Artificial Retina Technology Gives New Hope to the Blind
A breakthrough in medical technology known as ‘artificial retina’ offers hope to those who have lost their eyesight. This innovative approach, which focuses on restoring vision, includes various methods such as drug treatment, genetic engineering, and stem cell transplantation.
Typically, artificial retina research involves conducting animal experiments to test the effectiveness of the technology. This process is both time-consuming and costly, often encountering unexpected variables along the way.
Pioneering Research by Korean Scientists
In an exciting development, scientists from the Korea Institute of Science and Technology (KIST) have made significant progress in artificial retina technology. The team, led by Dr. Jaeheon Kim, Dr. Hyunseok Song, and Dr. Hongnam Kim, has managed to verify the function of artificial retina through in vitro cell experiments, eliminating the need for initial animal testing.
The researchers achieved this by creating an artificial photoreceptor with a level of visual function equivalent to that of a human. Moreover, they developed an artificial visual circuit platform to understand how electrical signals generated by the artificial photoreceptor are transmitted to other nerve cells. Essentially, this model replicates the human visual system, including the eyes, optic nerve, and brain, within a single device.
Overcoming Challenges and Enhancing Viability
The human retina consists of cone cells and rod cells, responsible for color perception and light-dark distinction, respectively. In 2018, the KIST team successfully produced an opsin protein. Building on their previous work, they focused on applying opsin proteins to nerve cells.
By forming nerve cells into clusters called spheroids and increasing cell interaction, the researchers were able to stabilize the expression of artificial photoreceptor proteins. This method notably improved the survivability rate of nerve cells, with over 80% of neurons remaining functional.
Advancing Neural Signal Transmission
Through their groundbreaking research, the KIST team sought to validate the transmission of electrical signals from the artificial photoreceptors to other media. To achieve this, they connected a light-reactive nerve spheroid simulating an eye to a regular nerve spheroid simulating the brain. This created an optic nerve circuit that detects color and sends signals to the brain, allowing the study of visual signal transmission.
Dr. Jaeheon Kim explained, “This platform not only reduces the reliance on animal testing but also minimizes research costs. In the future, we aim to develop a spheroid that can recognize all colors visible to humans and create a test kit for vision-related diseases and treatments.”
Paving the Way for Future Advancements
While these achievements lay the foundation for potential treatments, the research conducted by KIST represents a significant step toward addressing severe visual impairments. The institute remains committed to interdisciplinary convergence research under the GRaND Challenge initiative, supporting technologies that contribute to humanity.
The study, a collaborative effort among electronic, mechanical, chemical, and bioengineers, has been published in the esteemed international academic journal ‘Advanced Materials’.
* Description: A groundbreaking eye-mimicking neural network, composed of photosensitive neural spheroids with human opsin proteins, offers potential for vision restoration (doi.org/10.1002/adma.202302996).
By Choi Sang-guk, Journalist (skchoi@inews24.com)
[아이뉴스24 최상국 기자] ‘Artificial retina’ technology gives new hope to people who have lost their sight due to damage to the retina. Scientists are investigating various vision restoration technologies, such as drug treatment, genetic engineering methods, and biological transplantation using stem cells, to help patients who cannot use visual nerve cells at all.
Artificial retina research is a medical technology to be applied to the human body, and the research process mainly involves animal experiments. After causing retinal diseases in experimental animals, they go through a process to verify the effectiveness of artificial retina technology, and a significant amount of research money and time is invested in this process. Unexpected experimental variables also hinder technological development.
The Korea Institute of Science and Technology (KIST) team of Dr. Jaeheon Kim and Dr. Hyunseok Song from the Sensor System Research Center and Dr. Hongnam Kim’s team from the Brain Convergence Technology Research Center technology that can verify the visual artificial retina function through in vitro cell experiments before conducting animal experiments. The research team created an artificial photoreceptor with the same level of visual function as a human and developed an artificial visual circuit platform that can confirm the process by which electrical signals generated by receiving light from this artificial photoreceptor are transmitted to nerve cells others.
A model that reproduces the human visual system, which includes the eyes, optic nerve, and brain, using photoresponsive nerve cell spheroids (photospheroid) in a single device. Human photoreceptor opsin protein was produced within nerve cells to add light-responsive function, and placed with normal nerve cells (intact spheroids) within the device to form a neural network. When the left photoreactive nerve cell is stimulated with light, a nerve signal is transmitted along the neurite to the general nerve cell. [사진=KIST]
The human retina is made up of cone cells and rod cells. Cone cells produce photoreceptor proteins (opsin) that distinguish between the three colors red, green and blue, and rod cells produce photoreceptor proteins (rhodopsin) that distinguish between light and dark. The human eye sees objects through a process where light coming from outside is condensed on the retina to form an image, and is then transmitted to the brain via the optic nerve.
KIST researchers, who have been investigating vision restoration technology based on artificial photoreceptors for many years, succeeded in producing an opsin protein in 2018. In this study, we expanded this to the cell level and carried out research to apply opsin proteins to nerve cells.
The researchers created spheroids expressing rhodopsin and blue opsin proteins. A spheroid is a cell mass in which many cells are gathered together to form a sphere. Nerve cells have a short lifespan and poor viability, so the current methods used in artificial retina research had the problem of nerve cells losing function or necrosis before artificially expressing photoreceptor proteins.
To overcome this, the research team was able to stably express artificial photoreceptor proteins by forming nerve cells into a cluster called a spheroid and increasing interaction between cells. Previously, when photoreceptor proteins were injected during 2D cell culture, only 50% or less of neurons survived, but when neural spheroids were used, the survival rate was over 80%.
Color distinguishable light-reactive spheroids convert light information received from the outside into nerve signals and transmit signals from the cell body to the outside. Signals are transmitted radially along axons, which are bundles of nerves that extend from nerve cells.
The main focus of this study was to verify whether electrical signals generated by receiving light from artificially created photoreceptors could be transmitted to other media. To achieve this, the research team connected a light-reactive nerve spheroid simulating an eye and a regular nerve spheroid simulating the brain to operate an optic nerve circuit that detects color and transmits it to the brain. Through this, we managed to capture the process of expanding neurotransmission through a fluorescence microscope. We created a model of visual signal transmission that allows us to examine the process by which the human brain recognizes signals generated in the retina, that is, the process by which signals are transmitted from stimulated tissues to tissues which senses sensation.
This is said to be the first time that neural spheroids and artificial photoreceptors have been combined in vitro. The research team said, “Neural spheroids themselves are a cell aggregating technology that is already widely commercialised, but instead of culturing simple neural spheroids or previously studied organoids, neural spheroids (eyes) are used which n expressing photoreceptors and simple neural spheroids. “The difference from existing research is that the optic nerve was realized by building a circuit between the roid (brain),” he explained.
Dr said. Jaeheon Kim, “It is a platform that can reduce dependence on animal testing and reduce research costs by verifying the possibility of transmitting a visual signal from artificial photoreceptors in various ways.” He added, “In the future, we will create a spheroid that can recognize every color humans can see.” “We plan to manufacture and develop it into a test kit for vision-related diseases and treatments.” He also said, “In the distant future, we will produce cells freely within the human retina and operate cell layers to provide treatment technology through transplantation to people with severe visual impairment.” “I intend to do it.”
KIST supports the development of technologies that challenge and contribute to humanity through interdisciplinary convergent research under the name GRaND Challenge. This study is also the result of joint research by electronic, mechanical, chemical and bioengineers from different research departments within KIST.
The results of this research were published in the international academic journal ‘Advanced Materials’.
* Description: An eye-mimicking neural network composed of photosensitive neural spheroids with human opsin proteins (doi.org/10.1002/adma.202302996)
/Reporter Choi Sang-guk (skchoi@inews24.com)
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