Paul J. Tesar | |
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| Born | Cleveland, Ohio, US |
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| Website | tesarlab |
Paul J. Tesar is an American developmental biologist. He is the Dr. Donald and Ruth Weber Goodman Professor of Innovative Therapeutics at Case Western Reserve University School of Medicine. His research is focused on regenerative medicine.
Tesar was born in Cleveland, Ohio. [7] He graduated with a BSc in biology from Case Western Reserve University in 2003. As part of the National Institutes of Health Oxford-Cambridge Scholar Program, he earned a PhD in 2007. [8]
While a graduate student, Tesar published a paper describing epiblast-derived stem cells, a new type of pluripotent stem cell, [1] research for which he received both the Beddington Medal of the British Society for Developmental Biology [5] and the Harold M. Weintraub Award of the Fred Hutchinson Cancer Research Center. [9]
In 2010 he returned to Case Western Reserve University School of Medicine to teach. [10] In 2014 he was appointed to the Dr. Donald and Ruth Weber Goodman chair in innovative therapeutics. [11]
Tesar developed methods to generate and grow oligodendrocytes and oligodendrocyte progenitor cells (OPCs) from pluripotent stem cells and skin cells. [12] [13] He also made human brain organoids containing human myelin, called oligocortical spheroids. [14] [15] Tesar identified drugs that stimulate myelin regeneration and reverse paralysis in mice with multiple sclerosis. [16] Tesar also identified CRISPR and antisense oligonucleotide therapeutics that restored myelination and extended the lifespan of mice with Pelizaeus–Merzbacher disease. [17] [18] [19]
In vertebrates, most neuronal cell axons are encased in myelin. Simply put, myelin insulates axons and increases the rate at which electrical impulses are passed along the axon. The myelinated axon can be likened to an electrical wire with insulating material (myelin) around it. However, unlike the plastic covering on an electrical wire, myelin does not form a single long sheath over the entire length of the axon. Rather, myelin ensheaths the axon in segments: in general, each axon is encased in multiple long myelin sheaths separated by short gaps called nodes of Ranvier.
Pelizaeus–Merzbacher disease is an X-linked neurological disorder that damages oligodendrocytes in the central nervous system. It is caused by mutations in proteolipid protein 1 (PLP1), a major myelin protein. It is characterized by a decrease in the amount of insulating myelin surrounding the nerves (hypomyelination) and belongs to a group of genetic diseases referred to as leukodystrophies.
Oligodendrocytes, also known as oligodendroglia, are a type of neuroglia whose main functions are to provide support and insulation to axons within the central nervous system (CNS) of jawed vertebrates. Their function is similar to that of Schwann cells, which perform the same task in the peripheral nervous system (PNS). Oligodendrocytes accomplish this by forming the myelin sheath around axons. Unlike Schwann cells, a single oligodendrocyte can extend its processes to cover around 50 axons, with each axon being wrapped in approximately 1 μm of myelin sheath. Furthermore, an oligodendrocyte can provide myelin segments for multiple adjacent axons.
Glia, also called glial cells(gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. The neuroglia make up more than one half the volume of neural tissue in our body. They maintain homeostasis, form myelin in the peripheral nervous system, and provide support and protection for neurons. In the central nervous system, glial cells include oligodendrocytes, astrocytes, ependymal cells and microglia, and in the peripheral nervous system they include Schwann cells and satellite cells.
A demyelinating disease refers to any disease affecting the nervous system where the myelin sheath surrounding neurons is damaged. This damage disrupts the transmission of signals through the affected nerves, resulting in a decrease in their conduction ability. Consequently, this reduction in conduction can lead to deficiencies in sensation, movement, cognition, or other functions depending on the nerves affected.
Antisense therapy is a form of treatment that uses antisense oligonucleotides (ASOs) to target messenger RNA (mRNA). ASOs are capable of altering mRNA expression through a variety of mechanisms, including ribonuclease H mediated decay of the pre-mRNA, direct steric blockage, and exon content modulation through splicing site binding on pre-mRNA. Several ASOs have been approved in the United States, the European Union, and elsewhere.
Leukodystrophies are a group of, usually, inherited disorders, characterized by degeneration of the white matter in the brain. The word leukodystrophy comes from the Greek roots leuko, "white", dys, "abnormal" and troph, "growth". The leukodystrophies are caused by imperfect growth or development of the glial cells which produce the myelin sheath, the fatty insulating covering around nerve fibers. Leukodystrophies may be classified as hypomyelinating or demyelinating diseases, respectively, depending on whether the damage is present before birth or occurs after. Other demyelinating diseases are usually not congenital and have a toxic or autoimmune cause.
Oligodendrocyte progenitor cells (OPCs), also known as oligodendrocyte precursor cells, NG2-glia, O2A cells, or polydendrocytes, are a subtype of glia in the central nervous system named for their essential role as precursors to oligodendrocytes. They are typically identified in the human by co-expression of PDGFRA and CSPG4.
Multiple sclerosis and other demyelinating diseases of the central nervous system (CNS) produce lesions and glial scars or scleroses. They present different shapes and histological findings according to the underlying condition that produces them.
Remyelination is the process of propagating oligodendrocyte precursor cells to form oligodendrocytes to create new myelin sheaths on demyelinated axons in the CNS. This is a process naturally regulated in the body and tends to be very efficient in a healthy CNS. The process creates a thinner myelin sheath than normal, but it helps to protect the axon from further damage, from overall degeneration, and proves to increase conductance once again. The processes underlying remyelination are under investigation in the hope of finding treatments for demyelinating diseases, such as multiple sclerosis.
Myelin-associated glycoprotein is a type 1 transmembrane protein glycoprotein localized in periaxonal Schwann cell and oligodendrocyte membranes, where it plays a role in glial-axonal interactions. MAG is a member of the SIGLEC family of proteins and is a functional ligand of the NOGO-66 receptor, NgR. MAG is believed to be involved in myelination during nerve regeneration in the PNS and is vital for the long-term survival of the myelinated axons following myelinogenesis. In the CNS MAG is one of three main myelin-associated inhibitors of axonal regeneration after injury, making it an important protein for future research on neurogenesis in the CNS.
A galactosylceramide, or galactocerebroside is a type of cerebroside consisting of a ceramide with a galactose residue at the 1-hydroxyl moiety.
Proteolipid protein 1 (PLP1) is a form of myelin proteolipid protein (PLP). Mutations in PLP1 are associated with Pelizaeus–Merzbacher disease. It is a 4 transmembrane domain protein which is proposed to bind other copies of itself on the extracellular side of the membrane. In a myelin sheath, as the layers of myelin wraps come together, PLP will bind itself and tightly hold the cellular membranes together.
Myelinogenesis is the formation and development of myelin sheaths in the nervous system, typically initiated in late prenatal neurodevelopment and continuing throughout postnatal development. Myelinogenesis continues throughout the lifespan to support learning and memory via neural circuit plasticity as well as remyelination following injury. Successful myelination of axons increases action potential speed by enabling saltatory conduction, which is essential for timely signal conduction between spatially separate brain regions, as well as provides metabolic support to neurons.
Gap junction gamma-2 (GJC2), also known as connexin-46.6 (Cx46.6) and connexin-47 (Cx47) and gap junction alpha-12 (GJA12), is a protein that in humans is encoded by the GJC2 gene.
Endogenous regeneration in the brain is the ability of cells to engage in the repair and regeneration process. While the brain has a limited capacity for regeneration, endogenous neural stem cells, as well as numerous pro-regenerative molecules, can participate in replacing and repairing damaged or diseased neurons and glial cells. Another benefit that can be achieved by using endogenous regeneration could be avoiding an immune response from the host.
MOG antibody disease (MOGAD) or MOG antibody-associated encephalomyelitis (MOG-EM) is an inflammatory demyelinating disease of the central nervous system. Serum anti-myelin oligodendrocyte glycoprotein antibodies are present in up to half of patients with an acquired demyelinating syndrome and have been described in association with a range of phenotypic presentations, including acute disseminated encephalomyelitis, optic neuritis, transverse myelitis, and neuromyelitis optica.
David Rowitch, FMedSci, FRS is an American physician-scientist known for his contributions to developmental glial biology and treatment of white matter diseases. He heads the Department of Paediatrics at the University of Cambridge and is an adjunct professor of pediatrics at the University of California San Francisco (UCSF).
Valentina Fossati is an Italian stem cell biologist. She is a Senior Research Investigator at the New York Stem Cell Foundation. Her research is focused on developing human stem cell-based models to study the role of glia in neurodegeneration and neuroinflammation.
Myelinoids or myelin organoids are three dimensional in vitro cultured model derived from human pluripotent stem cells (hPSCs) that represent various brain regions, spinal cord or the peripheral nervous system in early fetal human development. They have the capacity to recapitulate aspects of brain developmental processes, microenvironments, cell to cell interaction, structural organization and cellular composition. The differentiating aspect dictating whether an organoid is deemed a cerebral organoid/brain organoid or myelinoid is the presence of myelination and compact myelin formation that is a defining feature of myelinoids. Due to the complex nature of the human brain, there is a need for model systems which can closely mimic complicated biological processes. Myelinoids provide a unique in vitro model through which myelin pathology, neurodegenerative diseases, developmental processes and therapeutic screening can be accomplished.
Their research was published online July 1 in the journal Nature. "The pre-clinical results were profound. PMD mouse models that typically die within a few weeks of birth were able to live a full lifespan after treatment," said Paul Tesar
