Background
In brief, stem cells refer to cells that have the potential to differentiate into other cell types. This differs from most other cells, such as skin cells, which are incapable of changing into a different cell type. For example, neurons cannot differentiate (turn into) liver cells, but stem cells can turn into either as a result of environmental surroundings.
Stem cells offer a high potential in clinical and scientific applications that may produce information about human development and human tissue diseases. These versatile cells form all of the tissues and organs that make up the complexity of the human bodies, starting as a single cell upon conception. Stem cells are the building blocks of life and can repair damaged cells and replace dead ones. In theory, stem cells are able to divide infinitely in order to replenish cells for the host as long as it is alive. Stem cells are undifferentiated cells with the ability to self-divide for renewal of its own type, but also can self-divide and differentiate to become specialized under various conditions. The most crucial application of stem cells in an organism, however, is the production of cells and tissues that can be used to replace damaged or malfunctioning tissues due to diseases and injuries.
Blood contains red and white blood cells, plasma and platelets, and are derived from stem cells in bone marrow. Stem cells retain the capacity of mitotic cell division and are divided into three basic types: totipotent, multipotent, and pluripotent. Totipotent stem cells have the capability of differentiating into all types of cells in the body. Multipotent stem cells are those that differentiate into a small number of different cell types, while pluripotent stem cells may develop into any type of cell in the body except those needed to develop fetal growth. Cell differentiation is a crucial topic in cancer research, as it is often in differentiation that cells turn down the path to tumor formation. Differentiated human stem cells provide an excellent starting ground for pharmaceutical screening.
Stem Cell Involvement in Disease
Cellular differentiation occurs as cells are programmed to create intracellular patterns depending on chemical signaling. In an embryo, such cells are directed to differentiate or become various tissue cells such as fat cells, nerve cells, muscle cells, epithelial cells, and so forth. A stem cell is uncommitted until instructed what to do. Embryonic (totipotent) stem cells are found in early embryo development and have the capacity to differentiate, or morph, into any of the 200 types of specialized cells found in the human body. Stem cells found in bone marrow are capable of producing different types of blood cells every second. An adult (multipotent) stem cell is found in various tissues and is able to multiply as part of maintenance and renewal.
Embryonic stem cells cultured in laboratory settings may be coaxed to divide multiple times. Such cells can also be coaxed into developing into muscle cells, nerve cells or blood cells. As a result of their abundant abilities, stem cells have the potential to help individuals affected by diseases such as Parkinson’s and leukemia, as well as heart attacks and paralysis. Adult stem cells have been used to create bone, nerve, and cartilage cells. However, adult stem cells are not as versatile as those found in embryonic tissues due to differentiation. Current research and development is also delving into umbilical cord blood stem cells to use as future cellular and tissue structures. Pluripotent stem cells may be cultivated from human embryonic tissues and used to create stem cell lines that are grown in a laboratory for research purposes. Such stem cell lines enable researchers and scientists to utilize these cultured stem cells without needing to isolate stem cells from their hosts. Stem cell lines may be grown in laboratory environments and frozen for storage.
Stem cell research has the potential of offering cures for many diseases, as well as for generating new cells that may be used to replace cells in individuals suffering from leukemia, cardiovascular disease, diabetes, and even spinal injuries. The future of stem cell research offers potential treatments and cures for over 70 illnesses and diseases and will eventually be a major contributor to medical treatments and protocols in the future.
An example of stem cells being used as potential treatments for disease is in a recent study by Gazdic et al. Human embryonic stem cell-derived oligodendrocyte progenitor cells (OPC) were transplanted into mice that had a spinal cord injury. In just seven days, the stem cells differentiated into mature oligodendrocytes and regenerated the myelin sheath for the spinal cord, greatly improving locomotor function. It was determined that the first week after spinal cord injury was the optimal time to transplant OPCs, as administration after 10 months had no significant difference in neurological outcomes than controls. Numerous studies showed the benefit of transplanting stem cells for their ability to recover neurological function. Though there are many advancements around stem cells and its applications in medicine, more research must be done to prevent immune rejection and other potential side effects (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5979319/).