Cells in the human body
The human body comprises more than 200 types of cells, and every one of these cell types arises from the zygote, the single cell that forms when an egg is fertilized by a sperm. Within a few days, that single cell divides over and over again until it forms a blastocyst, a hollow ball of 150 to 200 cells that give rise to every single cell type a human body needs to survive, including the umbilical cord and the placenta that nourishes the developing fetus.
What is a Stem Cell?
Stem cells are the foundation of development in plants, animals and humans. In humans, there are many different types of stem cells that come from different places in the body or are formed at different times in our lives. These include embryonic stem cells that exist only at the earliest stages of development and various types of tissue-specific (or adult) stem cells that appear during fetal development and remain in our bodies throughout life.
Every organ and tissue in our body grew out of a cluster of stem cells early in development. A stem cell differs from every other cell in the body in its ability to renew itself. It can divide into many more just like it.
Stem cells can repair and replace tissue in the human body. In other words, stem cells have the power to heal.
Think of our skin. The tissue in our skin needs constant renewal that could not take place without stem cells. Or muscle — stem cells in our muscles are what repair damaged tissue when we are injured.
Early in life, stem cells have the extraordinary potential to develop into any type of cell in the human body.
They start in the embryo as unprogrammed cells, then become specialized to create bone, muscle, skin, the heart, the brain, and over 250 other types of specialized cells. These are called pluripotent stem cells.
Stem cells are defined by two characteristics:
They can make copies of themselves, or self-renew
They can differentiate, or develop, into more specialized cells
Beyond these two things, though, stem cells differ a great deal in their behaviours and capabilities.
Using Stem Cells to Save People
Researchers have found that stem cells can be used to treat disease and injury. They stimulate the body to repair itself.
These procedures rely on transplanting stem cells derived from bone marrow and have dramatically altered the treatment of blood disorders and certain cancers such as leukemia.
In the past 20 years, significant new discoveries have emerged — breakthroughs that the original discoverers of stem cells never dreamed about. Researchers are finding new ways to use stem cells to rebuild tissue in many parts of the body where it has been damaged, such as the eye, the pancreas and the brain. Some revolutionary treatments for blindness, MS, stroke and spinal cord injury are already in early stage clinical trials.
Sources of Stem Cells
Much of the public discussion about stem cells has focused on where stem cells come from. Adult stem cells can be found in specific tissues in our bodies. As mature cells, they are already specialized to perform certain functions and are somewhat more limited in their application for therapeutic purposes. Generally, they can make only the kind of cells found in the tissue where they reside.
On the other hand, embryonic stem cells — derived from five-day old blastocysts that are precursors to embryos — are pluripotent in nature. They can generate any kind of cell in the body, any kind of tissue. This is why they are of such value to scientists doing both basic research in the lab and medical research in the clinic. They have the potential to regenerate tissue and cells that have been lost because of disease or injury.
Benefits of Stem Cell
Stem cells represent a revolution in health care, but we’re still in the early days. Bone marrow stem cell transplantation has been curing some kinds of cancer for decades, but in other potential areas we’ve barely begun scratching the surface.
Stem cells treatments are now used to help heal orthopaedic injuries, connective tissue damage, neurological problems, heart disease, immune rejection disorders and much more.
Benefits of stem cell treatments include speeding up healing time, lowering chronic pain, reducing need for medications, increasing functionality, decreasing nerve damage and improving collagen concentrations.
