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Background: Surgeons often encounter patients with intestinal failure due to inadequate intestinal length (“short bowel syndrome”/SBS). Treatment in these patients remains challenging and the process of physiologic adaptation may take years to complete, which frequently requires parenteral nutrition. We propose a proof-of-concept mechanical bowel elongation approach using a self-expanding prototype of an intestinal expansion sleeve (IES) for use in SBS to accelerate the adaptation process. Methods: IESs were deployed in the small intestines of Sprague Dawley rats. Mechanical characterization of these prototypes was performed. IES length–tension relationships and post-implant bowel expansion were measured ex vivo. Bowel histology before and after implantation was evaluated. Results: IES mechanical studies demonstrated decreasing expansive force with elongation. The deployment of IES devices produced an immediate 21 ± 8% increase in bowel length (p < 0.001, n = 11). Mechanical load testing data showed that the IESs expressed maximum expansive forces at 50% compression of the initial pre-contracted length. The small-intestine failure load in the rats was 1.88 ± 21 N. Intestinal histology post deployment of the IES showed significant expansive changes compared to unstretched bowel tissue. Conclusions: IES devices were scalable to the rat intestinal model in our study. The failure load of the rat small intestine was many times higher than the force exerted by the contraction of the IES. Histology demonstrated preservation of intestinal structure with some mucosal erosion. Future in vivo rat studies on distraction enterogenesis with this IES should help to define this organogenesis phenomenon.

Necrotizing enterocolitis (NEC) triggers an intense inflammatory response in the neonatal gut associated with cytokine activation, altered nutrient status and intracellular O 2 -deprivation. Endothelial cell adhesion molecules (ECAMs) play critical roles in driving immune cell infiltration into inflamed gut. Currently, relationships between inflammation, metabolism and ECAM expression remain poorly understood in NEC. We studied the effects of metabolic depletion (aglycemia/ hypoxia) on TNF-α mediated ECAM expression including ICAM-1, MAdCAM-1, VCAM-1 and E-selectin, in vitro in intestinal microvascular endothelial cells (IMEC). To study the effects of TNF-α, aglycemia and hypoxia (alone or in combination) IMECs expression of adhesion molecules was studied using cell surface ELISA and immunoblotting. Total VCAM-1 expression was induced TNF-α and by hypoxia + TNF-α, cell surface expression was induced by hypoxia, TNF-α, TNF- α+hypoxia, and TNF- α+hypoxia and aglycemia. Total ICAM-1 increased following TNF- α, TNF- α+hypoxia, hypoxia + aglycemia, and TNF- α+hypoxia + aglycemia. Total MAdCAM-1 protein expression was significantly induced by a combination of TNF-α+hypoxia + aglycemia and cell surface expression induced by TNF- α+hypoxia. Surface expression of E-selectin was induced by TNF- α+aglycemia and TNF- α+hypoxia + aglycemia. Energy metabolism influences inflammation induced injury through mobilization of intestinal ECAMs, and may represent an important mechanism in NEC pathology. [ABSTRACT FROM AUTHOR]

Abstract: Throughout the past 20 years, we have been investigating the potential therapeutic roles of heparin-binding EGF-like growth factor (HB-EGF), a member of the epidermal growth factor family, in various models of intestinal injury including necrotizing enterocolitis (NEC), intestinal ischemia/reperfusion (I/R) injury, and hemorrhagic shock and resuscitation (HS/R). Our studies have demonstrated that HB-EGF acts as an effective mitogen, a restitution-inducing reagent, a cellular trophic factor, an anti-apoptotic protein and a vasodilator, via its effects on various cell types in the intestine. In the current paper, we have reviewed the application and therapeutic effects of HB-EGF in three classic animal models of intestinal injury, with particular emphasis on its protection of the intestines from NEC. Additionally, we have summarized the protective functions of HB-EGF on various target cells in the intestine. Lastly, we have provided a brief discussion focusing on the future development of HB-EGF clinical applications for the treatment of various forms of intestinal injury including NEC. [Copyright &y& Elsevier]

Abstract: Necrotizing enterocolitis (NEC) is the most common surgical emergency occurring in neonatal intensive care unit (NICU) patients. Among patients with NEC, those that require surgery experience the poorest outcomes and highest mortality. Surgical intervention, while attempting to address the intestinal injury and ongoing mulitfactorial physiologic insults in NEC is associated with its own stresses that may compound the ongoing physiologic derangement. Surgery is thus reserved for those patients with clear indication for intervention such as pneumoperitoneum, confirmed stool or pus in the peritoneal cavity, or worsening clinical status. The purpose of this review is to briefly describe the physiologic stress induced by surgical intervention in the preterm, low birth weight patient with NEC and to provide a contemporary overview of available surgical management options for NEC. The optimal surgical plan employed is strongly influenced by clinical judgment and theoretical benefits in terms of minimizing physiologic stressors while providing temporary and/or definitive treatment in a timely fashion. While the choice of operation has not been shown to have a significant effect on any clinically important outcomes, ongoing investigations continue to study both short and long-term outcomes in patients with NEC. [Copyright &y& Elsevier]

Abstract: Toll-like receptors (TLRs) are a structurally related family of molecules that respond to a wide variety of endogenous and exogenous ligands, and which serve as important components of the innate immune system. While TLRs have established roles in host defense, these molecules have also been shown to play important roles in the development of various disease states. A particularly important example of the role of TLRs in disease induction includes necrotizing enterocolitis (NEC), which is the most common gastrointestinal disease in preterm infants, and which is associated with extremely high morbidity and mortality rates. The development of NEC is thought to reflect an abnormal interaction between microorganisms and the immature intestinal epithelium, and emerging evidence has clearly placed the spotlight on an important and exciting role for TLRs, particularly TLR4, in NEC pathogenesis. In premature infants, TLR4 signaling within the small intestinal epithelium regulates apoptosis, proliferation and migration of enterocytes, affects the differentiation of goblet cells, and reduces microcirculatory perfusion, which in combination result in the development of NEC. This review will explore the signaling properties of TLRs on hematopoietic and non-hematopoietic cells, and will examine the role of TLR4 signaling in the development of NEC. In addition, the effects of dampening TLR4 signaling using synthetic and endogenous TLR4 inhibitors and active components from amniotic fluid and human milk on NEC severity will be reviewed. In so doing, we hope to present a balanced approach to the understanding of the role of TLRs in both immunity and disease pathogenesis, and to dissect the precise roles for TLR4 in both the cause and therapeutic intervention of necrotizing enterocolitis. [Copyright &y& Elsevier]

Abstract: Necrotizing enterocolitis is a disease entity with multiple proposed pathways of pathogenesis. Various combinations of these risk factors, perhaps based on genetic predisposition, possibly lead to the mucosal and epithelial injury that is the hallmark of NEC. Intestinal epithelial integrity is controlled by a tightly regulated balance between proliferation and differentiation of epithelium from intestinal epithelial stem cells and cellular loss by apoptosis. various signaling pathways play a key role in creating and maintaining this balance. The aim of this review article is to outline intestinal epithelial barrier development and structure and the impact of these inflammatory signaling and regulatory pathways as they pertain to the pathogenesis of NEC. [Copyright &y& Elsevier]

Abstract: NEC remains a major concern for neonatologists, surgeons, and gastroenterologists due to its high morbidity and mortality. These infants often have poor developmental outcome, and contribute to significant economic burden resulting in marked stress in these families. By developing and adhering to strict feeding protocols, encouraging human milk feeding preferably from the infant's mother, use of probiotics, judicious antibiotic use, instituting blood transfusion protocols, the occurrence of NEC may possibly be reduced. However, because of its multifactorial etiology, it cannot be completely eradicated in the NICUs, particularly in the extremely premature infants. Ongoing surveillance of NEC and quality improvement projects may be beneficial. [Copyright &y& Elsevier]

Abstract: Neonatal necrotizing enterocolitis which develops after feeding preterm infants is characterized by severe intestinal inflammation and profound systemic metabolic acidosis. The fermentation of undigested dietary carbohydrate by colonic flora yields gases (CO2 and H2) and short chain organic acids. These organic acids can disrupt the intestinal mucosa and initiate inflammation driven predominantly by resident mast cells and by granulocytes which are recruited from blood. A systemic acidosis ensues derived from intestinal acids, not classic lactic acidosis produced from anaerobic metabolism. The systemic acidosis further compromises inflamed bowel leading to bowel necrosis. [Copyright &y& Elsevier]

Abstract: Necrotizing enterocolitis (NEC) is an enigmatic disease that affects primarily premature infants. It often occurs suddenly and when it occurs, treatment attempts at treatment often fail and results in death. If the infant survives, there is a significant risk of long term sequelae including neurodevelopmental delays. The pathophysiology of NEC is poorly understood and thus prevention has been difficult. In this review, we will provide an overview of why progress may be slow in our understanding of this disease, provide a brief review diagnosis, treatment and some of the current concepts about the pathophysiology of this disease. [Copyright &y& Elsevier]

Abstract: Background: The field of necrotizing enterocolitis (NEC) research has been in existence for over 60 years. During the first five decades little progress in NEC prevention and no definitive progress in treatment was achieved. One of the major determinants of this ineffectiveness may have been a global propensity to lump NEC into a single disease entity rather than a spectrum of diseases with a common outcome. The driver of this philosophy was most likely statistical, in that researchers desired large cohorts to optimize statistical power. Additionally, in the past quarter century, our preterm NEC cohorts were (and in some cases still are) contaminated with spontaneous intestinal perforations (SIP). This completely different acquired neonatal intestinal disease (ANID) markedly alters clinical characteristics and outcomes in NEC cohorts and subsets if not addressed. Unfortunately, cohort size has been proven to be less important than data quality when it comes to NEC over this last decade of research. Emerging progress in NEC prevention has been greatly enhanced as a result of dividing well-defined NEC into subsets of disease origin and investigating these entities individually. Review objectives: The purpose of this review is to offer the bedside clinician a concise, up-to-date review of recent advances in NEC reductionism. The reader should understand the history and basic theory behind NEC subsets, their application to NEC prevention, and comprehend that prevention of NEC requires a comprehensive quality improvement strategy that is likely best realized with a zero tolerance approach. Conclusions: We are entering a new era of NEC prevention. NICUs that embrace and achieve effective NEC prevention strategies will rapidly outpace their contemporaries. Because NEC is still the major driver of morbidity and mortality in most NICUs today, those who reject or fail in this pursuit will likely face increasingly severe consequences due to growing requirements for outcomes transparency. [Copyright &y& Elsevier]