Characterization of the microvascular glycocalyx in normal and injured spinal cord in the rat.

The glycocalyx of microvasculature in normal and injured spinal cord was characterized by using cationized ferritin to define anionic sites and the lectins concanavalin agglutinin (Con A) and Ricinus communis agglutinin I (RCA) to delineate carbohydrate moities. Binding of cationized ferritin was evaluated at the ultrastructural level in control animals and at 3 hours after spinal cord injury. Horseradish peroxidase (HRP) was administered intravenously before euthanasia. In control spinal cord, there was continuous even binding of cationized ferritin along the luminal front of microvasculature and no evidence of barrier permeability to HRP. After spinal cord injury, there was a reduction in binding of cationized ferritin in those regions of spinal cord that exhibited barrier breakdown to HRP. Lectin binding in the spinal cord was evaluated at 3 hours and 3 days postinjury. At the light microscopic level, there appeared to be increased binding of Con A and RCA in microvessels by 3 days postinjury as compared with the control spinal cord. At the ultrastructural level, a significant increase in RCA binding was noted along luminal fronts in the injured spinal cord. This increased binding coincided with a significant elaboration of the endothelial glycocalyx. These findings demonstrate that the charge, structure, and carbohydrate composition of the endothelial glycocalyx in microvessels in the spinal cord may be dramatically altered after spinal cord injury. Furthermore, there is an association between the loss of charge and disruption of the barrier, suggesting that anionic sites may contribute to maintenance of the blood-spinal cord barrier.