Stem cells have been at the centre of one of the most significant scientific debates to have taken place in the last 50 years.
In the early 1960s, Canadian scientists James Till and Ernest McCulloch published research that proved the existence of stem cells. These are unspecialised cells that have the ability to differentiate into other cells and to self-regenerate. Their ability to differentiate gives them the capacity to develop into other cell types.
In the past few decades, our understanding of the potential that stem cells hold as a curative or preventative solution for various conditions and diseases has grown. The debate around stem cell use has been heavily influenced by the ethical questions raised, leading U.S. President George W. Bush to restrict federal funding of human embryonic stem cell research in August 2001. Shortly after taking office in January 2009, U.S. President Barack Obama reversed the order, allowing research involving human stem cells.
In the six years that have passed since then, a number of developments have demonstrated the vast potential of stem cells.
In 2010, Advanced Cell Technology, a company involved in the development of regenerative medicine, received FDA approval to test stem cell therapy for those suffering from Stargardt's Macular Dystrophy, a degenerative eye disease. In July 2013, a group of Japanese scientists reported that they had grown human liver tissue from stem cells. The following year, British scientists developed custom-made organs and body parts using stem cells.
"One of the greatest advancements in stem cell research has been the identification of the human tooth as a viable source. "
One of the larger issues present in the ethical debate around stem cell use involves the methods used for the acquisition of stem cells. In 1998, University of Wisconsin (USA) scientist James Thomson isolated human embryonic stem cells and demonstrated their ability to rejuvenate. His research team had obtained the stem cells through a process that destroys human embryos, which effectively initiated the ethical debate around stem cell acquisition.
However, one of the greatest advancements in stem cell research has been the identification of the human tooth as a viable source for stem cells. Dental pulp is the soft living tissue inside a tooth; it's this tissue that contains stem cells, known as dental pulp stem cells.
Stem cells are found in baby teeth (milk teeth), especially the teeth in the front. Children typically begin losing these teeth from the age of five and continue losing them until they are 12.
The stem cells from the milk teeth are mesenchymal cells --cells that have the ability to generate a variety of cell types like chondrocytes, osteoblasts and adipocytes. (Chondrocytes are cells that have the ability to generate cartilage. Osteoblasts have the ability to generate bone. Adipocytes have the ability to repair damaged cardiac tissue following a heart attack.)
The dental pulp in the adult permanent teeth, such as wisdom teeth, also contains stem cells. The wisdom teeth usually don't participate in the chewing function. Also, due to their abnormal position, it's difficult to maintain oral hygiene around them, so they are more prone to decay. These teeth are very often extracted for orthodontic reasons. They are now seen as a source for potentially life-saving stem cells.
The identification of the human tooth as a source of stem cells represents an exciting development that offers great promise for the medical community.
Stem cell basics
While stem cells can be found in many organs in human beings, the most commonly known sources have been bone marrow and the umbilical cord, which is typically discarded when a baby is born. Banking the umbilical cord is common today.
There are mainly two types of stem cells found in humans:
Embryonic Stem Cells: These are "pluripotent" and have the ability to create all cell types in our bodies, while adult stem cells are multipotent and can form more limited types of cells. Embryonic stem cells are usually collected and cultured from embryonic cells, often resulting in the embryo's destruction.
Adult Stem Cells: Adult stem cells can be derived from different parts of the body and accordingly have different properties. They exist in several different tissues, including the umbilical cord blood, bone marrow, blood and brain. Some studies have suggested that adult stem cells are very versatile and can develop into many different cell types.