Analysis of gene expression profiles in tympanic membrane following perforation using PCR Array in rats--preliminary investigation

Enhanced Expression of Plasminogen Activators and Inhibitor in the Healing of Tympanic Membrane Perforation in Rats

The significance of plasminogen activation during the tympanic membrane (TM) healing is known mainly from studies performed on knock-out mice. In the previous study, we reported activation of genes coding proteins of plasminogen activation and inhibition system in rat's TM perforation healing. The aim of the present study was the evaluation of protein products expressed by these genes and their tissue distribution using Western blotting and immunofluorescent method, respectively, during 10-day observation period after injury. Otomicroscopical and histological evaluation were employed to assess the healing process. The expression of urokinase plasminogen activator (uPA) and its receptor (uPAR) were significantly upregulated in the proliferation phase, with subsequent gradual attenuation during remodeling phase of healing process, when keratinocyte migration was weakening. The expression of plasminogen activator inhibitor type 1 (PAI-1) also showed the highest levels during the proliferation phase. The increase of tissue plasminogen activator (tPA) expression was observed during the whole observation period, with the highest activity during the remodeling phase. Immunofluorescence of these proteins was present mainly in migrating epithelium. Our study found that plasminogen activation (uPA, uPAR, tPA) and inhibitory (PAI-1) molecules form a well-structured regulatory system of the epithelial migration that is critical to the healing of TM after its perforation.

Single Dose of N-Acetylcysteine in Local Anesthesia Increases Expression of HIF1α, MAPK1, TGFβ1 and Growth Factors in Rat Wound Healing

In this study, we aimed to investigate the influence of N-acetylcysteine (NAC) on the gene expression profile, neoangiogenesis, neutrophils and macrophages in a rat model of incisional wounds. Before creating wounds on the backs of 24 Sprague-Dawley rats, intradermal injections were made. Lidocaine-epinephrin solutions were supplemented with 0.015%, 0.03% or 0.045% solutions of NAC, or nothing (control group). Scars were harvested on the 3rd, 7th, 14th and 60th day post-surgery. We performed immunohistochemical staining in order to visualize macrophages (anti-CD68), neutrophils (anti-MPO) and newly formed blood vessels (anti-CD31). Additionally, RT-qPCR was used to measure the relative expression of 88 genes involved in the wound healing process. On the 14th day, the number of cells stained with anti-CD68 and anti-CD31 antibodies was significantly larger in the tissues treated with 0.03% NAC compared with the control. Among the selected genes, 52 were upregulated and six were downregulated at different time points. Interestingly, NAC exerted a significant effect on the expression of 45 genes 60 days after its administration. In summation, a 0.03% NAC addition to the pre-incisional anesthetic solution improves neovasculature and increases the macrophages' concentration at the wound site on the 14th day, as well as altering the expression of numerous genes that are responsible for the regenerative processes.

Expression of collagen type III in healing tympanic membrane

OBJECTIVES

Type III collagen plays significant role in skin wound healing, forming provisional matrix guiding the inflammatory cells and fibroblasts into the wound site. Our preliminary study performed on rat's tympanic membrane (TM) using Rat Wound Healing RT2 Profiler PCR Array revealed up-regulated expression of collagen type III α1 chain mRNA also during healing of TM. This study was undertaken to confirm and evaluate collagen type III protein expression and distribution during TM healing process.

METHODS

Sixty rats were used, of which 10 served as controls and the others had their TM perforated. The experimental animals were divided into five subgroups on the basis of time points (03, 06, 09, 14, 20 day after injury). Videootoscopy and histology were employed to assess morphology of the healing process. The expression of collagen type III was evaluated using Western blot analysis and its tissue localization was determined by the immunohistochemical method.

RESULTS

The expression of collagen type III remained on the same level as in control TM up to day 06. On day 09 abrupt (p = 0.01) increase of the collagen type III expression was observed and it maintained on the same level to the end of observation period. In perforated TM collagen type III was detected in the healing area along the perforation border and around dilated blood vessels. On day 14 and 20 collagen type III was found in the connective tissue filling up the TM previous defect.

CONCLUSIONS

Taking into consideration our recent and previous data, as well as results obtained by other authors, is seems possible that the increase of collagen type III expression in the late stage of TM healing contributes to proper scar formation.

Expression of collagens type I and V in healing rat's tympanic membrane

OBJECTIVES

Our preliminary study performed on perforated rat's tympanic membrane (TM) using Rat Wound Healing RT2 Profiler PCR Array showed significantly increased levels of mRNA for collagens type I and V. Enhanced expression of those genes does not assure that their protein products are indeed present, and in what quantity. Therefore, this study was undertaken to analyze the collagen type I and V content in the healing TM.

METHODS

Sixty rats were used, of which 10 served as controls and the others had their TM perforated. The experimental animals were divided into five subgroups on the basis of time points (03, 06, 09, 14, 20 day after injury). Videootoscopy and histology were employed to assess the morphology of the healing process. The expression of collagen type I and V was evaluated using Western blot analysis. Tissue localization of collagens was determined by the immunofluorescence method.

RESULTS

The collagen type I expression was three times higher on the third day after injury and remained on that level for whole period of observation, up to day 20. The increase of the collagen type V expression was gradual, reaching the highest level on day 14 following injury. In comparison to the control TM statistically significant increase in the level of expression was observed starting from day 09 to the end of observation period. In healing TM immunofluorescent labeling of collagen type I and V was seen on the surface of remnants of previous lamina propria and in the loose proliferating fibrous tissue. On day 20 immunofluorescence was present mainly on the surface of thin connective tissue layers forming the scar in the place of previous perforation.

CONCLUSION

Although the collagens type I and V are present only in subepithelial layer in the normal rat's TM they play significant role in TM healing process.

Rat model of chronic tympanic membrane perforation: A longitudinal histological evaluation of underlying mechanisms

OBJECTIVE

To evaluate histologically the progressive development and underlying mechanisms of chronic tympanic membrane perforation (TMP) in a rat model using a two-weeks ventilation tube (VT) treatment combined with topical application of mitomycin C/dexamethasone (VT-M/D), compared with normal tympanic membrane and acute TMPs.

METHODS

Fifty male Sprague-Dawley rats were divided into three experimental groups: a normal control group (n = 5), an acute TMP group (n = 5) (i.e. 3 days post-myringotomy) and a VT-M/D group (n = 40). The TMs were regularly assessed by otoscopy. The normal control animals were sacrificed on day 0 and the acute TMP group was sacrificed 3 days post-myringotomy for histological and immunohistochemical evaluations. The VT-M/D group was sacrificed at various time points - 14 and 17 days, 3, 4, 6, 8 and 10 weeks.

RESULTS

On longitudinal histological examination, compared with normal TM and acute TMP, the perforation edges at the later time points illustrated thickened stratified squamous epithelium rimming around the edges, significant increase in keratin and collagen deposition, increased macrophage infiltration as well as reduced cellular proliferation. Three phases of TMP healing process were identified - the acute healing phase (3-17 days), the transition phase (3-4 weeks) and the chronic phase (6-10 weeks).

CONCLUSION

Based on the histological results of this study, the progressive development of chronic TMPs appeared to be associated with increased epidermal thickening, collagen and keratin deposition, macrophage infiltration and reduced cellular proliferation. After the 3-4 weeks of transition phase, the TMPs seemed to have transformed into a non-healing chronic TMP between 6 and 10 weeks.

Mitochondrial and Metabolic Gene Expression in the Aged Rat Heart

Aging is associated with a decline in cardiac function. Exercise intervention has been suggested as a way to improve this decrement. Age-related decline in cardiac function is associated with decreases in fatty acid oxidation, mitochondrial function, and AMP-activated protein kinase (AMPK) activity. The molecular mechanisms involved with age-related changes in mitochondrial function and substrate metabolism are poorly understood. We determined gene expression differences in hearts of Young (6 mo), Old (33 mo), and old exercise trained (Old + EXE) (34 mo) FBN rats, using Qiagen PCR arrays for Glucose, Fatty acid, and Mitochondrial metabolism. Old rats demonstrated decreased (p < 0.05) expression for key genes in fatty acid oxidation, mitochondrial function, and AMPK signaling. There were no differences in the expression of genes involved in glucose metabolism with age. These gene expression changes occurred prior to altered protein translation as we found no differences in the protein content of peroxisome proliferator activated receptor gamma, coactivators 1 alpha (PGC-1α), peroxisome proliferator activated receptor alpha (PPARα), and AMPKα₂ between young and old hearts. Four months of exercise training did not attenuate the decline in the gene expression in aged hearts. Despite this lack of change in gene expression, exercise-trained rats demonstrated increased exercise capacity compared to their sedentary counterparts. Taken together, our results show that differential expression of genes associated with fatty acid metabolism, AMPK signaling and mitochondrial function decrease in the aging heart which may play a role in age-related declines in fatty acid oxidation, AMPK activity, and mitochondrial function in the heart.

Dietary Cocoa Powder Improves Hyperlipidemia and Reduces Atherosclerosis in apoE Deficient Mice through the Inhibition of Hepatic Endoplasmic Reticulum Stress

Cocoa powder is rich in flavonoids, which have many beneficial effects on human health, including antioxidative and anti-inflammatory effects. The aim of our study was to investigate whether the intake of cocoa powder has any influence on hyperlipidemia and atherosclerosis and examine the underlying molecular mechanisms. We fed apoE knockout mice a Western diet supplemented with either 0.2% (low group) or 2% (high group) cocoa powder for 12 weeks. The groups fed dietary cocoa powder showed a significant reduction in both plasma cholesterol levels and aortic atherosclerosis compared to the control group. Analysis of mRNA profiling of aortic atherosclerotic lesions revealed that the expression of several genes related to apoptosis, lipid metabolism, and inflammation was significantly reduced, while the antiapoptotic gene Bcl2 was significantly increased in the cocoa powder group compared to the control. RT-PCR analysis along with Western blotting revealed that a diet containing cocoa powder inhibited the expression of hepatic endoplasmic reticulum stress. These data suggest that cocoa powder intake improves hyperlipidemia and atherosclerosis, and such beneficial effects are possibly mediated through the suppression of hepatic endoplasmic reticulum stress.

Enhanced expression of hepatocyte growth factor in the healing of experimental acute tympanic membrane perforation

OBJECTIVES

The present study was performed to investigate the expression of hepatocyte (HGF), epidermal (EGF) and vascular endothelial (VEGF) growth factors in the course of healing of experimental tympanic membrane (TM) perforations in rats. The goal was to explain the role of these growth factors in the healing process of TM and to assess the possibility of their future application as healing promoters.

METHODS

Seventy rats were used, of which 10 served as controls and the others had their TM perforated. The experimental animals were divided into six subgroups on the basis of time points (01, 03, 05, 07, 09, 15 day after injury). Videootoscopy and histology were employed to assess the morphology of the healing process. The expressions of HGF, EGF and VEGF were evaluated using Western blot analysis. Tissue localization of HGF was determined by the immunofluorescence method.

RESULTS

HGF was hardly detectable in normal TM; however, a significant increase was noted in its expression starting from the third day after injury throughout the follow-up period, with the highest level on day 05. The analysis of HGF tissue localization with immunofluorescence revealed diffuse staining in the cytoplasm of proliferating epithelial cells. The expression of EGF was elevated on the first day after injury, not reaching statistical significance, and then returned to the level observed in the control TM. No significant differences were noted in the expression of VEGF.

CONCLUSION

High expression of HGF during the healing process of acute TM perforations makes it a promising candidate for further studies oriented towards its possible use in augmentation of TM healing.

The effects of insulin-like growth factor-1 gene therapy and cell transplantation on rat acute wound model

BACKGROUND

Wound healing is a complex process. Different types of skin cells, extracellular matrix and variety of growth factors are involved in wound healing. The use of recombinant growth factors in researches and production of skin substitutes are still a challenge.

OBJECTIVES

Much research has been done on the effects of gene therapy and cell therapy on wound healing. In this experimental study, the effect of insulin-like growth factor (IGF-1) gene transfer in fibroblast cells was assessed on acute dermal wound healing.

MATERIALS AND METHODS

Fibroblasts were cultured and transfected with IGF-1. Lipofectamine 2000 was used as a reagent of transfection. Transgene expression levels were measured by the enzyme linked immunosorbent assay (ELISA). To study in vivo, rats (weighing 170-200 g) were randomly divided into three groups (five/group) and full-thickness wounds were created on the dorsum region. Suspensions of transfected fibroblast cells were injected into the wound and were compared with wounds treated with native fibroblast cells and normal saline. For the microscopic examination, biopsy was performed on day seven.

RESULTS

In vitro, the maximum expression of IGF1 (96.95 pg/mL) in transfected fibroblast cells was 24 hours after gene transfer. In vivo, it was clear that IGF-1 gene therapy caused an increase in the number of keratinocyte cells during the wound healing process (mean of group A vs. group B with P value = 0.01, mean of group A vs. group C with P value = 0.000). Granulation of tissue formation in the transfected fibroblast group was more organized when compared with the normal saline group and native fibroblast cells.

CONCLUSIONS

This study indicated that the optimization of gene transfer increases the expression of IGF-1. High concentrations of IGF-1, in combination with cell therapy, have a significant effect on wound healing.

Ethanolic extract of sharah, Plectranthus aegyptiacus, enhances healing of skin wound in rats

Sharah, Plectranthus aegyptiacus (Forssk.) C. Chr. is a common native plant in the Taif region of Saudi Arabia. An ethanolic extract of freeze dried sharah leaves was added as 10% (w/w) to an ointment base of beeswax and sesame oil. The resultant ointment was examined as a potential enhancer of wound healing. Excision wounds in the nape region of the skin were induced in sixty albino Wistar rats. Animals were allocated in 4 groups (n=15) and kept individually in clean cages. The first group served as negative untreated controls without medication; the second group was treated with ointment base (vehicle); the third group represented the positive control and was treated with a reference ointment and the fourth one served as the experimental group and received the test plant extract (as ointment). Animal groups received the respective medications for 14 successive days. Wounds were measured and photographed every 3 days till the end of the experiment (day 21) in order to determine the wound closure rate (WCR). Specimens from wounds and surrounding skin were collected from sacrificed animals for histological and molecular studies. Both morphometric (based on WCR) and histological findings showed that the healing in animals treated with the sharah plant extract was better than those in control group or vehicle-treated group and was similar to that in the group that received the reference ointment. Moreover, the molecular findings concerning the expression levels of hepatocyte growth factor (HGF) and its receptor (c-Met) displayed a reasonable healing enhancing effect of the plant extract with the expression levels of both being higher in the extract-treated group than in the control group.