Have you noticed? After the limbs and even the bodies of animals such as geckos and leeches are half broken, the broken parts can soon grow back. The mystery lies in the fact that such creatures have a remarkable miracle cell that can differentiate and develop into the needed organ for self-repair.
Scientists have discovered that among the tens of trillions of cells in the human body, there is also this kind of cell with “all-powerful” development potential, which is like a “seed” buried in the human body and can differentiate into different kinds of body cells when planted on suitable soil. This amazing cell is a stem cell.
Does this mean that one stem cell can repair and regenerate damaged tissues in the human body? That one stem cell can grow human organs such as heart, kidney, liver, etc.? Will serious diseases such as cancer, paralysis, dementia, blindness, etc. be solved as a result? The future of stem cells is immeasurable.
Dr. Zhang Lei, deputy director of the National Engineering Research Center for Cellular Products, said that stem cells are a “miracle” that God has planted in living organisms.
”The word ‘stem’ in stem cells is translated from the English word ‘Stem’, which means ‘trunk’ and ‘origin ‘. It is similar to a tree trunk that can grow branches, leaves, flowers and fruits, etc. Somatic cells can die due to aging or injury, so certain animals have a reservoir of stem cells in their bodies ready to produce their replacements.” Dr. Lei Zhang said.
There is a very vivid statement about the uniqueness of stem cells. If somatic cells are likened to “specialists” with one skill, stem cells are “potential talents” that do not yet have a special talent but can be learned to become one, and can differentiate into many kinds of human cells. Once differentiation is completed, the “occupation” of these cells is determined. Compared to ordinary body cells, the “future” of stem cells has unlimited possibilities as cells in living organisms that are not fully differentiated and have the potential for self-renewal and differentiation.
Where do such amazing stem cells come from? Yu Hsiu-yung, director of the Medical Research Center of Guangdong Academy of Medical Sciences, told reporters that the first stem cells discovered by scientists existed in human embryos. Embryonic stem cells, also known as ES cells, are the cells in the inner cell mass when the fertilized egg divides and develops into the embryonic sac, which have unlimited developmental potential and can differentiate into all different kinds of specific tissue cells.
Due to the “all-purpose” nature of ES cells, it is technically optimal to use ES cells to culture human tissues and organs for disease treatment. However, embryonic stem cells need to be extracted from embryos, and “each embryonic stem cell removed is equivalent to destroying a life, which involves medical ethics, so scientists have conducted a lot of research to find their replacement.” Director Yu said.
After long-term scientific experiments, in 2007, both American and Japanese scientists discovered a way to convert ordinary skin fibroblasts into stem cells, and the resulting stem cells are called induced pluripotent stem cells, also known as iPS cells. This kind of stem cells induced from somatic cells has similar functions as embryonic stem cells, while the source is convenient, only cells from epidermis and other tissues can be, avoiding the ethical problems that embryonic stem cell research has been facing, and is expected to become an important source of future cell therapy, with very promising applications in the biological and medical fields. iPS cell discovery was thus named by Science The discovery of iPS cells was named by Science magazine as one of the top 10 technological advances in the world in 2008.
In addition, according to Director Yu, adult animals also have some stem cells in their bodies, called adult stem cells. For example, our bone marrow is like a stem cell bank. In addition to hematopoietic stem cells, there are many multifunctional bone marrow mesenchymal stem cells similar to hematopoietic stem cells, which are regulated to differentiate into tissue cells with special functions, such as fibroblasts, osteoblasts, chondrocytes and adipocytes.
The beauty of stem cells is that they can generate mature somatic cells by dividing as soon as the body needs them, following the developmental pathway. Perhaps one day it will suddenly be discovered that human organs can be produced in the laboratory on demand and by process, and that replacement of blood cells, brain cells, bones, hearts, livers, kidneys, nerves, etc. will be no problem.
Is this the end dream of human medicine?!
So, how to make this miraculous “seed” of stem cells obediently and directionally “planted” into a specific tissue? Director Yu told the reporter that one way is to use a syringe to inject the cultivated stem cells directly into the body so that they can differentiate into specific tissues. “However, the fact is that most of the stem cells injected into the body undergo apoptosis or heterodimerization and turn into other cells.” For example, when cardiac stem cells are punched into the body through the peripheral blood vessels in an attempt to make it associate with existing cardiac muscle cells to form new tissue, many of the stem cells flow through the respiratory system to the lungs instead of being distributed into heart and muscle tissue as specified. To solve the problem of targeted “distribution” of stem cells within the body, scientists have developed a tissue engineering approach in which stem cells are attached to an artificial scaffold in a controlled laboratory to grow into the specific tissue needed. For example, to address the problem of the “unknown destination” of heart muscle stem cells injected into the body, a patch of heart muscle can be generated in a laboratory culture tube and then targeted for implantation into the heart.
Director Yu painted a blueprint for the future: scientists can generate human organs such as heart, liver and kidney in the laboratory by inducing stem cells from human epidermal cells to greatly solve the medical problems faced today. For example, today’s heart transplants still need to be supplied through a living body, but the living heart is very rare, the future only need to extract a small amount of cells from the skin on the back of the hand, you can “make” another heart in the laboratory. What a tantalizing prospect. Patients, including those with severe burns, could also regain beautiful skin through stem cell transplantation. “The use of tissue engineering is an important means to solve the problem of organ transplantation in the future.” Director Yu affirmed.
This wonderful vision is in the process of being realized. According to the British medical journal The Lancet, in June 2008, a medical team of researchers from several countries completed the world’s first “artificial trachea” transplant in Spain, which was cultured from the patient’s own stem cells. The artificial trachea was grown from the patient’s own stem cells. Five months after the operation, the 30-year-old female patient has made a full recovery. Martin A Birchall, of the University of Bristol, said it would take about 20 years for the stem cell-grown organ transplant technique to become routine. The successful performance of this operation is a major breakthrough in stem cell technology and has the potential to change the future of surgery as a result.
As an amazing multipotential cell with the ability to differentiate, stem cells have been a boon to many patients with difficult diseases and have thus become a familiar and trendy medical term. Scientists in various fields of medicine have been conducting research around stem cells and have achieved remarkable results, enabling human beings to enjoy the benefits of medical progress.
According to Director Yu, at present, stem cell transplantation technology has reached the stage of clinical application in some medical research fields. For example, in chronic granulocytic leukemia, treatment with chemical drugs alone can only improve the symptoms of the chronic phase, while treatment with autologous hematopoietic stem cell transplantation has a very high relapse rate, while allogeneic peripheral blood hematopoietic stem cell transplantation is the most reliable primary treatment method that can greatly improve the cure rate of leukemia.
Among the cases treated clinically through stem cell transplantation, the innovative procedure of bone marrow stem cell transplantation technology for femoral head necrosis at Guangdong Provincial People’s Hospital is a successful example. Femoral head necrosis is a lesion in which the blood supply to the human femoral head is impaired by various lesions, causing necrosis of bone cells and bone tissue in the femoral head tissue. Femoral head necrosis will eventually lose the ability to move and work. According to Zheng Qiujian, director of the orthopedic department of Guangdong Provincial People’s Hospital, the incidence of “femoral head necrosis” has been rising due to the large amount of hormones and alcoholic beverages taken by people, and there are 150,000 to 200,000 new cases in China every year. For this disease, the past to take a variety of methods of treatment, including each implant bone, osteotomy, or vascular implantation, but the effect varies from person to person, the efficacy is not exact; artificial joint replacement can only be applied to patients with severe osteonecrosis of the femoral head. Last year, the provincial people’s hospital successfully carried out the treatment through the patient’s autologous bone marrow stem cell transplantation, which made the clinical diagnosis and treatment of this disease leap to a higher level. The reason why a lizard’s tail grows back after it is cut off and why the head and tail of a piece of leech can be regenerated is that stem cells exist throughout its body. The stem cells move to the severed area, and through proliferation and differentiation, the whole process of regeneration of the lizard’s tail and the lamellipod is completed. It is the same principle to use bone marrow stem cell transplantation technology to treat femoral head necrosis, said Director Cheng. “Stem cells are isolated from the patient’s healthy bone marrow, attached to a scaffold made from the patient’s own bone, and implanted into the femoral head, allowing the stem cells to ‘settle’ inside like seeds and differentiate into osteoblasts with the body’s self-regulatory mechanism, taking on the job of repairing osteonecrosis and rebuilding the femoral head structure.”
In the past, femoral head necrosis surgery had a wound of more than 20 centimeters, but now only a small incision of about one centimeter is needed, and the surgery used to take two to three hours to complete, but now it can be completed in less than an hour, and the patient can walk on the ground the next day after the surgery, greatly reducing the patient’s pain. At present, the cure rate of more than 40 cases of femoral head necrosis treated by bone marrow stem cell transplantation technology performed by Director Zheng is as high as 98%.
In addition, stem cell transplantation technology is currently clinically applied in the fields of blood diseases and myocardial infarction, while other fields are mostly in the experimental research stage. At the same time, Director Yu said, “Stem cell transplantation still has many basic research problems that have not been solved, and there are a sea of unknowns in the future.”
Nowadays, if you open a search engine and type in the keyword “stem cells” and another name of the disease you care about, such as Parkinson’s disease, cerebral palsy, diabetes, hemiplegia, vegetative, etc., you will be surprised to find that almost all of the above diseases are treated with the latest technology of stem cell transplantation on the web.
Director Yu said that although stem cell transplantation is currently being hyped up, the basic research problems of stem cells in many fields have not been solved yet, and most of them are still in the laboratory research stage. The cause of type 1 diabetes, for example, is the loss of Beta cells, which are responsible for insulin secretion in the human body, and scientists are now using stem cell transplantation technology to induce stem cells into Beta cells and let them secrete insulin again to treat diabetes. This technology is certainly advanced, “but as far as I know, it is mostly a research application at Harvard University at the moment, and it will take some time for large-scale clinical application.”
Although the research and clinical application of stem cell transplantation technology has a long way to go, there are many medical institutions that make a big deal out of stem cells and make profits from them when the efficacy is not confirmed. Professor Zhang Shizhong, deputy director of neurosurgery at Zhujiang Hospital, told reporters that too many unknown patients have been misled and taken advantage of because they are in a hurry to seek treatment. For example, the number of stem cell transplantation techniques in the human nervous system has not been overcome yet. Many diseases about the nervous system, Alzheimer’s disease, Parkinson’s disease, cerebral palsy, etc. are again plaguing more and more modern people. The recovery of neural stem cells has therefore become a very important research direction in current stem cell research. However, “rigorously speaking, the research of neural stem cells is still in the laboratory stage, and there is no case of clinical application of neural stem cells with real efficacy yet.”
Professor Zhang said he has done research on neural stem cells for Parkinson’s disease by inducing dopamine neurons through neural stem cells for therapeutic purposes. “Experimenting on rats with Parkinson’s, the effect was very good, but when injected into humans, the dopamine neurons mostly apoptotic and did not work to repair the nerves. Humans have evolved to be more sophisticated and better than animals, distinguishing them from the average animal and demanding more.” However, in reality, there are many medical units charging a lot of money for clinical treatment when the efficacy of neural stem cells against neurological diseases is not exact. Professor Zhang believes these actions are very irresponsible. “The human nervous system is very complex, and the nerves in the spinal cord are like a bundle of thin nerves consisting of telephone lines, each of which is useful and controls the corresponding part of the body, and damage to any one nerve is equivalent to an area where the ‘telephone line’ is not working.” Professor Zhang said that to repair such a sophisticated and complex system, autologous rehabilitation is impossible, and the hope for the future lies in genetically encapsulated stem cell technology to repair damaged nerves, “but it is still a long way to go to reach this step.
While stem cells have benefited mankind, they have opened Pandora’s Box, unleashing all sorts of rebellions and challenges to life and the ethical order.
The first embryonic stem cells discovered by scientists were called “universal cells”, capable of differentiating into various human cells and promising to treat many modern diseases at the root. However, these stem cells can only be obtained from eight cells of the embryonic blastocyst, and any one of these eight cells can grow into an individual life. Is it ethical to create a life and then destroy it in order to obtain embryonic stem cells? Embryonic stem cell technology raises widely questioned ethical issues. For this reason, embryonic stem cell research and experimentation is strictly limited and regulated in many countries.
Since stem cells can grow artificial organs, is it possible to grow a human body in the lab without reproduction? Director Yu said, “Just like a computer, it is useless to have a chip and a hard disk, but it needs an operating system and software to work. It is theoretically possible to assemble a human being in a test tube through stem cell tissue engineering, but the ‘product’ can hardly be called a ‘human being’ and it will be difficult to make him have human intelligence and regulatory system for several hundred years. ” In his opinion, this is a longer road than the research of intelligent robots to go.
Continuing to think about the future, Director Yu believes that if a person can be cloned through embryonic stem cells, thousands of people can be cloned, which will undoubtedly be a disaster for humanity. “The cloned people and the existing people are two types of people, they not only have to compete with humans for survival resources on earth, but also may form an army and invade human territories, if the cloned people intermarry with naturally bred humans and reproduce offspring, then it will make the whole human race mutate, the consequences are unimaginable.”
Director Zheng Qiujian also expressed his concern about the future prospect of stem cells: “The ability to make whatever organs you need is the most attractive aspect of stem cells, and I believe that one day we will be able to reach this step technically, but with it will come the impact on society, morality and ethics. Even if there is no technical problem, how will these cloned people identify themselves and how will they relate to the people around them? If a real person and a ‘clone’ come home at the same time, which one should be accepted?” Director Zheng paints a dystopian scenario of the future.
Often, when God gives you an apple, he also slips you a devil. The tantalizing future and the accompanying consequences make it difficult to remain simply optimistic about the “bright future” of stem cells. Stem cells can be angels that rescue humans, or they can be demons of desire in a moment. In this way, the replicants in the Hollywood movies “Star Wars” and “The Sixth Day” do not exist only in science fiction.