Assessment of hepatic inflammation after spinal cord injury using intravital microscopy

Objectives: The liver has been shown to play a particularly important role in the initiation and progression of the early systemic inflammatory response (SIR) to spinal cord injury (SCI). The purpose of this study was to determine the time course of leucocyte recruitment to the liver, and to determine the effect of injury severity on the magnitude of leucocyte recruitment and hepatic injury.

Methods: Rats were randomly assigned to one of the following groups: uninjured, sham-injured (laminectomy and no cord injury), cord compressed or cord transected. At 30 min and 90 min after SCI rats had the left lobe of their livers externalised and visualised using intravital video microscopy.

Results: Thirty minutes after injury the total number of leucocytes per post-sinusoidal venule was significantly increased after cord transection compared to that in uninjured and sham-injured rats (P<0.05). Of these leucocytes, significantly more were adherent to venule walls (P<0.05). At 90 min the total number of leucocytes per post-sinusoidal venule and the number of adherent and rolling leucocytes was significantly increased after cord transection and cord compression (P<0.05).

Discussion: This is the first study to use intravital microscopy to visualise systemic inflammation in the liver following SCI. We have demonstrated immediate leucocyte recruitment to the liver within 30 min after injury and have shown that systemic inflammation increases with time after injury and with severity of injury.