Age-related macular degeneration treated with a stem cell retinal patch

Researchers developed retinal eye patch made from human embryonic stem cells to treat age-related macular degeneration. Researchers grew retinal pigment epithelial cells from stem cells and used synthetic basement membrane to create a retinal patch. Phase 1 clinical trial findings are reported in the journal Nature Biotechnology.

Age-related macular degeneration is the most common cause of visual impairment in the developed world. This condition usually affects people over 50 years. Age-related macular degeneration affects central vision.

The phase 1 study investigated if the stem cell retinal patch could restore vision by regenerating diseased cells. They surgically implanted the patch into the eye of two subjects. Results showed noted improvement in vision over 12 months. Further testing using biomicroscopy and optical coherence tomography showed that stem cell retinal patch survived.  To prevent tissue rejection they had to use local immunosuppression.

“This study represents real progress in regenerative medicine and opens the door on new treatment options for people with age-related macular degeneration,” said co-author Peter Coffey, a professor at UCSB’s Neuroscience Research Institute and co-director of the campus’s Center for Stem Cell Biology & Engineering.

Reference: Cruz, Lyndon Da, Kate Fynes, Odysseas Georgiadis, Julie Kerby, Yvonne H. Luo, Ahmad Ahmado, Amanda Vernon, Julie T. Daniels, Britta Nommiste, Shazeen M. Hasan, Sakina B. Gooljar, Amanda-Jayne F. Carr, Anthony Vugler, Conor M. Ramsden, Magda Bictash, Mike Fenster, Juliette Steer, Tricia Harbinson, Anna Wilbrey, Adnan Tufail, Gang Feng, Mark Whitlock, Anthony G. Robson, Graham E. Holder, Mandeep S. Sagoo, Peter T. Loudon, Paul Whiting, and Peter J. Coffey. “Phase 1 Clinical Study of an Embryonic Stem Cell–derived Retinal Pigment Epithelium Patch in Age-related Macular Degeneration.” Nature Biotechnology, 2018. doi:10.1038/nbt.4114.

Institutions involved in research

  • The London Project to Cure Blindness, ORBIT, Institute of Ophthalmology, University College London (UCL).
  • NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust, UCL Institute of Ophthalmology.
  • Moorfields Eye Hospital NHS Foundation Trust.
  • Wellcome/EPSRC Centre for Interventional & Surgical Sciences (WEISS), Charles Bell House.
  • Pfizer.
  • Cell and Gene Therapy Catapult.
  • Cells for Sight, Transplantation & Research Program, UCL Institute of Ophthalmology.
  • UCL Institute of Neurology.
  • Center for Stem Cell Biology and Engineering, NRI, UC, Santa Barbara.

Adapted from press release by the University of California Santa Barbara.

New body-on-a-chip technology to advance pharmacological research

Researchers from MIT have developed “physiome on chip” technology that could be used to evaluate new drugs and detect side effects before the drugs are tested in human clinical trials. This could be used an alternative to animal testing for pharmacological testing before human clinical trials.

Body on a chip. Credit: Felice Frankel

They used a microfluidic platform that connects engineered tissues from ten different organs,. By doing so, the researchers were able to accurately replicate human organ interactions considerable periods at a time, allowing them to measure the effects of medication on different organs. This system is also well designed to test immunotherapy as the antibodies are unique to humans and could not be reliably tested in animals. This research is published in the journal Scientific Reports.

“Some of these effects are really hard to predict from animal models because the situations that lead to them are idiosyncratic,” says Linda Griffith, one of the senior authors of the study. “With our chip, you can distribute a drug and then look for the effects on other tissues and measure the exposure and how it is metabolized.”

Griffith believes that the immediate applications of this technology involve modeling  on fewer organ systems. Griffith’s lab is now developing a model system to investigate the role of the gut microbiome in Parkinson’s disease by creating body on chip that contains  brain, liver, and gastrointestinal tissue.

“An advantage of our platform is that we can scale it up or down and accommodate a lot of different configurations,” Griffith says. “I think the field is going to go through a transition where we start to get more information out of a three-organ or four-organ system, and it will start to become cost-competitive because the information you’re getting is so much more valuable.”

Citation: Edington, Collin D., Wen Li Kelly Chen, Emily Geishecker, Timothy Kassis, Luis R. Soenksen, Brij M. Bhushan, Duncan Freake, Jared Kirschner, Christian Maass, Nikolaos Tsamandouras, Jorge Valdez, Christi D. Cook, Tom Parent, Stephen Snyder, Jiajie Yu, Emily Suter, Michael Shockley, Jason Velazquez, Jeremy J. Velazquez, Linda Stockdale, Julia P. Papps, Iris Lee, Nicholas Vann, Mario Gamboa, Matthew E. Labarge, Zhe Zhong, Xin Wang, Laurie A. Boyer, Douglas A. Lauffenburger, Rebecca L. Carrier, Catherine Communal, Steven R. Tannenbaum, Cynthia L. Stokes, David J. Hughes, Gaurav Rohatgi, David L. Trumper, Murat Cirit, and Linda G. Griffith. “Interconnected Microphysiological Systems for Quantitative Biology and Pharmacology Studies.” Scientific Reports 8, no. 1 (2018). doi:10.1038/s41598-018-22749-0.

Research funding: U.S. Army Research Office and DARPA.

Adapted from press release by MIT.

Mutations play a significant role in skeletal muscle aging

A new study by researchers at Karolinska Institutet in Sweden who investigated mutations in muscle’s stem cells (satellite cells) shows how an unexpectedly high number of mutations which resulted in impaired cell regeneration leading to aging of skeletal muscles. The study is published in Nature Communications.

“What is most surprising is the high number of mutations. We have seen how a healthy 70-year-old has accumulated more than 1,000 mutations in each stem cell in the muscle, and that these mutations are not random but there are certain regions that are better protected,” explains Maria Eriksson, Professor at the Department of Biosciences and Nutrition at Karolinska Institutet.

The mutations occur during natural cell division, and the regions that are protected are those that are important for the function or survival of the cells. Nonetheless, the researchers were able to identify that this protection declines with age.

“We can demonstrate that this protection diminishes the older you become, indicating an impairment in the cell’s capacity to repair their DNA. And this is something we should be able to influence with new drugs,” explains Maria Eriksson.

“We achieved this in the skeletal muscle tissue, which is absolutely unique. We have also found that there is very little overlap of mutations, despite the cells being located close to each other, representing an extremely complex mutational burden,” explains the study’s first author, Irene Franco, Postdoc in Maria Eriksson’s research group.

The researchers will continue their work to find out if  physical activity influences number of accumulated mutations.

“We aim to discover whether it is possible to individually influence the burden of mutations. Our results may be beneficial for the development of exercise programmes, particularly those designed for an ageing population,” explains Maria Eriksson.

The researchers gained access to the muscle tissue used in the study via a close collaboration with clinical researchers, including Helene Fischer at the Unit for Clinical Physiology at Karolinska University Hospital.

Citation: Franco, Irene, Anna Johansson, Karl Olsson, Peter Vrtačnik, Pär Lundin, Hafdis T. Helgadottir, Malin Larsson, Gwladys Revêchon, Carla Bosia, Andrea Pagnani, Paolo Provero, Thomas Gustafsson, Helene Fischer, and Maria Eriksson. “Somatic mutagenesis in satellite cells associates with human skeletal muscle aging.” Nature Communications 9, no. 1 (2018). doi:10.1038/s41467-018-03244-6.

Research Funding: the Swedish Research Council, CIMED (Centre for Innovative Medicine), the David and Astrid Hagelén Foundation, the Swedish Society of Medicine, the Gun and Bertil Stohnes Foundation, the Osterman Foundation, the Marianne and Marcus Wallenberg Foundation, Wallenberg Advanced Bioinformatics Infrastructure and the EU Commission funding programme, Marie Skodowska-Curie

Adapted from press release by Karolinska Institutet.

Calorie restricted diet promotes intestinal regeneration after injury

Dramatic calorie restriction have long been known to boost healthy lifespan and reduce the risk of heart attack, diabetes and other age-related conditions. In animal studies it is shown to extend life span in most animal species examined. Further research has shown that animals fed restricted-calorie diets are also better able to regenerate numerous tissues after injury.

When mice were allowed to eat without limit and were then exposed to radiation, their intestinal cells’ (in red) regeneration was limited (left). Mice fed a calorie-restricted diet showed a greatly enhanced regenerative capacity in their intestinal tissue (right). Credit: University of Pennsylvania.

A new study led by University of Pennsylvania researchers pinpoints the cell responsible for these improved regenerative abilities in the intestines. According to the scientists’ work, when a calorie-restricted mouse is subjected to radiation, a particular type of stem cell in the intestines, known as reserve stem cells, can survive and quickly rebuild intestinal tissues. The findings align with observations by oncologists that short-term fasting prior to chemotherapy can mitigate the severity of gastrointestinal destruction.

Christopher Lengner, an associate professor in Penn’s School of Veterinary Medicine collaborated on the work with lead author Maryam Yousefi, a graduate student in the Cell and Molecular Biology program at Penn Medicine and a Howard Hughes Medical Institute International Student Fellow, and other colleagues from Penn and China Agricultural University. Their work appears in the journal Stem Cell Reports.

One theory has been that calorie restriction slows age-related degeneration and enables more efficient tissue function by influencing the integrity and activity of adult stem cells, the precursor cells that dwell within specific tissues and give rise to the diversity of cell types that compose that tissue.

In prior work, Lengner’s lab has studied how certain stem cells in the intestines resist DNA damage. Perhaps, the researchers reasoned, calorie restriction is somehow targeting these stem cells to enhance their ability to resist damage.

Recent studies focused on the effects of calorie restriction on the active intestinal stem cells. While these active stem cells bear the burden of daily tissue turnover and act as the workhorses of intestinal function, they are also known to be highly susceptible to DNA damage, such as that induced by radiation exposure, and thus are unlikely to be the cells mediating the enhanced regeneration seen under calorie restriction, the Penn team reasoned.

Instead of looking at these active stem cells, Lengner’s group examined a second population of intestinal stem cells known as reserve stem cells. Lengner’s group and others had previously shown that these reserve stem cells normally reside in a dormant state and are protected from chemotherapy and radiation. Upon a strong injury that kills the active cells, these reserve stem cells “wake up” to regenerate the tissue.

To investigate this hypothesis, the scientists focused on how a subpopulation of mouse intestinal stem cells responded under calorie restriction and then when the animals were exposed to radiation. When mice were fed a diet reduced in calories by 40 percent from normal, the researchers observed that reserve intestinal stem cells expanded five-fold. Paradoxically, these cells also seemed to divide less frequently, a mystery the researchers hope to follow up on in later work.

When the research team selectively deleted the reserve stem cells in calorie-restricted mice, their intestinal tissue’s regeneration capabilities were cut in half, implicating these cells as having an important role in carrying out the benefits of calorie restriction.

“These reserve stem cells are rare cells,” Lengner said. “In a normal animal they may make up less than half a percentage of the intestinal epithelium and in calorie restricted animals maybe slightly more. Normally, in the absence of injury, the tissue can tolerate the loss, due to the presence of the active stem cells, but, when you injure the animal, the regeneration is compromised and the enhanced regeneration after calorie restriction was compromised in the absence of the reserve stem cell pool.”

To tease out the mechanism by which these cells were acting, the researchers compared the genes that were turned on in normal versus calorie-restricted animals. “It was very obvious,” Lengner said. “These reserve stem cells that we had shown were important for the beneficial effects of calorie restriction, were repressing many pathways that are all known to be regulated by the protein complex mTOR, which is most well known as being a nutrient-sensing complex.”

The finding made intuitive sense; researchers studying other tissue types had shown that activating mTOR can drive dormant cells out of quiescence, a necessary step for regeneration. Here, researchers found that reserve stem cells had low mTOR activity, and this was even lower upon calorie restriction. Lower mTOR activity correlated with resistance to injury. Yet in order to regenerate after the injury was over, these cells would need mTOR again.

“Curiously, we see that, when they’re injured, the calorie-restricted mice were actually better able to activate mTOR than their counterparts,” Lengner said. “So somehow, even though mTOR is being suppressed initially, it’s also better poised to become activated after injury. That’s something we don’t fully understand.”

The researchers, led by Yousefi, conducted experiments using leucine, an amino acid that activates mTOR, and rapamycin, a drug -which inhibits mTOR, to confirm that mTOR acted within these reserve stem cells to regulate their activity. Reserve stem cells exposed to leucine proliferated, while those exposed to rapamycin were blocked.

Pretreating the animals with leucine make the reserve stem cells more sensitive to radiation and less able to regenerate tissue following radiation injury, while rapamycin protected the reserve stem cells as they were more likely to remain dormant.

Lengner cautions, however, that rapamycin cannot be used as a stand-in for calorie restriction, as it would linger and continue to block mTOR activation even following injury, hindering the ability of the reserve stem cells to spring into action and regenerate intestinal tissue.

In future work, the researchers hope to drill down deeper, looking beyond nutrient signaling to see what type of signaling molecules can modulate the activation of reserve stem cells.

doi: 10.1016/j.stemcr.2018.01.026

Research funding: Howard Hughes Medical Institute, National Natural Science Foundation of China, National Institute of Diabetes and Digestive and Kidney Diseases, National Cancer Institute, and Center for Molecular Studies in Digestive and Liver Diseases.

Adapted from press release by the University of Pennsylvania.

The role of PRC2 in controlling gene activity in human stem cells.

Researchers at the Babraham Institute have revealed a new understanding of the molecular switches that control gene activity in human embryonic stem cells.

In the developing embryo and during the specialisation of stem cells, the activity of genes must be tightly controlled so that the correct genes are switched on and off at the right time and in the right cells. One of the main ways that this process is regulated is by a protein complex called Polycomb Repressive Complex 2 (PRC2), which keeps genes switched off until they are needed. Earlier research showed that PRC2 is necessary for controlling gene activity during the development of the fruit fly and the mouse. Current research study focusses PRC2’s role in human embryonic stem cells.

As described in the journal Cell Reports, the researchers used the CRISPR gene editing technique to delete PRC2 from human embryonic stem cells. Loss of PRC2 caused the cells to switch on many genes that are not normally active in these cells. These changes led to the inability of embryonic stem cells lacking PRC2 to specialize correctly into mature cell types.

Dr Peter Rugg-Gunn, senior author on the research paper and research group leader at the Babraham Institute explained: “This work is exciting because it reveals that gene activity is controlled by similar molecular switches in human development as in other species such as the fly and mouse. We have also uncovered human-specific differences in the way that embryonic stem cells respond to genes being misregulated. These findings provide new insights into the development of our own species, and might enable new ways to turn embryonic stem cells into useful cell types, such as heart and pancreas, which can be used for cell-replacement therapies.”

References: Collinson, Adam, Amanda J. Collier, Natasha P. Morgan, Arnold R. Sienerth, Tamir Chandra, Simon Andrews, and Peter J. Rugg-Gunn. “Deletion of the Polycomb-Group Protein EZH2 Leads to Compromised Self-Renewal and Differentiation Defects in Human Embryonic Stem Cells.” Cell Reports 17, no. 10 (2016): 2700-714.
Research funding: The Wellcome Trust, Medical Research Council, Biotechnology and Biological Sciences Research Council.
Adapted from press release by Babraham Institute.

New bright-red fluorescent protein mScarlet to help with cellular staining

After years of trying, biologists have succeeded in creating an extremely bright red fluorescent protein in the lab. This is good news for researchers, including cancer and stem cell researchers, who use fluorescent proteins to track essential cellular processes. The researchers at the University of Amsterdam, the Institut de Biologie structurale and the European Synchrotron in Grenoble describe their approach in the latest edition of the journal Nature Methods.

Molecule structure protein mScarlet
Credit: Dr. Marten Postma, UvA
Professor of Molecular Cytology Dorus Gadella and doctoral researchers Daphne Bindels and Lindsay Haarbosch have succeeded in creating a spectacularly bright-red fluorescent protein. They have dubbed the protein mScarlet and expect it to be used by research groups across the world, for example to gain a better understanding of how disruption of cellular processes causes uncontrolled cell division found in cancer cells. 
The research group created mScarlet by comparing the genetic blueprints of a range of red fluorescent proteins from corals. They searched for sequences that consistently occurred in the various genetic codes since these apparently are indispensable. The group assembled these essential pieces of code and then had a company synthesise a complete DNA strand. They introduced that synthetic DNA into a bacterium, which converted it into a protein.

They assessed the brightness of each protein produced in this way under a microscope and then tinkered some more with the DNA code, observing how modifications affected the brightness. The entire process was a kind of lab-based evolutionary experiment which resulted in Gadella and his colleagues creating mScarlet, the protein with the highest brightness.

That brightness will serve cellular microscopy well as it ensures the visibility of the proteins studied by scientists. Moreover, mScarlet is an ideal illuminating agent as it does not affect the functioning of the proteins to which it is tagged.

In order to fully understand mScarlet, the biologists eventually sent their red creation to the Institut de Biologie Structurale in Grenoble. A team of researchers led by structural biologist Antoine Royant utilized the European Synchrotron Radiation Facility (ESRF), one of the most powerful particle accelerators in the world, to reveal the molecular structure of the protein. Royant: ‘We discovered that mScarlet’s bright fluorescence is due to fact that the chromophore, the part of the molecule that absorbs light and then emits red light, is held rigidly flat by the protein wrapped around it.’

Citation: “mScarlet: a bright monomeric red fluorescent protein for cellular imaging”. Daphne S Bindels, Lindsay Haarbosch, Laura van Weeren, Marten Postma, Katrin E Wiese, Marieke Mastop, Sylvain Aumonier, Guillaume Gotthard, Antoine Royant, Mark A Hink & Theodorus W J Gadella Jr. Nature Methods, 2016.
DOI: 10.1038/nmeth.4074
Adapted from press release by University of Amsterdam.

Parkinson disease treatment break through – using stem cells to develop dopaminergic neurons.

The first transplantation of stem cells in patients with Parkinson’s disease is almost within reach. However, it remains a challenge for researchers to control stem cells accurately in the lab in order to achieve successful and functional stem cell therapies for patients.

“In our preclinical assessments of stem cell-derived dopamine neurons we noticed that the outcome in animal models varied dramatically, even though the cells were very similar at the time of transplantation. This has been frustrating and puzzling, and has significantly delayed the establishment of clinical cell production protocols”, says Malin Parmar, who led the study conducted at Lund University as part of the EU network NeuroStemcellRepair.

The Lund experiments use modern global gene expression studies to better understand the path from a stem cell to a dopamine neuron. The data has been generated in close collaboration with a team of scientists at Karolinska Institute lead by Professor Thomas Perlmann, and is closely linked with a second study from the same cluster of scientists. The second study sheds new light on how dopamine neurons are formed during development, and what makes them different from other similar and neighbouring neurons.

This new insight has enabled a streamlined differentiation process resulting in pure populations of dopamine neurons of high quality.

We have identified a specific set of markers that correlate with high dopaminergic yield and graft function after transplantation in animal models of Parkinson’s disease. Guided by this information, we have developed a better and more accurate methods for producing dopamine cells for clinical use in a reproducible way, says first author Agnete Kirkeby.

The new results, published in two back-to-back articles in the leading journal in the field, Cell Stem Cell, propel stem cell therapy for Parkinson’s disease towards clinical application. The first transplants are expected to be only a few years away.

1. Predictive Markers Guide Differentiation to Improve Graft Outcome in Clinical Translation of hESC-Based Therapy for Parkinson’s Disease. Authors: Agnete Kirkeby, Sara Nolbrant,  Katarina Tiklova, Andreas Heuer, Nigel Kee, Tiago Cardoso1, Daniella Rylander Ottosson, Mariah J. Lelos, Pedro Rifes, Stephen B. Dunnett, Shane Grealish1, Thomas Perlmann, Malin Parmar.
Journal: Cell Stem Cell

2. Single-Cell Analysis Reveals a Close Relationship between Differentiating Dopamine and Subthalamic Nucleus Neuronal Lineages. Authors: Nigel Kee, Nikolaos Volakakis, Agnete Kirkeby, Lina Dahl, Helena Storvall, Sara Nolbrant, Laura Lahti, Åsa K. Björklund, Linda Gillberg, Eliza Joodmardi, Rickard Sandberg, Malin Parmar, Thomas Perlmann.
Journal: Cell Stem Cell

Adapted from press release from Lund University 

Biosafety studies of Hematopoietic Stem Cell Gene Therapy for Mucopolysaccharidosis I shows promise for human trials

Extensive biosafety studies of hematopoietic stem cell (HSC) gene therapy, intended to replace a protein that patients with the inherited disease mucopolysaccaridosis I (MPS I) cannot produce, support clinical testing of the stem cell-based gene addition approach in MPS I patients. Evidence derived from these studies not only indicates that the HSC gene therapy is safe and well tolerated in mice, but also that it can produce sufficient amounts of the missing protein to affect MPS I without harming a patient’s hematopoietic stem cells, according to an article in Human Gene Therapy.

The article entitled “Preclinical Testing of the Safety and Tolerability of Lentiviral Vector-Mediated Above-Normal Alpha-L-Iduronidase Expression in Murine and Human Hematopoietic Cells Using Toxicology and Biodistribution Good Laboratory Practice Studies  is part of a special joint issue on stem cell gene therapy in Human Gene Therapy and Stem Cells & Development guest edited by Luigi Naldini, MD, Scientific Director, San Raffaele Telethon Institute for Gene Therapy, Milan, Italy.

Ilaria Visigalli, Stefania Delai, Alessandra Biffi, Luigi Naldini and colleagues from San Raffaele Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, and Vita Salute San Raffaele University (Milan, Italy), Glaxo Smith Kline R&D (U.K.), Sanofi (Montpellier, France), and Royal Manchester Children’s Hospital (Manchester, U.K.), describe the lentiviral vector-based gene therapy approach they developed to deliver normal copies of the alpha-iduronidase (IDUA) gene, which contains a mutation in patients with MPS I, to HSCs. They assessed the safety of the HSC gene therapy method by studying the effects of IDUA gene transfer and production of the enzyme on human and mouse HSCs, and followed the modified HSCs and their progeny in treated mice.

“Members of this group have previously shown that lentiviral gene transfer into hematopoietic stem cells can serve as a platform for curative gene therapy of genetic diseases,” says Editor-in-Chief Terence R. Flotte, MD, Celia and Isaac Haidak Professor of Medical Education and Dean, Provost, and Executive Deputy Chancellor, University of Massachusetts Medical School, Worcester, MA. “This study sets the stage for a pivotal clinical trial to determine whether MPS I patients may also be successfully treated with this approach.”

Publication: Preclinical Testing of the Safety and Tolerability of Lentiviral Vector–Mediated Above-Normal Alpha-L-Iduronidase Expression in Murine and Human Hematopoietic Cells Using Toxicology and Biodistribution Good Laboratory Practice Studies.

Press release by Mary Ann Liebert, Inc., Publishers