Macular degeneration is a crushing condition, leading to loss of visual acuity, and in some cases, eventual blindness. Even those who don’t experience total eyesight loss suffer a frustrating degradation of central vision, which makes driving, using the computer or other devices, recognizing faces, reading and many other activities nearly impossible to do. However, recent advancements in stem cell treatments for macular degeneration are providing a beacon of hope to many.
While these new treatments are an important and potentially life-saving step forward, the cannot heal all cases of macular degeneration. Depending on the severity, the damage to the retina may prove too complete, making stem cell treatments ineffective. However, while stems cells don’t mean a cure for everyone with macular degeneration, stem cells do provide a potential source of healing for individuals with this devastating disease.
A Deeper Look At Stem Cell Treatments For Macular Degeneration
In this article:
- What to Expect With Macular Degeneration
- What Is Age-Related Macular Degeneration?
- What Are Stem Cells and How Do They Work?
- How Do Stem Cells Help with Macular Degeneration?
- What Is the Process Like?
- What Risks and Benefits Are Associated with Stem Cell Treatments for Eyesight?
- What Clinical Studies Have Been Done with Stem Cells for Macular Degeneration?
In order to explore this topic thoroughly, it’s necessary to do an overview of age-related macular degeneration. Next comes an overview of stem cell treatments for macular degeneration, as well as an exploration of what the process of using stem cells to heal vision is like. Lastly, those considering this treatment should understand what the risks and benefits are, as well as who constitutes a good candidate.
What Is Age-Related Macular Degeneration?
Age-related macular degeneration is also known as macular degeneration, AMD, and ARMD. This condition causes blurry vision and blind spots in the central vision.
Two forms of the disease exists: dry age-related macular degeneration and wet age-related macular degeneration. The dry form occurs when the eye deposits pigment in the macula, a small structure at the front of the retina. It also occurs from aging and thinning of the macula, which bears the brunt of responsibility for central visual acuity.
The wet form occurs from growth of blood vessels in the macular area. As such, it is also referred to as the neovascular form (as opposed to the non-neovascular dry form). This succeeds the dry form, and results from the body’s attempt to bring more oxygen and resources to the area. Because of this, the blood vessels unfortunately tend to end up occluding eyesight even more.
Often, macular degeneration stems from degradation of the retinal pigment epithelium (RPE) as well. This layer of cells lies just under the retina, responsible for providing the necessary nourishment to keep the eyes healthy.
When the RPE stops functioning effectively, the eyes cannot absorb light properly, react to changes in ambient light, receive images clearly, or maintain immune function. The overall result is mild to serious loss of vision.
What Are Stem Cells and How Do They Work?
In previous years, macular degeneration proved a tough nut to crack. That’s because the eye is incapable of making new retinal cells to replace old damaged ones. In the absence of new cells, the eye remains compromised indefinitely.
However, recent advances in regenerative medicine make it possible to replace those old damaged cells with stem cells. These stem cells are capable of transforming into a variety of new cells.
Stem cells come in four main types:
- Embryonic Stem Cells (ESCs) – These are sourced from early stage human embryos.
- Perinatal Stem Cells – These are found within the various perinatal tissues, such as amniotic fluid and tissue, placental blood and tissue, or umbilical cord blood and tissue.
- Adult Stem Cells – These are sourced from tissues within a living human being.
- Induced Pluripotent Stem Cells (iPSCs) – These are cells that are created in a lab through genetically reprogramming. Because they are created from mature adult cells, they are non-controversial.
The most versatile type of regenerative cell is a pluripotent stem cell, because it can become any of the 200 different tissues that form a human being. Only embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are pluripotent.
Pluripotent stem cells are known as “master cells,” because of their capacity to replicate and differentiate into a wide range of human tissues. In addition, they are capable of endless self-renewal. Unlike other cells in the body, which have an expiration date and will commit cell suicide after a certain number of divisions, pluripotent stem cells can keep dividing and repopulating forever.
In contrast, both perinatal and adult stem cells are both multipotent. This means they can become a limited range of tissue types. Multipotent stem cells are found in many parts of the adult body, including:
- Blood and blood vessels
- Bones and muscle tissue
- The brain
- The liver
- The gut
- The heart
- The ovaries and testes
- The skin
- Fat tissue
How Do Stem Cells Help with Macular Degeneration?
Macular degeneration, whether wet or dry, is fundamentally an issue of old or damaged cells, which are unable to repair themselves. Unfortunately, many structures in the body lack the ability to self-renew after a certain amount of time, and the eye is one such structure.
Stem cells provide a new lease on life in the form of cells that physicians can induce to become eye cells. Once introduced to the macula, they can heal and repair it by replacing the existing eye tissue. Over time, patients may experience a partial or complete reversal of eye damage.
What Is the Process Like?
First, physicians harvest stem cells from the patient, usually from the blood or adipose (fat) tissue. In the lab, they induce these master cells to become retinal cells, after which they inject those cells back into the patient.
They can introduce the cells in a variety of ways, including:
- placing them behind the eye (retrobulbar)
- intravenously (in the vein)
- intravitreal (into the eye itself)
The best method will depend on the patient’s state of health, the advancement and severity of their disease, and their preferences, along with several other factors. The treatments can take place in either an operating room or right in a clinic.
The exact protocol also varies on how long the treatment should be. For more severe cases, the patient will receive more injections. Doctors will speak with the patient before proceeding and agree on an exact protocol that addresses the patient’s needs most effectively.
What Risks and Benefits Are Associated with Stem Cell Treatments for Eyesight?
One of the major concerns of stem cell use is completely mitigated in the case of macular degeneration, and that’s the risk of reintroducing disease.
In the case of diseases such as cancer, this might not prove a safe method of acquiring stem cells due to the danger that they may unintentionally harvest cancerous cells and reintroduce them to the patient later. However, in the case of macular degeneration, and since there are no harmful cells, only degenerated cells, this concern does not apply.
There do exist other risks, though, explains The Conversation. The two main risks are inflammation, which could potentially decrease eyesight further, and tumor development. Because stem cells are capable of endless self-replication, there is a danger that they may grow out of control. Again, this will further reduce eyesight by increasing pressure on the eye.
On the other hand, the potential benefits of stem cell treatments for macular degeneration are huge.
What Clinical Studies Have Been Done with Stem Cells for Macular Degeneration?
In 2009, preclinical data showed that a stem cell therapeutic could promote vision recovery, at least in rats. In this study, induced pluripotent stem cells (iPSCs) were used to create retinal pigment epithelium (RPE) cells. These cells were then administered into rats with vision loss. The rodents showed improvement.
Shortly thereafter in 2014, physicians at the RIKEN Center in Kobe, Japan, transplanted induced pluripotent stem cell (iPSC) derived cell sheets in a human with macular degeneration. One year later, progression of vision loss stopped. An area with photoreceptors recovery was observed and the patient’s vision remained stable. There were no symptoms of immune rejection or tumor development.
In March 2017, Japanese scientists took this research a step further. They announced that they had treated a 60-year-old man with vision loss using stem cells from another person. This is called an allogeneic transplant. He received retinal cells that had been created from another person’s induced pluripotent stem cells.
In December 2019, the U.S. NIH announced it was undertaking the first U.S. clinical trial of this type. The goal of the trial is to restore vision loss. This Phase I/IIa clinical trial involves 12 patients who are receiving a stem cell treatment in one eye. It is supported by the Ocular and Stem Cell Translational Research Section of the National Eye Institute (NEI). The NEI is part of the NIH.
While these trials represent early-stage research, stem cells for treating macular degeneration are clearly gaining momentum.
Stem Cell Treatments for Macular Degeneration
Fighting blindness has been a major concern of the medical industry for centuries, and it looks as though the human race may finally have an answer. Hopefully, as these stem cell treatments advance, anyone healthy enough to withstand surgery will have the option of reading, driving, and seeing their grandchildren smile again.
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