Successful Gene Therapy Delivery to the Brain, Through the Eyes-

Introduction-

While looking into treatments for a mouse's eye infection, I happened to run across a study from 2015. The study entitled “Eye Drops Deliver Gene Therapy for Brain Disorders”, was enacted on mice. The study used eyedrops to deliver a genetic growth factor directly to the brains of mice, through the eye. Needless to say the study caught my eye and I wanted to look further into the study, and where it has lead.

Mouse Study using G-CSF-

In 2015 a group of scientists funded by the National Institute of Biomedical Engineering developed a method of delivering, and monitoring the effects of a certain genetic growth factor in brain disorders. Previous studies utilizing the same method had been conducted on humans, but the method for tracking the growth factor had not been developed, and therefore the human trial effectiveness was difficult to determine. The mouse study sought not only to determine the effectiveness of the growth factor but to also track its location.

The study used a special formula in the form of eyedrops filled with a genetic growth factor called Ganulocyte² Colony Stimulating Factor (G-CSF). The growth factor was designed to increase blood flow in mice afflicted with ischemia¹ of the brain. The eyedrops containing the growth factor were dropped into the eye of the mice. From the eye the G-CSF was tracked by MRI scans as it entered the brain.

The treatment lead to a significant reduction in neurological defects, brain atrophy, and death of mice normally caused by ischemia. This study showed promising results and may be implimented in further human studies.

Human Studies using G-CSF-

G-CSF treatment has been looked at as a form of treatment for various diseases caused by ischemia, not only in the brain, but in other organs such as the heart as well. Getting G-CSF to the brain is considered a possible treatment for diseases such as Alzheimer's, Parkinson's, and ALS. There is speculation that a G-CSF treatment, or a similar formula could be carried on emergency vehicles in an eye drop form. The eyedrops would be kept on hand in cases where lack of blood flow to the brain may be of concern in cases of stroke for example.

Studies have been held on humans, but the technique for monitoring the G-CSF expression did not exist, prior to the mouse study of 2015 discussed above. In a human study of over 400 stroke patients, G-CSF eye drop treatments did not improve outcomes of patients, or reduce the effects of stroke. This failure had long diminished enthusiasm about the treatment. Without being able to track the G-CSF after it entered the body, it could not be determined whether the growth factor either had no effect on the human brain, or if it the brain simply never received the growth factor in significant doses. Some doctors still see the promise of such a therapy, and believe that using the MRI techniques developed in the mouse study could help to establish whether the therapy is reaching the human brain, and if it may ever be affective.

In the words of Richard Conroy, Ph.D., Director of the NIBIB Division of Applied Science and Technology:

“This new, rapid, non-invasive administration and evaluation of gene therapy has the potential to be successfully translated to humans,” Conroy says “The use of MRI to specifically image and verify gene expression, now gives us a much clearer picture of how effective the gene therapy is. The dramatic reduction in brain atrophy in mice, if verified in humans, could lead to highly effective emergency treatments for stroke and other diseases that often cause brain damage such as heart attack.”

Thoughts in Review-

As someone generally skeptical of genetic modification, or alteration I was inspired to research deeper into this study and type of therapy. I could not have imagined a genetic therapy with as many possible implications as this one carries. This type of therapy, though it can certainly be used in a beneficial manner, can also have unforeseen side effects, and may not always carry a formula meant to help. If a drop in the eyes can send genetic growth factors to the brain directly, we must realize that this type of therapy has risks, and could be implimented on a massive scale quite easily.

Though the human studies showed no effect, it can not be disregarded that the mice study proved successful at delivering genetic therapy directly to the brain using only the eyeball as a vector. These same techniques could be possible in people as well, and what is delivered may not always be beneficial to us.

Similar News-

A drug called Luxturna, used to treat a rare eye condition called Leber's congenital amaurosis, has recently been recommended for approval by the FDA. The FDA will decide final approval of Luxturna by January 12^th of 2018. Luxturna is a genetic therapy that is injected into the eye (with a microscopic needle), and alters the genetics of the retina using a virus to modify the gene attributed to the retinal disease, using a virus to spread genetic information. Luxturna began testing on human participants in 2012, and has shown to improve the vision of those with Leber's. I hope to cover this topic deeper in a future article, stay tuned for more.

Footnotes-

1. Ischemia or ischaemia- is a restriction in blood supply to tissues, causing a shortage of oxygen and glucoseneeded for cellular metabolism (to keep tissue alive) https://en.wikipedia.org/wiki/Ischemia

2. Ganulocyte- “Granulocytes are a category of white blood cells characterized by the presence of granules in their cytoplasm.”- https://en.wikipedia.org/wiki/Granulocyte

References-

1. "Eye drops deliver gene therapy for brain disorders – NIH mouse study." National Institute of Biomedical Imaging and Bioengineering. November 03, 2015. Accessed October 28, 2017. https://www.nibib.nih.gov/news-events/newsroom/eye-drops-deliver-gene-therapy-brain-disorders-%E2%80%93-nih-mouse-study.

2. "ClinicalKey." ClinicalKey. Accessed November 04, 2017. https://www.clinicalkey.com/#!/content/playContent/1-s2.0-S0140673617318688.
3. Taylor, Phil. "Spark Therapeutics' Luxturna advisory committee vote sets gene therapy landmark." FierceBiotech. October 13, 2017. Accessed November 04, 2017. http://www.fiercebiotech.com/biotech/spark-therapeutics-luxturna-adcomm-vote-sets-gene-therapy-landmark.