Zoledronic acid impairs re-epithelialization through down-regulation of integrin αvβ6 and transforming growth factor beta signalling in a three-dimensional in vitro wound healing model

This study examined the negative effects of zoledronic acid on the re-epithelialization of oral mucosa in a three-dimensional in vitro oral mucosa wound healing model. A living oral mucosa equivalent was constructed by seeding a mixture of primary human oral keratinocytes and fibroblasts, at a cell density of 1.5 × 10⁵ cm² each, onto human cadaver dermis. This was cultured in a submerged condition in 1.2 mM Ca²⁺ EpiLife for 5 days, and then in an air–liquid interface for 14 days. The equivalent was wounded by excising a linear 2-mm-wide epithelial layer on day 8 and subsequently incubated with 10 μM zoledronic acid for an additional 11 days. Histological and immunohistochemical observations revealed zoledronic acid to significantly suppress the epithelial thickness and Ki-67-labelling index. Zoledronic acid also abolished integrin αvβ6 expression, implying impaired keratinocyte migration. Zoledronic acid did not attenuate the total transforming growth factor beta 1 (TGF-β1) production into the supernatant, but down-regulated TGF-β receptor types I and II expression and Smad3 phosphorylation, as was also confirmed by immunofluorescence microscopy. This study therefore showed zoledronic acid to abrogate integrin αvβ6 expression, cause the down-regulation of TGF-β/Smad signalling in oral keratinocytes, and impair re-epithelialization, suggesting compromised oral mucosa homeostasis in patients receiving zoledronic acid.     

Re-epithelialization of the Buccal Mucosa after Alkaline Chemical Injury

Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water and bicarbonate toothpaste. However, the effects of an alkaline pH on the oral mucosa had not been elucidated. The purpose of this study was to investigate how basal keratinocytes are actively involved in re-epithelialization after alkaline chemical injury. We generated epithelial defects in the oral mucosa of mice by applying an alkaline chemical, and the localization of cytokeratin 13, cytokeratin 14, PCNA and p63 was investigated during the re-epithelialization process. PCNA- and p63-positive staining was seen in basal cells covering the wound surface at 1 day after the chemical injury. Cytokeratin 14-positive and PCNA-negative basal keratinocytes were localized in a few layers of the wound epithelium during epithelial outgrowth. Cytokeratin 14-positive and PCNA-positive basal keratinocytes, indicating proliferation, were localized over the entire layer of the epithelium at the wound margin. These results imply that basal keratinocytes at the wound margin migrate to the wound surface, provoke differentiation and keratinization during epithelial outgrowth and that epithelial cells are supplied from the wound margin to the epithelial outgrowth after alkaline chemical injury.     

Therapeutic utility of antibacterial peptides in wound healing

Cationic antimicrobial peptides were first thought to fight infection in animal models by disintegrating bacterial peptides and later by inhibiting bacteria-specific intracellular processes. However, ever increasing evidences indicate that cationic peptides accumulate around and modulate the immune system both systemically and in cutaneous and mucosal surfaces where injuries and infections occur. Native and designer antibacterial peptides as well as cationic peptides, never considered as antibiotics, promote wound healing at every step of cutaneous tissue regeneration. This article provides an introductory list of examples of how cationic peptides are involved in immunostimulation and epithelial tissue repair, eliminating wound infections and promoting wound healing in potential therapeutic utility in sight. Although a few antimicrobial peptides reached the Phase II clinical trial stage, toxicity concerns limit the potential administration routes. Resistance induction to both microbiology actions and the integrity of the innate immune system has to be carefully monitored.     

Predictors for squamous re-epithelialization of Barrett's esophagus after endoscopic biopsy

BACKGROUND AND AIM: Acid suppressive therapy has been reported to regress Barrett's esophagus. However, it is still controversial as to whether all Barrett's esophagus patients respond to this therapy. The factors that might facilitate newly developed squamous re-epithelialization after biopsy excision of Barrett's mucosa were evaluated to identity individuals who may favorably respond to the regression therapy. METHODS: Two hundred and forty-seven biopsy sites from 185 patients with Barrett's esophagus were examined by endoscopy to investigate possible squamous re-epithelialization of Barrett's mucosa after endoscopic biopsy. Before endoscopic examination, all participants were requested to answer questionnaires concerning sociodemographic characteristics, lifestyle habits and drugs usage. The mucin phenotype, Cdx2 expression, cyclooxygenase-2 expression, cellular proliferation and apoptosis of Barrett's mucosa were immunohistochemically investigated in the biopsy samples taken from Barrett's esophagus. The influence of these factors on the newly developed squamous re-epithelialization of Barrett's mucosa after endoscopic biopsy excision was evaluated. RESULTS: By multivariate analysis, the independent factors that favored squamous re-epithelialization were the gastric mucin predominant phenotype of Barrett's mucosa and the absence of Cdx2 protein expression. In Barrett's mucosa with the gastric predominant mucin phenotype, proton pump inhibitor administration, the absence of reflux esophagitis and a low proliferating cell nuclear antigen index were found to be independent predictors for squamous re-epithelialization. CONCLUSIONS: The absence of the intestinal predominant mucin phenotype was a positive predictor for newly developed squamous re-epithelialization at the site of biopsy of Barrett's mucosa. Only Barrett's esophagus with the gastric predominant mucin phenotype may predict a favorable response to acid suppressive therapy.     

Transgenic overexpression of keratinocyte-specific VEGF and Ang1 in combination promotes wound healing under nondiabetic but not diabetic conditions

VEGF and Angiopoietin (Ang)1 are growth factors that independently improve wound healing outcomes. Using a tet-repressible mouse model coupled with streptozotocin-induced diabetes, we examined wound healing in diabetic and nondiabetic mice engineered to overexpress keratinocyte-specific (K5) VEGF, Ang1 or Ang1-VEGF combined. All nondiabetic mice healed more rapidly than their diabetic counterparts; however overexpression of VEGF, Ang1 or the combination failed to improve wound closure under diabetic conditions. Conversely, under nondiabetic conditions, combining Ang1 and VEGF resulted in rapid wound closure. Molecular analyses of diabetic and nondiabetic K5-Ang1-VEGF skin revealed no differences in VEGF expression but an 80% decrease in Ang1 under diabetic conditions, suggesting an integral role for Ang1. Nondiabetic K5-Ang1 mice healed more quickly and had significant increases in granulation tissue and a 60% decrease in re-epithelialization 7 days after wounding. Furthermore, Ang1 stimulated primary mouse keratinocytes showed significantly less migration into a wound bed in an in vitro wound healing bioassay and had decreased pMAPK, pNFκB, pAkt, and pStat3 signaling. These data suggest that combined Ang1-VEGF overexpression cannot overcome diabetes-induced delays in wound healing but is efficacious under nondiabetic conditions possibly via Ang1-mediated delays in re-epithelialization and enhancement of granulation tissue formation, thereby allowing more rapid secondary intention healing.     

The Effect of Amino Acids on Wound Healing: A Systematic Review and Meta-Analysis on Arginine and Glutamine

Under stress conditions, the metabolic demand for nutrients increases, which, if not met, may slow down or indeed stop the wound from healing, thus, becoming chronic wounds. This study aims to perform a systematic review and meta-analysis of the effect of arginine and glutamine supplementation on wound healing. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed for the systematic review and ten electronic databases were used. Five and 39 human studies met the inclusion criteria for arginine and glutamine, respectively. The overall meta-analysis demonstrated a significant effect of arginine supplementation on hydroxyproline content (MD: 4.49, 95% CI: 3.54, 4.45, p < 0.00001). Regarding glutamine supplementation, there was significant effect on nitrogen balance levels (MD: 0.39, 95% CI: 0.21, 0.58, p < 0.0001), IL-6 levels (MD: −5.78, 95% CI: −8.71, −2.86, p = 0.0001), TNFα levels (MD: −8.15, 95% CI: −9.34, −6.96, p < 0.00001), lactulose/mannitol (L/M) ratio (MD: −0.01, 95% CI: −0.02, −0.01, p < 0.00001), patient mortality (OR: 0.48, 95% CI: 0.32, 0.72, p = 0.0004), C-reactive protein (CRP) levels (MD: −1.10, 95% CI: −1.26, −0.93, p < 0.00001) and length of hospital stay (LOS) (MD: −2.65, 95% CI: −3.10, −2.21, p < 0.00001). Regarding T-cell lymphocytes, a slight decrease was observed, although it failed to reach significance (MD: −0.16, 95% CI: −0.33, 0.01, p = 0.07). Conclusion: The wound healing might be enhanced in one or at various stages by nutritional supplementation in the right dose.     

Cost-Effectiveness of a Nonpharmacological Intervention in Pediatric Burn Care

ObjectiveTo report the cost-effectiveness of a tailored handheld computerized procedural preparation and distraction intervention (Ditto) used during pediatric burn wound care in comparison to standard practice.MethodsAn economic evaluation was performed alongside a randomized controlled trial of 75 children aged 4 to 13 years who presented with a burn to the Royal Children’s Hospital, Brisbane, Australia. Participants were randomized to either the Ditto intervention (n = 35) or standard practice (n = 40) to measure the effect of the intervention on days taken for burns to re-epithelialize. Direct medical, direct nonmedical, and indirect cost data during burn re-epithelialization were extracted from the randomized controlled trial data and combined with scar management cost data obtained retrospectively from medical charts. Nonparametric bootstrapping was used to estimate statistical uncertainty in cost and effect differences and cost-effectiveness ratios.ResultsOn average, the Ditto intervention reduced the time to re-epithelialize by 3 days at AU$194 less cost for each patient compared with standard practice. The incremental cost-effectiveness plane showed that 78% of the simulated results were within the more effective and less costly quadrant and 22% were in the more effective and more costly quadrant, suggesting a 78% probability that the Ditto intervention dominates standard practice (i.e., cost-saving). At a willingness-to-pay threshold of AU$120, there is a 95% probability that the Ditto intervention is cost-effective (or cost-saving) against standard care.ConclusionsThis economic evaluation showed the Ditto intervention to be highly cost-effective against standard practice at a minimal cost for the significant benefits gained, supporting the implementation of the Ditto intervention during burn wound care.     

A Randomized Controlled Trial of Silver Sulfadiazine, Biafine, and Saline-soaked Gauze in the Treatment of Superficial Partial-thickness Burn Wounds in Pigs

Silver sulfadiazine 1% cream (SSD) and biafine (an oil-in-water emulsion containing alginate) are used for the treatment of superficial partial-thickness burns, but comparative effectiveness studies are lacking. OBJECTIVES: To compare the uses of SSD, Biafine (Labortoires Medix, Houdan, France), and saline-soaked gauze in the treatment of superficial partial-thickness burns in pigs. METHODS: This was a randomized controlled trial in four anesthetized young pigs. Four equal sets of partial-thickness contact burns were inflicted on the pigs. Each burn was randomly assigned to treatment with biafine, SSD, or saline-soaked gauze with dressing changes every other day. Assessment of wound re-epithelialization was performed every other day, for a total of two weeks. The treatment groups were compared by univariable and multivariable analyses of variance (ANOVAs), controlling for the pig and the location of the burns on each pig. RESULTS: Thirty-two burns were inflicted on the pigs. Time to re-epithelialization of the burns was 13.5 days (SD +/- 0.9 days) in pigs treated with biafine, 13.3 days (+/-1.3 days) in pigs treated with SSD, and 13.5 days (+/-1.0 days) in pigs treated with saline-soaked gauze (p = not significant [NS]). The decreases in burn area from day 2 to day 12 were 21.4 cm(2) (+/-6.0 cm(2)) in pigs treated with biafine, 20.0 cm(2) (+/-6.3 cm(2)) in pigs treated with SSD, and 19.8 cm(2) (+/-5.9 cm(2)) in pigs treated with saline-soaked gauze (p = NS). A multivariable ANOVA showed a similar decrease in burn area between the treatment arms (p = NS) and a significant difference between the pigs (p = 0.015). CONCLUSION: Partial-thickness porcine burns treated with SSD, biafine, and soaked saline gauze re-epithelialize at similar rates.     

REG Ialpha protein expression in Barrett's esophagus

Background and Aim: Accelerated cellular proliferation in Barrett's esophagus has been implicated in Barrett's elongation and malignant transformation. Therefore, growth factors may play important roles in the pathophysiology of Barrett's esophagus. Regenerating gene (REG), an epithelial growth factor, has been reported to link mucosal inflammation and subsequent carcinogenesis in the gastrointestinal tract. The aim of this study was to investigate whether REG is expressed in Barrett's esophagus and to elucidate the relationship between REG protein expression and clinicopathological factors of Barrett's esophagus. Methods: Between July 2003 and June 2004, 266 patients with endoscopically and histologically proven Barrett's esophagus were enrolled in this study. Before endoscopic examination, all participants were requested to answer structured questionnaires on gastroesophageal reflux symptoms and drugs usage. Mucin phenotype, cyclooxygenase‐2 expression, cellular proliferation, apoptosis and REG Iα protein expression were investigated in the biopsy samples taken from Barrett's esophagus. Clinicopathological factors that correlated with REG Iα protein expression in patients with Barrett's esophagus were evaluated using multivariate logistic regression analysis. Results: REG Iα protein expression was observed in 48 (18.0%) of 266 patients with Barrett's esophagus by immunohistochemistry. Newly developed squamous re‐epithelialization of Barrett's esophagus at biopsy sites, presence of hiatal hernia and aging were shown to correlate with REG Iα protein expression. Conclusions: The present study is the first to show REG expression in Barrett's esophagus. Expression of REG Iα was more frequently observed in patients who showed squamous re‐epithelialization of Barrett's esophagus at biopsy sites.