Effects of epidermal growth factor (EGF) on the development of EGF-receptor (EGF-R) binding in fetal rabbit lung organ culture

3D printing technology and applied materials in eardrum regeneration

Tympanic membrane perforation is a common condition in clinical otolaryngology. Although some eardrum patients can self-heal, a long period of non-healing perforation leads to persistent otitis media, conductive deafness, and poor quality of life. Tympanic membrane repair with autologous materials requires a second incision, and the sampling site may get infected. It is challenging to repair tympanic membranes while maintaining high functionality, safety, affordability, and aesthetics. 3D bioprinting can be used to fabricate tissue patches with materials, factors, and cells in a design manner. This paper reviews 3D printing technology that is being used widely in recent years to construct eardrum stents and the utilized applied materials for tympanic membrane repair. The paper begins with an introduction of the physiological structure of the tympanic membrane, briefly reviews the current clinical method thereafter, highlights the recent 3D printing-related strategies in tympanic membrane repair, describes the materials and cells that might play an important role in 3D printing, and finally provides a perspective of this field.

miR-124 regulates fetal pulmonary epithelial cell maturation

MicroRNAs are a family of small noncoding RNAs that regulate the expression of their target proteins at the posttranscriptional level. Their functions cover almost every aspect of cell physiology. However, the roles of microRNAs in fetal lung development are not completely understood. The objective of this study is to investigate the regulation and molecular mechanisms of alveolar epithelial cell maturation during fetal lung development by miR-124. We discovered that miR-124 was downregulated during rat fetal lung development and predominantly expressed in the epithelial cells at late stage of the lung development. Overexpression of miR-124 with an adenovirus vector led to the inhibition of epithelial maturation in rat fetal lung organ cultures and fetal alveolar epithelial type II cells, as demonstrated by a decrease in the type II cell marker expression and an increase in glycogen content. We further demonstrated by luciferase reporter assays that miR-124 inhibited the NF-κB, cAMP/PKA, and MAPK/ERK pathways. In addition, nuclear factor I/B (NFIB), a critical protein in fetal lung maturation, was validated as a direct target of miR-124. Furthermore, miR-124 expression was induced by the Wnt/β-catenin signaling pathway through a direct interaction of LEF1 and the miR-124 promoter region. We concluded that miR-124 downregulation is critical to fetal lung epithelial maturation and miR-124 inhibits this maturation process at least partially through the inhibition of NFIB.

Role of epidermal growth factor in pathogenesis of uterine leiomyomas

OBJECTIVE

To investigate the role of epidermal growth factor (EGF) in the pathogenesis of uterine leiomyomas.

METHODS

Human myometrial smooth muscle cells (HM-SMCs) and smooth muscle cells of human uterine leiomyomas (HL-SMCs) were separated from patients' specimens and cultured. After processed by EGF or PD98059 (inhibitor of MKK/MEK) +EGF, the proliferation rate of both SMCs was detected by BrdU method and the phosphorylation level of p44/42 mitogen-activated protein kinase (MAPK) was determined by Western-blot. After different processing time by EGF, the phosphorylation levels of p44/42 MAPK and AKT and p27 expression level in both SMCs were detected by Western-blot.

RESULTS

EGF could significantly promote HL-SMCs proliferation and PD98059 could inhibit this effect (P<0.05); besides, PD98059 could inhibit the increase of the phosphorylation level of p44/42 MAPK in both SMCs induced by EGF. When the processing time by EGF was over 15min, the phosphorylation levels of p44/42 MAPK and AKT in both SMCs decreased sharply and were close to zero; p27 expression in HM-SMCs raised significantly while the upregulation in HL-SMCs was little.

CONCLUSIONS

EGF could not cause activation of EGFR because of the dephosphorylation of p44/42 MAPK and AKT in HL-SMCs, which caused p27 expression insufficiently and cell cycle dysregulation.

Role of matrix metalloprotease-9 in hyperoxic injury in developing lung

Matrix metalloprotease-9 (MMP-9) is increased in lung injury following hyperoxia exposure in neonatal mice, in association with impaired alveolar development. We studied the role of MMP-9 in the mechanism of hyperoxia-induced functional and histological changes in neonatal mouse lung. Reduced alveolarization with remodeling of ECM is a major morbidity component of oxidant injury in developing lung. MMP-9 mediates oxidant injury in developing lung causing altered lung remodeling. Five-day-old neonatal wild-type (WT) and MMP-9 (-/-) mice were exposed to hyperoxia for 8 days. The lungs were inflation fixed, and sections were examined for morphometry. The mean linear intercept and alveolar counts were evaluated. Immunohistochemistry for MMP-9 and elastin was performed. MMP-2, MMP-9, type I collagen, and tropoelastin were measured by Western blot analysis. Lung quasistatic compliance was studied in anaesthetized mice. MMP-2 and MMP-9 were significantly increased in lungs of WT mice exposed to hyperoxia compared with controls. Immunohistochemistry showed an increase in MMP-9 in mesenchyme and alveolar epithelium of hyperoxic lungs. The lungs of hyperoxia-exposed WT mice had less gas exchange surface area and were less compliant compared with room air-exposed WT and hyperoxia-exposed MMP-9 (-/-) mice. Type I collagen and tropoelastin were increased in hyperoxia-exposed WT with aberrant elastin staining. These changes were ameliorated in hyperoxia-exposed MMP-9 (-/-) mice. MMP-9 plays an important role in the structural changes consequent to oxygen-induced lung injury. Blocking MMP-9 activity may lead to novel therapeutic approaches in preventing bronchopulmonary dysplasia.

The role of IL-6 and IL-11 in hyperoxic injury in developing lung

We examined the cytoprotective effect of interleukin-6 (IL-6) and interleukin-11 (IL-11) during oxidant injury in neonatal lung and the regulators of cell death in vitro and in vivo after oxidant exposure. Type II cells from day 21 fetal neonatal rat lungs were treated with varying concentrations of either IL-6 or IL-11 for 24 hr prior to exposure to H(2)O(2). Three-day-old transgenic lung-specific IL-11 and IL-6 overexpressing and wild type (WT) mouse pups were exposed to hyperoxia or room air for 3 days. Type II cells exposed to either IL-6 or IL-11 prior to oxidant injury exhibited improved survival compared to controls, 67% +/- 2.6 survivals in IL-6 pretreated cells compared to 48% +/- 1.6 in control; 63% +/- 3 survivals in IL-11 pretreated cells compared to 49% +/- 2.6 in control. The number of TUNEL positive cells in hyperoxia-exposed lungs was increased compared to room air animals (27 +/- 0.9 vs. 4 +/- 0.4; mean +/- SEM; P < 0.05). In contrast, the number of TUNEL positive cells was reduced in hyperoxia-exposed lungs from IL-11 (+) mice (15.2 +/- 2.2; mean +/- SEM; P < 0.05). There was an enhanced accumulation of Bcl-2 and reduction of Bax protein in hyperoxia-exposed IL-11 (+) compared to room air-exposed mice. This was not seen in hyperoxia-exposed IL-6 (+) pups. An increase in caspase-3 was seen in hyperoxia-exposed lungs of WT pups compared to IL-11 (+) pups. IL-11 and IL-6 provide protective effects against oxidant-mediated injury in fetal type II cells and IL-11 provides protection in vivo by down-regulation of caspase-mediated cell death.

Inhibition of EGFR signaling abrogates smooth muscle proliferation resulting from sustained distension of the urinary bladder

Urinary bladder outlet obstruction results in sustained stretch of the detrusor muscle and can lead to pathological smooth muscle hyperplasia and hypertrophy. The epidermal growth factor receptor (EGFR) is a cognate receptor for mitogens implicated in bladder hyperplasia/hypertrophy. Here, we investigated the potential for modulation of this pathway by pharmacologic targeting with a clinically available EGFR antagonist using an organ culture model of bladder stretch injury as a test system. Urinary bladders from adult female rats were distended in vivo with medium containing the EGFR inhibitor ZD1839 (gefitinib, Iressa). The bladders were excised and incubated in ex vivo organ culture for 4-24 h. EGFR phosphorylation, DNA proliferation, and the extent of apoptosis in the cultured tissues were assessed. To verify that the smooth muscle cells (SMC) are a target of the EGFR inhibitor, primary culture human and rat bladder SMC were subjected to cyclic mechanical stretch in vitro in the presence of ZD1839. Levels of phosphorylated EGFR were significantly increased in the detrusor muscle with 12 h of stretch in the organ cultures. This activation coincided with a subsequent 23-fold increase in DNA synthesis and a 30-fold decrease in apoptosis in the muscle compartment at 24 h. In the presence of ZD1839, DNA synthesis was reduced to basal levels without an increase in the rate of apoptosis under ex vivo conditions. Mechanical stretch of bladder SMC in vitro resulted in a significant increase in DNA synthesis, which was completely abrogated by treatment with ZD1839 but not by AG825, an inhibitor of the related receptor, ErbB2. Our results indicate that the EGFR pathway is a physiologically relevant signaling mechanism in hypertrophic bladder disease resulting from mechanical distension and may be amenable to pharmacologic intervention.