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Positive Stem Cell Clinical Trial Results for Stargardt Disease and Dry Macular Degeneration

A retinal photograph of dry AMD

On October 14, 2014, Advanced Cell Technology, Inc. announced positive results from its small (18-patient) early-stage clinical trials of human embryonic stem cells (hESC) for the treatment of dry age-related macular degeneration and Stargardt disease.

Advanced Cell Technology, Inc. (ACT) is a Massachusetts-based clinical-stage biotechnology company focused on the development of regenerative medicine and cell therapy technology. ACT's most advanced products are in clinical trials for the treatment of dry age-related macular degeneration, Stargardt disease, and myopic macular degeneration.

Although the primary goal of this small early-stage clinical trial was to assess the safety of the transplanted stem cells, the treatment also had unexpected positive benefits: Ten out of 18 study participants reported improvements in vision, with some subjects reporting dramatic improvements. In addition, the treatment appears to have halted the progression of the disease in 17 of the 18 subjects.

Please note: Although this stem cell research has produced promising results thus far, it is in its very earliest stages and must be subjected to additional, longer-term, more demanding clinical trials, encompassing many more years of study.

The Research: The Lancet

The Lancet logo

The research, entitled Human embryonic stem cell-derived retinal pigment epithelium in patients with age-related macular degeneration and Stargardt's macular dystrophy: follow-up of two open-label phase 1/2 studies (explained below), has been published online ahead of print in the October 15, 2014 issue of The Lancet.

The Lancet, which has been published continuously for 180 years, is one of the world's leading independent medical journals, without affiliation to a medical or scientific organization. The journal, which is committed to international health concerns, publishes high-quality clinical trials that influence the course of medical practice.

The authors are Steven D. Schwartz, Carl D. Regillo, Byron L. Lam, Dean Eliott, Philip J. Rosenfeld, Ninel Z. Gregori, Jean-Pierre Hubschman, Janet L. Davis, Gad Heilwell, Marc Spirn, Joseph Maguire, Roger Gay, Jane Bateman, Rosaleen M. Ostrick, Debra Morris, Matthew Vincent, Eddy Anglade, Lucian V. Del Priore, and Robert Lanza.

The authors represent the following institutions: Jules Stein Eye Institute and David Geffen School of Medicine, University of California, Los Angeles; Wills Eye Hospital and Thomas Jefferson University, Philadelphia, PA; Bascom Palmer Eye Institute, Miami, FL; Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, MA; Advanced Cell Technology, Marlborough, MA; and Storm Eye Institute, Medical University of South Carolina, Charleston, SC.

First, Some Background and History

Since November 2010, VisionAware has followed Advanced Cell Technology's (ACT) quest to implement successful clinical trials for macular eye disease, using human embryonic stem cells. ACT's US Phase 1/2 clinical trials for Stargardt disease and dry age-related macular degeneration (AMD) involved a total of 18 patients, in groups of three (also called cohorts in research terminology). The first group/cohort received a dosage of 50,000 cells; the second received 100,000 cells; and the third received 150,000 cells.

To better understand this latest development, here is background information from prior VisionAware blog posts about ACT's initial stem cell clinical trial for Stargardt disease, its subsequent clinical trial for dry age-related macular degeneration, and a 2013 update about the status of all ACT ongoing clinical trials:

On November 22, 2010, the U.S. Food and Drug Administration (FDA) lifted a prior clinical hold on stem cell research to clear Advanced Cell Technology's Investigational New Drug (IND) application and initiate a Phase 1/2 multicenter study, using retinal cells derived from human embryonic stem cells to treat patients with Stargardt disease. ACT's product is a human embryonic stem cell trained to become a retinal cell.

On January 3, 2011, ACT announced that they had received FDA clearance for yet another new clinical trial, this time using embryonic stem cells to treat dry AMD.

Information about ACT's ongoing clinical trials is available at ClinicalTrials.gov, with the following Identifiers: NCT01345006 (U.S. Stargardt disease) and NCT01344993 (U.S. dry AMD).

More about the Research

From Groundbreaking stem-cell research, via Boston Business Journal:

Advanced Cell Technology (ACT) [has] announced results from an early-stage trial indicating that its treatment helped improve vision in 10 out of 18 patients with two kinds of macular degeneration. ACT's embryonic stem cell-based treatment was administered at least six months ago in all 18 patients, although the median period was 22 months and two of the patients were treated more than three years ago.

[Editor's note: Called retinal pigment epithelial cells, these cells are created by taking stem cells from a days-old embryo created in a fertility clinic and inducing the embryonic cells to differentiate into more specialized cells.]

All 18 patients in the Phase 1/2 trial have either Stargardt's macular degeneration, an inherited disorder, or dry age-related macular degeneration, neither of which have any effective treatments on the market today. The patients received a transplant of … retinal pigment epithelium (or RPE) cells, which protect photoreceptors in the eye, using ACT's cells made from embryonic stem cells.

The main goal of the study was to show that process is safe, but the treatment appeared to have stopped progression of the disease in 17 out of 18 of the patients. In addition, the majority of them performed better on the Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity exam.

the EDTRS eye chart

The ETDRS Eye Chart

The trial data not only represents a victory in eye treatments, it’s also the first evidence of long-term safety, survival, and biologic activity in humans of stem cells in any disease.

More about the Study from The Lancet

From the research summary:

Background: Since they were first derived more than three decades ago, embryonic stem cells have been proposed as a source of replacement cells in regenerative medicine, but their plasticity and unlimited capacity for self-renewal raises concerns about their safety, including tumor formation ability, potential immune rejection, and the risk of differentiating into unwanted cell types. We report the medium-term to long-term safety of cells derived from human embryonic stem cells (hESC) transplanted into patients.

Methods: In the USA, two prospective phase 1/2 studies were done to assess the … safety and tolerability of subretinal transplantation of hESC-derived retinal pigment epithelium in nine patients with Stargardt's macular dystrophy (age >18 years) and nine with atrophic age-related macular degeneration (age >55 years).

Three dose cohorts (50,000, 100,000, and 150,000 cells) were treated for each eye disorder. Transplanted patients were followed up for a median of 22 months by use of serial systemic, ophthalmic, and imaging examinations.

Findings: There was no evidence of adverse proliferation, rejection, or serious ocular or systemic safety issues related to the transplanted tissue. Adverse events were associated with vitreoretinal surgery and immunosuppression. 13 (72%) of 18 patients had patches of increasing subretinal pigmentation consistent with transplanted retinal pigment epithelium.

Best-corrected visual acuity, monitored as part of the safety protocol, improved in ten eyes, improved or remained the same in seven eyes, and decreased by more than ten letters in one eye, whereas the untreated fellow eyes did not show similar improvements in visual acuity.

Vision-related quality-of-life measures increased for general and peripheral vision, and near and distance activities, improving by 16-25 points 3 to 12 months after transplantation in patients with atrophic age-related macular degeneration and 8-20 points in patients with Stargardt's macular dystrophy.

Interpretation: The results of this study provide the first evidence of the medium-term to long-term safety, graft survival, and possible biological activity of [stem cells] in individuals with any disease. Our results suggest that hESC-derived cells could provide a potentially safe new source of cells for the treatment of various unmet medical disorders requiring tissue repair or replacement.

About Clinical Trials

Most clinical trials are designated as Phase 1, 2, or 3, based on the questions the study is seeking to answer:

  • In Phase 1 clinical trials, researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe and effective dosage range, and identify possible side effects.
  • In Phase 2 clinical trials, the study drug or treatment is given to a larger group of people to determine if it is effective and to further evaluate its safety.
  • In Phase 3 studies, the study drug or treatment is given to even larger groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
  • In Phase 4 studies, after the United States Food and Drug Administration (FDA) has approved the drug, continuing studies will determine additional information, such as the drug's risks, side effects, benefits, and optimal use.

VisionAware will provide updates on this important stem cell research as they become available.

Additional Information about Stem Cell Research


Topics:
Low Vision
In the News
Medical Updates
Clinical Trials
Macular Degeneration

Eye Injury Prevention Month: Halloween, Lady Gaga, and Cosmetic Contact Lenses

Every year, during Eye Injury Prevention Month – and as Halloween approaches – I begin fielding questions from neighbors, friends, and colleagues about the safety of circle (also called "cosmetic" or "costume") contact lenses. For the uninitiated, "circle lenses," which first became popular in Asia approximately ten years ago, are contact lenses that give the wearer a doll-eyed or doe-eyed "innocent" look:

Venus Palermo with circle lenses

Venus Palermo, the "Human Barbie Doll"

What are Circle or Cosmetic Contact Lenses?

Here is more information about circle lenses from Wikipedia:

Circle contact lenses, also known as "big-eye contact lenses" and "circle lenses," are cosmetic contact lenses that make the eye's iris appear larger. They have become a trend in Japan, South Korea, and China, and are largely produced in these countries.

Circle lenses are tinted not only in areas that cover the iris of the eye, but also prominently in the extra-wide outer rim of the lens. The result is the appearance of a bigger, wider iris and creation of an illusion of large eyes.

The lenses are popular among teenagers and young adults. Many people consider circle lens to be a fashion accessory, rather than a medical device.

According to CBS News Medical Correspondent Dr. Jennifer Ashton, circle lenses "…make the eyes look very large, and it's because the contact lens part actually extends beyond the iris or the colored part of the eye and in doing so, makes the eye look a little bit larger. It's purely cosmetic."

An array of multicolored circle lenses

Examples of circle lenses

Lady Gaga and Circle Lenses

As part of my research into the growing popularity of cosmetic contact lenses, I revisited Lady Gaga's Bad Romance video and discovered that she was indeed wearing what appeared to be "anime-style" circle lenses:

Lady Gaga in a still from Bad Romance

But there's a problem: They're illegal in the United States and can cause severe and permanent eye damage. The New York Times was among the first news organizations to address these issues in an article by Catherine Saint Louis, entitled What Big Eyes You Have, Dear, but Are Those Contacts Risky?:

Of all the strange outfits and accessories Lady Gaga wore in her "Bad Romance" video, who would have guessed that the look that would catch fire would be the huge anime-style eyes she flashed in the bathtub?

These lenses might be just another beauty fad if not for the facts that they are contraband and that eye doctors express grave concern over them. It is illegal in the United States to sell any contact lenses — corrective or cosmetic — without a prescription, and no major maker of contact lenses in the United States currently sells circle lenses.

Sites that sell contact lenses approved by the Food and Drug Administration (FDA) are supposed to verify customers' prescriptions with their eye doctors. By contrast, circle lens websites allow customers to choose the strength of their lenses as freely as their color.

A Definitive Statement from the American Academy of Ophthalmology

The American Academy of Ophthalmology (AAO) has repeatedly warned the public about the many risks associated with the use of costume contact lenses during the Halloween party season. From Four Frightening Ways Non-Prescription Costume Contact Lenses Can Ruin Your Vision:

To avoid a real-life Halloween horror story – going blind because of a costume accessory – the American Academy of Ophthalmology is warning the public against wearing costume contact lenses purchased without a prescription. These illegally-sold cosmetic lenses may not be sterile and can cause a host of serious eye problems capable of morphing a fun Halloween night into a nightmare.

Tiger eyes, checkered pupils: Non-prescription decorative lenses (also called cosmetic, costume or plano contact lenses) come in many different patterns and colors.

In 2005, after reports of them causing eye injuries and infections, the FDA classified all contact lenses as medical devices and restricted their distribution to licensed eye care professionals, effectively banning sales of non-prescription contact lenses.

Despite that, these items remain available on the Internet, in convenience stores, and at flea markets. Here are four frightening ways that non-prescription decorative lenses can hurt your eyes:

  1. Scratches: Because over-the-counter lenses are not fitted and sized for the person wearing the contacts, they can easily scrape the outer layer of the eye. The resulting corneal abrasions can cause redness, light sensitivity, discharge, pain, plus the feeling that something is stuck under the eyelid.
  2. Sores: Costume contact lenses can literally create an eye sore called a corneal ulcer, with symptoms similar to corneal abrasions. The ulcers sometimes appear as a white dot on the iris – the colored part of the eye. When the ulcers heal, they can scar over and can in some cases permanently affect vision.
  3. Infections: Both corneal abrasions and ulcers create openings in the eye, making them more vulnerable to bacteria, viruses and amoebas. All of these organisms can cause serious eye infections known as keratitis. Some infections, such as herpes simplex, can be recurring and difficult to eradicate, while a number of bacteria have become resistant to common antibiotics.
  4. Blindness: In the most extreme cases, complications from wearing costume contact lenses may require surgery or end in blindness. For instance, extensive scarring from an infection can distort the cornea or make it opaque, requiring a corneal transplant to restore vision.

Complications from Cosmetic/Costume Contact Lenses

Because most purchases of cosmetic, costume, and circle contact lenses are neither prescribed nor regulated, eye infections are more common than you might think. And infections, in some cases, can lead to blindness. Here are some additional complications that can occur from purchasing online or "over-the-counter" contact lenses:

Cosmetic/Costume Contact Lens Safety Guidelines

To wear decorative contact lenses safely this Halloween, or any time of year, the American Academy of Ophthalmology recommends following these guidelines:

  • Only buy decorative contact lenses from an eye care professional, such as an ophthalmologist or optometrist, or a retailer that requires a prescription and sells FDA-approved products.
  • If you don't already have a contact lens prescription, obtain a valid prescription and eye exam from an ophthalmologist or optometrist.
  • Even if you have [regular or unimpaired] vision, a [comprehensive] eye exam and prescription are mandatory in order to fit the right size contacts. Do not fall victim to false advertising claims and lenses labeled as "one size fits all" or "no need to see an eye specialist."
  • Follow the directions for cleaning, disinfecting and wearing the lenses. Contacts that are left in for too long or that are not properly cleaned and disinfected can significantly increase the risk of an eye infection.
  • Never share contact lenses with another person or wear expired lenses.
  • If you notice redness, swelling, excessive discharge, pain or discomfort from wearing contact lenses, remove the lenses and seek immediate medical attention. Eye infections like keratitis can become serious quickly and cause blindness if left untreated.

To all of our valued readers: Please have a happy – and safe – Halloween by following these critically important safety guidelines. Enjoy your holiday!

Acknowledgements

Note: Lady Gaga Bad Romance is a screenshot from a copyrighted music video or promotional video for a music artist. The use of a limited number of web-resolution screenshots for identification and critical commentary on the music video qualifies as fair use under United States copyright law.

Note: Circle contact lens and Venus Palermo photos are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.


Topics:
In the News
Medical Updates

New Research Demonstrates that Changes in the Eye and Retina Can Predict the Onset of Dementia

black-and-white drawing of the brain

A group of United States-based researchers has discovered a direct correlation with functional cell loss in the retina and signs of dementia in people with a genetic risk for fronto-temporal dementia (FTD).

The study also demonstrates that changes in the retina occur much earlier than do the dementia-related changes that appear in an individual's behavior.

The Journal of Experimental Medicine

This cutting-edge eye/brain research was published in the September 2014 issue of The Journal of Experimental Medicine. Since its inception in 1896 at the Johns Hopkins School of Medicine, The Journal of Experimental Medicine has published papers on the physiological, pathological, and molecular aspects of disease. The journal is also committed to publishing studies that involve human subjects. You can read more about the journal's history on its Wikipedia page.

The authors are Michael E. Ward, Alice Taubes, Robert Chen, Bruce L. Miller Chantelle F. Sephton, Jeffrey M. Gelfand, Sakura Minami; John Boscardin, Lauren Herl Martens, William W. Seeley, Gang Yu, Joachim Herz, Anthony J. Filiano, Andrew E. Arrant, Erik D. Roberson, Timothy W. Kraft, Robert V. Farese Jr., Ari Green, and Li Gan, who represent the following institutions: University of California, San Francisco; University of Texas Southwestern Medical Center, Dallas; and the University of Alabama at Birmingham.

What is Fronto-Temporal Dementia?

Excerpted from Frontotemporal Dementia at the Alzheimer's Association website:

Frontotemporal dementia (FTD) is a group of disorders caused by progressive cell degeneration in the brain's frontal lobes (the areas behind your forehead) or its temporal lobes (the regions behind your ears).

The cell damage caused by frontotemporal dementia leads to tissue shrinkage and reduced function in the brain's frontal and temporal lobes, which control planning and judgment; emotions, speaking and understanding speech; and certain types of movement.

FTD used to be called Pick's disease after Arnold Pick, a physician who in 1892 first described a patient with distinct symptoms affecting language. Some doctors still use the term "Pick's disease." FTD was once considered rare, but it's now thought to account for up to 10 to 15 percent of all dementia cases.

There is no single test — or any combination of tests — that can conclusively diagnose frontotemporal dementia. FTD is a "clinical" diagnosis representing a doctor's best professional judgment about the reason for a person's symptoms. Magnetic resonance imaging (MRI) often plays a key role in diagnosis because it can detect shrinkage in the brain's frontal and temporal lobes, which is a hallmark of FTD.

In some cases, it may be hard to distinguish FTD from Alzheimer's disease. In the future, tests to detect specific protein abnormalities linked to Alzheimer's and FTD may help clarify the diagnosis in difficult cases. Most people with FTD are diagnosed in their 50s and early 60s. Only about 10 percent are diagnosed after age 70. Alzheimer's, on the other hand, grows more common with increasing age.

More about the Research

Changes in the eye might predict onset of frontotemporal dementia, via the University of Alabama at Birmingham (UAB) School of Medicine News:

Changes to the eyes might help diagnose the onset of frontotemporal dementia (FTD), the second most common form of dementia, according to new research from scientists at the University of Alabama at Birmingham, Gladstone Institutes, and the University of California, San Francisco. Findings … show that a loss of cells in the retina is one of the earliest signs of FTD in people with a genetic risk for the disorder – even before any changes appear in their behavior.

The researchers studied a group of individuals who had a certain genetic mutation that is known to result in FTD. They discovered that, before any cognitive signs of dementia were present, these individuals showed a significant thinning of the retina compared with people who did not have the gene mutation.

"This finding suggests that the retina acts as a type of window to the brain," said [co-author] Erik Roberson. Retinal degeneration was detectable in mutation carriers prior to the onset of cognitive symptoms, establishing retinal thinning as one of the earliest observable signs of familial FTD," he said. "This means that retinal thinning could be an easily measured outcome for clinical trials."

Although it is located in the eye, the retina is made up of neurons with direct connections to the brain. This means that studying the retina is one of the easiest and most accessible ways to examine and track changes in neurons.

[Editor's note: The researchers used an electroretinogram (ERG) as the measuring device in their subjects. An ERG is an "electrocardiogram (EKG) for the eye" that measures the electrical signal activity of ganglion cells, a type of neuron located near the inner surface of the retina. Ganglion cells transmit image-forming and non-image forming visual information to the brain.

The researchers compared ganglion cell activity in healthy subjects with subjects known to have frontotemporal dementia, noting a significant decrease in cell activity in the retina of subjects with dementia.]

"We have a more complete understanding about how the retina functions as opposed to the operations of the complex brain,” said [co-author] Timothy Kraft. "That makes it much easier to use the retina as a tool for better understanding FTD."

"The results of this study have shown that we can use the thinning of retinal cells as a marker for this type of dementia," said Roberson. "Further studies may also help determine whether the changes in the retina can be utilized as a marker of disease progression. We may also be able to use the retina as a means of gauging the effectiveness of new therapies."

VisionAware will continue to report the results of this innovative dementia research as they become available.

Additional Information


Topics:
In the News
Medical Updates

Celebrating White Cane Safety Day and Blind Americans Equality Day: October 15, 2014

White Cane Safety Day logo

White Cane Safety Day is an international observance that is celebrated on October 15 of each year since 1964. Its purpose is to (a) celebrate the achievements of people who are blind or visually impaired and (b) acknowledge and pay tribute to the long white cane, a critically important mobility tool and potent symbol of independence.

In 2011, White Cane Safety Day was also declared Blind Americans Equality Day by President Barak Obama.

Here is more information about the history of White Cane Safety Day from the National Federation of the Blind:

The National Federation of the Blind in convention, assembled on July 6, 1963, called upon the governors of the 50 states to proclaim October 15 of each year as White Cane Safety Day in each of our 50 states. On October 6, 1964, a joint resolution of the Congress, H.R. 753, was signed into law authorizing the President of the United States to proclaim October 15 of each year as "White Cane Safety Day."

This resolution said: "Resolved by the Senate and House of Representatives, that the President is hereby authorized to issue annually a proclamation designating October 15 as White Cane Safety Day and calling upon the people of the United States to observe such a day with appropriate ceremonies and activities."

Within hours of the passage of the congressional joint resolution authorizing the President to proclaim October 15 as White Cane Safety Day, then-President Lyndon B. Johnson recognized the importance of the white cane as a staff of independence for blind people.

A History of Orientation and Mobility

The profession of Orientation and Mobility began to develop during, and immediately after, World War II.

Soldiers who had been blinded in battle were sent to recuperate at Valley Forge Army General Hospital before entering Avon Old Farms Convalescent Hospital, the U.S. Army's former experimental rehabilitation center for blind soldiers in Avon, Connecticut.

In order to better serve the large number of blind soldiers who required special training and services, the military recruited Richard E. Hoover, an army sergeant, who was assigned to the center for the treatment of blinded soldiers at Valley Forge Army Hospital in 1944.

During the same year, Russell Williams, who was blinded by enemy action in France, received medical rehabilitation at the Valley Forge Army Hospital, and in 1947, C. Warren Bledsoe joined the Hospital. These three men made significant contributions to the development of a new profession: Orientation and Mobility.

The war-blinded soldiers were highly motivated to be successful, and Richard Hoover believed that the traditional strategies taught and used to travel independently were inadequate. In response, he developed a technique for using a cane that was lightweight and longer than a support cane. This technique and cane revolutionized independent travel for blind people and remain in use today.

You can learn more about the history and development of the profession of Orientation and Mobility at the VisionAware website.

Does the Cane Have to Be White to Be Effective? An Answer from Dona Sauerburger, COMS

Dona Sauerburger

Dona is a Certified Orientation and Mobility Specialist (COMS) who provides itinerant orientation and mobility services to blind and visually impaired adults and teenagers.

She is the author of An Introduction to Orientation and Mobility Skills on the VisionAware website and Independence without Sight or Sound: Suggestions for Practitioners Working with Deaf-Blind Adults, which received the C. Warren Bledsoe Publication Award.

Canes for Outdoor Travel

When used properly, a cane can provide information and protection, regardless of its color – it does not have to be white to be effective. Most canes used by blind people are white, but they are also available in red, black, yellow, and blue. For example, these canes (pictured below) from AmbuTech are available in a range of colors.

However, only a white cane identifies the user as a person who is blind or has low vision. This can be an important consideration when crossing streets and requesting information from store clerks, bus drivers, and the general public.

It's likely that people will be more willing to help if they realize you're asking for information because you are blind or have low vision.

Photo of AmbuTech cane colors

About "White Cane Laws"

Many people are under the impression that each state's White Cane Law contains a provision that requires drivers to stop for, and/or yield to, pedestrians who are carrying white canes. This is not correct. The laws in each state vary widely and drivers do not always reliably stop for pedestrians who carry white canes.

When drivers see pedestrians who are carrying white canes:

  • Some states require that drivers yield.
  • Some states require drivers to come to a full stop.
  • Some states require only that drivers exercise caution when in the presence of pedestrians with white canes.
  • Some states provide no special rights and protections to pedestrians who are carrying white canes that are not provided to all pedestrians.

Check your state's White Cane Law to determine the language that describes driver and pedestrian rights and responsibilities.

For more information about the history of White Cane Laws in the United States, you can read the Pedestrian Safety Handbook at the American Council of the Blind website.

Photo credit: AmbuTech. Used with permission.

Additional Orientation and Mobility Information


Topics:
In the News
Orientation and Mobility
Getting Around

Newly-Discovered Corneal Stem Cells Could Be a Potential Source for Treatment of Retinal Disease

The PLoS ONE logo

New research from the United Kingdom has demonstrated that stem cells found in the cornea could provide a source of photoreceptor cells for transplant in persons with degenerative retinal conditions, such as age-related macular degeneration or retinitis pigmentosa.

Please note: This "proof of concept" research is in its earliest stages and has been conducted only with laboratory mice. Human clinical trials using corneal stem cells will likely not begin until 2019 or 2020, at minimum.

The research, entitled Adult Limbal Neurosphere Cells: A Potential Autologous Cell Resource for Retinal Cell Generation (terminology explained below), was published in the October 1, 2014 issue of PLoS ONE, an international, peer-reviewed, open-access online journal, published monthly by the Public Library of Science (PLoS). The PLoS is a non-profit organization of scientists and physicians who are committed to making the world's scientific and medical literature a freely available public resource.

The authors are Xiaoli Chen, Heather Thomson, Jessica Cooke, Jennifer Scott, Parwez Hossain, and Andrew Lotery, who represent the following United Kingdom-based institutions: University of Southampton, Southampton General Hospital; University of Bristol, Bristol Eye Hospital; and University Hospital Southampton NHS Foundation Trust.

Some Definitions of Terminology

  • "Limbal" or limbus: a transitional zone, about 1-2 mm wide, where the cornea joins the sclera (the "white of the eye"); the junction of the cornea and sclera
  • Cornea: a transparent dome-shaped tissue that forms the front surface of the eye; functions as a window that allows light to enter the eye.
  • Sclera: a tough white outer coating of fibrous tissue that covers the entire eyeball, except for the cornea. The muscles that move the eye are attached to the sclera.
  • Photoreceptors: retinal cells that convert light into electrical impulses for transmission of images to the brain
side view diagram of the eye

Diagram of the eye, viewed from the side
Source: National Institutes of Health

  • Neurosphere: a culture system composed of clusters of neural [i.e., nervous system] stem cells. Since neural stem cells cannot be studied in vivo [i.e., within a living organism], neurospheres provide a method to investigate neural cells in vitro [i.e., in a test tube or culture dish, typically in a laboratory].
  • Autologous: Cells or tissues derived from the same individual; one individual is both donor and recipient.

About the Research

From Corneal stem cells a potential source for retinal transplant, via Optometry Today:

Researchers at the University of Southampton discovered that stem cells taken from the corneal limbus, at the junction of the cornea and the sclera, can be programmed to form photoreceptors.

According to Andrew Lotery, Professor of Ophthalmology at the University of Southampton who led the research, "These cells are available throughout life and we hope eventually that they would be useful for retinal transplantation to repair disease, to be used in cell therapies for diseases that involve retinal degeneration, such as macular degeneration or retinitis pigmentosa."

Previous work by the team had shown that the stem cells, called limbal neurosphere cells (LNC), could be extracted from the cornea and cultured in the lab to form neurons.

In the latest experiments, LNCs taken from the corneas of mice were grown with developing retina cells in the lab, and developed themselves into retinal cells. The team also showed that when LNCs were implanted into the retinas of mice, they [developed] key characteristics of retinal cells.

While researchers are trying to find new sources of stem cells for retinal transplantation, there are pros and cons to each source.

Embryonic stem cells (ESCs), which can form any cell type in the body, are in short supply and due to their origins, have many ethical issues attached. Induced pluripotent stem cells (iPSC), which are reprogrammed adult cells, require chemicals to reprogram the cells, which have the potential to cause tumors.

"[LNCs] are another possible source of stem cells that would be taken from an accessible site and, because they are taken from the patient, they wouldn’t be at risk of rejecting the cells. These are the things that we think make it worth exploring as a source of cells for, hopefully, retinal transplantation," said Professor Lotery.

The team are now hoping to carry out further research, including tweaking the conditions needed for human cells.

More about the Study from PLoS

From the article Introduction and Discussion:

Retinal diseases are the leading cause of untreatable blindness worldwide. These conditions include age related macular degeneration (AMD) and a wide spectrum of inherited retinal diseases. Irreversible visual impairment arises due to a gradual loss of light sensory neurons – photoreceptors and/or their supportive cells the retinal pigment epithelium (RPE).

Unlike lower vertebrates, adult mammals cannot regenerate retinal neurons. The visual disability caused by these diseases carries a formidable clinical and socio-economic burden in western countries.

Cell-based therapies are an attractive approach to treat retinal disease. They offer the potential to restore functional vision. Recent studies have demonstrated that transplanted photoreceptor progenitor [i.e., "parent" or originating] cells can form … connections with the host retina and improve visual function in animal models of retinal degeneration.

Identifying practical cell sources to generate sufficient functional cells for transplantation remains challenging, however. Utilizing embryonic or fetal tissue is difficult due to limited resources, ethical issues, or risks of tumor formation. In addition, transplant rejection may occur due to chronic immune responses…. Therefore, immune-matched autologous cell resources [i.e., one individual as both donor and recipient] have considerable advantages.

… In summary, this data demonstrates the potential of mouse and human limbal neurosphere cells (LNS) to differentiate into retinal lineages in vitro [i.e., in the laboratory] and in vivo [i.e., within a living organism]. The regulation of human LNS differentiation … appears more comprehensive than with mouse LNS cells.

As a readily accessible progenitor [i.e., the "parent" or originating] cell resource that can be derived from individuals up to 97 years of age, limbal neurosphere cells remain an attractive cell resource for the development of novel therapeutic approaches for degenerative retinal diseases.

About Clinical Trials

Most clinical trials are designated as Phase I, II, or III, based on the questions the study is seeking to answer:

  • In Phase I clinical trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe and effective dosage range, and identify possible side effects.
  • In Phase II clinical trials, the study drug or treatment is given to a larger group of people (100-300) to determine if it is effective and to further evaluate its safety.
  • In Phase III studies, the study drug or treatment is given to even larger groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
  • In Phase IV studies, after the United States Food and Drug Administration (FDA) has approved the drug, continuing studies will determine additional information, such as the drug's risks, side effects, benefits, and optimal use.

VisionAware will provide updates on this important stem cell research as they become available.

Additional Information about Stem Cell Research


Topics:
Low Vision
In the News
Medical Updates
Macular Degeneration
Retinitis Pigmentosa

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