Gas6 enhances axonal ensheathment by MBP+ membranous processes in human DRG/OL promyelinating co-cultures.
The molecular requirements for human myelination are incompletely defined, and further study is needed to fully understand the cellular mechanisms involved during development and in demyelinating diseases. We have established a human co-culture model to study myelination. Our earlier observations showed that addition of human γ-carboxylated growth-arrest-specific protein 6 (Gas6) to human oligodendrocyte progenitor cell (OPC) cultures enhanced their survival and maturation. Therefore, we explored the effect of Gas6 in co-cultures of enriched OPCs plated on axons of human fetal dorsal root ganglia explant. Gas6 significantly enhanced the number of myelin basic protein-positive (MBP+) oligodendrocytes with membranous processes parallel with and ensheathing axons relative to co-cultures maintained in defined medium only for 14 days. Gas6 did not increase the overall number of MBP+ oligodendrocytes/culture; however, it significantly increased the length of MBP+ oligodendrocyte processes in contact with and wrapping axons. Multiple oligodendrocytes were in contact with a single axon, and several processes from one oligodendrocyte made contact with one or multiple axons. Electron microscopy supported confocal Z-series microscopy demonstrating axonal ensheathment by MBP+ oligodendrocyte membranous processes in Gas6-treated co-cultures. Contacts between the axonal and oligodendrocyte membranes were evident and multiple wraps of oligodendrocyte membrane around the axon were visible supporting a model system in which to study events in human myelination and aspects of non-compact myelin formation.
*Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue Bronx, NY 10461, U.S.A.
Kathleen N
KN
O'Guin
*Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue Bronx, NY 10461, U.S.A.
Ross C
RC
Gruber
*Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue Bronx, NY 10461, U.S.A.
Cedric S
CS
Raine
†Analytical Imaging Facility, Albert Einstein College of Medicine, 1300 Morris Park Avenue Bronx, NY 10461, U.S.A.
Hillary M
HM
Guzik
*Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue Bronx, NY 10461, U.S.A.
Bradford K
BK
Poulos
*Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue Bronx, NY 10461, U.S.A.
Bridget
B
Shafit-Zagardo
D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D018920:Coculture Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D005727:Ganglia, Spinal / Q000648:ultrastructure; D006801:Humans; D020287:In Situ Nick-End Labeling; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D004676:Myelin Basic Protein / Q000378:metabolism*; D009186:Myelin Sheath; D009836:Oligodendroglia / Q000378:metabolism / Q000648:ultrastructure*; D000099255:Growth Arrest-Specific Protein 6
D036341:Intercellular Signaling Peptides and Proteins; D004676:Myelin Basic Protein; D000099255:Growth Arrest-Specific Protein 6