Most cells in our body are specialized for certain tasks: red blood cells carry oxygen from the lungs to the tissues and carbon dioxide in the opposite direction, gland cells produce specific molecules and “send” them through the bloodstream to other cells, retinal cells capture light and transmit signals to the brain. Stem cells are the “mother of all cells”, progenitor cells capable of differentiating, i.e. transforming into specialized cells. Stem cells are responsible for renewing worn-out cells in our body, and they hold great potential for vision recovery, aiding in the regeneration of retinal cells and restoring lost eyesight.
Corneal regeneration and vision recovery
Normally, the cornea is surrounded by the limbus, a translucent ring containing stem cells. These cells form an epithelial layer that protects and supports the cornea. When injury or infection occurs, the supply of stem cells is depleted, the cornea does not regenerate and becomes cloudy, resulting in impaired vision. The damaged cornea can be replaced with a donor cornea, but without stem cells, it will eventually suffer the same fate as the native cornea.
To solve this problem, stem cells are transplanted into the damaged eye. They are taken from a healthy eye and grown on a sample of amniotic membrane, a layer of placenta that has long been used to accelerate the healing of damaged corneas. When the stem cell sheet reaches the right size, it is transplanted into the damaged eye. For patients with a depleted stem cell supply but an intact cornea, this procedure is sufficient to restore vision recovery. Other patients, in addition to stem cell transplantation, require a corneal transplant from a donor.
Retinal restoration and vision recovery
In people over the age of 60, vision often deteriorates due to age-related degeneration of the yellow spot, an area at the back of the retina. This disease affects nearly 200 million people worldwide. The disease develops due to the destruction of the retinal pigment epithelium, a layer of cells that provides nutrients to the photoreceptors. The photoreceptors in the human retina include three types of cones, which are responsible for color vision, and one type of rod, which is responsible for twilight vision. Destruction of the epithelial cells leads to photoreceptor death and loss of vision. Pigment epithelial cells can also be damaged in various eye diseases, such as diabetic retinopathy, but stem cell-based therapies offer the potential for vision recovery by regenerating damaged retinal tissues.
Attempts to transplant pigment epithelial cells grown from stem cells have long been unsuccessful. By 2013, good results were achieved by transplanting the cells not individually, but in a continuous layer. This is the approach taken by Kapil Bharti, a cell biologist at the National Eye Institute in Bethesda, USA. He grows pigment epithelial cells on a biodegradable polymer scaffold, already approved by the FDA, and transplants them as a whole sheet.
To produce these cells, Bharti uses induced stem cells derived from the patient’s own blood cells. The advantage of this approach is that immunosuppressant drugs that prevent graft rejection can be avoided. Bharti is working with ophthalmologist David David Gamm, who uses stem cells to grow photoreceptors, offering the potential for vision recovery for patients with retinal damage.
Glaucoma
Glaucoma is a condition in which increased intraocular pressure damages the optic nerve, which can lead to blindness. Current glaucoma treatments (eye drops, surgery) aim to reduce pressure but do not repair damaged nerve cells.
The use of stem cells to regenerate optic nerve cells is being investigated. One approach is to transplant stem cells into tissue damaged by glaucoma. This can help restore lost neurons and improve the transmission of signals from the retina to the brain, offering the potential for vision recovery. For example, scientists are using stem cells of neural origin, such as brain cells or stem cells from bone marrow, to stimulate optic nerve repair and promote vision recovery in patients with glaucoma.
3D tissue bioprinting for vision recovery
In recent years, 3D bioprinting, a technique that allows for the printing of organic tissues using stem cells, has been developing. In the context of vision recovery, this could mean creating cellular structures that would be used to recreate damaged parts of the eye, such as the retina or cornea. Unlike traditional transplants, in which tissue is taken from donors, 3D printing using stem cells can create tissue that is more compatible with the patient’s body, reducing the risk of rejection. This area is still in the development stage, but there are already the first successful experiments to create cell layers for the treatment of eye diseases, offering new hope for vision recovery.
Conclusion
The use of stem cells to restore vision opens new perspectives in the treatment of eye diseases. Such methods can help in repairing damaged parts of the eye, such as the cornea and retina, as well as in treating glaucoma, in which the optic nerve is damaged. A promising direction is the use of stem cells taken from the patient’s own tissues, which reduces the risk of rejection. 3D tissue printing technologies are also being actively developed, which can create more appropriate cellular structures for the patient. Although these methods are still in the research stage, they are already showing good results and may in the future significantly improve vision recovery and quality of life for people with various eye diseases, offering hope for vision recovery to those affected by these conditions.
