Eye Cell Replacement Success Sparks Hope for Glaucoma Treatment

Successful transplantation of retinal ganglion cells into animals
Transplanted cells respond to light stimulation
Hope for treatment of optic nerve disorders like glaucoma

Scientists have been successful in transplanting retinal ganglion cells into mice. These transplanted cells developed a morphology similar to the cells in the retina with dendrites tending towards the inner plexiform layer and axons growing towards the optic nerve.

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‘Retinal ganglion cell transplant will be a boon for glaucoma patients, as affected cells can be replaced with fully functional cells.’

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The cells showed electrical response and stimulation to light, though not as rapid as the original retinal ganglion cells.

Glaucoma is the leading cause of irreversible eyesight loss in the world. The high incidence of this disease condition and its potential to drastically affect the quality of life of the patient has led to January, being declared the glaucoma awareness month. It is caused due to varied reasons that include mutations in the genes and it results in the loss of retinal ganglion cells, which are necessary to carry information from the photoreceptor cells to the nerve center of the brain. Therefore, scientists believe that if these damaged cells are replaced with new retinal ganglion cells (RGC), then there could be a possible cure for the disease.

Challenges Faced in Retinal Ganglion Cell (RGC) Replacement

The neurons have to face distal and local wiring after intravitreal injection.
Retinal guidance molecules that exist undergo developmental changes making it difficult for transplanted cells to train their axons towards the nerve head.

Steps Taken to Promote RGC Migration

Local dendrites sent into the inner plexiform layer.
Axons are elongated to reach the optic nerve head.
Regenerating the axons in the affected optic nerve, up to the optic chiasma and till the brain.

Isolation of the Retinal Cells

The retinal cells were isolated from newborn rats and then treated to remove endothelial cells and macrophages. The cultures of retinal ganglion cells were directed towards the optic nerve head by a process called electro-spinning.

Scaffolds were used to elongate the RGC to mimic the real retinal ganglion cells and to improve their chances of survival. These scaffolds were also used as a cell delivery system.

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This is the first time retinal ganglion cells have been successfully injected into the eye as previous studies that attempted to inject these cells have been unsuccessful. This could be due to the fact that these scientists used cells that were fully differentiated rather than undifferentiated cells used in previous studies.

Researchers Jeffrey Goldberg, Praseeda Venugopalan and colleagues injected 152 healthy adult mice with the cultures of RGC with a success rate of 1 in 5. This, according to Goldberg, is a high success rate for such a delicate procedure.

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Future Prospects

The current study injected the retinal ganglion cells into healthy mice. It would be interesting to study the progress of the retinal ganglion cells in mice that suffer from glaucoma

Breakthroughs in ocular transplantation science aid in harboring hope for more effective therapies. Retinal transplants are believed to bring hope for people suffering from retinitis pigmentosa and age-related macular degeneration. In this study, retinal ganglion cells have been transplanted improving the chance for a better treatment measure for glaucoma.

References:

1. Venugopalan P Wang Y Nguyen T, Huang A, Muller KJ3, Goldberg JL “Transplanted neurons integrate into adult retinas and respond to light.” Nat Commun. 2016 Feb 4;

2. Karl E. Kador, Ramon B. Montero, Praseeda Venugopalan, Jonathan Hertz, Allison N. Zindell, Daniel A. Valenzuela, Mohammed S. Uddin, Erin B. Lavik, Kenneth J. Muller, Fotios M. Andreopoulos, and Jeffrey L. Goldberga. “Tissue Engineering the Retinal Ganglion Cell Nerve Fiber Layer”. doi: 10.1016/j.biomaterials.2013.02.027

Source-Medindia