title: Mesenchymal Stromal Cells Promote Axonal Outgrowth Alone and Synergistically with Astrocytes via tPA.
abstract: We reported that mesenchymal stromal cells (MSCs) enhance neurological recovery from experimental stroke and increase tissue plasminogen activator (tPA) expression in astrocytes. Here, we investigate mechanisms by which tPA mediates MSC enhanced axonal outgrowth. Primary murine neurons and astrocytes were isolated from wild-type (WT) and tPA-knockout (KO) cortices of embryos. Mouse MSCs (WT) were purchased from Cognate Inc. Neurons (WT or KO) were seeded in soma side of Xona microfluidic chambers, and astrocytes (WT or KO) and/or MSCs in axon side. The chambers were cultured as usual (normoxia) or subjected to oxygen deprivation. Primary neurons (seeded in plates) were co-cultured with astrocytes and/or MSCs (in inserts) for Western blot. In chambers, WT axons grew significantly longer than KO axons and exogenous tPA enhanced axonal outgrowth. MSCs increased WT axonal outgrowth alone and synergistically with WT astrocytes at both normoxia and oxygen deprivation conditions. The synergistic effect was inhibited by U0126, an ERK inhibitor, and receptor associated protein (RAP), a low density lipoprotein receptor related protein 1 (LRP1) ligand antagonist. However, MSCs exerted neither individual nor synergistic effects on KO axonal outgrowth. Western blot showed that MSCs promoted astrocytic tPA expression and increased neuronal tPA alone and synergistically with astrocytes. Also, MSCs activated neuronal ERK alone and synergistically with astrocytes, which was inhibited by RAP. We conclude: (1) MSCs promote axonal outgrowth via neuronal tPA and synergistically with astrocytic tPA; (2) neuronal tPA is critical to observe the synergistic effect of MSC and astrocytes on axonal outgrowth; and (3) tPA mediates MSC treatment-induced axonal outgrowth through the LRP1 receptor and ERK.
authors.affiliation: Department of Neurology, Henry Ford Hospital, Detroit, Michigan, United States of America.
authors.forename: Jian-Yong
authors.initials: JY
authors.lastname: Qian
authors.affiliation: Department of Neurology, Henry Ford Hospital, Detroit, Michigan, United States of America.|Department of Physics, Oakland University, Rochester, Michigan, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
authors.affiliation: Department of Neurology, Henry Ford Hospital, Detroit, Michigan, United States of America.
authors.forename: Zhongwu
authors.identifier: http://orcid.org/0000-0002-8571-8112
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism; D001369:Axons / Q000378:metabolism*; D002070:Butadienes / Q000737:chemistry; D018920:Coculture Techniques; D004791:Enzyme Inhibitors / Q000737:chemistry; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D044085:Microfluidics; D016501:Neurites / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009570:Nitriles / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism; D020521:Stroke / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; D010959:Tissue Plasminogen Activator; D010100:Oxygen