Necrotizing enterocolitis (NEC) is an often catastrophic disease that typically affects premature newborns. Although the exact etiology of NEC is uncertain, the disease is associated with formula feeding, bacterial colonization of the gut, hypoxia, and hypoperfusion. In light of the pathogenesis of NEC, the integrity and function of the intestinal mucosa plays a major defensive role against the initiation of NEC. Various forms of intestinal injury, including NEC, injure the intestinal epithelial cell (IEC) lineages, including the intestinal stem cells (ISCs), thereby disrupting the normal homeostasis needed to maintain gut barrier function. In the current study we examined the effects of HB-EGF administration on enterocytes, goblet cells, neuroendocrine cells and intestinal stem cells in a newborn rat model of experimental NEC. We also examined the cytoprotective effects of heparin-binding EGF-like growth factor (HB-EGF) on intestinal stem cells in in vitro cell cultures and in ex vivo crypt-villous organoid cultures. We found that HB-EGF protects all intestinal epithelial cell lineages, including intestinal stem cells, from injury. We further found that HB-EGF protects isolated intestinal stem cells from hypoxic injury in vitro, and promotes intestinal stem cell activation and survival, and the expansion of crypt transit amplifying cells, in ex vivo crypt-villous organoid cultures. The protective effects of HB-EGF were dependent upon EGF receptor activation, and were mediated via the MEK1/2 and PI3K signaling pathways. These results demonstrate that the intestinal cytoprotective effects of HB-EGF are mediated, at least in part, through its ability to protect intestinal stem cells from injury.

Background Surgical management of long segment tracheal disease is limited by a paucity of donor tissue and poor performance of synthetic materials. A potential solution is the development of a tissue-engineered tracheal graft (TETG), which promises an autologous airway conduit with growth capacity. Methods We created a TETG by vacuum seeding bone marrow-derived mononuclear cells (BM-MNCs) on a polymeric nanofiber scaffold. First, we evaluated the role of scaffold porosity on cell seeding efficiency in vitro. We then determined the effect of cell seeding on graft performance in vivo using an ovine model. Results Seeding efficiency of normal porosity (NP) grafts was significantly increased when compared to high porosity (HP) grafts (NP: 360.3 ± 69.19 ×103 cells/mm2; HP: 133.7 ± 22.73 ×103 cells/mm2; p<0.004). Lambs received unseeded (n=2) or seeded (n=3) NP scaffolds as tracheal interposition grafts for 6 weeks. Three animals were terminated early due to respiratory complications (n=2 unseeded, n=1 seeded). Seeded TETG explants demonstrated wound healing, epithelial migration, and delayed stenosis when compared to their unseeded counterparts. Conclusion Vacuum seeding BM-MNCs on nanofiber scaffolds for immediate implantation as tracheal interposition grafts is a viable approach to generate TETGs, but further preclinical research is warranted before advocating this technology for clinical application.

Background Acute respiratory distress syndrome continues to be a major source of morbidity and mortality in critically-ill patients. Heparin binding EGF-like growth factor (HB-EGF) is a biologically active protein that acts as an intestinal cytoprotective agent. We have previously demonstrated that HB-EGF protects the intestines from injury in several different animal models of intestinal injury. In the current study, we investigated the ability of HB-EGF to protect the lungs from remote organ injury after intestinal ischemia/reperfusion (I/R). Methods Mice were randomly assigned to one of the following groups: 1) sham-operated; 2) sham + HB-EGF (1200 µg/kg in 0.6 mL administered by intra-luminal injection at the jejuno-ileal junction immediately after identification of the superior mesenteric artery); 3) superior mesenteric artery occlusion for 45 min followed by reperfusion for 6 h (I/R); or 4) I/R+HB-EGF (1200 µg/kg in 0.6 mL) administered 15 min after vascular occlusion. The severity of acute lung injury was determined by histology, morphometric analysis and invasive pulmonary function testing. Animal survival was evaluated using Kaplan-Meier analysis. Results Mice subjected to intestinal I/R injury showed histological and functional evidence of acute lung injury and decreased survival compared to sham-operated animals. Compared to mice treated with HB-EGF (I/R + HB-EGF), the I/R group had more severe acute lung injury, and decreased survival. Conclusion Our results demonstrate that HB-EGF reduces the severity of acute lung injury after intestinal I/R in mice. These data demonstrate that HB-EGF may be a potential novel systemic anti-inflammatory agent for the prevention of the systemic inflammatory response syndrome (SIRS) after intestinal injury.

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Background-We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) promotes angiogenesis and preserves mesenteric microvascular blood flow in several models of intestinal injury. The current study was designed to evaluate the effect of HB-EGF on pericytes, since these cells function to regulate capillary blood flow and new capillary growth.

Decellularized allograft heart valves have been used as tissue-engineered heart valve (TEHV) scaffolds with promising results; however, little is known about the cellular mechanisms underlying TEHV neotissue formation. To better understand this phenomenon, we developed a murine model of decellularized pulmonary heart valve transplantation using a hemodynamically unloaded heart transplant model. Furthermore, because the hemodynamics of blood flow through a heart valve may influence morphology and subsequent function, we describe a modified loaded heterotopic heart transplant model that led to an increase in blood flow through the pulmonary valve. We report host cell infiltration and endothelialization of implanted decellularized pulmonary valves (dPV) and provide an experimental approach for the study of TEHVs using mouse models.

Background The morbidity and mortality associated with bacterial peritonitis remain high. Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) is a potent intestinal cytoprotective agent. The aim of this study was to evaluate the effect of HB-EGF in a model of murine peritonitis. Methods HB-EGF(−/−) knockout (KO) mice and their HB-EGF(+/+) wild-type (WT) counterparts were subjected to sham operation, cecal ligation and puncture (CLP), or CLP with HB-EGF treatment (800 µg/kg IP daily). Villous length, intestinal permeability, intestinal epithelial cell (IEC) apoptosis, bacterial load in peritoneal fluid (PF) and mesenteric lymph nodes (MLN), inflammatory cytokine levels, and survival were determined. Results After exposure to CLP, HB-EGF KO mice had significantly shorter villi (1.37 ± 0.13 vs 1.96 ± 0.4 relative units; P < .03), increased intestinal permeability (17.01 ± 5.18 vs 11.50 ± 4.67 nL/min/cm2; P < .03), increased IEC apoptotic indices (0.0093 ± 0.0033 vs 0.0016 ± 0.0014; P < .01), and increased bacterial counts in PF (25,313 ± 17,558 vs 11,955 ± 6,653 colony forming units [CFU]/mL; P < .05) and MLN (19,009 ± 11,200 vs 5,948 ± 2,988 CFU/mL/g; P < .01) compared with WT mice. Administration of HB-EGF to WT and HB-EGF KO mice exposed to CLP led to significantly increased villous length and decreased intestinal permeability, IEC apoptosis and bacterial counts in MLN (P < .05). Survival of HB-EGF KO mice subjected to CLP was significantly improved with administration of HB-EGF (P < .05). Conclusion HB-EGF gene KO increases susceptibility to peritonitis-induced intestinal injury, which can be reversed by administration of HB-EGF. These results support a protective role of HB-EGF in peritonitis-induced sepsis.

Background We have shown that HB-EGF protects the intestines from injury in several different animal models including hemorrhagic shock and resuscitation (HS/R). The current study was designed to explore the mechanisms underlying the anti-inflammatory role of HB-EGF in preservation of gut barrier function after injury. Methods In vivo, HS/R was induced in wild type and neutropenic mice, with or without administration of HB-EGF, and intestinal permeability determined using the everted gut sac method. In vitro, cultured human umbilical vein endothelial cells (HUVEC) and freshly isolated human peripheral blood mononuclear cells (PMN) were used to determine the effects of HB-EGF on HUVEC-PMN adhesion, reactive oxygen species (ROS) production in PMN, adhesion molecule expression in HUVEC and PMN, and the signaling pathways involved. Results We found that administration of HB-EGF to normal mice led to preservation of gut barrier function after HS/R. Likewise, induction of neutropenia in mice also led to preservation of gut barrier function after HS/R. Administration of HB-EGF to neutropenic mice did not lead to further improvement in gut barrier function. In vitro studies showed that HB-EGF decreased neutrophil-endothelial cell (PMN-EC) adherence by down-regulating adhesion molecule expression in EC via the PI3K-Akt pathway, and by inhibiting adhesion molecule surface mobilization and reactive oxygen species (ROS) production in PMN. Conclusions These results indicate that HB-EGF preserves gut barrier function by inhibiting PMN and EC activation, thereby blocking PMN-EC adherence after HS/R in mice, and support the future use of HB-EGF in disease states manifested by hypoperfusion injury.