Regeneration Of Tracheal Epithelium Research Articles

Expression and role of Oct3/4, Nanog and Sox2 in regeneration of rat tracheal epithelium

To explore the role of Oct3/4, Nanog and Sox2 in regeneration of rat tracheal epithelium. An ex vivo model of rat tracheal epithelial regeneration using 5-fluorouracil (5-FU) was developed, to induce injury. Expression levels of Oct3/4, Nanog and Sox2 were examined using Western blot analysis, RT-PCR or microscopically observed immunofluorescence, and cell morphological changes were observed using HE staining, during the recovery process. Oct3/4, Nanog and Sox2 were not detectable in normal tracheal epithelium. After treatment with 5-FU, the normally proliferating tracheal epithelium desquamated and only a few cells in G0 phase of the cell cycle were left on the basement membrane and Oct3/4, Nanog and Sox2 could be observed at this time. Thereafter, the number of Oct3/4-, Nanog- and Sox2-positive cells increased gradually. When the cells differentiated into ciliate cells, mucous cells or basal cells, and restored pseudostratified mucociliary epithelium, the number of Oct3/4-, Nanog- and Sox2-positive cells decreased and gradually disappeared. G0 phase cells with resistance to 5-FU damage expressed Oct3/4, Nanog and Sox2. This indicated that these cells were undifferentiated, but had the ability to terminally differentiate into downstream-type cells. They possessed stem cell properties. The results are consistent with Oct3/4, Nanog and Sox2-expressing cells being considered as tracheal stem cells.

Expression and role of Notch signalling in the regeneration of rat tracheal epithelium

This study is to explore the role of Notch signalling during the regeneration of rat tracheal epithelium after injury induced by 5-fluorouracil (5-FU). We developed an ex vivo model of rat tracheal epithelial regeneration using 5-FU to induce injury. Expression levels of members of the Notch signalling pathway, ABCG2, CK19, and proliferating cell nuclear antigen (PCNA) were examined by reverse transcription-polymerase chain reaction, Western blot, and immunofluorescence. One group of tracheas were cultured in the medium with a gamma-secretase inhibitor or Jag-1 peptide after 5-FU treatment and another group were pre-treated with the gamma-secretase inhibitor or Jag-1 peptide before 5-FU treatment. The expression changes of ABCG2, CK19, and PCNA were examined by Western blot or immunofluorescence and the morphologic changes were observed by haematoxylin and eosin stain during the recovery process. Expression levels of Notch3, Jagged1, and Hey1 were increased in rat tracheal epithelial cells after treatment with 5-FU. During injury recovery, disruption of Notch signalling by treatment with the gamma-secretase inhibitor reduced expression of ABCG2 and PCNA, but promoted expression of CK19, while persistent activation of Notch signalling promoted expression of ABCG2 and PCNA, but reduced expression of CK19. Under both conditions, recovery from injury was reduced. However, blocking Notch signalling prior to 5-FU treatment led to the complete blockage of recovery, while activating Notch signalling before 5-FU treatment promoted recovery. During tracheal epithelial regeneration, Notch signalling maintains an undifferentiated state and promotes proliferation among a population of tracheal epithelial cells.

Contribution of antioxidant systems to regeneration of tracheal epithelium after burn of upper respiratory tract

Study was performed using a rat model of thermal burn of upper respiratory tract (URT). The URT burn in rats was induced by intratracheal instillation of 70 °C water vapor using a micro-vapor generator. In a week after the intervention about 50 % of the ciliated epithelium was destructed. In 2 weeks after the intervention the inflammatory response enhanced and tissue edema increased. In 4 weeks after the intervention partial irregular restoration of tracheal epithelium cells was observed. Both IL-1 and IL-4 expression did not change significantly during restoration of tracheal epithelium, but IL-8 and IL-10 expression increased and was high even 1 month after the burn. Simultaneously, dramatic increase in expression of peroxyredoxine 6, which is the main antioxidant protein in trachea, was observed during regeneration of trachea epithelium. Iimmunohistochemical investigations showed that the increase in peroxyredoxine 6 in trachea during the regeneration of trachea epithelium after the burn could be related to increased peroxyredoxine expression in goblet cells. Therefore, activation of peroxyredoxine 6 synthesis by goblet cells appears to be the key step in activation of epithelium defense systems after thermal burn.

An animal model study for tissue-engineered trachea fabricated from a biodegradable scaffold using chondrocytes to augment repair of tracheal stenosis

Introduction We have designed an engineered graft fabricated from a biodegradable scaffold using chondrocytes and applied this construct to augment repair of tracheal stenosis. This study investigated the feasibility of using such tissue-engineered airways with autologous chondrocytes in a rabbit model. Material and Methods Chondrocytes were isolated and expanded from the auricular cartilage of New Zealand white rabbits, then seeded onto composite 3-layer scaffolds consisting of a collagen sheet, a polyglycolic acid mesh, and a copolymer ( l-lactide/ ɛ-caprolactone) coarse mesh. The engineered grafts were implanted into a 0.5 × 0.8-cm defect created in the midventral portion of the cervical trachea. Gelatin sponges that slowly released basic fibroblast growth factor (b-FGF) were then placed on the constructs, which were retrieved 1 or 3 months after implantation. Results The biodegradable scaffold seeded with chondrocytes could maintain airway structure up to 3 months after implantation. Tracheal epithelial regeneration occurred in the internal lumen of this composite scaffold. Three months after implantation, staining of the sections showed cartilage accumulation in the engineered tracheal wall. Conclusion This composite biodegradable scaffold may be useful for developing engineered trachea. A gelatin sponge slowly releasing b-FGF might enhance chondrogenesis.

Potential of Heterotopic Fibroblasts as Autologous Transplanted Cells for Tracheal Epithelial Regeneration

The tracheal epithelium maintains the health of the respiratory tract through mucociliary clearance and regulation of ion and water balance. When the trachea is surgically removed, artificial grafts have been clinically used by our group to regenerate the trachea. In such cases, the tracheal epithelium needs 2 months for functional regeneration. Previous study has shown that fibroblasts facilitate tracheal epithelial regeneration. In this study, heterotopic fibroblasts originating from the dermis, nasal, and gingival mucosa were cocultured with tracheal epithelial cells to evaluate their potential as autologous transplanted cells for tracheal epithelial regeneration. The epithelia induced by the heterotopic fibroblasts showed differences in structure, cilia development, mucin secretion, and expression of ion and water channels. These results indicated that nasal fibroblasts could not induce mature tracheal epithelium and that dermal fibroblasts induced epidermis-like epithelium. Only the gingival fibroblasts (GFBs) could induce morphologically and functionally normalized tracheal epithelium comparable to the epithelium induced by tracheal fibroblasts. Epithelial cell proliferation and migration were also upregulated by GFBs. These results indicate that GFBs are useful as autologous transplant cells for tracheal epithelial regeneration.

Effect of Fibroblasts on Tracheal Epithelial Regeneration in Vitro

Effect of Fibroblasts on Tracheal Epithelial Regeneration in Vitro

In vivo effect of wood smoke on the expression of two mucin genes in rat airways.

A short-term, time-dependent smoke exposure of rats in a nose-only chamber to burning wood and 24-h recovery time revealed inflammation of the airways with varying degrees of injury from loss of cilia, degeneration of epithelium, and squamous metaplasia to submucosal edema. These histological changes were reflected in variable expression of the secretory Muc5AC and low expression of membrane-associated Muc4 mucin genes. 20-min smoke exposure in extended recovery experiments showed marked disorder of tracheal epithelium for up to 72 h of recovery with a return to normal by 7 days. Gene expressions were elevated at 24 and 48 h of recovery. 30-min smoke exposure showed a more severe degeneration of the epithelium and a longer recovery time. Muc5AC expression decreased after 72 h of recovery, while there was upregulation of Muc4 gene from 48 through 96 h. Because Muc4 upregulation and histological results correlate and it has reportedly been associated with epithelium renewal, Muc4 gene may be a useful marker for the regeneration of tracheal epithelium.

Airway epithelial damage induced by sulfur mustard in guinea pigs, effects of glucocorticoids.

Sulfur mustard (SM) represents a potential chemical warfare agent. In order to characterize SM-induced airway epithelial damage, we studied the effects of an intratracheal injection of 0.3 mg/kg of SM in guinea pigs, 5 h, 24 h, 14 days and 35 days after exposure. During the acute period, lesions prevailed in tracheal epithelium exhibiting intra-epithelial blisters, inflammatory cell infiltration and columnar cell shedding with exposure of basal cells. Fourteen days after intoxication, tracheal epithelium appeared disorganized and showed a significant decrease in height and cell density. Tracheal epithelium recovery was still not complete even 35 days after SM-intoxication. At day 14, in SM-intoxicated guinea pigs treated with betamethasone from day 7 to day 14, epithelium height, cell density and cell proliferation (evaluated by immunohistochemistry) were significantly increased compared to untreated guinea pigs. In conclusion, the lesions observed in SM-intoxicated guinea pigs seem to be in accordance with clinical human observations and are relevant to the study of airway epithelial damage induced by SM. This animal model could be used to illustrate tracheal epithelium regeneration mainly derived from basal cells and to show glucocorticoid effects on airway epithelial recovery after chemical aggression.

Growth and differentiation of tracheal epithelial progenitor cells.

The purpose of these studies was to determine whether both basal and secretory rat tracheal epithelial (RTE) cells served as multipotent epithelial progenitors and whether both cell types gave rise to a similar "poorly differentiated" cell during the early phase of epithelial regeneration in denuded tracheal grafts. Griffonia simplicifolia I (GSI) lectin and flow cytometry were used for cell sorting. More than 98% of GSI-positive cells expressed plasma membrane alpha 1-3 terminal galactose (Gal), and 95% contained keratin 14 (K14), phenotypic markers for basal cells; < 1% were secretory or ciliated cells. Less than 2% of the GSI-negative cells expressed Gal or K14, but this fraction contained 16% ciliated cells and 54-79% secretory cells, dependent on whether periodic acid-Schiff staining or binding of an anti-secretory cell monoclonal antibody (RTE 12) was used as the criterion. Equal numbers of viable cells from either fraction were inoculated into denuded tracheal grafts, which were studied on days 1-14. At 24 h, greater numbers of GSI-negative than -positive cells were found attached to the graft wall; the keratin staining pattern of the attached cells was similar to that of the parent cell populations, but monoclonal antibody-detectable secretory and ciliated cell epitopes, originally present in the GSI-negative fraction, were lost. 5-Bromo-2'-deoxyuridine uptake was not seen at 24 h, but by 48 h all epithelial cells from both fractions entered the cell cycle. From 48 to 96 h, cells derived from either fraction were ultrastructurally indistinguishable; they were poorly differentiated and highly proliferative, and all expressed Gal and K14. A mature epithelium evolved from the poorly differentiated cells in both sets of grafts, but secretory and ciliated cells appeared earlier in grafts inoculated with GSI-negative cells. The results strongly suggest that in this model of tracheal epithelial regeneration both basal and secretory cells "dedifferentiated" into a similar highly proliferative phenotype from which a mucociliary epithelium "redifferentiated."

Expression of "cell-type-specific" markers during rat tracheal epithelial regeneration.

Previous studies showed that Griffonia simplicifolia I-isolectin B4 (GS I-B4) and monoclonal antibodies (mAbs) against keratin 14 labeled basal cells in the adult rat trachea while other mAbs specifically stained secretory and/or ciliated cells. We used these "cell-type-specific" markers to study cellular differentiation during tracheal epithelial regeneration. Denuded tracheal grafts were inoculated with rat tracheal epithelial cells and were implanted in syngeneic hosts. Marker expression was correlated with the appearance of morphologically defined cell types. At 4 days, the epithelium was squamoid, one to three cell layers thick, and was apparently composed of a single morphologic cell type. Because this cell did not exhibit distinguishing features of any mature tracheal cell, we provisionally termed it the "poorly differentiated cell" (PD cell). PD cells expressed keratin 14 and GS I-B4 binding sites; they contained glycogen and had lipid droplets but did not react with secretory or ciliated cell-specific mAbs. At 7 days, areas of the epithelium were pseudostratified and secretory cell-specific markers were present at the apex of differentiating columnar cells; ultrastructurally, these cells resembled secretory cells in adult tracheas. Simultaneously, a few preciliated and ciliated cells appeared that expressed a ciliated cell-specific epitope. No cells were observed coexpressing secretory and ciliated cell markers. Basal cells also became recognizable on day 7. These expressed keratin 14 and GS I-B4 binding sites throughout the study. Newly appearing secretory and ciliated cells also expressed these two markers initially but lost them gradually as the mucociliary epithelium matured. In the tracheal graft model of epithelial regeneration, the PD cells were pivotal intermediates from which all differentiated cells developed. Basal cells continued to express the same markers as PD cells, which were gradually lost in secretory and ciliated cells as they acquired new sets of specific epitopes.

The effect of basic fibroblast growth factor and omentopexy on revascularization and epithelial regeneration of heterotopic rat tracheal isografts

Donor airway ischemia is a significant problem after clinical lung transplantation despite the use of omentopexy for accelerated local bronchial revascularization. Several growth factors have been shown to induce angiogenesis in vitro and in vivo. In the present study the quantitative effects on tracheal revascularization and epithelial regeneration of omentopexy and continuous local administration of basic fibroblast growth factor were investigated in a heterotopic rat tracheal isograft model. Tracheas were harvested from donor rats and heterotopically implanted into the omentum of syngeneic recipient rats. Animals were randomly assigned to study groups differing only in treatment of the tracheal segments: omental wrap for 2, 7, or 14 days; omental wrap plus continuous local administration of basic fibroblast growth factor for 7 or 14 days; or omental wrap plus local application of saline for 7 or 14 days. Two, 7, or 14 days after the animals were put to death, the vascularity of the tracheal segments and attached omentum and the tracheal epithelial morphology were assessed in a blinded fashion with use of light microscopy and morphometric image analysis. Vascularity in tracheal segments treated with basic fibroblast growth factor was significantly (p less than 0.05) greater than in control tracheas after 7 and 14 days. Epithelial regeneration was also improved in the basic fibroblast growth factor-treated groups at days 7 and 14 (p less than 0.05). We conclude that continuous local administration of basic fibroblast growth factor enhances early revascularization of tracheal segments induced by omentopexy and accelerates epithelial regeneration in a heterotopic rat tracheal isograft model.

Microsurgical reconstruction of the trachea in rats: (An experiment study)

This study was carried out to evaluate the use of 'Zenoderm' (enzyme treated procine dermis) as a patch for the repair of tracheal defects in rats, with particular reference to its application in the treatment of some cases of tracheal stenosis. Fifty-three rats were included in the study. Using microsurgical techniques, a defect was created in the cervical trachea and repaired using a suitable patch of 'Zenoderm' (two groups with different sized defects). In a further group of rats, healing of the trachea was studied after excision of a segment and end to end anastomosis. A set number of rats were sacrificed after intervals of 14, 28, 91 and 182 days when the trachea was excised and evaluated. Healing of the tracheae following end to end anastomosis was satisfactory in all cases with no evidence of stenosis. The two groups of tracheae with Zenoderm patches showed progressive stenosis at the area of the repair but there was no evidence of respiratory obstruction or distress. The Zenoderm patch and the regenerating epithelium were both evaluated by light microscopy and scanning electromicroscopy. The Zenoderm patch showed gradual absorption and was replaced by host collagen. There was gradual regeneration of epithelium which showed slow maturation from flat non-ciliated epithelium to partially cuboidal and columnar epithelium with some cilia showing early differentiation to respiratory epithelium. In conclusion, this experimental study confirmed the biocompatibility of 'Zenoderm' in rats. It provided a suitable surface for regeneration of tracheal epithelium. Replacement of the patch by the host collagen is promising but requires further study to assess its rigidity and ability to withstand pressure changes in the trachea.

Regeneration of Tracheal Epithelium after Mechanical Injury in Puppy

Regeneration of Tracheal Epithelium after Mechanical Injury in Puppy

Effect of vitamin A on tracheal epithelial regeneration and its significance for influenzal pneumonia

Das metaplastische Plattenepithel wird als eine Regenerationsart des Bronchialepithels erlautert. Unter hochdosierter Vitamin A-Behandlung wurde statt der ublichen metaplastischen Regeneration eine Direktregeneration des Flimmerepithels beobachtet. Die Komplikation der post-grippalen Bronchopneumonie bei der akuten Grippetracheobronchitis wird als Folge eines Verlustes der Flimmermotilitat bei metaplastischem Ersatz des Flimmerepithels angesehen. Die experimentell mogliche Stimulation des Regenerationsmodus berechtigt zu dem Vorschlag einer Vitamin A-Behandlung bei der Grippetracheobronchitis.

Regeneration of tracheal epithelium.

Regeneration of tracheal epithelium.

Tumorous Growths in the Pituitary and Trachea Following Radio toxic Dosages of I131.

SummaryFollowing doses of radioactive iodine sufficient to cause destruction of most or all of the thyroid, tumorous enlargements were found in the pituitary glands and tracheas of mice. Hypophyseal growths as large as 240 milligrams (control, 2.1 mg) were found. Less than 10%percnt; of animals sacrificed more than 250 days after I131 administration had pituitaries smaller than 10 mg in weight.Tracheal tumors of the fibrous tunica propria, obstructing the tracheal lumen, were of lower incidence (4%percnt;) but appeared earlier. Fibrous thickenings of the tunica propria, and metaplastic regeneration of tracheal epithelium were more common.