Scientist for centuries, have known that certain animals can regenerate missing parts of their bodies. Humans share this ability with animals like the starfish and the newt. Although humans cannot replace a missing leg or a finger, our bodies are constantly regenerating skin, blood and other tissues. Experiments conducted in the 1950s with bone marrow, established the existence of stem cells as powerful cells that allow us to regenerate some tissues. This led to the development of bone marrow transplantation, a therapy now widely used in medicine.
WHAT IS A STEM CELL?
Every cell in the human body can be traced back to a fertilized egg that came into existence from the union of an egg and a sperm. The human body is made up of not just one, but over 200 different types of cells and all of these cell types comes from a pool of stem cells in the early embryo.
Stem cells are unspecialized cells that develop into specialized cells, which in turn make up the different types of tissues in the human body. During the period of early development as well as later in life, various types of stem cells give rise to specialized or differentiated cells, such as the skin, blood, muscle and nerve cells, which carry out the specific functions of the body (Figs 1.1 and 1.2).
In humans, stem cells have been identified in the inner cell mass of the early embryo, in some tissues of the fetus, the umbilical cord, the placenta and in several adult organs. In some of the adult organs, the stem cells give rise to more than one specialized cell type within that organ (e.g.: the neural stem cells give rise to three different cell types found in the brain neurons, glial cells and astrocytes) (Figs 1.3 to 1.5).
Defining Features of a Stem Cell
- Stem cell “self-renews”, i.e. a stem cell undergoes cell division when it is called into action. While one daughter cell remains a stem cell, the other becomes more committed to forming a particular cell type (a “committed progenitor”) by a process called “asymmetric division”.
- Stem cell forms multiple cell types, i.e. “multipotent”.
- A single stem cell, when transplanted within the body, completely “reforms” a particular tissue.
Stem cells have thus been long regarded as undifferentiated cells capable of proliferation, self renewal, production of a large number of differentiated progeny, and regeneration of tissues (Fig. 1.6).
How do Stem Cells Look Like under the Microscope (Fig. 1.7)?
The Ultimate in Preventative Therapies
Research shows that on comparison new stem cells are able to multiply, and make repairs, more than older stem cells, such as those existing in aging bodies. The availability of newborn stem cells, such as those we offer, makes the body maintenance processes much more active.
As damaged cells are identified by the immune system, and are then replaced by circulating stem cells, dangerous conditions such as cancer are likely to be prevented. In fact, stem cells can be considered the ultimate preventive health measure.
Stem cell therapy involves the introduction of healthy new stem cells to, (potentially) repair, and replace damaged or lost cells. The ability to repair damaged tissues and rejuvenate aging organs makes it very effective at reversing various disease processes, as well as the signs and symptoms of aging.
