22 April 2013 Sprouting Cells Every inch inside our bodies is covered with a tree-like network of blood vessels. New branches grow from cells in the vessel walls that ‘sprout’ like shoots growing through the skin of a potato. This is controlled by molecules called growth factors. In these six-day-old mouse retinas (visualised using two techniques), new vessels are developing. A red fluorescent dye has been used to observe the patterns of two injected growth factors: VEGF-A (left two images) and VEGF-C (right two). Cell nuclei, both inside and outside the vessels, are stained blue, and the cells that make up the vessel walls are stained white. Both growth factors are densest around the vessel walls, and the green arrowheads point to where they have been taken into individual sprouting cells. Understanding this process may lead to new tools against diseases like cancer, as growth factors enable some tumours to develop their own blood supply. Written by Emma Stoye — Ralf Adams Masanori Nakayama Max Planck Institute for Molecular Biomedicine, Germany Publiehd in Nature Cell Biology 15: 249-260. Reprinted by permission from Macmillan Publishers Ltd: Copyright 2013
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22 April 2013

Sprouting Cells

Every inch inside our bodies is covered with a tree-like network of blood vessels. New branches grow from cells in the vessel walls that ‘sprout’ like shoots growing through the skin of a potato. This is controlled by molecules called growth factors. In these six-day-old mouse retinas (visualised using two techniques), new vessels are developing. A red fluorescent dye has been used to observe the patterns of two injected growth factors: VEGF-A (left two images) and VEGF-C (right two). Cell nuclei, both inside and outside the vessels, are stained blue, and the cells that make up the vessel walls are stained white. Both growth factors are densest around the vessel walls, and the green arrowheads point to where they have been taken into individual sprouting cells. Understanding this process may lead to new tools against diseases like cancer, as growth factors enable some tumours to develop their own blood supply.

Written by Emma Stoye

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Eye Insights The eyes of fish grow larger throughout their lives because stem cells produce new tissue in the retina, the light-sensitive lining at the back of the eye. Humans and other mammals lack these stem cells, so the retina can neither grow nor be repaired naturally. Studies of zebrafish show that the development of stem cells in the retina is controlled by chemicals from nerve cells nearby. This research may lead to a better understanding of degenerative diseases of the eyes and nervous system in humans and the causes of cancer, which can occur when stem cells go out of control. Pictured is a cross-section of a zebrafish eye. The ring stained green with the dark centre is the lens, with the retina appearing as a semi-circle around it. Stem cells are concentrated in the regions at either end of the red-stained arcs of nerve connecting tissue. Written by Mick Warwicker — Kara Cerveny Zebrafish Research, UCL, London
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Eye Insights

The eyes of fish grow larger throughout their lives because stem cells produce new tissue in the retina, the light-sensitive lining at the back of the eye. Humans and other mammals lack these stem cells, so the retina can neither grow nor be repaired naturally. Studies of zebrafish show that the development of stem cells in the retina is controlled by chemicals from nerve cells nearby. This research may lead to a better understanding of degenerative diseases of the eyes and nervous system in humans and the causes of cancer, which can occur when stem cells go out of control. Pictured is a cross-section of a zebrafish eye. The ring stained green with the dark centre is the lens, with the retina appearing as a semi-circle around it. Stem cells are concentrated in the regions at either end of the red-stained arcs of nerve connecting tissue.

Written by Mick Warwicker

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Source: bpod.mrc.ac.uk

Through New Eyes Our vision relies on a multi-layered structure on the inner surface of the eye, the retina, bearing specialised light-sensitive neurons known as photoreceptors. Progressive degeneration of these cells leads to blindness, as in inherited diseases such as retinitis pigmentosa. While this cannot be reversed, transplanting healthy cells into the eye may provide a solution. Photoreceptor precursor cells are injected into the retina, where they mature into functional light detectors. In mice genetically modified to show symptoms of these diseases, transplants can restore normal responses to light. Pictured are donor cells (stained green), successfully integrating into the host retina (stained blue) of healthy mice (top left corner) and of mouse models of three different genetic diseases causing blindness in humans. Though the extent of integration still depends on the nature and progression of the disease, this technique raises hopes of recovering sight from a range of conditions. Written by Emmanuelle Briolat — Rachael Pearson & Robin Ali University College London Institute of Ophthalmology, UK Published in PNAS 110(1): 354-359
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Through New Eyes

Our vision relies on a multi-layered structure on the inner surface of the eye, the retina, bearing specialised light-sensitive neurons known as photoreceptors. Progressive degeneration of these cells leads to blindness, as in inherited diseases such as retinitis pigmentosa. While this cannot be reversed, transplanting healthy cells into the eye may provide a solution. Photoreceptor precursor cells are injected into the retina, where they mature into functional light detectors. In mice genetically modified to show symptoms of these diseases, transplants can restore normal responses to light. Pictured are donor cells (stained green), successfully integrating into the host retina (stained blue) of healthy mice (top left corner) and of mouse models of three different genetic diseases causing blindness in humans. Though the extent of integration still depends on the nature and progression of the disease, this technique raises hopes of recovering sight from a range of conditions.

Written by Emmanuelle Briolat

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Source: bpod.mrc.ac.uk

Seeing Blind The human eye can distinguish about ten million colours thanks to the light-sensitive lining at the back of our eye. Containing millions of cells, called rods and cones, the retina (pictured flattened out from a mouse eye) absorbs light and transmits this visual information to the brain. Also within this specialised layer are thousands of melanopsin retinal ganglion cells (stained purple) that control our subconscious responses to light, such as the shrinking and expanding of our pupils. Scientists reveal that these cells also provide unexpected amounts of visual information to the brain during conscious vision. In mice completely lacking rods and cones, the contribution of these ganglion cells was enough to prompt responses to light. This discovery may help to solve the mystery of why some people who lose rods and cones as a result of eye disease can still consciously detect the presence of light even when blind. Written by Lux Fatimathas — Robert Lucas, University of Manchester, UK Satchidananda Panda, Salk Institute for Biological Studies, USA Originally published under Creative Commons (CC-BY 2.0) Published in PLoS Biology 8(12): e1000558
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Seeing Blind

The human eye can distinguish about ten million colours thanks to the light-sensitive lining at the back of our eye. Containing millions of cells, called rods and cones, the retina (pictured flattened out from a mouse eye) absorbs light and transmits this visual information to the brain. Also within this specialised layer are thousands of melanopsin retinal ganglion cells (stained purple) that control our subconscious responses to light, such as the shrinking and expanding of our pupils. Scientists reveal that these cells also provide unexpected amounts of visual information to the brain during conscious vision. In mice completely lacking rods and cones, the contribution of these ganglion cells was enough to prompt responses to light. This discovery may help to solve the mystery of why some people who lose rods and cones as a result of eye disease can still consciously detect the presence of light even when blind.

Written by Lux Fatimathas

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Source: bpod.mrc.ac.uk

See Blind Mice

Over 160 million people worldwide are visually impaired according to the World Health Organisation. New treatments could soon be available following pioneering transplant research in mice. Cells extracted from young healthy mice were injected into night-blind mice restoring their ability to see in the dark. Immature rod-photoreceptor cells, essential for sight in poorly lit conditions, were transferred into the retina of affected mice. The behaviour of treated and non-treated mice in a dimly lit maze was compared to normal mice. This video demonstrates the results: treated and normal mice were able to find the platform allowing them to exit the water after a short time. Non-treated night-blind mice could only find the platform after a lengthy search. The findings hold promise for eye treatment and scientists will now explore the potential for humans, although they have a few more complications to overcome.

Written by Josh Woods

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Source: bpod.mrc.ac.uk

Living under Pressure A small chamber at the front of our eyeballs is constantly replenished with plasma-like fluid. A tiny tract called Schlemm’s canal drains waste and excess fluid to the bloodstream. As the fluid level fluctuates, this narrow pipe maintains the correct pressure in the chamber by providing resistance. Researchers are studying the proteinsthat keep the canal lining attached in this unusual environment. If this endothelial celllayer (pictured; nuclei stained brown) is displaced it could cause an obstruction. And if Schlemm’s canal blocks, pressure builds up and sight-threatening glaucoma may develop. The combination of proteins shown, tagged with green, red and purple fluorescence, may provide clues to causes and treatments for glaucoma, which affects over 10,000 people a year in the UK. Written by Lindsey Goff — Dr Darryl Overby Dept of Bioengineering, Imperial College, London Published in Molecular Vision 17: 199-209
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Living under Pressure

A small chamber at the front of our eyeballs is constantly replenished with plasma-like fluid. A tiny tract called Schlemm’s canal drains waste and excess fluid to the bloodstream. As the fluid level fluctuates, this narrow pipe maintains the correct pressure in the chamber by providing resistance. Researchers are studying the proteinsthat keep the canal lining attached in this unusual environment. If this endothelial celllayer (pictured; nuclei stained brown) is displaced it could cause an obstruction. And if Schlemm’s canal blocks, pressure builds up and sight-threatening glaucoma may develop. The combination of proteins shown, tagged with green, red and purple fluorescence, may provide clues to causes and treatments for glaucoma, which affects over 10,000 people a year in the UK.

Written by Lindsey Goff

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Source: bpod.mrc.ac.uk