Stem cells are different from the other types of cells in the human body. Although they can be harvested from various sources, they all share some of the same properties. In fact, stem cells are essentially a repair system in the human body. They can divide in unlimited numbers to replenish other cells, with new cells remaining a stem cell or becoming a more specialised cell with a specific purpose.
i. Stem Cells can divide and Renew themselves:
Stem cells have a special ability to divide and renew themselves for extended periods of time. Cells such as muscle or nerve don't normally replicate, but stem cells will repeatedly proliferate. This basically means that they produce copies of themselves many times over. In fact, an initial population of stem cells can produce millions of cells within mere months in a laboratory setting. It is when the produced cells remain unspecialised that the long-term self-renewal is apparent.
Understanding why stem cells divide and renew as they do can help scientists discover what happens during dysfunctional cell division that leads to cancer cells. It can also help them answer the question of how the cells' proliferation and differentiation is regulated.
Embryonic stem cells appear to be able to proliferate for a year or even longer without ever developing into specialised cells, contrasting with adult cells. Researchers are questioning why this occurs as well as what aspects regulate stem cell renewal.
ii. Stem cells are unspecialized:
The unspecialised nature of stem cells is an important one. It means that stem cells lack the specific parts that allow them to perform specialised functions in the body. If you think about your heart muscle, it functions to pump blood through your body. Also consider a nerve cell that sends signals to other nerve cells and the rest of your body, allowing you to move. A stem call does not have a specialised function but it has the capacity to differentiate into a specialised cell that can carry out these functions.
The exact factors that allow stem cells to be unspecialised are still somewhat of a mystery to researchers. Research has allowed scientists to grow stem cells in the laboratory, but the precise signals that trigger a stem cell to proliferate are still largely unknown. Once this is determined, scientists will be able to grow stem cells in the laboratory with greater success.
iii. Stem cells can give rise to specialised cells:
The ability of stem cells to give rise to specialised cells is a crucial one. In this process of differentiation, unspecialised stem cells produce specialised cells. It is thought that a cell's genes regulate the internal signals that trigger this process. These genes carry the specific code, or instructions, for all the parts and functions of a cell. External signals are those outside of the cell, which include chemicals released from other cells, physical connections with nearby cells and various other molecules in the surrounding area. Currently, scientists are searching for similarities and differences between the signals from one stem cell to another. Ultimately, answers will allow researchers to find ways to control stem cell differentiation. With control, scientists can more easily grow cells and tissues for specific functions.
Stem cells are clearly unique cells with special attributes. It is these special attributes that offer the vast potential to treat numerous diseases and save lives. With further research, scientists will hopefully be able to understand more about the intriguing properties of stem cells and can then find ways to manipulate these properties for therapeutic value.