Three-Dimensional Changes in Cervical Spinal Cord Microvasculature During the Chronic Phase of Hemicontusion Spinal Cord Injury in Rats

BACKGROUND: The angioarchitecture of the spinal cord and microvascular changes after acute and subacute spinal cord injury ( SCI) have been reported in rodents. Microvascular changes after chronic SCI have not been explored. We characterized three-dimensional microvascular changes during the chronic phase of cervical hemicontusion SCI in rats. METHODS: At 12 weeks after 1.2-mm hemicontusion injury, microvascular parameters, including vascular volume, ratio of vascular volume to tissue volume, vascular number, and vascular separation, were measured at the epicenter and each cord segment, and the percentage and volume of spinal vessels with different diameters were measured by micro computed tomography at the injury segment. RESULTS: The 1.2-mm hemicontusion injury applied a compressive force of 1.050 +/- 0.103 N to the cord, resulting in a cavity and a significant decrease in microvasculature at the epicenter. The vascular volume, ratio of vascular volume to tissue volume, and vascular number of the C5 cord decreased by 40%, 38%, and 36% at 12 weeks after SCI, whereas vascular separation increased by 54% compared with the control group. In the chronic phase after SCI, the percentage and volume of spinal microvessels at the contusion segment decreased significantly (especially vessels with diameters <40 mu m). CONCLUSIONS: Blood supply to the cervical spinal cord is insufficient during the chronic phase of cervical hemicontusion SCI, especially in microvessels with diameters < 40 mu m. These results may provide a basis to explore microvascular changes of SCI during the chronic phase.