Abstract
Chronic spinal cord compression is the most common cause of spinal cord impairment worldwide. Objective of this study is to assess the ultrastructural features of the neurovascular unit (NVU) in a rat model of chronic compressive spinal cord injury, 24 SD rats were divided into two groups: the control group (n = 12), and the compression group (n = 12). A C6 semi-laminectomy was performed in the control group, whereas a water-absorbent polyurethane polymer was implanted into the C6 epidural space in the compression group. The Basso Beattie Bresnahan (BBB) scores and the somatosensory evoked potentials (SEP) were used to evaluate neurological functions. Transmission Electron Microscopy (TEM) was performed to investigate the change of NVU at the 28th day after modeling. Compared with the control group, the compression group shows a significant reduction (P < 0.05) of BBB score and a significant severity (P < 0.05) of abnormal SEP. TEM results of the compression group showed a striking increase in endothelial caveolae and vacuoles; a number of small spaces in tight junctions; a significant increase in pericyte processing area and vessel coverage; an expansion of the basement membrane region; swollen astrocyte endfeet and mitochondria; and the degeneration of neurons and axons. Our study revealed that damage to NVU components occurred followed by chronic compressive spinal cord injury. Several compensatory changes characterized by thicker endothelium, expansive BM, increased pericyte processing area and vessel coverage were also observed.
Highlights
Chronic spinal cord compression is the most common cause of spinal cord impairment worldwide
Focusing on neurovascular units is becoming a prerequisite for investigating the physiology and pathology of the central nervous system (CNS), contributing to discovery of therapeutic targets and drug candidates (Muoio et al, 2014)
The normal physiological function of the spinal cord depends on the integrity of neurovascular unit (NVU) and the regular interactions among various CNS cells
Summary
Chronic spinal cord compression is the most common cause of spinal cord impairment worldwide. Cervical spondylosis myelopathy is characterized by progressive stenosis of the cervical canal and compression of the spinal cord due to the herniated cervical discs and degenerative changes. The neurovascular unit (NVU) is a specialized structure comprised of vascular endothelium, pericytes, astrocytes, neurons, and, in a broader context, the extracellular matrix (Muoio et al, 2014). This structure plays a crucial role in maintaining normal homeostasis in the spinal parenchyma, and serves as an important defense during chronic compression and other pathologies (Muoio et al, 2014). Assessing the ultrastructure features of NVU in the chronic compressive segment of the cervical cord could help to clarify interactions among various components of the unit and to determine which structural change is responsible for the high permeability and functional neural deficits, and could possibly shed light on new and inclusive therapies for chronic spinal cord injury diseases
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