Development of a murine model of blunt hepatic trauma.

Despite the prevalence of blunt hepatic trauma in humans, there are few rodent models of blunt trauma that can be used to study the associated inflammatory responses. We present a mouse model of blunt hepatic trauma that was created by using a cortical contusion device. Male mice were anesthetized with ketamine-xylazine-buprenorphine and placed in left lateral recumbency. A position of 2 mm ventral to the posterior axillary line and 5 mm caudal to the costal margin on the right side was targeted for impact. An impact velocity of 6 m/s and a piston depth of 12 mm produced a consistent pattern of hepatic injury with low mortality. All mice that recovered from anesthesia survived without complication for the length of the study. Mice were euthanized at various time points (n = 5 per group) until 7 d after injury for gross examination and collection of blood and peritoneal lavage fluids. Some mice were reanesthetized for serial monitoring of hepatic lesions via MRI. At 2 h after trauma, mice consistently displayed laceration, hematoma, and discoloration of the right lateral and caudate liver lobes, with intraabdominal hemorrhage but no other gross injuries. Blood and peritoneal lavage fluid were collected from all mice for cytokine analysis. At 2 h after trauma, there were significant increases in plasma IL10 as well as peritoneal lavage fluid IL6 and CXCL1/KC; however, these levels decreased within 24 h. At 7 d after trauma, the mice had regained body weight, and the hepatic lesions, which initially had increased in size during the first 48 h, had returned to their original size. In summary, this technique produced a reliable, low mortality, murine model that recreates features of blunt abdominal liver injury in human subjects with similar acute inflammatory response.