Transplantation of artificial organs

Since ancient times, human beings have had this idea: if an organ of the body has a disease, can it be replaced like a machine replacing parts?

From 65438 to 0954, Boston physicians Hartwell Harrison and joseph murray successfully completed the first human organ transplant-kidney transplant. In order to avoid the biggest problem that the body rejects foreign tissues, this operation was performed on a pair of twins. Nevertheless, it initiated a new era of human organ transplantation.

1963, doctors tried lung and liver transplantation. Then, Dr. Christiaan Barnard in South Africa and Dr. Norman Shamway and Dr. Denton Cooley in the United States successively completed heart transplantation. Organ transplantation did not become a routine therapy until the late 1970s, when cyclosporine, a drug that can inhibit the body's tendency to attack foreign organs, was developed.

It has been 90 years, and now organ transplantation between human beings has become very common. At present, there are about 1 1,000 kidney transplantation, 1 1,000 lung transplantation, 2,000 heart transplantation, 4,000 liver transplantation and 1 1,000 pancreas transplantation in the world every year. So far, tens of thousands of patients have been reborn through organs donated by others. There are many obstacles to organ transplantation.

However, the development obstacles encountered in organ transplantation have also caused headaches for doctors all over the world.

First of all, when a person's organ is transplanted into another person, it is inevitable that there will be rejection. Just like a person who has lived in the tropics for decades suddenly lets him live in the Arctic, the cold climate in the Arctic will definitely reject him. At present, patients receiving organ transplantation must take inhibitory drugs for life to prevent rejection in the body. But at the same time, these drugs have an impact on the whole immune system, which will reduce patients' ability to resist diseases.

Another obstacle is that the emergence of organ transplant surgery has made many patients see the dawn of health. There are more and more people waiting for organ transplantation, but not so many people are willing to donate organs. It is estimated that there are about 250,000 patients waiting for organ transplantation in the world, but only about 50,000 patients have the opportunity to undergo this operation every year. For example, Spain has the largest organ donation per capita in the world, with 27 per million residents donating organs, but 500 people in Spain need organ transplants every year. The United States began to implement the paid supply of organs from 1984, and the sales volume increased year by year. "Human organ bank" and "cell bank" have developed rapidly in the United States. These "organ banks" collect heart valves, skin, blood vessels and liver cells donated by brain-dead people and people with cardiac arrest, and provide them to people who need organ transplants or new drug developers for a fee. The "benefits" of this business are great. Now about 70 enterprises, including the Red Cross, have joined the "National Association of Human Organ Banks". If we add non-member organizations and enterprises engaged in the commercialization of cells and genetic genes, the number will exceed hundreds, and the number and sales of enterprises are increasing year by year. A lawyer in Washington estimated that "including reproductive organs and other businesses, the size of the' human organ market' in the United States has exceeded $654.38+000 billion".

Despite this, the human organ market is still obviously in short supply. How to find a breakthrough for human organ transplantation is something that scientists should think hard about. They first thought of replacing human organs with animal organs, and later thought of replacing human organs with artificial organs. Can people use animal organs?

The earliest allograft was in 1906. Doctors boldly transplanted the kidneys of pigs and goats to two patients respectively. Unfortunately, due to the unknown rejection at that time, the patient died soon. 1992, the University of Pittsburgh Medical Center started another attempt. They transplanted the liver of a baboon to a 35-year-old man who suffered from hepatitis B, causing liver necrosis. They first removed the liver of a male baboon aged 15 and implanted it into the dying man. Doctors are worried that after transplanting human liver, the new liver will also be destroyed by hepatitis B virus, so they decided to use baboon liver. The day after the operation, the baboon's liver began to function. In order to reduce the rejection of baboon liver, doctors used a variety of anti-rejection drugs, including FK506, which is still in the experimental stage. On July 2, the man shaved for the first time after surgery, began to eat liquid food and could walk on the ground. However, two months later, the man developed fever. After X-ray bile duct examination, he found blood infection and died soon.

The failure of transplanting animal organs into human body did not discourage scientists. In order to find out the secret of this cross-species organ transplant operation, they conducted similar experiments in animals. Scientists at the University of Cambridge in the United Kingdom began to raise the first batch of pigs with human genes in their hearts from 1992. Scientists have cultivated this kind of pig by implanting human genes into pig eggs.