G. Brook

TGF-β1 and TGF-β2 expression after traumatic human spinal cord injury

Study design:Immunohistochemical investigation in control and lesioned human spinal cords.Objectives:To assess the spatial and temporal expression patterns of transforming growth factor-β1 and -β2 (TGF-β1 and TGF-β2) in the human spinal cord after traumatic injury.Setting:Germany, Aachen, Aachen University Hospital.Methods:Sections from human spinal cords from 4 control patients and from 14 patients who died at different time points after traumatic spinal cord injury (SCI) were investigated immunohistochemically.Results:In control cases, TGF-β1 was confined to occasional blood vessels, intravascular monocytes and some motoneurons, whereas TGF-β2 was only found in intravascular monocytes. After traumatic SCI, TGF-β1 immunoreactivity was dramatically upregulated by 2 days after injury (the earliest survival time investigated) and was detected within neurons, astrocytes and invading macrophages. The staining was most intense over the first weeks after injury but gradually declined by 1 year. TGF-β2 immunoreactivity was first detected 24 days after injury. It was located in macrophages and astrocytes and remained elevated for up to 1 year. In white matter tracts undergoing Wallerian degeneration, there was no induction of either isoform.Conclusion:The early induction of TGF-β1 at the point of SCI suggests a role in the acute inflammatory response and formation of the glial scar, while the later induction of TGF-β2 may indicate a role in the maintenance of the scar. Neither of these TGF-β isoforms appears to contribute to the astrocytic scar formation in nerve fibre tracts undergoing Wallerian degeneration.

Post-mortem assessment of rat spinal cord injury and white matter sparing using inversion recovery-supported proton density magnetic resonance imaging

Study design:This was an experimental study.Objectives:White matter sparing influences locomotor recovery after traumatic spinal cord injury (SCI). The objective of the present post-mortem magnetic resonance imaging (MRI) investigation was to assess the potential of a simple inversion recovery (IR) sequence in combination with high-resolution proton density (PD) images to selectively depict spared white matter after experimental SCI in the rat.Setting:This study was conducted at University of Liège and Centre Hospitalier Universitaire, Liège, Belgium and Hasselt University, Diepenbeek, Belgium.Methods:Post-mortem 9.4 tesla (T) MRI was obtained from five excised rat spines 2 months after compressive SCI. The locomotor recovery had been followed weekly using the standardized Basso–Beattie–Bresnahan scale. IR MRI was used to depict normal white matter as very hypo-intense. Preserved white matter, cord atrophy and lesion volume were assessed, and histology was used to confirm MRI data.Results:MRI showed lesion severity and white matter sparing in accordance with the degree of locomotor recovery. IR MRI enhanced detection of spared and injured white matter by selectively altering the signal of spared white matter. Even subtle white matter changes could be detected, increasing diagnostic accuracy as compared to PD alone. MRI accuracy was confirmed by histology.Conclusion:High-resolution IR-supported PD MRI provides useful micro-anatomical information about white matter damage and sparing in the post-mortem assessment of chronic rat SCI.