Ya-Hui Tsai, Shih-Hua Lee, Chia-Chi Weng, Yun Chen

Department of Surgery, Far Eastern Memorial Hospital, Taipei, Taiwan, Taiwan

Background: Ischemic preconditioning (IPC) had been reported to evidently lower the oxidative stress and inflammatory injury of ischemia-reperfusion (I/R) in liver, brain, and intestinal tissue. However, the role of intestinal stem cells on the regeneration of intestinal epithelial cells has never been investigated. Since the intestinal stem cells control the growth and recovery of intestine villi, we investigated the quantity of intestinal stem cells after IPC treatment and the repair function of these intestinal stem cells.

Materials and Methods: The intestine of B6 mice was treated with IPC by clamping the superior mesenteric artery for three times of 10 minutes and the intestinal tissue was collected 24, 48, and 72 hours later. After tissue fractionation, the quantity of stem cells within the crypt phase was indexed by the expression of stem cell markers, including Lgr5, Bmi1,  and Msi1 by real-time PCR and in situ hybridization. The repair ability of these intestinal stem cells has been investigated both in vitro and in vivo.

Results: When compared with the control mice with laparotomy only, the mice received IPC procedures showed significant increase of intestinal stem cells by up-regulating the expression of the intestinal stem cells markers Lgr5 and Bmi1 with a 55%- and 41%- increase, respectively. By in situ hybridization, expression of Lgr5 RNA was observed in great abundance at the crypt base evidently at the day1 after IPC procedure. Moreover, the ISCs harvested from IPC-treated mice displayed better repairing efficiency than the ISCs from control mice when seeded onto the mucosa-ablated intestine tissue in vitro and submucosa injection in vivo.

Conclusion: We demonstrated that IPC efficiently increases the quantity of intestinal stem cells and enhances their repair function. This is the first report demonstrating IPC positively correlated with the enrichment of intestinal stem cells, thus helping the recovery of intestinal villi.

Key words: ischemic preconditioning, intestinal stem cell, Lgr5, Bmi 1.