fluid-borne hepatocyte growth factor protects rat pups against experimental necrotizing enterocolitis. Am J Physiol Gastrointest Liver Physiol 306: G361-G369, 2014. First published January 9, 2014; doi:10.1152/ajpgi.00272.2013.-Fetal swallowing of amniotic fluid, which contains numerous cytokines and growth factors, plays a key role in gut mucosal development. Preterm birth interrupts this exposure to amniotic fluid-borne growth factors, possibly contributing to the increased risk of necrotizing enterocolitis (NEC) in premature infants. We hypothesized that supplementation of formula feeds with amniotic fluid can provide amniotic fluid-borne growth factors and prevent experimental NEC in rat pups. We compared NEC-like injury in rat pups fed with infant formula vs. formula supplemented either with 30% amniotic fluid or recombinant hepatocyte growth factor (HGF). Cytokines/growth factors in amniotic fluid were measured by immunoassays. Amniotic fluid and HGF effects on enterocyte migration, proliferation, and survival were measured in cultured IEC6 intestinal epithelial cells. Finally, we used an antibody array to investigate receptor tyrosine kinase (RTK) activation and immunoblots to measure phosphoinositide 3-kinase (PI3K) signaling. Amniotic fluid supplementation in oral feeds protected rat pups against NEC-like injury. HGF was the most abundant growth factor in rat amniotic fluid in our panel of analytes. Amniotic fluid increased cell migration, proliferation, and cell survival in vitro. These effects were reproduced by HGF and blocked by anti-HGF antibody or a PI3K inhibitor. HGF transactivated several RTKs in IEC6 cells, indicating that its effects extended to multiple signaling pathways. Finally, similar to amniotic fluid, recombinant HGF also reduced the frequency and severity of NEC-like injury in rat pups. Amniotic fluid supplementation protects rat pups against experimental NEC, which is mediated, at least in part, by HGF. amniotic fluid; NEC; HGF; inflammation; phosphoinositide 3-kinase NECROTIZING ENTEROCOLITIS (NEC), an inflammatory bowel necrosis of preterm infants, is a leading cause of death among neonates born before 32 wk of gestation or with a birth weight Ͻ1,500 g (20, 27). Although the etiology of NEC remains unclear, epidemiological studies show an association with diverse risk factors such as maternal chorioamnionitis, perinatal asphyxia, indomethacin therapy, viral infections, and blood transfusions (20). Current pathophysiological models suggest that NEC occurs when altered/disrupted epithelial barrier in the preterm intestine allows luminal bacteria to translocate across the epithelial barrier into the lamina propria, triggering a severe mucosal inflammatory response and tissue damage (21).During intrauterine development, the fetus ingests progressively large volumes of amniotic fluid, which contains several cytokines and growth factors known to promote gut mucosal development (19). In the third trimester, the human fetus swallows nearly 550 ml/day amniotic fluid (29, 40). We hypothesiz...