These little cells are called hair cells. They detect sound waves and then they convert them into nerve signals. Inside our ear there is a part that helps us hear called the cochlea. In each cochlea there about 15,000 hair cells and any cell that dies is gone and irreplaceable. This is a main cause of loss of hearing.
However these cells being irreplaceable may no longer be true! There is now new hope for restoring that lost hearing! Scientists have figured out a way to regrow hair cells in massive numbers.
As we said before when these hair cells died they were originally irreplaceable but scientists found that this isn’t the case with animals. In birds and amphibians hair cells cells do grow back. Ateam of researchers from Brigham & Women's Hospital, MIT and Massachusetts Eye & Ear were excited with this fact and want to use it to see if they can get hair cell reproduction in humans too.
There is already previous research available on regenerating intestinal cells. Using that idea as a proof of concept, they tried seeing if they could do something similar with hair cells. Two different methods were found and one was sixty times more efficient than the other.
In one method the researchers placed immature cochlear progenitor cells from mice in a lab dish. Progenitor cells are like stem cells. They can convert into other types of cells. Changing into the cells needed is called differentiation. In order to bring about this differentiation, the researchers first added drugs to cause those cells to multiply rapidly. After they grew a sufficient number of those progenitor cells, the researchers then used other drugs to cause the cells to differentiate into mature hair cells. This method worked well but they discovered a faster far more efficient method.
Researchers used progenitor cells straight on an extracted mouse cochlea. What happened was that besides multiplying the cells, somehow the cochlea had already signaled the cells to differentiate by themselves without more drugs to do it. This brought about the production of 60 times more hair cells than the first method, in which progenitor cells had to first be grown and then prompted to differentiate.
The method that used mouse cochlea also worked when tried on humans so the researchers are very optimistic and excited about the possibility of treating hearing loss in this manner. It may be possible to simply administer an injection to the ear and the cells will replicate and regrow hair cells in the cochlea!
Following up on their research, these researchers already have have formed a spinoff company to commercialize the technology. They hope to begin clinical trials within 18 months.
This is yet another miracle from the world of medicine. May G-d grant that we should be healthy!