools will appear yellowish white and clay color. The urine color will deepen with the increase of jaundice. Their diapers can be dyed yellow, and they will gradually lose their appetite, malnutrition, hepatomegaly, splenomegaly, and abdominal distention. With the development of the disease, biliary cirrhosis and portal hypertension will eventually occur, including epistaxis, ecchymosis of skin and mucosa, gastrointestinal bleeding caused by esophageal varices, liver coma, liver failure and death. More importantly, there is no good treatment. Many parents of children have tried many drugs, including traditional Chinese medicine, which are basically ineffective. Therefore, liver transplantation has become the only effective treatment.
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Figure 4 Cut off and see the patient's hardened liver
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Figure 5 The appearance of sclerotic liver after cutting
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Figure 6 Microscopic appearance of sclerotic liver (obviously different from Figure 2)
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Figure 7 Yellow brown cholestasis in circle
In liver transplantation for this disease, parents or immediate relatives of the child donate a small part of the liver to the child, usually 15% - 20% of the whole liver can meet the needs of the child. Because human liver has a powerful regenerative function, liver donors need not worry about whether their liver and body will be affected. At the same time, the donated liver will also grow with the growth of the child.
The advantages of liver transplantation from relatives: 1) saved a young life; 2) The provider has no worries about his/her future health; 3) Preoperative CT, MRI and other examinations can be performed on the donor, which helps to select the volume according to the optimal proportion, so that the transplanted liver can be more matched with the recipient. Preoperative anatomical factors such as blood vessels can also be understood through various examinations, which is conducive to vascular reconstruction; 4) According to ABO The results of blood group, leukocyte antigen and HLA analysis were used to obtain more suitable donor recipient histocompatibility matching; 5) It helps to achieve family psychological effect, and families are more integrated together.
In a word, for the sake of the child's liver, let's carry out liver transplantation among relatives with great fanfare!
