Dormant Stem Cells Could be Key to Remedying Brain Damage
Stem cells are characterized by their self-renewal capacity and potential to differentiate into single or multiple types of daughter cells. Stem cells in different tissues are governed by general genetic programs that maintain their stem cell natures, although the critical genes functioning in these programs are likely to differ across stem cell types.
A common property of stem cells is quiescence in terms of the cell cycle. The rarity of stem cells in vivo and relative quiescence has made it impossible to confirm this directly.
The long-term maintenance of stem cells largely depends on the interaction with their specific microenvironments, niches. And the epidermal stem cell niche is an ideal system to study the regulation of stem cell quiescence because stem cell identity and location are well organized.
The “Quiescence” of stem cells is critical to ensure lifelong tissue maintenance and to protect the stem cell pool from premature exhaustion under conditions of various stresses.
Now, scientists at the University of Cambridge have identified a such a stem cell, called “G2 quiescent stem cell” in the brain which they believe possesses high potential for repair following brain injury or disease.
Importantly, G2 quiescent stem cells awaken to make the key types of cell in the brain – neurons and glia – much faster than known quiescent stem cells, making them attractive targets for therapeutic design.
The brain is poor at repairing itself; however, it may become possible to improve repair without surgery by targeting stem cells residing in patients’ brains. Stem cells have the unique capacity to produce all of the cells in the brain but are normally kept inactive in a form of cellular ‘sleep’ known as quiescence. Quiescent cells do not proliferate or generate new cells. Thus, any regenerative therapy targeting stem cells must first awaken them from quiescence.
In their investigation, the team studied and identified a gene known as tribbles in the fruit fly which was found to selectively regulate G2 quiescent stem cells. This gene has counterparts in the mammalian genome that are expressed in stem cells in the brain. The researchers believe that drugs that target tribbles might be one route to awakening G2 quiescent stem cells.
Further, the researchers are invested in trying to identify potential drug-like molecules that block this gene and awaken a person’s stem cells. They believe this discovery could help improve or develop new regenerative medicines.
