Introduction: Stem cells, the "source" cells of the human body, have unlimited regenerative potential and are gradually leading the medical revolution. From hematopoiesis to immune modulation, they miraculously repair and reshape life. But what about stem cells**? How safe and effective is it? What's the point of storing stem cells? Let's unravel this mystery and explore the future code of health.
Stem cells are a kind of pluripotent cells in the human body with the ability to proliferate, replicate and differentiate in multiple directions, and can differentiate into a variety of different cells under certain conditions, just like branches, leaves, and flowers can be born on the trunk of a tree. At present, stem cells are widely used in the field of disease and anti-aging, which is expected to solve the major medical problems faced by human beings, help human beings realize the dream of health and longevity, and trigger a new round of medical technology revolution.
Let's take a look at 7 key questions about stem cells.
1. What is the function of stem cells?
Stem cells play an extremely important role in the field of regenerative medicine, and they contribute to the advancement of regenerative medicine in many ways and are gradually being applied in the clinic**. Various types of stem cells have their own unique functional properties and scope of application.
Hematopoietic stem cells are one of the most studied and widely used stem cell types. They are able to rebuild the entire blood system, including the immune system. Through the infusion of hematopoietic stem cells, many hematologic tumors can be made, and this intervention method is of epoch-making significance, so it was awarded the Nobel Prize in Medicine or Physiology in 1990.
Embryonic stem cells and induced pluripotent stem cells have multiple differentiation potentials and are capable of differentiating into many types of cells in the human body. They have great potential for applications in regenerative medicine, so they won the Nobel Prize in 2007 and 2012, respectively.
Mesenchymal stem cells are a special type of stem cell that has the ability to differentiate, but unlike most other stem cells, they do not function through differentiation. Instead, they have a variety of functional properties such as immune regulation, anti-inflammation, support hematopoiesis, and promote repair.
Mesenchymal stem cells are the "king" of the stem cell family, and are the most widely used stem cells in clinical research, which belong to pluripotent stem cells, which can be differentiated into fat, bone marrow, cartilage, muscle, tendon, ligament, nerve, liver, myocardium, endothelium and other tissue cells under specific induction conditions in vivo or in vitro.
Completed trials have shown that mesenchymal stem cells are safe and effective for a wide range of diseases, including graft-versus-host disease, spinal cord injury, autoimmune diseases, cardiovascular disease, bone and cartilage damage repair, Crohn's disease, diabetes and its complications.
2. Do stem cells change human genes?
The first thing to be clear is that all cells in the human body do not have the ability to change the genes of other cells. To change the genes of human cells, that is, to carry out gene editing, some tools are needed, among which common tools include lentivirus, adenovirus and adeno-associated virus, especially adeno-associated virus with good safety.
However, only genes that alter germ cells (sperm and egg) can be passed on to offspring. For example, a bone marrow transplant does not change the patient's genes, nor does the transfusion of allogeneic immune cells, red blood cells, mesenchymal stem cells, etc., change the patient's own genes.
Even embryonic stem cells and induced pluripotent stem cells, which have a high risk of tumorigenicity, do not alter the patient's own genes or the genes of the germ cells. Therefore, the use of stem cells does not alter the genetic information of the individual.
3. What is the choice between autologous stem cells and allogeneic stem cells?
Autologous stem cells, as the name suggests, use the patient's own stem cells, usually collected from adipose tissue, peripheral blood, or the patient's own bone marrow.
Allogeneic stem cell transplantation, also well understood, is the use of stem cells from a donor (donor). We know that stem cells can be collected from umbilical cord blood or tissue or placental blood in newborns.
Both methods use good stem cells to replace damaged cells in the patient's body, whether autologous or allogeneic stem cells**.
Autologous stem cells, all from the patient himself, can reduce the risk of ***. Faster integration in the production of new blood and immune system cells with less rejection and less risk. And it can be used repeatedly and repeatedly, and the use effect is superimposed, and the clinical effect is better. Autologous stem cell transplantation also avoids the associated ethical debates. Because it is self-contained, it is not circulated as a drug, does not affect the public interest, does not violate international ethics, is legal and compliant, and there are no potential safety hazards, and there is no cross-infection and immune rejection for autologous use. The disadvantage is that it is difficult to cultivate, and the number and activity of stem cells in the human body decreases with age.
Allogeneic also has unique advantages, its cell activity is high, the number is large, and the onset of action is fast, which can be used for patients with bone marrow diseases, and the effect is similar to that of autologous stem cells. Because it is not necessary to extract from itself, it can be used at any time, and it has the advantage of broad-spectrum, so it has also become one of the choices of some patients. However, its disadvantages are also obvious, the relative lack of stability, and the inevitable rejection of different strengths.
The claims of some people about how safe the transplantation of autologous stem cells are and the risk of rejection of allogeneic stem cells are mostly marketing tactics that avoid the important and trivialize. In fact, as long as cells have been cultured and expanded in vitro, their safety should be re-evaluated. For patients with refractory disease problems, stem cell transplantation is indeed a promising method. For patients who are considering exposure to stem cell transplantation**, it is important to follow the advice of a professional.
4. Will the impurity of stem cells make me sick and turn into tumor cells?
If the foreign stem cells are not pure enough, will they make me sick? Will it become a tumor cell?
This is nothing more than the fear that the reinfused stem cells carry pathogenic genes and will affect the body, but the clinical allogeneic mesenchymal stem cells are all screened, and as human "primary" cells, they reflect the most primitive state of the cell.
As far as the reinfusion of mesenchymal stem cells is concerned, it will not cause disease in the recipient due to the carrying of bad genes, let alone cause tumors.
Multiple double-blind randomized comparative clinical trials (RCTs) found no difference in infection rates between the MSC** combination control group, making it clear that MSC** did not increase the risk of infection, and there was no difference in cachexia and tumorigenesis between the MSC** and control groups.
The analysis of the current literature (meta-analysis) of a large number of clinical trials found that there is a certain association between MSC input ** and fever, up to 39%, and there is no necessary connection with the adverse reactions reported in other literature, and MSC** is considered safe. (plos one2012.7(10)：e47559)
5. What are the main differences between stem cell research at home and abroad?
The basic research of stem cells in China has caught up with the level of foreign research. However, when it comes to the culture and cell quality of MSC, the level of foreign countries is obviously inferior to that of domestic scientific research institutions and cell enterprises. For example, in 2018, a survey led by Professor Francesco Dazzi in the United Kingdom involving 22 institutions focused on investigating 17 institutions in Europe and the United States that carried out MSC**, and the survey involved the MSC production quality systems of these 17 institutions. The results of the survey found that the expression of MSC cell phenotypes CD73, CD90 and CD105 in 56% of MSC products did not meet the definition criteria of MSC (95%). CD45 expression in 50% of MSC products did not meet the definition criteria for MSC (2%). This shows that at least 50% of the 17 institutions in the EU that carry out MSC** have obvious insufficient cell purity and too many heterocells.
The quality of MSC cells in foreign countries is obviously inferior to that of MSC cells in China, and one of the important reasons is that foreign countries like to use MSCs with fat and bone marrow**, while MSCs with umbilical cord** are used in China. There were differences in functional intensity between different MSCs, and in general, the umbilical cord MSCs had the best cell quality.
Of course, the cell culture system is another important factor in determining the quality of MSC cells.
Pei Gang, academician of the Chinese Academy of Sciences and honorary chairman of the Chinese Society of Cell Biology, said that theoretically speaking, stem cells have the potential to change the fate of everyone and the entire human society, but the biggest problem we face is whether we can transform the basic research of stem cells into clinical results in a timely and effective manner, which is the direction we should work towards.
6. Will there be dependence after using stem cells?
All stem cells are not addictive. The use of mesenchymal stem cells (MSCs) can significantly improve physical health, thanks to the multiple advantages of MSC in enhancing immunity, promoting hematopoietic function, promoting vascular reconstruction, improving blood circulation, reducing inflammation and repairing damaged tissues and organs. These effects help to significantly improve the fatigue or aging state of the body, helping it to regain its youthful state. This improvement effect is not dependent, but a direct effect of MSC on the body. After stopping the use of mesenchymal stem cells (MSCs)**, the body does not experience withdrawal symptoms similar to those of addictive drugs or drug use, and does not lead to exacerbation of the condition. Instead, the body continues to age naturally following normal biological processes. Therefore, the use of stem cells** does not cause dependence on the body.
7. Why is it recommended to store stem cells in advance?
In fact, storing limited renewable resources as early as possible is a very forward-looking and healthy investment.
There is a certain number of stem cells in the human body, which will continue to decrease with age, and eventually cannot provide enough new stem cells or new functional cells to the body.
And, with the development of science and technology and society, stem cells play a greater role in the disease. Therefore, cell storage is also the basic link in the development of stem cells.