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Researchers at Johns Hopkins University School of Medicine in Baltimore, Maryland have grown a type of human stem cells in a lab to create an artificial retina. The tissue contains functional photoreceptor cells that are light-sensitive.
The study was conducted by assistant professor M. Valerie Canto-Soler of Johns Hopkins University, and has since been published in the multidisciplinary journal Nature Communications. The information in the research details how the team was able to successfully create a semi-functional retina using induced pluripotent stem cells (iPS). Induced pluripotent stem cells are cells that have been genetically reverted back to their original state. They can develop into almost all of the 200 cell types in a human body, according to the team. Canto-Soler’s group is hopeful the iPS cells will pave the way to genetically engineered cell transplants that are capable of stopping or reversing progressive blindness. The researchers were able to stimulate the iPS cells in order to produce retinal progenitor cells. These cells are designed with the specific purpose of lining the back of the human eye with retinal tissue.
Retinal tissue is composed of seven major cell types that all absorb and process light. Those signals are then transmitted back to the brain to be interpreted as images. The team implemented this knowledge into their experiment by designing a 3-D cellular structure.
According to one of the researchers in the lab, Xiufeng Zhong, the artificial growth corresponded with the amount of time a fetus’ retinae takes to develop to the same stage. The tissue developed by the team is physiologically equivalent to tissue that had naturally matured in the womb over a period of 28 weeks. In addition, the photoreceptor cells were able to grow outer functions, which are essential structures in cellular function. After they created their sample tissue, the researchers tested the light-sensitivity of the retinas by placing an electrode into a photoreceptor cell. It was discovered that both the photoreceptors and natural retina rods react to light in the same manner. “We have basically created a miniature human retina…that not only has the architectural organization of the retina but also has the ability to sense light,” Canto-Soler said.
As is true of many different processes within the human body, vision relies upon various types of cells working in unison towards one specific goal. In this instance, the desired result is to have the cells transform light into something recognizable by the brain as an image.
The research conducted on the stem cells grown in a lab to create an artificial retina was designed to assist people suffering from retinal diseases. According to Canto-Soler, their findings have created the potential for more personalized medicine, which includes administering drugs unique to individual patients with a retinal condition. Additionally, the team hopes their study may one day restore vision to some people by replacing dead retinal tissue with lab-grown material.
Canto-Soler was quick to acknowledge that while the tissue reacts in a satisfactory manner, it is only one step in a much more complex process that requires structures which have not yet been successfully created in a lab environment. Canto-Solar said, “Is our lab retina capable of producing a visual signal that the brain can interpret as an image? Probably not, but this is a good start.”
The first human stem cells grown in a lab to create an artificial retina have been produced by researchers at John Hopkins. Their findings open up new possibilities for those with retinal diseases.
By Samuel Williams