Stem cell therapy is a form of regenerative medicine designed to repair damaged cells within the body by reducing inflammation and modulating the immune system. This phenomenon makes stem cell therapy a viable treatment option for a variety of medical conditions.
What is stem cell therapy?
The term stem cell therapy refers to any treatment involving the use of viable human stem cells including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells. By being able to differentiate into the specific cell types necessary for repairing diseased tissues, stem cells are the ideal solution for tissue and organ transplantation.
As stem cell-based therapies are complex, researchers often seek stable, safe, and readily available sources of stem cells that can differentiate into multiple lineages. As such, choosing stem cells with clinical applications in mind is of the utmost importance
The hierarchy of stem cells
In general, stem cells fall into three categories. In addition to self-renewal, all three share a unique ability to differentiate. However, stem cells do not exist in a homogeneous form, but rather in a developmental hierarchy. Among all stem cells, totipotent cells are the most basic and least developed. These cells are capable of developing into a complete embryo while forming the extraembryonic tissue at the same time. During the fertilization of the ovum, this unique property begins and ends when the embryo reaches the stage of four to eight cells.
As the cell divides further, it loses its totipotency property and becomes a pluripotent cell, capable of dividing into each of the three embryonic germ layers (ectoderm, mesoderm, and endoderm). These cells are referred to as “embryonic stem cells” and are isolated from the inner cell mass of the blastocyst after the embryo is destroyed.
The property of pluripotency is lost with successive divisions, resulting in a more limited differentiation capability in which the cells can only differentiate into limited types of cells related to their origins. “Adult stem cells” have this property, which helps maintain homeostasis throughout the organism’s lifespan. It is known that adult stem cells are present in most specialized tissue types of the body in a metabolically quiescent state, including bone marrow and oral and dental tissue.
According to many authors, adult stem cells are the gold standard for stem cell-based therapies. A number of trials involving adult stem cells have shown promising results, especially in the transplantation of hematopoietic stem cells.
Stem cell research for treating disease
In 2006, Shinya Yamanka achieved a scientific breakthrough in stem cell research by generating cells with the same properties as embryonic stem cells. In fully differentiated somatic cells, namely fibroblasts, four transcription factors were transiently over-expressed, including OCT4, SOX2, KLF4, and MYC. As a result of the discovery of these cells, stem cell research has been transformed ever since. Similar to embryonic stem cells, these cells are capable of dividing into any of the germ layers. As a result of the development of iPSC technology, disease identification and treatment have become more innovative. IPSCs are therefore promising as a source of pluripotent derived patient-matched cells that can be used for autologous transplants because they can be generated from the patient’s own cells.
It is believed that stem cells, due to their unique capacity to regenerate, may hold new potential for treating diseases such as diabetes and heart disease. Despite this, there remains much work to be done in the laboratory and clinic to determine how these cells can be used in regenerative or reparative medicine to treat diseases.
Studies of stem cells in the laboratory allow scientists to gain a better understanding of the cells’ essential properties as well as what makes them different from specialized cell types. Researchers are already using stem cells to test new drugs and develop model systems for studying normal development and identifying the causes of birth defects in the laboratory.
The study of stem cells continues to advance our understanding of the development of an organism from a single cell and of how healthy cells replace damaged cells in adult organisms. Research on stem cells is one of the most fascinating areas of contemporary biology, but, as with many fields of science that expand rapidly, it raises as many questions as it answers.
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