What Are Stem Cells?

In simple terms, stem cells are a type of cells with unlimited or immortal self-renewal ability, capable of producing at least one type of highly differentiated progeny cells ^[1] .

The "stem" of stem cell (SC), translated from English "stem", means "stem", "stem" and "origin". The function of the stem cell population is to control and maintain cell regeneration. Generally, there is an intermediate progenitor cell called a "directional progenitor cell" between the stem cell and its terminally differentiated progeny cells

The scientific classification of stem cells helps to accurately grasp and understand the concept of stem cells and their biological characteristics. At present, the following methods can be used to classify stem cells ^[1]

In adult animals, many tissues such as skin, blood, and small intestinal epithelium have short life spans and need to be constantly replaced by corresponding new cells. One of the ways for mature individuals to generate new differentiated cells is to form new differentiated cells through simple multiplication of existing differentiated cells, that is, to divide

Although stem cells are present in many tissues, they are small in number and cannot be clearly distinguished from other cells in these tissues under a microscope. Therefore, how to find a simple and effective method to distinguish such rare cells scientifically and accurately has been a subject that scientists have been exploring ^[1]

It is inevitable that stem cell research has received widespread attention from scientists and the world. Stem cells have extremely broad application prospects in the fields of life sciences, developmental biology, and pharmacology ^[1] .

Stem cells as seed cells for cell therapy and tissue replacement

Tissue and organ damage and functional failure have always been a major problem facing human health. Perfect repair or replacement

Disability of tissues, organs or limbs caused by diseases, war injuries, accidents or genetic factors has always been a human dream, and it is also a difficult medical peak. The current treatments are difficult to completely repair damaged tissues, organs or restore their function for a long time ^[1] .

After long-term exploration and hard work, scientists finally set their sights on stem cells. The living body realizes cell renewal and guarantees continuous growth through the division of stem cells. The research and application of stem cells will make it possible for humans to perfect repair damaged tissue And organ dreams. For years, scientists have been working to find ways to use stem cell replication and differentiation to replace damaged cells or tissues. With the development of tissue engineering, embryo engineering, cell engineering, genetic engineering and other biotechnology developments and breakthroughs in the field of stem cell biology research, it shows an extremely broad prospect. It has become possible to artificially culture and isolate stem cells in vitro according to a certain purpose. The use of stem cells to construct various cells, tissues, and organs as the source of transplantation will become the main direction of stem cell applications ^[1] .

Stem cells explore regulatory mechanisms of embryonic development

Developmental biology is the forefront of life sciences. In recent decades, there has been a deeper understanding of this basic field of developmental biology. However, there are still many unsolved problems in the field of developmental biology, such as how a single cell-fertilized egg cell develops into a complex tissue, organ, system, or even a complete organic individual ^[1] ?

The biggest mystery of life is to explore how a fertilized egg develops into a complex organism. However, due to the inaccessibility of the fertilized egg after it is implanted in the uterus, people's discussion of the embryonic development mechanism is affected. The establishment of human embryonic stem cell lines will help us explore the influencing factors and regulatory mechanisms during development. In the study of key regulatory mechanisms in embryonic development, embryonic stem cells have undoubtedly become an important tool. For example, it is possible to compare the expression of Keegan between embryonic stem cells and differentiated cells in different time and space. Molecular mechanism ^[1] .

Stem cells as a carrier for disease gene therapy

Stem cells are an ideal vehicle for gene therapy of diseases. Hematopoietic stem cells have the characteristics of self-renewal, multi-directional differentiation and reconstruction of long-term hematopoietic, easy collection and in vitro processing. Therefore, it is one of the most ideal carrier cells for gene therapy. Based on this gene therapy, it has broad application prospects in the fields of severe immunodeficiency, genetic diseases, malignant tumors, hematopoietic stem cell protection, AIDS and other fields ^[1] .

Bone marrow mesenchymal stem cells are easy to introduce and express foreign genes. This feature, combined with the multi-directional differentiation potential of bone marrow mesenchymal stem cells, may make them an ideal target cell for gene therapy. In addition, human embryonic stem cells can continuously self-renew, and can still stably proliferate in vitro after genetic manipulation. Using this as a carrier for gene therapy will likely solve the problem that the cells used as carriers in gene therapy currently cannot be used in vitro. Problems of stable transformation and passage. The genetic modification of embryonic stem cells will likely be used in the treatment of hereditary diseases. At present, people are generally concerned about the progress of stem cell isolation and purification technology, the improvement of gene transfection efficiency, the continuous improvement of gene transfer vectors (liposomes, retroviruses, adenoviruses, adeno-associated viruses, etc.) and the expansion and orientation of transgenic cells In-depth research in the fields of induced differentiation, discovery of new target genes, stable expression and regulation of target genes after transfection will make stem cell-related gene therapy more effective and widely used in clinical applications ^[1] .

Stem cells integrate foreign genes in vitro to study gene function

The combination of embryonic stem cells and gene localization integration technology is useful for studying the expression and function of genes in embryos.

Very important. The use of this technology can knock out specific genes during development and study gene loss in animals. This also has important effects on molecular regulatory mechanisms that have not been fully demonstrated in the body. In addition, Gene-acquired mutations can be used at the stem cell level to make specific genes transient or long-term expressed in vivo to study the role of genes in different developmental stages of the embryo ^[1] .

Establishment of stem cell drug screening platform, pharmacological research and new drug development

Embryonic stem cells can differentiate into multiple cell types and continuously self-renew, which has a wide range of uses in the field of pharmaceutical research. At present, cells used for drug screening are derived from abnormal human cells such as animals or cancer cells. Embryonic stem cells can be induced in vitro to provide humans with cells of various tissue types. This is useful for drug screening, identification and toxicology. Research provides a solid foundation and helps to establish a cell model of human disease and the development of new drugs ^[1] .