Artificial retina engineered from ancient protein now in space

Image courtesy of NASA

Plans to perfect an artificial retina able to mimic the functions of the light-sensitive tissue at the back of the eye have taken flight, with work now being done in space.

The National Institute of Health is supporting testing on the International Space Station (ISS) to determine whether manufacturing it there results in a successful treatment option for patients with blinding eye diseases.

According to an NIH release, LambdaVision, a Farmington, Connecticut-based biotech firm that developed the artificial retina, is exploring optimizing production of the artificial retina in space. In a series of missions to the ISS, the company will test whether microgravity on the station provides just the right conditions for constructing the multilayered protein-based artificial retina. The company hopes to restore meaningful vision for patients who are blind or have lost significant sight due to advanced retinal degenerative diseases, including retinitis pigmentosa (RP) and age-related macular degeneration (AMD).

The National Aeronautics and Space Administration (NASA), along with its partner, Space Tango, a Lexington, Kentucky-based firm that provides the logistical support for space-based research, put up a $5 million commercialization award to LambdaVision to get the project off the ground. LambdaVision also received from NASA a Small Business Innovation Research (SBIR) Phase II award, worth $750,000 over two years.

The work can go a long way in developing and perfecting the artificial retina.

“When gravity is nearly eliminated, so too are forces such as surface tension, sedimentation, convection driven buoyancy, all of which can interfere with the orientation and alignment important in the creation of crystalline structures, nanoparticles, or improved uniformity in layering processes,” Jana Stoudemire, a commercial innovation officer at Space Tango, said in a statement.

Stoudemire noted that Space Tango is building out not only the feasibility of manufacturing in orbit, but also the good manufacturing practices (GMP) capabilities that enable us to produce products in space for use in people.

“The hope is that surgically placing the artificial retina in the eye will restore vision among people with advanced-stage forms of diseases for which there is no treatment such as retinitis pigmentosa and age-related macular degeneration (AMD), a leading cause of vision loss among people age 50 and older,” Jordan Greco, PhD, chief scientific officer at LambdaVision, said in the NIH statement.

The goal of the project is for the LambdaVision artificial retina to replace the function of photoreceptors in patients who have lost the neurons from disease-related damage.

The National Eye Institute in 2014 gave LambdaVision funding to test a prototype of the artificial retina in animal models.

A look at the artificial retina

According to LambdaVision, its artificial retina relies on bacteriorhodopsin, a light-activated protein that acts as a proton pump. Bacteriorhodopsin is synthesized by halobacterium salinarum, a microorganism found in extremely salty marshes. Halobacteria are of the Archaea domain, which are among the oldest forms of life on Earth.

Bacteriorhodopsin shares some similarities with rhodopsin, the light-activated visual pigment protein within photoreceptors. Both proteins contain retinal, a chromophore that is key to absorbing light energy. In the case of bacteriorhodopsin, light energy is converted into metabolic energy. When light activates bacteriorhodopsin, hydrogen ions get pumped across a membrane, creating a proton gradient.

Robert Birge, PhD, LambdaVision’s founder and distinguished chair in chemistry at the University of Connecticut, has been studying bacteriorhodopsin for more than 40 years and has made a career of incorporating light-activated proteins into biomolecular electronic and therapeutic applications, including the protein-based artificial retina.

Within LambdaVision’s artificial retina, purified bacteriorhodopsin is layered onto an ion permeable membrane. The layers are repeated multiple times with the aim of absorbing enough light to generate an ion gradient that can stimulate the neural circuitry of the bipolar and retinal ganglion cells within the retina, Greco said in the statement.

Nicole Wagner, PhD, LambdaVision’s president and CEO, noted that in patients who have lost their vision from advanced-stage retinal diseases, the artificial retina would mimic the function of photoreceptors.

“Activated by light entering the eye, the artificial retina pumps protons toward the bipolar and ganglion cells,” she said in a statement. “Receptors on those cells detect the protons, which triggers them to send signals to the optic nerve, where they travel to the brain.”

For the artificial retina to function, the bacteriorhodopsin molecular structures must be precisely oriented within each layer to create a unidirectional gradient. That exacting degree of orientation may be more easily established in microgravity, and once achieved, Greco anticipates it should persist even after the implants are exposed to gravity on Earth.

According to LambdaVision, it plans to seek FDA approval of the artificial retina for the indication of retinitis pigmentosa. Collection of the preclinical data required to launch a clinical trial is still underway and have yet to be published.

Greco noted that partnering with NASA and Space Tango continues to be an important catalyst towards addressing the production requirements associated with the company’s artificial retina technology.

“Their support and resources offer a unique environment that allows us to generate high-quality artificial retinas that have the potential to restore visual acuity for blind patients,” Greco said in a statement. “While our focus at this time is fully on our ability to restore meaningful sight to patients with retinitis pigmentosa and age-related macular degeneration, we are continually bolstered by the great potential of LEO for broader implications across industries.”

Over the next 3 years, the LambdaVision-Space Tango partnership will serve to evaluate and improve on-orbit production processes, and to produce artificial retinas that will then be evaluated on Earth. Once validated, this process could also provide the foundation for products in a range of industries that could be manufactured in space with potential clinical benefit to patients on Earth.