Description: The role of NADPH oxidase (Nox) in both the promotion and impairment of compensatory collateral growth remains controversial because the specific Nox and reactive oxygen species involved are unclear. The aim of this study was to identify the primary Nox and reactive oxygen species associated with early stage compensatory collateral growth in young, healthy animals. Ligation of the feed arteries that form primary collateral pathways in rat mesentery and mouse hindlimb was used to assess the role of Nox during collateral growth. Changes in mesenteric collateral artery Nox mRNA expression determined by real-time PCR at 1, 3, and 7 days relative to same-animal control arteries suggested a role for Nox subunits Nox2 and p47 phox . Administration of apocynin or Nox2ds-tat suppressed collateral growth in both rat and mouse models, suggesting the Nox2/p47 phox interaction was involved. Functional significance of p47 phox expression was assessed by evaluation of collateral growth in rats administered p47 phox small interfering RNA and in p47 phox–/– mice. Diameter measurements of collateral mesenteric and gracilis arteries at 7 and 14 days, respectively, indicated no significant collateral growth compared with control rats or C57BL/6 mice. Chronic polyethylene glycol-conjugated catalase administration significantly suppressed collateral development in rats and mice, implying a requirement for H 2 O 2 . Taken together, these results suggest that Nox2, modulated at least in part by p47 phox , mediates early stage compensatory collateral development via a process dependent upon peroxide generation. These results have important implications for the use of antioxidants and the development of therapies for peripheral arterial disease.

Description: Damage to the enteric nervous system (ENS) associated with intestinal inflammation may underlie persistent alterations to gut functions, suggesting that enteric neurons are viable targets for novel therapies. Mesenchymal stem cells (MSCs) offer therapeutic benefits for attenuation of neurodegenerative diseases by homing to areas of inflammation and exhibiting neuroprotective, anti-inflammatory, and immunomodulatory properties. In culture, MSCs release soluble bioactive factors promoting neuronal survival and suppressing inflammation suggesting that MSC-conditioned medium (CM) provides essential factors to repair damaged tissues. We investigated whether MSC and CM treatments administered by enema attenuate 2,4,6-trinitrobenzene-sulfonic acid (TNBS)-induced enteric neuropathy and motility dysfunction in the guinea pig colon. Guinea pigs were randomly assigned to experimental groups and received a single application of TNBS (30 mg/kg) followed by 1 x 10 6 human bone marrow-derived MSCs, 300 μl CM, or 300 μl unconditioned medium 3 h later. After 7 days, the effect of these treatments on enteric neurons was assessed by histological, immunohistochemical, and motility analyses. MSC and CM treatments prevented inflammation-associated weight loss and gross morphological damage in the colon; decreased the quantity of immune infiltrate in the colonic wall ( P 〈 0.01) and at the level of the myenteric ganglia ( P 〈 0.001); prevented loss of myenteric neurons ( P 〈 0.05) and damage to nerve processes, changes in ChAT, and nNOS immunoreactivity ( P 〈 0.05); and alleviated inflammation-induced colonic dysmotility (contraction speed; P 〈 0.001, contractions/min; P 〈 0.05). These results provide strong evidence that both MSC and CM treatments can effectively prevent damage to the ENS and alleviate gut dysfunction caused by TNBS-induced colitis.

Description: The enteric nervous system (ENS) is composed of neural crest-derived neurons (also known as ganglion cells) the cell bodies of which are located in the submucosal and myenteric plexuses of the intestinal wall. Intramucosal ganglion cells are known to exist but are rare and often considered ectopic. Also derived from the neural crest are enteric glial cells that populate the ganglia and the associated nerves, as well as the lamina propria of the intestinal mucosa. In Hirschsprung disease (HSCR), ganglion cells are absent from the distal gut because of a failure of neural crest-derived progenitor cells to complete their rostrocaudal migration during embryogenesis. The fate of intramucosal glial cells in human HSCR is essentially unknown. We demonstrate a network of intramucosal cells that exhibit dendritic morphology typical of neurons and glial cells. These dendritic cells are present throughout the human gut and express Tuj1, S100, glial fibrillary acidic protein, CD56, synaptophysin, and calretinin, consistent with mixed or overlapping neuroglial differentiation. The cells are present in aganglionic colon from patients with HSCR, but with an altered immunophenotype. Coexpression of Tuj1 and HNK1 in this cell population supports a neural crest origin. These findings extend and challenge the current understanding of ENS microanatomy and suggest the existence of an intramucosal population of neural crest-derived cells, present in HSCR, with overlapping immunophenotype of neurons and glia. Intramucosal neuroglial cells have not been previously recognized, and their presence in HSCR poses new questions about ENS development and the pathobiology of HSCR that merit further investigation.