Tuesday, 6 October 2015
Researchers have succeed in producing photoreceptors from human embryonic stem cells
Tuesday, 06 October 2015
Age-related macular degeneration (AMRD) could be treated by transplanting photoreceptors produced by the directed differentiation of stem cells, thanks to findings published today by Professor Gilbert Bernier of the University of Montreal and its affiliated Maisonneuve-Rosemont Hospital. ARMD is a common eye problem caused by the loss of cones. Bernier's team has developed a highly effective in vitro technique for producing light sensitive retina cells from human embryonic stem cells.
"Our method has the capacity to differentiate 80% of the stem cells into pure cones," Professor Gilbert explained.
"Within 45 days, the cones that we allowed to grow towards confluence spontaneously formed organised retinal tissue that was 150 microns thick. This has never been achieved before."
In order to verify the technique, Bernier injected clusters of retinal cells into the eyes of healthy mice. The transplanted photoreceptors migrated naturally within the retina of their host.
"Cone transplant represents a therapeutic solution for retinal pathologies caused by the degeneration of photoreceptor cells," Bernier explained.
"To date, it has been difficult to obtain great quantities of human cones."
His discovery offers a way to overcome this problem, offering hope that treatments may be developed for currently non-curable degenerative diseases, like Stargardt disease and ARMD.
"Researchers have been trying to achieve this kind of trial for years," he said.
"Thanks to our simple and effective approach, any laboratory in the world will now be able to create masses of photoreceptors. Even if there's a long way to go before launching clinical trials, this means, in theory, that will be eventually be able to treat countless patients."
The findings are particularly significant in the light of improving life expectancies and the associated increase in cases of ARMD. ARMD is in fact the greatest cause of blindness amongst people over the age of 50 and affects millions of people worldwide. And as we age, it is more and more difficult to avoid - amongst people over 80, this accelerated aging of the retina affects nearly one in four. People with ARMD gradually lose their perception of colours and details to the point that they can no longer read, write, watch television or even recognize a face.
ARMD is due to the degeneration of the macula, which is the central part of the retina that enables the majority of eyesight. This degeneration is caused by the destruction of the cones and cells in the retinal pigment epithelium (RPE), a tissue that is responsible for the reparation of the visual cells in the retina and for the elimination of cells that are too worn out. However, there is only so much reparation that can be done as we are born with a fixed number of cones. They therefore cannot naturally be replaced. Moreover, as we age, the RPE's maintenance is less and less effective - waste accumulates, forming deposits.
"Differentiating RPE cells is quite easy. But in order to undertake a complete therapy, we need neuronal tissue that links all RPE cells to the cones. That is much more complex to develop," Bernier explains, noting nonetheless that he believes his research team is up to the challenge.
Bernier has been interested in the genes that code and enable the induction of the retina during embryonic development since completing his PhD in Molecular Biology in 1997.
"During my post-doc at the Max-Planck Institute in Germany, I developed the idea that there was a natural molecule that must exist and be capable of forcing embryonic stem cells into becoming cones," he said.
Indeed, bioinformatics analysis led him to predict the existence of a mysterious protein: COCO, a "recombinational" human molecule that is normally expressed within photoreceptors during their development.
In 2001, he launched his laboratory at Maisonneuve-Rosemont Hospital and immediately isolated the molecule. But it took several years of research to demystify the molecular pathways involved in the photoreceptors development mechanism. His latest research shows that in order to create cones, COCO can systematically block all the signalling pathways leading to the differentiation of the other retinal cells in the eye. It's by uncovering this molecular process that Bernier was able to produce photoreceptors. More specifically, he has produced S-cones, which are photoreceptor prototypes that are found in the most primitive organisms.
Beyond the clinical applications, Professor Bernier's findings could enable the modelling of human retinal degenerative diseases through the use of induced pluripotent stem cells, offering the possibility of directly testing potential avenues for therapy on the patient's own tissues.
Source: University of Montréal
Contact: William Raillant-Clark
Differentiation of human embryonic stem cells into cone photoreceptors through simultaneous inhibition of BMP, TGFβ and Wnt signaling
Shufeng Zhou, Anthony Flamier, Mohamed Abdouh, Nicolas Tétreault, Andrea Barabino, Shashi Wadhwa and Gilbert Bernier
Development, 42, 3294-3306, October 1, 2015, doi: 10.1242/dev.125385
For more on stem cells and cloning, go to CellNEWS at
Thursday, 3 September 2015
Study Reveals the Genetic Start-up of a Human Embryo
Thursday, 03 September 2015
An international team of scientists led from Sweden’s Karolinska Institutet has for the first time mapped all the genes that are activated in the first few days of a fertilised human egg. The study, which is being published in the journal Nature Communications, provides an in-depth understanding of early embryonic development in human – and scientists now hope that the results will help finding for example new therapies against infertility.
At the start of an individual’s life there is a single fertilised egg cell. One day after fertilisation there are two cells, after two days four, after three days eight and so on, until there are billions of cells at birth. The order in which our genes are activated after fertilisation has remained one of the last uncharted territories of human development.
Juha Kere is a Professor of Molecular Genetics at
Karolinska Institutet. Credit: Ulf Sirborn.
“These genes are the ‘ignition key’ that is needed to turn on human embryonic development. It is like dropping a stone into water and then watching the waves spread across the surface”, says principal investigator Juha Kere, professor at theDepartment of Biosciences and Nutrition at Karolinska Institutet and also affiliated to the SciLifeLab facility in Stockholm.
The researchers had to develop a new way of analysing the results in order to find the new genes. Most genes code for proteins but there are a number of repeated DNA sequences that are often considered to be so-called ‘junk DNA’, but are in fact important in regulating gene expression.
Treatment of infertility
In the current study, the researchers show that the newly identified genes can interact with the ‘junk DNA’, and that this is essential to the start of development.
Outi Hovatta is a Professor of Obstetrics and
Gynaecology at Karolinska Institutet. Credit:
The study was a collaboration between three research groups from Sweden and Switzerland that each provided a unique set of skills and expertise. The work was supported by the Karolinska Institutet Distinguished Professor Award, the Swedish Research Council, the Strategic Research Program for Diabetes funding at Karolinska Institutet, Stockholm County, the Jane & Aatos Erkko Foundation, the Instrumentarium Science Foundation, and the Åke Wiberg and Magnus Bergvall foundations. The computations were performed on resources provided by SNIC through Uppsala Multidisciplinary Center for Advanced Computational Science (UPPMAX).
Source: Karolinska Institutet
Contact: KI Press Office
Novel PRD-like homeodomain transcription factors and retrotransposon elements in early human development
Virpi Töhönen, Shintaro Katayama, Liselotte Vesterlund, Eeva-Mari Jouhilahti, Mona Sheikhi, Elo Madissoon, Giuditta Filippini-Cattaneo, Marisa Jaconi, Anna Johnsson, Thomas R. Bürglin, Sten Linnarsson, Outi Hovatta and Juha Kere
Nature Communications, 3 September 2015, doi: 10.1038/NCOMMS9207
For more on stem cells and cloning, go to CellNEWS at
Wednesday, 19 August 2015
Once licensed, model likely to accelerate study of Alzheimer’s, autism, more
Wednesday, 19 August 2015
Scientists at The Ohio State University have developed a nearly complete human brain in a dish that equals the brain maturity of a 5-week-old foetus.
The brain organoid, engineered from adult human skin cells, is the most complete human brain model yet developed, said Rene Anand, professor of biological chemistry and pharmacology at Ohio State.
The lab-grown brain, about the size of a pencil eraser, has an identifiable structure and contains 99 percent of the genes present in the human foetal brain. Such a system will enable ethical and more rapid and accurate testing of experimental drugs before the clinical trial stage and advance studies of genetic and environmental causes of central nervous system disorders.
“It not only looks like the developing brain, its diverse cell types express nearly all genes like a brain,” Anand said.
“We’ve struggled for a long time trying to solve complex brain disease problems that cause tremendous pain and suffering. The power of this brain model bodes very well for human health because it gives us better and more relevant options to test and develop therapeutics other than rodents.”
Anand reported on his lab-grown brain Tuesday (Aug. 18) at the 2015 Military Health System Research Symposium in Ft. Lauderdale, Florida.
Anand, who studies the association between nicotinic receptors and central nervous system disorders, was inspired to pursue a model of human neural biology after encountering disappointing results in a rodent study of an experimental autism drug. Taking a chance with a shoestring budget compared to other researchers doing similar projects, he added stem-cell engineering to his research program. Four years later, he had built himself a replica of the human brain.
The main thing missing in this model is a vascular system. What is there – a spinal cord, all major regions of the brain, multiple cell types, signalling circuitry and even a retina – has the potential to dramatically accelerate the pace of neuroscience research, said Anand, also a professor of neuroscience.
“In central nervous system diseases, this will enable studies of either underlying genetic susceptibility or purely environmental influences, or a combination,” he said.
“Genomic science infers there are up to 600 genes that give rise to autism, but we are stuck there. Mathematical correlations and statistical methods are insufficient to in themselves identify causation. You need an experimental system – you need a human brain.”
Converting adult skin cells into pluripotent cells – immature stem cells that can be programmed to become any tissue in the body – is a rapidly developing area of science that earned the researcher who discovered the technique, Shinya Yamanaka, a Nobel Prize in 2012.
“Once a cell is in that pluripotent state, it can become any organ – if you know what to do to support it to become that organ,” Anand said.
“The brain has been the holy grail because of its enormous complexity compared to any other organ. Other groups are attempting to do this as well.”
Anand’s method is proprietary and he has filed an invention disclosure with the university.
He said he used techniques to differentiate pluripotent stem cells into cells that are designed to become neural tissue, components of the central nervous system or other brain regions.
“We provide the best possible environment and conditions that replicate what’s going on in utero to support the brain,” he said of the work he completed with colleague Susan McKay, a research associate in biological chemistry and pharmacology.
High-resolution imaging of the organoid identifies functioning neurons and their signal-carrying extensions – axons and dendrites – as well as astrocytes, oligodendrocytes and microglia. The model also activates markers for cells that have the classic excitatory and inhibitory functions in the brain, and that enable chemical signals to travel throughout the structure.
It takes about 15 weeks to build a model system developed to match the 5-week-old foetal human brain. Anand and McKay have let the model continue to grow to the 12-week point, observing expected maturation changes along the way.
“If we let it go to 16 or 20 weeks, that might complete it, filling in that 1 percent of missing genes. We don’t know yet,” he said.
He and McKay have already used the platform to launch their own projects, creating brain organoid models of Alzheimer’s and Parkinson’s diseases and autism in a dish. They hope that with further development and the addition of a pumping blood supply, the model could be used for stroke therapy studies. For military purposes, the system offers a new platform for the study of Gulf War illness, traumatic brain injury and post-traumatic stress disorder.
Anand hopes his brain model could be incorporated into the Microphysiological Systems program, a platform the Defense Advanced Research Projects Agency is developing by using engineered human tissue to mimic human physiological systems.
Support for the work came from the Marci and Bill Ingram Research Fund for Autism Spectrum Disorders and the Ohio State University Wexner Medical Center Research Fund.
Anand and McKay are co-founders of a Columbus-based start-up company, NeurXstem, to commercialize the brain organoid platform, and have applied for funding from the federal Small Business Technology Transfer program to accelerate its drug discovery applications.
Source: Ohio State University
Contact: Rene Anand
For more on stem cells and cloning, go to CellNEWS at