Development of techniques for time-lapse imaging of the dynamics of glial-axonal interactions in the central nervous system

Ioannidou, Kalliopi (2012) Development of techniques for time-lapse imaging of the dynamics of glial-axonal interactions in the central nervous system. PhD thesis, University of Glasgow.

Abstract

Background: Myelination is an exquisite and dynamic example of heterologous cell-cell interaction, which consists of the concentric wrapping of multiple layers of oligodendrocyte membrane around neuronal axons. Understanding the mechanism by which oligodendrocytes ensheath axons may bring us closer to designing strategies to promote remyelination in demyelinating diseases. The main aim of this study was to follow glial-axonal interactions over time both in vitro and ex vivo to visualise the various stages of myelination.

Methodology/Principal findings: Two approaches have been taken to follow myelination over time i) time-lapse imaging of mixed CNS myelinating cultures generated from mouse spinal cord to which exogenous GFP-labelled murine cells were added, and ii) ex vivo imaging of the spinal cord of shiverer (Mbp mutant) mice, transplanted with GFP-labelled murine neurospheres. The data demonstrate that oligodendrocyte-axonal interactions are dynamic events with continuous retraction and extension of oligodendroglial processes. Using cytoplasmic and membrane-GFP labelled cells to examine different components of the myelin-like sheath, evidence from time-lapse fluorescence microscopy and confocal microscopy suggest that the oligodendrocytes’ cytoplasm-filled processes initially spiral around the axon in a corkscrew-like manner. This is followed subsequently by focal expansion of the corkscrew process to form short cuffs which then extend longitudinally along the axons. From this model it is predicted that these spiral cuffs must extend over each other first before extending to form internodes of myelin.

Conclusion: These experiments show the feasibility of visualising the dynamics of glial-axonal interaction during myelination over time. Moreover, these approaches complement each other with the in vitro approach allowing visualisation of an entire internodal length of myelin and the ex vivo approach validating the in vitro data.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Part of this thesis has been published in PLoS ONE.
• Keywords: Myelination, Oligodendrocytes, Axonal ensheathment, Time-Lapse, Glial-Axonal interactions
• Subjects: R Medicine > R Medicine (General); Q Science > Q Science (General)
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Supervisor's Name: Barnett, Prof. Susan and Edgar, Dr. Julia
• Date of Award: 2012
• Depositing User: Miss Kalliopi Ioannidou
• Unique ID: glathesis:2012-3435
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 08 Jun 2012
• Last Modified: 10 Dec 2012 14:07
• URI: https://theses.gla.ac.uk/id/eprint/3435