人妻少妇专区 vision scientist can barely contain his excitement as he shares time-lapse videos showing immune cells moving through living retinal tissue at the back of an eye.
In one clip, immune cells crawl so slowly along the inside edge of a blood vessel that the video must be sped up 25 times to show their progress. Another cell slowly treads against the flow of blood in a vessel, like a salmon fighting its way upstream. Other immune cells leave the blood vessels and inch through the surrounding tissue, then congregate in a swarm, forming a beehive of activity.
Schallek and his vision lab at the 人妻少妇专区 Center for Visual Science and , have created a new microscopy technique, described in the journal , that builds upon groundbreaking adaptive optics developed at the University more than 20 years ago.
Combined with time lapse videography and artificial intelligence software, the new technique enables researchers for the first time to noninvasively image and track鈥攚ithout labeling鈥攖he interactions of translucent immune cells within live retinal tissue in animals. Until now, the immune cells had to be labeled with fluorescent agents and often reinjected in order to image them鈥攔aising questions about how this might change the behavior of the cells. Another common, but limiting approach is to remove cells and study them with a microscope in a dish.
CELLULAR DETAILS: Using the new techique, researchers in the lab of Rochester vision scientist Jesse Shallek captured images of the same retinal location and tracked it over two months as the area responded to injury. Single immune cells arrive and respond with vigor at 6 hours and 24 hours after the injury. The retina then returns to normal conditions after weeks to months (Courtesy of Schallek lab)
Schallek鈥檚 lab avoids both complications by imaging immune cells in the living eye without requiring dyes at all鈥攖he first study of its kind to do so.
鈥淲e think of the eye as this beautiful window where we can peer in, noninvasively, without having to cut or insert a camera into places where we would rather it didn鈥檛 go,鈥� says Schallek, an assistant professor of ophthalmology and neuroscience.
鈥淭he eye is an extension of our brain, and therefore with this technology we have some of our first glimpses into immune cell function deep in the central nervous system. This is a critical step forward for basic science and clinical study alike.鈥�
Schallek鈥檚 lab is now adapting the new technique for use with human patients.
鈥淲e think this will be a game changer for ophthalmology and for our understanding of retinal diseases that lead to blindness,鈥� says Schallek.
What role do immune cells play in inflammation?
Immune cells are at the center of 鈥渁 whole cascade of events鈥� that cause the inflammation that is characteristic of most retinal eye diseases that lead to blindness, Schallek says. For example, in addition to immune cells arriving at the affected tissue, and releasing compounds that recruit more immune cells, there are also changes in blood flow鈥攁ll of which interfere with vision and complicate the progression of the disease.
Until now, the tools available to measure inflammation in retinal tissue have been limited.
What is adaptive optics?
The new imaging technique draws on adaptive optics, a process developed by astronomers to take clear pictures of the sky without distortions from Earth鈥檚 atmosphere. Rochester vision scientist David Williams pioneered the use of adaptive optics to obtain very sharp images from inside the eye. More about adaptive optics
Optical coherence tomography, for example, has been used to measure the thickness of retinal tissue at the back of the eye. 鈥淭he thickness of that tissue is thought to be a marker for how inflamed the tissue is,鈥� Schallek says. 鈥淗owever useful that might be, it doesn鈥檛 really tell you what the cells in that tissue are doing.鈥�
The new technology developed by his lab does that by:
- Building on the adaptive optics technology created at Rochester by , director of the Center for Visual Science and his colleagues more than 20 years ago. Adaptive optics provided a way to correct for aberrations of the eye so that researchers for the first time could visualize individual cells at the back of the eye.
- Integrating into adaptive optics a new phase contrast technique 鈥� much like differential interference contrast microscopy–which can capture images of translucent objects such as immune cells.
- Using time lapsed videography to capture images of immune cell activity in the retina over periods ranging from milliseconds to months. Adjusting the playback speed allows the slow movements of those cells can be more easily tracked.
- Using artificial intelligence (AI) computer code deployed by the lab to identify the different kinds of immune cells captured in the images.
- Using ultra-high-speed imaging of individual red blood cells to simultaneously track blood flow and how it changes in response to the inflammation.
The study was led by first authors Aby Joseph, a PhD candidate at the and Colin Chu, an ophthalmologist and visiting senior research fellow from University of Bristol who spent three months in Schallek鈥檚 lab.
鈥淭his was a wonderful collaboration, merging expertise in immunology and cutting-edge imaging technology,鈥� says Chu. 鈥淎 defining characteristic of immune cells is that they are truly mobile and incredibly dynamic, rushing to wherever inflammation occurs. The first time we successfully imaged them was astounding, as we were essentially spying on them as they worked within their actual native setting. Even now watching the recordings continues to mesmerize me.鈥�
Using his optics background, Joseph added key engineering advances rendering immune cell imaging and blood flow quantification in the retina. 鈥淭he use of low levels of infrared light to achieve this means that our approach can be safely translated to human study,鈥� says Joseph.
鈥淎dditionally, the use of high-speed imaging to measure blood flow revealed surprising details about how inflammation behaves in the central nervous system. We found that veins and arteries achieve an increase in blood flow to the inflamed retina through markedly different ways. This could become important for designing and testing future treatments to resolve inflammation,鈥� says Joseph.
This new technology is exciting not only from a scientific and clinical standpoint, but especially for pharmaceutical applications, Schallek says. 鈥淐ompanies will now have way to look at how well specific drugs target specific components within the immune system. They鈥檒l be able to see if they can improve the efficacy of drugs that are already approved, and others that are still in development.鈥�
Other coauthors of the study include Guanping Feng and Kosha Dholakia, also students in Schallek鈥檚 lab.
The project was supported with funding from the National Eye Institute of the National Institutes of Health, Research to Prevent Blindness, F. Hoffmann-La Roche Ltd. Roche Academy of Distinguished Scholars, the Dana Foundation and the World Universities Network WUN Research Mobility Programme award.
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