Stem cell secretions, called exosomes, seem to protect cells in the retina, which is the tissue in the back of the eye, according to new research. The findings could potentially help designing better therapies for glaucoma, one of the leading causes of blindness in the United States.
The research, published in the journal Stem Cells Translational Medicine, was carried out by scientists at the National Eye Institute (NEI), part of the National Institutes of Health.
Stem Cell Exosomes, Potential Treatment For Glaucoma
Exosomes are small membrane-enclosed packages that appear inside of cells before getting expelled. For a long time, researchers believed they were part of a cellular disposal system, but have recently discovered that they contain certain lipids, proteins, and gene-regulating RNA.
Previous research has suggested that exosomes from one cell can be incorporated in another, by fusing with the membrane of the target cell and then spurring it to produce new proteins. Additionally, exosomes also facilitate the interaction between cells and they have a significant signaling role, allowing them to be used for therapeutic purposes.
In the research, Ben Mead, Ph.D. from the National Eye Institute (NEI), analyzed the importance of stem cells exosomes when it comes to retinal ganglion cells, a kind of retinal cell that forms in the optic nerve carrying the visual information from the eye to the brain. When retinal ganglion cells die, vision loss can occur in glaucoma and other optic neuropathies.
"The present study aimed to isolate exosomes from bone marrow-derived mesenchymal stem cells (BMSC) and test them in a rat optic nerve crush model. Treatment of primary retinal cultures with BMSC-exosomes demonstrated significant neuroprotective and neuritogenic effects," noted the research.
Therapeutic attempts all over the scientific community have been focused on stem cells, employed to replace or repair tissues, mainly due to their capacity to transform into any type of body cell. It is much practical, however, to employ exosomes isolated from stem cells, as this procedure has key advantages that start with transplanting the whole stem cells.
Additionally, another benefit of exosomes is their lack of risks when it comes to transplanting live stem cells into the eye. This procedure could normally cause complications, among which unwanted cell growth and immune rejection.
"Exosomes offer a cell-free alternative to BMSC therapy, which can be easily isolated, purified and stored. They lack the risk of complications associated with transplanting live cells into the vitreous (immune rejection, unwanted proliferation/differentiation). It is however currently unknown what the ideal timeframe for treatment is, whether a single injection of exosomes is sufficient or weekly/bi-weekly/monthly injections are required," the study concluded.
According to the study, future academic research should focus on determining the ideal timeframe for the therapy, and better characterizing the exosomes and their targets to employ them in future treatment.
Glaucoma, A Dangerous Disease
More than 3 million people live with glaucoma across the United States, 2.7 million of whom are aged 40 or older and are affected by open-angle glaucoma, the most common form of the condition.
Worldwide, 60.5 million people were suffering from glaucoma in 2010. Given the fact that the world's population is aging, this number could increase up to 80 million by 2020.