The expression of nestin delineates skeletal muscle differentiation in the developing rat esophagus

Histology and Ultrastructure of the Esophagus in European Beaver (Castor fiber) Displays Features Adapted to Seasonal Changes in Diet

The European beaver is a herbivorous rodent whose diet changes seasonally, and in winter consists of large quantities of woody plants. It is distinguished among other mammals by a unique organization of the stomach that comprises the cardiogastric gland and by the unusual process of mucus formation in the gastric mucosa. The aim of study was to (i) characterize the structure of the beaver esophagus with particular attention to the mucosal epithelium; (ii) compare the histological structure of the esophagi collected in spring, summer, and winter; (iii) provide preliminary data on the structure of the esophagus in beaver fetuses. The study was conducted on esophagi of 18 adult beavers captured in Poland in April, August, and December, and on 3 fetal organs. The results obtained in adults show that the mucosa is lined with thick stratified squamous keratinized epithelium with a structure similar to that of the skin epidermis. Ultrastructural studies reveal the presence of multiple lamellar and non-lamellar bodies in granular cells, whose morphology and location gradually change while reaching the upper epithelial layers. The muscularis mucosa comprises a layer of longitudinally oriented bundles of smooth muscle cells. Both mucosa and submucosa do not comprise any glands. The thick muscularis externa consists mainly of internal circular and external longitudinal layers of striated muscle fibers. The keratinized layer of mucosa epithelium was 2-3-fold thicker in esophagi collected in winter than in those collected in spring and summer, while the epithelial cell layer thickness remained unchanged regardless of the season. Immunolabeling for proliferating cell nuclear antigen shows a higher index of epithelium proliferation in esophagi collected in winter than in spring and summer. No seasonal differences were noted in other layers of the esophagus. Fetal organs have epithelium covered with a keratinized layer, thinner than in adults, and the muscularis externa comprises both striated and smooth muscle cells.

Immunomodulation and Mobilization of Progenitor Cells by Extracellular Matrix Bioscaffolds for Volumetric Muscle Loss Treatment

Acellular bioscaffolds composed of extracellular matrix (ECM) have been effectively used to promote functional tissue remodeling in both preclinical and clinical studies of volumetric muscle loss, but the mechanisms that contribute to such outcomes are not fully understood. Thirty-two C57bl/6 mice were divided into eight groups of four animals each. A critical-sized defect was created in the quadriceps muscle and was repaired with a small intestinal submucosa ECM bioscaffold or left untreated. Animals were sacrificed at 3, 7, 14, or 56 days after surgery. The spatiotemporal cellular response in both treated and untreated groups was characterized by immunolabeling methods. Early time points showed a robust M2-like macrophage phenotype following ECM treatment in contrast to the predominant M1-like macrophage phenotype present in the untreated group. ECM implantation promoted perivascular stem cell mobilization, increased presence of neurogenic progenitor cells, and was associated with myotube formation. These cell types were present not only at the periphery of the defect near uninjured muscle, but also in the center of the ECM-filled defect. ECM bioscaffolds modify the default response to skeletal muscle injury, and provide a microenvironment conducive to a constructive healing response.

Expression of nestin in embryonic tissues and its effects on clinicopathological characteristics of patients with placenta previa

In this study, we examined expression of nestin in the spinal cord, lung, kidney, stomach, colon, and intestine tissues at different stages of embryos in patients with placenta previa. Fetuses of 75 patients with placenta previa were assigned to case group and 80 fetuses from healthy pregnant women with normal placenta who voluntarily terminated pregnancy to control group. Clinical data of pregnant women were collected at the time of admission. Blood from elbow vein was collected to determine expression of serum nestin. Tissues from spinal cord, lung, kidney, stomach, colon, and intestine in 3-7 months fetuses of the two groups were extracted. Expression of nestin in tissues was detected by immunohistochemistry, Western blotting and RT-qPCR. The mRNA expression of nestin in the case group was increased. Nestin expression was correlated with the gestational age, age of foetus, and type of placenta previa in patients with placenta previa. Positive nestin expression was detected in the spinal cord, lung, kidney, stomach, intestine, and colon tissues in normal and placenta previa embryo at Stage I. The positive cell density and nestin expression decreased at Stage II, and further decreased at Stage III. The case group had higher nestin mRNA and protein levels throughout human fetal development. Findings of this study suggested that, nestin, as a specific marker of neural precursor cells, was expressed in various tissues of the embryo in patients with placenta previa and nestin expression was lower with increased maturation of the embryo.

Enteric co-innervation of striated muscle in the esophagus: still enigmatic?

The existence of a distinct ganglionated myenteric plexus between the two layers of the striated tunica muscularis of the mammalian esophagus has represented an enigma for quite a while. Although an enteric co-innervation of vagally innervated motor endplates in the esophagus has been suggested repeatedly, it was not possible until recently to demonstrate this dual innervation. Twenty-two years ago, we were able to demonstrate that motor endplates in the rat esophagus receive dual innervation from both vagal nerve fibers originating in the brain stem and from varicose enteric nerve fibers originating in the myenteric plexus. Meanwhile, a considerable amount of data has been gathered on enteric co-innervation and its occurrence in the esophagus of a variety of species including humans, its neurochemistry, spatial relationships on motor endplates, ontogeny and possible functional roles. These data underline the significance of this newly discovered innervation component, although its function in vivo is still largely unknown. The aim of this review, which is an update of our previous paper (Wörl and Neuhuber in Histochem Cell Biol 123(2):117-130. doi: 10.1007/s00418-005-0764-7 , 2005a), is to summarize the current knowledge about enteric co-innervation of esophageal striated muscle and to provide some hints as to its functional significance.

Strain induced esophageal growth in a novel rodent model

PURPOSE

Longitudinal esophageal strain has been shown to increase esophageal length but the contribution of tissue hyperplasia to this growth is unknown. We used a novel model of esophageal stretch to determine the cellular response to the strain stimulus.

METHODS

Male Sprague-Dawley rats underwent transection of the distal esophagus. The distal stump was ligated and stretched over a silicone tube. The proximal esophageal stump was anastomosed to the stomach to restore continuity. After two, four, or seven days, the silicone tube was removed and the esophageal segment was measured and compared to its initial length. Sham animals had only a thin piece of silicone tubing placed. Standardized histologic sections were evaluated for wall thickness. Immunofluorescence with DAPI, Ki-67, and Myogenin antibodies was used to assess nuclear density, proliferation indices, and myoblast differentiation indices.

RESULTS

Experimental animals demonstrated a significant increase in esophageal length compared to sham controls at four and seven days with no difference at two days. There was significant lengthening between four and seven days among the experimental animals. There was no change in wall thickness between experimental and sham animals at any time point. Nuclear density was increased at all time points, although this only reached significance at day four. Proliferation indices were significantly increased relative to sham controls at all time points. Esophageal strain induced significantly increased myoblast differentiation.

CONCLUSION

In this novel rat model of esophageal strain, lengthening is associated with stable esophageal wall thickness, increased nuclear density, increased cellular proliferation, and increased myogenin expression. These data suggest that true tissue hyperplasia may contribute to the increased length seen after esophageal strain.

Fibroblast growth factor-2 up-regulates the expression of nestin through the Ras-Raf-ERK-Sp1 signaling axis in C6 glioma cells

Nestin is a 240-kDa intermediate filament protein expressed mainly in neural and myogenic stem cells. Although a substantial number of studies have focused on the expression of nestin during development of the central nervous system, little is known about the factors that induce and regulate its expression. Fibroblast growth factor-2 (FGF-2) is an effective mitogen and stimulates the proliferation and differentiation of a subset of nestin-expressing cells, including neural progenitor cells, glial precursor cells, and smooth muscle cells. To assess whether FGF-2 is a potent factor that induces the expression of nestin, C6 glioma cells were used. The results showed that nestin expression was up-regulated by FGF-2 via de novo RNA and protein synthesis. Our RT-PCR results showed that C6 glioma cells express FGFR1/3, and FGFRs is required for FGF-2-induced nestin expression. Further signaling analysis also revealed that FGF-2-induced nestin expression is mediated through FGFR-MAPK-ERK signaling axis and the transcriptional factor Sp1. These findings provide new insight into the regulation of nestin in glial system and enable the further studies on the function of nestin in glial cells.

Identification and cytoprotective function of a novel nestin isoform, Nes-S, in dorsal root ganglia neurons

In this study, the first nestin isoform, Nes-S, was identified in neurons of dorsal root ganglia (DRG) of adult rats. Nes-S cannot form filaments by itself in cytoplasmic intermediate filament-free SW13 cells. Instead, it co-assembles into filaments with vimentin when transfected into vimentin(+) SW13 cells, and with peripherin and neurofilament proteins when transfected into N2a cells. In primary DRG neurons, endogenous Nes-S co-assembles with peripherin and neurofilament proteins. The expression of Nes-S first appears in DRG at postnatal day 5 and persists to adulthood. Among the adult tissues we examined, the expression of Nes-S is restricted to the sensory and motor neurons. Finally, exogenous Nes-S enhances viability when transfected into N2a cells, and knockdown of endogenous Nes-S impairs the survival of DRG neurons in primary cultures. Taken together, Nes-S is a new neuronal intermediate filament protein that exerts a cytoprotective function in mature sensory and motor neurons.

Postnatal changes in vagal control of esophageal muscle contractions in rats

AIMS

Replacement of smooth muscles by striated muscles occurs in the esophagus during the early postnatal period. The aim of this study was to clarify postnatal changes in vagal control of esophageal muscle contractions in rats.

MAIN METHODS

An isolated segment of the neonatal rat esophagus was placed in an organ bath and the contractile responses were recorded using a force transducer.

KEY FINDINGS

Electrical stimulation of the vagus trunk evoked a biphasic contractile response in the neonatal esophageal segment. The first and second components of the contractions were inhibited by α-bungarotoxin and atropine, respectively. Ganglion blockers, hexamethonium and mecamylamine, did not affect vagally mediated contractions. The first component gradually enlarged with age in days, whereas the second component declined during the first week after birth. Application of d-tubocurarine or acetylcholine caused an apparent contraction in the esophageal striated muscle at postnatal day 0, but responses to these drugs were not observed at 1 week after birth. The neonatal esophagus expressed the γ-subunit of nicotinic acetylcholine receptors. In contrast, the ε-subunit was dominantly expressed in the adult esophagus.

SIGNIFICANCE

The vagus nerves directly innervate both the esophageal striated muscles and smooth muscles in the early neonatal period. During the process of muscle rearrangement, the property of the striated muscles is altered substantially. The specific features of striated muscles in the neonatal rat esophagus might compensate for immature formation of neuromuscular junctions. Unsuccessful conversion of the striated muscle property during postnatal muscle rearrangement would be related to disorders of esophageal motility.