myelin

Researchers at Case Western Reserve University School of Medicine have developed a cutting-edge laboratory technique able to turn human stem cells – special cells able to grow into any type of cell in the body – into brain-like tissues in a culture dish. They intend to use their tool to study how myelination – the deposition of myelin around nerve cells – occurs in the central nervous system, and how diseases such as multiple sclerosis (MS) impair this process. The experimental protocol to grow these structures outside an organis) is described in the study, "Induction of myelinating oligodendrocytes in human cortical spheroids," published in the journal Nature Methods. These structures, called “oligocortical spheroids,” are small spheres that contain all the major cell types usually found in the human brain, including oligodendrocytes — cells that produce myelin, which is the fatty substance that insulates nerve fibers. Previous cerebral organoid techniques failed to include oligodendrocytes. “We have taken the organoid system and added the third major cell type in the central nervous system — oligodendrocytes — and now have a more accurate representation of cellular interactions that occur during human brain development,” Paul Tesar, PhD, associate professor of genetics and genome sciences at Case Western's medical school and the study's senior author, said in a press release. Oligodendrocytes are essential to good brain health. Without these cells, myelin production is hampered and nerve cells cannot communicate effectively, and eventually they start to deteriorate. This is the starting point for many neurological disorders caused by myelin defects, including MS and rare pediatric genetic disorders like Gaucher disease. Using this new organoid system and these myelin-producing cells, researchers intend to study the process of myelination — how it occurs in normal circumstances and how neurodegenerative diseases disrupt this process. “This is a powerful platform to understand human development and neurological disease,” Tesar said. “Using stem cell technology we can generate nearly unlimited quantities of human brain-like tissue in the lab. Our method creates a ‘mini-cortex,’ containing neurons, astrocytes, and now oligodendrocytes producing myelin. This is a major step toward unlocking stages of human brain development that previously were inaccessible.” Researchers not only demonstrated that they were capable of generating mature oligodendrocytes derived from human stem cells in vitro, but they also showed these cells were able to exert their function and produce myelin starting at week 20 in a culture dish. Their improved organoid system could also be used to test the effectiveness of potential myelin-enhancing treatments. “These organoids provide a way to predict the safety and efficacy of new myelin therapeutics on human brain-like tissue in the laboratory prior to clinical testing in humans,” said Mayur Madhavan, PhD, co-first author on the study. To prove this point, researchers treated organoids with promyelinating compounds known to enhance myelin production in mice, and measured the rate and extent of oligodendrocyte generation and myelination. Under normal conditions, adding promyelinating drugs to cultured organoids increased the rate and extent of oligodendrocyte generation and myelin production, the team reported. But results differed in important ways using diseased organoids.  Specifically, treating organoids generated from patients with Pelizaeus-Merzbacher disease — a fatal genetic myelin disorder — brought an in vitro recapitulation of the patients' symptoms. “Pelizaeus-Merzbacher disease has been a complicated disorder to study due to the many different mutations that can cause it and the inaccessibility of patient brain tissue,” said Zachary Nevin, PhD, co-first author on the study. “But these new organoids allow us to directly study brain-like tissue from many patients simultaneously and test potential therapies.” Altogether, these findings demonstrate that oligocortical spheroids could be a versatile in vitro system to study how myelination occurs in the central nervous system, and a possible model for testing new therapies for neurodegenerative disorders. “Our method enables generation of human brain tissue in the laboratory from any patient,” Tesar said. “More broadly, it can accurately recapitulate how the human nervous system is built and identify what goes wrong in certain neurological conditions.”

Activation of the immune response mediated by cells called microglia favors remyelination and myelin repair in multiple sclerosis (MS), according to a new Canadian study using mice. The research, “mCSF-Induced Microglial Activation Prevents Myelin Loss and Promotes Its Repair in a Mouse Model of Multiple Sclerosis,” was…

A better understanding of the processes behind a continual and healthy renewal of myelin — the fatty, protective substance wrapping nerve cell fibers — may now exist. Researchers identified an enzyme, called PRMT5, that they believe regulates the number of myelin-producing cells in the brain and spinal cord. Their discovery…

Researchers have unveiled a new cell death mechanism called pyroptosis — also known as “fiery death” — as a main factor driving neurodegeneration and loss of myelin in people with multiple sclerosis (MS). An inhibitor of pyroptosis, currently undergoing testing in human clinical trials for epilepsy, decreased central nervous system inflammation…

Infection with lymphocytic choriomeningitis virus triggers expression of a factor called TOX in immune cells strengthening their migration into the brain and promoting damaging effects, including inflammation and tissue destruction. These findings represent a new piece of the puzzle about the mechanism underlying autoimmune diseases  like multiple sclerosis (MS).

A molecule responsible for preventing the repair of white matter in the brain, a process critical to treating multiple sclerosis (MS) and cerebral palsy, has been identified. The research, “A TLR/AKT/FoxO3 immune-tolerance like pathway disrupts the repair capacity of oligodendrocyte progenitors,” was published in The Journal…

Emerald Health‘s investigational cannabidiol-derived EHP-101 reduces neuroinflammation, the risk of loss of myelin, and nerve cell damage in two mouse models of multiple sclerosis (MS), a new study shows. These results support the potential therapeutic benefits of EHP-101 for MS, and Emerald Health Pharmaceuticals expects to launch a human…

One way the body may protect itself from nerve cell inflammation is to have cells in the blood-brain barrier increase their production of a protein that keeps immune cells from entering the brain, researchers in Germany and Canada report. The finding suggests that scientists could develop a multiple sclerosis therapy around the protein, known as EGFL7. It would work by preventing as many inflammation-generating immune cells from entering the brain. The underlying trigger for MS is immune cells crossing the blood-brain barrier to invade the central nervous system (CNS). The barrier is a selective membrane that shields the CNS from general blood circulation. Therapies that prevent immune cells from entering the brain can help control the disease, studies have shown. They include Tysabri (natalizumab, marketed by Biogen). But “as with other highly effective disease-modifying therapies which influence a broad range of peripheral immune cells, potential devastating adverse events limit the use of this therapy as a first-line agent,” the researchers wrote. The team at Mainz University Medical Center in Germany and the University of Montreal wondered if epidermal growth factor-like protein 7 (EGFL7) could prevent the brain inflammation in MS.  Although scientists had not previously linked it to MS, it was shown to regulate the migration of immune cells into breast cancer tumors. The CNS response to the chronic inflammation seen in MS patients and a mouse model of the disease was to increase EGFL7 in the blood-brain barrier, the researchers found. Researchers said the increase prevented pro-inflammatory immune cells from crossing into the CNS. Endothelial cells that line blood capillaries in the blood-brain barrier are the ones that secrete EGFL7. “We postulate that EGFL7 upregulation by BBB-ECs [brain blood barrier-endothelial cells] is induced as a compensatory mechanism to promote survival and recovery of BBB function in neuroinflammatory conditions,” the team wrote. Researchers then tested what happened in mice that lacked EGFL7. They found that the mice developed MS earlier and that their blood-brain barrier membrane was less efficient at keeping immune cells out. Treatment with EGFL7 improved the disease severity in the MS mice and tightened the blood-brain barrier, they said. “In light of our findings, smaller EGFL7 agonists, in development for other diseases, could therefore constitute an appealing therapeutic avenue for MS,” the team concluded.

University at Buffalo researchers are working on ways to improve multiple sclerosis patients’ cognitive function and to repair damage to the mylein coating that protects nerve cells. The National Multiple Sclerosis Society awarded the researchers more than $1.1 million to conduct the studies. One, “The Effects of Working Memory…

Clene Nanomedicine says its pre-clinical studies demonstrate the remyelination effects of CNM-Au8, supporting its potential to treat multiple sclerosis (MS) and other demyelinating disorders. Clene presented its data in a session, “Nanocrystalline Gold As a Novel Remyelination Therapeutic for Multiple Sclerosis,” that took place at the third annual Americas…