Cecal Slurry Injection in Neonatal and Adult Mice

Abstract

Studying the pathophysiology of sepsis still requires animal models, and the mouse remains the most commonly used species. Here we discuss the "cecal slurry" (CS) model of polymicrobial, peritoneal sepsis and compare and contrast it to other commonly used methods. Among the different murine models of sepsis, cecal ligation and puncture (CLP), and not the CS, is often considered the "gold standard" to induce polymicrobial sepsis in laboratory animals. CLP is a well-described model involving a simple surgical procedure that closely mimics the clinical course of intra-abdominal sepsis. However, CLP may not be an option for experiments involving newborn pups, where the cecum is indistinguishable from small bowel, where differences in microbiome content may affect the experiment, or where surgical procedures/anesthesia exposure needs to be limited. An important alternative method is the CS model, involving the intraperitoneal injection of cecal contents from a donor animal into the peritoneal cavity of a recipient animal to induce polymicrobial sepsis. Furthermore, CS is an effective alternative model of intraperitoneal polymicrobial sepsis in adult mice and can now be considered the "gold standard" for experiments in neonatal mice.

Keywords: Cecal slurry; Infection; Murine sepsis; Neonatal sepsis; Polymicrobial sepsis; Sepsis.

1.

Excised cecum aseptically collected from a mouse donor. Following euthanasia of the CS donor mouse, open the skin and localize the cecum at the junction of the ileum and the proximal colon. Excise the cecum and place it on a sterile disposable petri dish.

2.

Cecal slurry solution (80 mg/mL in 5% dextrose). Extrude the cecal contents out of the epithelium onto a pre-weighted conical polypropylene centrifuge tube, and prepare 80–100 mg/mL CS with dextrose 5%.

3.

Injection of 1.1 – 1.3 mg/g BW of cecal slurry into a 6-day-old B6 neonatal mouse. Secure the pup by the back of the neck and the lower back and inject the weight-adjusted dose of CS (1.1–1.3 mg/g BW), waiting 10 seconds to ensure that the correct CS dose is delivered.