For patients with macular degeneration, new hope for restored sight
An implant, combined with the glasses and tiny video camera modeled in this photo, could improve the eyesight of millions of people with degenerative eye diseases in the coming years.
For millions of people with macular degeneration, treatment options are slim. The disease causes loss of central vision, which allows us to see straight ahead, and is highly dependent on age, with people over 75 at approximately 30% risk of developing the disorder. The BrightFocus Foundation estimates 11 million people in the U.S. currently have one of three forms of the disease.
Recently, ophthalmologists including Daniel Palanker at Stanford University published research showing advances in the PRIMA retinal implant, which could help people with advanced, age-related macular degeneration regain some of their sight. In a feasibility study, five patients had a pixelated chip implanted behind the retina, and three were able to see using their remaining peripheral vision and—thanks to the implant—their partially restored central vision at the same time.
Should people with macular degeneration be excited about these results?
“Every week, if not every day, patients come to me with this question because it's devastating when they lose their central vision,” says retinal surgeon Lynn Huang. About 40% of her patients have macular degeneration. Huang tells them that these implants, along with new medications and stem cell therapies, could be useful in the coming years.
“The goal here is to replace the missing photoreceptors with photovoltaic pixels, basically like little solar panels,” Palanker says.
That implant, a pixelated chip, works together with a tiny video camera on a specially designed pair of eyeglasses, which can be adjusted for each patient’s prescription. The video camera relays processed images to the chip, which electrically stimulates inner retinal neurons. These neurons, in turn, relay information to the brain’s visual cortex through the optic nerve. The chip restores patients’ central sight, but not completely. The artificial vision is basically monochromatic (whitish-yellowish) and fairly blurry; patients were still legally blind even after the implant, except when using a zoom function on the camera, but those with proper chip placement could make out large letters.
“The goal here is to replace the missing photoreceptors with photovoltaic pixels, basically like little solar panels,” Palanker says. These pixels, located on the implanted chip, convert light into pulsed electrical currents that stimulate retinal neurons. In time, Palanker hopes to improve the chips, resulting in bigger boosts to visual acuity.
The pixelated chips are surgically implanted during a process Palanker admits is still “a surgical learning curve.” In the study, three chips were implanted correctly, one was placed incorrectly, and another patient’s chip moved after the procedure; he did not follow post-surgical recommendations. One patient passed away during the study for unrelated reasons.
University of Maryland retinal specialist Kenneth Taubenslag, who was not involved in the study, said that subretinal surgeries have become less common in recent years, but expects implants to spur improvements in these techniques. “I think as people get more experience, [they’ll] probably get more reliable placement of the implant,” he said, pointing out that even the patient with the misplaced chip was able to gain some light perception, if not the same visual acuity as other patients.
Retinal implants have come under scrutiny lately. IEEE Spectrum reported that Second Sight, manufacturer of the Argus II implant used for people with retinitis pigmentosa, a genetic disease that causes vision loss, would no longer support the product. After selling hundreds of the implants at $150,000 apiece, company leaders announced they’d “decided to pursue an orderly wind down” of Second Sight in March 2020 in the wake of financial issues. Last month, the company announced a merger, shifting its focus to a new retinal implant, raising questions for patients who have Argus II implants.
Retinal surgeon Eugene de Juan of the University of California, San Francisco, was involved with early studies of the Argus implants, though his participation ended over a decade ago, before the device was marketed by Second Sight. He says he would consider recommending future implants to patients with macular degeneration, given the promise of the technology and the lack of other alternatives.
“I tell my patients that this is an area of active research and development, and it's getting better and better, so let's not give up hope,” de Juan says. He believes cautious optimism for Palanker’s implant is appropriate: “It's not the first, it's not the only, but it's a good approach with a good team.”
Gene Transfer Leads to Longer Life and Healthspan
In August, a study provided the first proof-of-principle that genetic material transferred from one species to another can increase both longevity and healthspan in the recipient animal.
The naked mole rat won’t win any beauty contests, but it could possibly win in the talent category. Its superpower: fighting the aging process to live several times longer than other animals its size, in a state of youthful vigor.
It’s believed that naked mole rats experience all the normal processes of wear and tear over their lifespan, but that they’re exceptionally good at repairing the damage from oxygen free radicals and the DNA errors that accumulate over time. Even though they possess genes that make them vulnerable to cancer, they rarely develop the disease, or any other age-related disease, for that matter. Naked mole rats are known to live for over 40 years without any signs of aging, whereas mice live on average about two years and are highly prone to cancer.
Now, these remarkable animals may be able to share their superpower with other species. In August, a study provided what may be the first proof-of-principle that genetic material transferred from one species can increase both longevity and healthspan in a recipient animal.
There are several theories to explain the naked mole rat’s longevity, but the one explored in the study, published in Nature, is based on the abundance of large-molecule high-molecular mass hyaluronic acid (HMM-HA).
A small molecule version of hyaluronic acid is commonly added to skin moisturizers and cosmetics that are marketed as ways to keep skin youthful, but this version, just applied to the skin, won’t have a dramatic anti-aging effect. The naked mole rat has an abundance of the much-larger molecule, HMM-HA, in the chemical-rich solution between cells throughout its body. But does the HMM-HA actually govern the extraordinary longevity and healthspan of the naked mole rat?
To answer this question, Dr. Vera Gorbunova, a professor of biology and oncology at the University of Rochester, and her team created a mouse model containing the naked mole rat gene hyaluronic acid synthase 2, or nmrHas2. It turned out that the mice receiving this gene during their early developmental stage also expressed HMM-HA.
The researchers found that the effects of the HMM-HA molecule in the mice were marked and diverse, exceeding the expectations of the study’s co-authors. High-molecular mass hyaluronic acid was more abundant in kidneys, muscles and other organs of the Has2 mice compared to control mice.
In addition, the altered mice had a much lower incidence of cancer. Seventy percent of the control mice eventually developed cancer, compared to only 57 percent of the altered mice, even after several techniques were used to induce the disease. The biggest difference occurred in the oldest mice, where the cancer incidence for the Has2 mice and the controls was 47 percent and 83 percent, respectively.
With regard to longevity, Has2 males increased their lifespan by more than 16 percent and the females added 9 percent. “Somehow the effect is much more pronounced in male mice, and we don’t have a perfect answer as to why,” says Dr. Gorbunova. Another improvement was in the healthspan of the altered mice: the number of years they spent in a state of relative youth. There’s a frailty index for mice, which includes body weight, mobility, grip strength, vision and hearing, in addition to overall conditions such as the health of the coat and body temperature. The Has2 mice scored lower in frailty than the controls by all measures. They also performed better in tests of locomotion and coordination, and in bone density.
Gorbunova’s results show that a gene artificially transferred from one species can have a beneficial effect on another species for longevity, something that had never been demonstrated before. This finding is “quite spectacular,” said Steven Austad, a biologist at the University of Alabama at Birmingham, who was not involved in the study.
Just as in lifespan, the effects in various organs and systems varied between the sexes, a common occurrence in longevity research, according to Austad, who authored the book Methuselah’s Zoo and specializes in the biological differences between species. “We have ten drugs that we can give to mice to make them live longer,” he says, “and all of them work better in one sex than in the other.” This suggests that more attention needs to be paid to the different effects of anti-aging strategies between the sexes, as well as gender differences in healthspan.
According to the study authors, the HMM-HA molecule delivered these benefits by reducing inflammation and senescence (cell dysfunction and death). The molecule also caused a variety of other benefits, including an upregulation of genes involved in the function of mitochondria, the powerhouses of the cells. These mechanisms are implicated in the aging process, and in human disease. In humans, virtually all noncommunicable diseases entail an acceleration of the aging process.
So, would the gene that creates HMM-HA have similar benefits for longevity in humans? “We think about these questions a lot,” Gorbunova says. “It’s been done by injections in certain patients, but it has a local effect in the treatment of organs affected by disease,” which could offer some benefits, she added.
“Mice are very short-lived and cancer-prone, and the effects are small,” says Steven Austad, a biologist at the University of Alabama at Birmingham. “But they did live longer and stay healthy longer, which is remarkable.”
As for a gene therapy to introduce the nmrHas2 gene into humans to obtain a global result, she’s skeptical because of the complexity involved. Gorbunova notes that there are potential dangers in introducing an animal gene into humans, such as immune responses or allergic reactions.
Austad is equally cautious about a gene therapy. “What this study says is that you can take something a species does well and transfer at least some of that into a new species. It opens up the way, but you may need to transfer six or eight or ten genes into a human” to get the large effect desired. Humans are much more complex and contain many more genes than mice, and all systems in a biological organism are intricately connected. One naked mole rat gene may not make a big difference when it interacts with human genes, metabolism and physiology.
Still, Austad thinks the possibilities are tantalizing. “Mice are very short-lived and cancer-prone, and the effects are small,” he says. “But they did live longer and stay healthy longer, which is remarkable.”
As for further research, says Austad, “The first place to look is the skin” to see if the nmrHas2 gene and the HMM-HA it produces can reduce the chance of cancer. Austad added that it would be straightforward to use the gene to try to prevent cancer in skin cells in a dish to see if it prevents cancer. It would not be hard to do. “We don’t know of any downsides to hyaluronic acid in skin, because it’s already used in skin products, and you could look at this fairly quickly.”
“Aging mechanisms evolved over a long time,” says Gorbunova, “so in aging there are multiple mechanisms working together that affect each other.” All of these processes could play a part and almost certainly differ from one species to the next.
“HMM-HA molecules are large, but we’re now looking for a small-molecule drug that would slow it’s breakdown,” she says. “And we’re looking for inhibitors, now being tested in mice, that would hinder the breakdown of hyaluronic acid.” Gorbunova has found a natural, plant-based product that acts as an inhibitor and could potentially be taken as a supplement. Ultimately, though, she thinks that drug development will be the safest and most effective approach to delivering HMM-HA for anti-aging.
A new study provides key insights in what causes Alzheimer's: a breakdown in the brain’s system for clearing waste.
In recent years, researchers of Alzheimer’s have made progress in figuring out the complex factors that lead to the disease. Yet, the root cause, or causes, of Alzheimer’s are still pretty much a mystery.
In fact, many people get Alzheimer’s even though they lack the gene variant we know can play a role in the disease. This is a critical knowledge gap for research to address because the vast majority of Alzheimer’s patients don’t have this variant.
A new study provides key insights into what’s causing the disease. The research, published in Nature Communications, points to a breakdown over time in the brain’s system for clearing waste, an issue that seems to happen in some people as they get older.
Michael Glickman, a biologist at Technion – Israel Institute of Technology, helped lead this research. I asked him to tell me about his approach to studying how this breakdown occurs in the brain, and how he tested a treatment that has potential to fix the problem at its earliest stages.
Dr. Michael Glickman is internationally renowned for his research on the ubiquitin-proteasome system (UPS), the brain's system for clearing the waste that is involved in diseases such as Huntington's, Alzheimer's, and Parkinson's. He is the head of the Lab for Protein Characterization in the Faculty of Biology at the Technion – Israel Institute of Technology. In the lab, Michael and his team focus on protein recycling and the ubiquitin-proteasome system, which protects against serious diseases like Alzheimer’s, Parkinson’s, cystic fibrosis, and diabetes. After earning his PhD at the University of California at Berkeley in 1994, Michael joined the Technion as a Senior Lecturer in 1998 and has served as a full professor since 2009.
Dr. Michael Glickman