Long ago it was unknown that humans could grow new brain cells. Years later it was discovered that through a process called “neurogenesis,” new brain cells could be created, even in adults. These days scientists are learning more ways in which people are able to grow new neurons as well as deciphering the degree to which these new neurons are beneficial. In fact, one Harvard neurobiologist was recently given $2.75 million from the National Institute of Mental Health to specifically study neurogenesis.
Most experts hypothesize that the ability to grow new brain cells is promotes brain health and prevents cognitive decline. When it comes to the creation of brain cells though, it seems that other species, specifically the crayfish may have a unique advantage over us humans. Recent research has demonstrated that crayfish are able to convert their own blood cells into fully functional brain cells.
How Crayfish Regenerate Brain Cells (Neurons) with Blood Cells
Crayfish are able to regenerate their neurons through a relatively simple process. Their blood cells (called “hemocytes”) attach to an area of the crayfish brain called the “neurogenic niche.” The neurogenic niche is located at the base of the brain and essentially serves as an incubator whereby hemocytes transition into partially formed “precursor” neurons. Upon entering the neurogenic niche, hemocytes will eventually transition into partially-formed, precursor neurons.
It typically takes several weeks before the hemocytes morph into precursor neurons in the niche. In the crayfish, hundreds of precursor neurons are being formed daily. Once these cells are partially formed, they end up leaving the niche and travel to specialized sensory processing areas of the brain. Specificially, they end up relocating to areas of the brain involved in olfactory (smell) and visual processing (e.g. eye stalks).
When the precursor neurons arrive at their specialized sites, they make final transitions into fully formed neurons. This process can take up to an additional 2 months, but eventually they will exhibit full neurotransmission. These new neurons ultimately help improve the sensory abilities of the crayfish. Researchers noted that the process of neurogenesis never stops in the brain of a crayfish.
Additionally they discovered that there was a correlation between the total number of hemocytes and the number of cells within the neurogenic niche. Researchers also noted that the immune system plays a direct role in facilitating the entire process of blood-to-brain cell conversion.
- Source: http://www.sciencedirect.com/science/article/pii/S1534580714004055
The Research: Published in “Developmental Cell” (August 2014)
You may be wondering how researchers came across this discovery. A lead researcher, Barbara Beltz (Wellesley College in Massachusetts) had previously conducted experiments on crayfish hemocytes in a Petri dish. She observed that these blood cells were naturally attracted to the neurogenic niche. She then discovered that the blood cells transitioned into neurons.
To better understand this process she utilized “Astakine 1,” a chemical used to control hemocyte (blood cell) production. She essentially manipulated the number of hemocytes that were inside various living crayfish and found that this manipulation changed the number of cells within the neurogenic niche. When she increased the number of cells in the niche, she discovered that it lead to an increased production of neurons.
Additionally the researchers collected hemocytes from various donor crayfish, used a non-toxic dye to track them, and injected them into completely different crayfish. The dyed hemocytes that were transferred from the donor to the new crayfish showed up in the neurogenic niche within just three days after the transfer. Within one week, they had already relocated to the base of various sensory nerve clusters. In less than two months after the transfusion, the dyed hemocytes became fully formed neurons involved in sensory processing.
Future Possibilities: Could This Apply To Humans?
It’s not necessarily an important finding, but it is a unique one that will fascinate many. People like learning about unique biological processes that occur within other species; especially when this biological process is something that does not occur within humans. Humans are able to create new neurons through a process called neurogenesis, but humans are not able to create brain cells from blood cells.
This study is considered a breakthrough because multiple cell systems (blood and brain) were initially thought to function independently. It was not known that blood cells are connected with, and can transition into, brain cells. Researchers speculate that if the mechanisms behind findings could be applied to humans, it may be useful for treating neurodegenerative diseases such as Alzheimer’s, dementia, and Parkinson’s.
It was also noted that human stem cells are pretty similar to the precursor cells found in crayfish, but the underlying biological regeneration process is different. Although we are likely a far cry from manipulating human cells to regenerate the brain, a better understanding of this process could pave the way for a future breakthrough in regenerative medicine. Further research will be warranted in this area to better understand how this process occurs.