Botond Roska (2020):
New Vision for the Blind
Most visual disorders can be traced back to inherited and age-dependent defects in the retina. Roska and his colleagues have carried out the pioneering work of tracking down the approximately 100 different types of cells in the retina and of achieving an understanding of their complicated signal processing. In the process, the team was able to trace many retinal diseases back to gene defects in individual cells. The researchers are now working on gene therapies to alleviate or heal them. Furthermore, as early as 2008 Roska—using gene ferries—succeeded in injecting light-sensitive channel proteins from green algae into retinal cells of blind mice, thus giving the rodents a rudimentary form of sight. A similar method of treatment is currently being tested on blind humans
New vision for the blind
Text: Claus-Peter Sesín
Photos: Friedrun Reinhold
Most visual disorders can be traced back to inherited and age-dependent defects in the retina. Roska and his colleagues have carried out the pioneering work of tracking down the approximately 100 different types of cells in the retina and of achieving an understanding of their complicated signal processing. In the process, the team was able to trace many retinal diseases back to gene defects in individual cells. The researchers are now working on gene therapies to alleviate or heal them. Furthermore, as early as 2008 Roska—using gene ferries—succeeded in injecting light-sensitive channel proteins from green algae into retinal cells of blind mice, thus giving the rodents a rudimentary form of sight. A similar method of treatment is currently being tested on blind humans.
A poll among 2000 Americans showed that they consider blindness the worst conceivable illness, even worse than Alzheimer’s, cancer, or the immune deficiency AIDS. Eye diseases are becoming much more common because people are getting older. Worldwide 36 million people are blind, and over a billion suffer from a substantial visual impairment. “Being able to see is so very important to humans, not least because a large portion of the exchange of information in today’s world takes place via visual devices such as cell phones or displays”. A person whose vision is poor thus also suffers a reduced capacity to communicate. These are reasons enough for Botond Roska to ponder how to help the many who are affected.
Roska initially studied cello but had to give up his musical career prematurely because of an injury to a hand. He subsequently studied medicine and mathematics and conducted research as a neurobiologist in the United States. From 2005 to 2017 he headed a research group at the Friedrich Miescher Institute for Biomedical Research in Basel. He has been a professor at the University of Basel since 2014. Together with Professor Hendrik Scholl, he was founding director of the Institute for Molecular and Clinical Ophthalmology Basel (IOB) in December 2017.
Roska’s research has revolutionized ophthalmology
Physicians have traditionally examined the eye’s retina primarily as tissue. Botond Roska, in contrast, for the first time made the effort to intensively study the approximately 100 types of cells in the retina and how they interacted functionally. His team also localized and mapped numerous gene defects that lead to eye disorders. The researchers thus created a pool of new knowledge that has revolutionized ophthalmology. For a long time, innovations in ophthalmology took place at a frustratingly slow pace. “This resulted from the fact”, as Roska explains, “that the scientists conducting basic research often did not know the needs of clinics precisely enough” — for example because they lacked direct contact with patients. The teams of doctors in the clinics, in contrast, were usually inadequately informed about the newest developments in basic research. In order to close this gap, the IOB has pursued an interdisciplinary approach since 2017, in which “scientists conducting basic research and clinicians work together hand in hand every day”.
Nuclear resonance reveals molecular structrues
The retina is located in the back of the eyeball, opposite the eye’s lens that projects images onto it. Its lightsensitive elements are called rods and cones. The rods are particularly sensitive and make it possible for us to see in the dark or at night. The cones ensure precise and color vision in light. The rods and cones have lightsensitive “antennas”, which convert the incoming light into electrical signals. These signals undergo elaborate preprocessing in the retina’s nerve cells; the output reaches the visual centers of the cerebrum via the optic nerve. “The retina is an outgrowth of the brain. Its complex network of nerve cells processes the signals similar to a computer”, says Roska.
The retina’s complicated structure also makes it particularly vulnerable, however. “The retina is the organ of the body that is most affected by genetic diseases”, says Hendrik Scholl, the Director of the Clinical Research Center at the IOB, with whom Roska collaborates closely.
“We are bringing basic research and medicine together and, in this way, developing new methods of treatment. I want my work to contribute to the blind regaining their vision.”
The Team tested it´s initial gene therapies on mice
Eye researchers around the world have in the meantime identified hundreds of gene defects that lead to retinal diseases. Roska pays special attention to the genetic eye disease that is the most widespread, namely retinitis pigmentosa. This disease manifests itself at an early stage, beginning with decreased night vision due to the death of rods. Later the cones lose their sensitivity to light, and it is at this stage that those affected can go blind. Retinitis pigmentosa can be triggered by defects in approximately 70 different genes and has been considered incurable until now. It is possible that the illness can be treated at an early stage by employing virus-based gene replacement therapy or by gene editing. This is unfortunately no longer possible once blindness has become complete. In the latter case, Roska and his colleague José-Alain Sahel from Paris are now focusing on a therapeutic method that he first successfully employed in experiments on mice in 2008. By using gene ferries, light-sensitive protein channels stemming from algae, fungi, or bacteria are inserted into intact retinal cells. The cells reprogrammed in this way take over the task of photoreceptor cells and could make it possible to at least partially restore vision. The researchers now expect that wearing light-amplifying glasses would enable those affected to orient themselves in their environment once again. A clinical study on this issue with five participants is already in progress
The mascula is responsible fpr visual aguity
Age-dependent macular degeneration (AMD) is another widespread illness of photoreceptors. The only area affected is the central region of the retina, referred to as the macula or the fovea, which is responsible for visual acuity such as for reading or for recognizing faces. Botond Roska’s team recently developed technology that may make it possible in the future to restore the sight function of the degenerated fovea of AMD patients. To achieve this, the scientists sensitize the human retina for infrared light, which can be projected onto the fovea with the aid of a special pair of glasses.
Roska’s most recent breakthrough is an important tool for implementing the results of basic research in therapeutic practice. Together with his colleagues he succeeded in culturing artificial retinas in Petri dishes that exhibited a diversity of cell types and layers of structure similar to those of a normal retina. In this work, the team employed a standard procedure from gene technology to reprogram adult cells into what are called induced pluripotent stem cells.
In order to culture the artificial retinas, Roska’s team takes a sample of skin from the patient, out of which the induced pluripotent stem cells are created using the method mentioned above. The scientists then let these cells, so to speak, go through the prenatal process of differentiation a second time, yet this time not in a womb but in a Petri dish with a specially prepared solution of nutrients. After some 30 weeks—this is also how long it takes in a uterus—the pluripotent stem cells differentiate into what are called retinal organoids. These small structures, which are approximately 2 by 2 mm in size, contain similar types of cells with the same or related functions as a fully grown retina.
If the patient from whom the skin sample was taken has gene defects in their retina, then these defects will also be found in the artificially cultured organoids. Using these miniature retinas, the physicians can now test whether certain gene therapies function, trying out different approaches in the process.
Viruses transport new genetic material into cells
Viruses are ideal vehicles for transporting genetic material since they by nature transfer their own hereditary material during every infection. Viruses consist of a short piece of RNA or DNA, usually enclosed by a protective outer layer, or viral envelope. To infect a host cell (of a human or an animal), the virus uses its envelope to dock onto a corresponding receptor on the surface of the host cell. In this way, the virus can enter the host cell. Once inside, the virus’s protective cover dissolves. The virus’s genes are now exposed and reprogram the host cell so that it produces more and more new viruses.
The trick used by gene therapists consists in, so to speak, denucleating the virus. They remove the virus’s original genome, either entirely or partially, and fill the virus’s empty protective cover with, for example, a human gene. Such a gene that is foreign to the virus is also called a transgene. Despite this extreme intervention, the virus is still in a position to infect host cells since the properties of its protective cover are still present.
The difference is that the virus, after docking and entering, passes on the transgene to the host cell instead of its own genome. This transgene can repair genetic defects of the cell or compensate for them.
Gene therapy helped blind mice see again
In his experiments with mice in 2008, Roska employed viruses to insert light-sensitive channel proteins that stem from green algae in one of the two bipolar groups of cells. As a result, these bipolar cells in the middle layer of the retina were turned into, as it were, artificial photoreceptors. They replaced the rods and cones that had died in the blind mice. These artificial cells enabled the mice to once again react to simple visual stimuli. For example, they sought cover when they were exposed to bright light and moved their heads toward patterns that the scientists showed them.
The fundamentals of vision can be explored especially well in animal experiments. In experiments with rabbits, Roska linked ganglia cells with very fine glass pipettes. These micropipettes serve on the one hand as electrodes to measure—depending on the light signals directed at the retina—the electrical activity in the ganglia cells. On the other hand, the scientists can inject a stain through the pipettes that spreads quickly via the dendritic outgrowths. This is how the neuronal networks of the respective ganglia cells are made visible.
Such experiments may not be performed on humans for ethical reasons. Yet thanks to the retinas from organ donors, Roska and his colleagues have been able to make important discoveries. In 2018 the team succeeded in “keeping the donated retina of a deceased person in unbelievably good condition so that it responded to light for an entire day”, reports Magdalena Renner, who heads the organoid group for Roska.
Viruses for gene therapy
For the gene therapy, Roska’s team uses the adeno-associated virus (AAV), which can be artificially produced in bioreactors. These viruses are not dangerous for humans. They also cannot breed independently in the cell. In 2019, the team published a library of 230 different AAV, a number of which can be employed in the therapy of a certain type of retinal cell that is affected by a genetic disorder. The Roska team prepares the transgene in the viruses so that it can help as many patients as possible. Whether universal application of this transgene is possible also depends, however, on the nature of the respective therapy. If the virus can pass a fault-free version of the gene into the cell, then it is possible for a whole series of patients with mutations in this gene to be helped, independent of the precise location of the mutation in the individual case. It is only important that the gene defect is actually in this precise gene. The situation is different if a virus is employed that contains special repair machinery. Such viruses only help patients that exhibit precisely this mutation. Both therapeutic approaches can be evaluated prior to treatment by conducting in vitro tests on organoids from the patient.
The emphasis is on basic research
Botond Roska expects gene therapy to be “the next big thing” in medicine. “Eye diseases are particularly well suited for gene therapies because the immune system is not very active in the area around the eyes”, Roska says. This is the reason that there are few adverse reactions in the eye to injected medications or to viruses.
Botond Roska spends two thirds of his work doing basic research. “We have set ourselves the task of understanding the structure and function of the eye as precisely as possible and to examine vision in the different stages of the process all the way to the visual cortex”, according to Roska. The team’s approach is interdisciplinary and combines genetics, virology, molecular biology, organoid research, electrophysiology, two-photon imaging, and computer models.
Roska and his colleagues gathered their first fundamental details about the structure of the retina in animal experiments. The retina consists of five layers. Three of them contain cell bodies of nerve cells, while both of the intermediate ones support neuronal signal processing and communication between the layers. The layer with the photosensitive rods and cones is, surprisingly, the one furthest from the eye’s lens, just as it is also the rearmost layer of the retina. This does not impair vision, however, since all five of the retinal layers—including the four to the front—are largely transparent.
The middle retinal layer contains, among other things, two of the main types of bipolar cells that can amplify or suppress the electrical signals that they receive from the rods and cones. The bipolar cells conduct their neuronal output to the retinal ganglia cells, which are located in the front layer of the retina, which is situated closest to the eye’s lens. The axon outgrowths of the ganglia cells form the optic nerve, which transports the visual signals—which have already been elaborately preprocessed in the retina—to the visual center of the cerebral cortex via an intermediate station. Overall, the scientists identified about one hundred types of nerve cells that are involved in the signal processing in the retina.
“Eye diseases are particularly well suited for gene therapies because the immune system is not very active in the area around the eyes.”
Experiments with retinas from organ donors
To listen in on the activity of cells from a donated retina, it is placed on a special chip (a high density multielectrode array), which resembles the light-sensitive chip of a camera. The ganglia cells of the retina then no longer conduct their electric signals to the brain but to the electrodes on the chip. In this way, the activity of numerous ganglia cells can be monitored simultaneously.
At the latest after one day the rods and cones of donated retinas lose their activity. Roska’s team, however, succeeded in inserting light-sensitive channel proteins in these retinas—similar to in the earlier mouse experiment— with the aid of viruses. As a result, the donated retinas react to light signals for up to 14 weeks long, making it possible for the scientists to conduct further instructive experiments in this time.
These and other experiments encouraged Gensight Biologics, a company based in Paris, to transplant the light-sensitive proteins into the retinas of blind individuals. “This is an ongoing clinical study”, according to Roska. “The results will presumably be published at the end of 2020 and are confidential until then”.
In his studies on the elementary fundamentals of vision, Botond Roska has determined that the approximately 100 types of nerve cells in a retina work together in 30 circuit modules. `These modules render what we see in 30 different ›films,‹ as it were, each with its own particular aspect of the scene´. Several of these films only show the outlines of objects, similar to a line drawing. Other films provide information about the movement in what we see and its direction. Further films capture the predominantly shady or bright regions. Functioning as the directors of these films are 30 different types of ganglia cells in the retina. Via the optic nerve, the 30 films reach the visual centers of the cerebrum, where they are then assembled to form one complete film of what we see.
In his mouse experiments Roska also discovered that many retinal cells perform multiple functions. In poor light, for example, rods function as sensory cells. If bright light falls on the retina, then the cones—responsible for color vision—become active, and the function of the rods changes. The rods then operate as nerve cells that support the cones in processing signals. The shift from one state to the other occurs abruptly.
Nearsightedness is in creasing around the world
Roska and other IOB colleagues continue to study how the eye’s growth is regulated, with the goal of limiting the nearsightedness that is increasing greatly around the world. In Germany approximately a quarter of all adults are nearsighted, while in parts of Asia 90% of all adolescents are. Nearsightedness usually develops gradually during adolescence because the eyeball becomes slightly longer as the result of genetic and environmental factors (including much reading in artificial light). As a result, the focal point of the eye’s lens moves in front of the retina and the images of very distant objects become blurred. Those who are nearsighted can then only see objects sharply at a close distance. One reason for the increase in nearsightedness is the stronger and stronger spread of smartphones.
The real concern of the IOB scientists is however not nearsightedness itself, which can be easily compensated by glasses or laser treatment. A much greater threat is posed by the considerably increased risk of grave eye diseases that accompanies increasing myopia. The danger of retinal detachment increases many times over with strong nearsightedness, which leads to blindness if left untreated. Also substantially raised are the risks for a glaucoma or macular degeneration. “Such disorders are among”, according to Botond Roska, “the primary causes of invalidity and the loss of an independent way of life in demographically aging societies”. Thus Roska’s vision of understanding eyesight will continue to stay closely linked to his mission of effectively helping those affected.
“Retinal organoids contain similar types of cells with the same or related functions as a fully grown retina.”
Botond Roska the son of a musician and a computer scientist, grew up in Budapest: `My father aroused my interest in mathematics while I was still young. He loved to contemplate, just like I do.´ Yet initially his mother’s artistic influence was predominant. Roska studied cello at the Academy of Music in Budapest and practiced 6 to 8 hours a day, but was forced by an injury to his hand to abandon his musical career prematurely.
Subsequently Roska studied mathematics and medicine in Budapest. He earned his doctorate in neurobiology at the University of California in Berkeley. As a Junior Fellow at Harvard University, he intensified his work in genetics and virology. From 2005 to 2017 he headed a research group at the Friedrich Miescher Institute for Biomedical Research in Basel. He has been a professor at the University of Basel since 2014. Together with Professor Hendrik Scholl, he was founding director of the Institute for Molecular and Clinical Ophthalmology Basel (IOB) in December 2017.
Although there has been a large increase in the incidence of eye diseases around the world as a consequence of increasing longevity, there has been little innovation in ophthalmology. Roska revolutionized both basic research and medical research by examining in detail for the first time the approximately 100 types of cells in the retina where most eye diseases occur. In the process one of the facts he discovered was which cell defects triggered specific illnesses. To cure them, Roska and Scholl are now developing modern gene therapies. His team is currently primarily pursuing retinitis pigmentosa, an inherited disorder.
In basic research, Roska is studying the elementary functioning of vision and tracing the signal paths of information from the retina to the depths of the brain. He has already been awarded numerous distinguished science prizes.
Roska’s daily routine is strictly structured: “In the morning I think, in the afternoon I speak with people.” After getting up, he first solves mathematical problems for an hour as brain training. Afterwards he reflects in a concentrated manner on his research. In his scant leisure time the winner of the Prize still enjoys playing cello or listening to music, from Bach to Beethoven to Chopin.
“The motto of the foundation is ‘changing society for the better’, and I think that Botond Roska embodies it in exemplary fashion because his basic research is rigorously directed toward the well-being of patients.”
Former Member of the Executive Board of Körber-Stiftung
Awards Ceremony 2021
Photos of the presentation of the Körber European Science Prize 2020 to Botond Roska in the Hamburg City Hall. These photos are free to use in the context of news coverage with the credits given below.