The preventive effect of halofuginone on posterior glottic stenosis in a rabbit model

An Acquired Anterior Glottic Web Model by Heat Injury with a Laryngoscopic Approach in a Rabbit

Acquired anterior glottic webs (AGW) can lead to abnormally elevated phonatory pitch, dysphonia, and airway obstruction requiring urgent intervention. In this study, we construct a novel AGW rabbit model using heat injury by a laryngoscopic way. A primary study was conducted to identify the injury depth in rabbits' vocal folds (VFs) by graded heat energy, and the heat energy for the incurrence of epithelial layer, lamina propria, and muscular layer (ML) injury was 25, 30 and 35 W, respectively. Then, four different models were designed based on the depth and degree of the injury to determine the optimal procedure for AGW formation. Morphological features, vibratory capacity, and histopathologic features of the AGW were correspondingly evaluated. The procedure for conferring the heat injury to the depth of ML and the extent of anterior commissure and middle part of bilateral VFs showed the highest success rate of AGW formation (95%, 19/20). For its low cost, effectiveness, and stability for AGW formation, the heat injury rabbit model with a laryngoscopic approach may provide a new platform for testing novel anti-adhesion materials and bioengineered therapies. Impact Statement Tissue engineering based on biomaterials has been a very hot research field and may be introduced to prevent the acquired anterior glottic web (AGW) formation. However, lacking a widely recognized animal model for AGW has limited the trial of anti-adhesion materials in the larynx. In this study, we have developed a novel rabbit model for AGW formation by conferring a heat injury under a laryngoscope; this model is cheap, effective, and stable for the anti-adhesion materials and bioengineered therapies. Thus, this research would arouse crucial interest and be widely employed.

Effects of corticosteroids vs halofuginone on vocal fold wound healing in an ovine model

OBJECTIVES

To evaluate antifibrotic effects of corticosteroids and halofuginone, a small molecule inhibitor of Smad3, in an ovine model of vocal fold (VF) injury.

METHODS

Thirty sheep, using a paired study design, underwent controlled right VF injury by biopsy and then were treated with either no treatment, oral dexamethasone, intralesional triamcinolone, or oral halofuginone. Larynges were evaluated for histological evidence of fibrosis, immunohistochemical presence of Smad3, and vibratory parameters. Outcomes were compared across treatment groups.

RESULTS

Following injury, VF collagen density decreased in both halofuginone-treated and dexamethasone-treated sheep but not in triamcinolone treated sheep. A significant difference was noted between halofuginone and triamcinolone treated sheep (27.8% vs 37%, P = .017). Elastin was preserved postinjury by halofuginone treatment in contrast with all steroid treated animals where significant loss of elastin was noted (P <.05). Smad3 staining was up-regulated at all injury sites compared to normal left VFs however halofuginone and dexamethasone treatment reduced Smad3 activity significantly whereas triamcinolone treatment did not (P <.05). Ex-vivo stroboscopic evaluation demonstrated mucosal wave in all excised larynges with a normalized glottal gap less than 3, suggesting adequate glottal closure.

CONCLUSIONS

VF injury in an ovine model results in a wound response able to be modified by Smad3 inhibitor, halofuginone, with benefit to vibratory function. Halofuginone treated sheep demonstrated reduced collagenization of lamina propria with greater elastin density after injury, than sheep treated with either steroid medication. These data support this pathway as a suitable target for manipulation to prevent or reverse fibrosis in the glottis and restore voice quality.Level of Evidence: NA.

The Effects of Halofuginone on Wound Healing in the Rat Nasal Mucosa

Background

Halofuginone is an alkaloid febrifugine analogue and bioactive molecule that was isolated incidentally from the Dichroa febrifuga plant. The therapeutic efficacy of halofuginone in parasitic infections, scleroderma, inflammation, and fibrosis-related diseases, as well as in some types of cancer, has been previously reported. The effects of halofuginone on nasal mucosal damage are not yet known.

Objective

The aim of this study was to investigate the potential effect of topically applied halofuginone on wound healing in the mechanically injured nasal mucosa of rats.

Methods

A unilateral mucosal wound was created in the nasal cavity of 32 rats (aged 4 weeks) using the brushing technique. These rats were randomly divided into 4 groups. Although the control group did not receive an intervention, a dry pad, a saline-impregnated pad, or a pad impregnated with halofuginone were placed in the rats of the other 3 groups and left for 5 minutes. Rats were sacrificed on the 14th day, and a histological examination was performed. The nasal mucosa was assessed via hematoxylin-eosin and Masson’s trichrome staining.

Results

There were no statistically significant differences in epithelial thickness, inflammation, goblet cell formation, and epithelial disarray values between the halofuginone group and the control group ( P > .05). The subepithelial thickness was significantly decreased in the saline-treated group and the halofuginone-treated group ( P < .05), but a significantly lower level of subepithelial fibrosis was only observed in the halofuginone group compared to the other groups ( P < .05).

Conclusions

Topical halofuginone administration reduces the development of fibrosis and subepithelial edema after experimentally induced nasal mucosal injury, but it does not exert therapeutic or preventive effects on epithelial damage, inflammation, and goblet cell hyperplasia.

Profilactic role of simvastatin and mitomycin C in tracheal stenosis after tracheal damage: Study in rats

OBJECTIVES

We aimed to investigate the prophylactic effect simvastatin of and mitomycin C (MMC) on laryngeal and tracheal stenosis in tracheotomised rats by histopathological evaluation of laryngotracheal segment. Randomized prospective single-blind.

MATERIAL AND METHOD

Standard vertical tracheotomy was performed on 24 rats. Then the animals were randomly divided into three groups as A, B and C. In group A 0.4 mg/day once daily mitomycin C was injected to the paratracheal region for 14 days. In group B daily 30 mg/kg/day simvastatin was given via gavage to rats for 14 days. In group C 2 cc/day intraperitoneal saline given to rats and the created control group by 14 days follow up. After 10 days, tracheal cannulas were removed. Three weeks later, all animals were euthanized and trachea specimens were harvested. The present study investigates the effects of MMC and Simvastatin on fibrosis, inflammation, stenosis index and tracheal wall thickness in a tracheal injury model.

RESULTS

The difference between the groups in terms of degree of inflammation scores was statistically insignificant (P = 0,187). Differences between the groups were found to be insignificant in terms of the preventionof fibrosis (P = 0,993). There was no significant difference between groups in terms of stenosis index (P = 0.645). In terms of wall thickness, control, simvastatin and mitomycin C groups were statistically different (p = 0.038). The difference between post-hoc test results was between Mitomycin C and control groups (p = 0.036). Maximum wall thickness in the MMC group (0,299 mm) was significantly lower compared to the control group (0,382 mm)(P < 0,0001). Maximum wall thickness was statistically lower in the simvastatin (0.324 mm) group compared with the control group (0.382 mm) (P < 0.0001). There was no statistically significant difference between the simvastatin group (0,198 mm) and control group (0,200 mm) with respect to minimum wall thickness (P = 0.982). Minimum wall thickness was significantly lower in the mitomycin-C group (0,160 mm) comparison to the control group (0,200 mm) (P < 0.0001).

CONCLUSION

It was detected that the simvastatin and MMC is not effective in preventing the tracheal stenosis, inflammation and fibrosis formation.

Response of an ovine laryngeal injury model to a novel fibrosis inhibitor

BACKGROUND

Vocal fold injury results in severe voice alteration that limits occupational function and social interaction. An ovine model of laryngeal injury has been developed, validated and utilized to examine laryngeal wound healing and the effect of a novel collagen inhibitor (halofuginone) on surgical wound healing. The study design includes basic research and animal model.

METHODS

An ovine laryngeal model was utilized to study controlled vocal fold injury and healing. Twenty-five sheep were divided into five groups. Sheep underwent right vocal fold injury preceded or followed by administration of halofuginone orally, topically or intralesionally. Biopsies were taken at commencement, 1 month and larynges explanted at 3 months. Specimens were examined for elastin and collagen density and epithelial changes. Pearson correlation statistics and Student's t-tests were used to assess inter-relationships.

RESULTS

All sheep tolerated halofuginone. One sheep death occurred in an untreated sheep. Vocal fold tissue demonstrated a predictable histological response to injury. Elastin was significantly reduced post-injury in the glottis. Halofuginone administered orally for 10 weeks prevented elastin loss and demonstrated a trend of reducing collagen density post-injury.

CONCLUSION

In an ovine laryngeal injury model, administration of a fibrosis inhibitor resulted in altered elastin and collagen deposition after injury in the glottis. Further investigation is warranted to examine whether these tissue changes affect vocal fold dynamics.

Novel experimental rabbit model of anterior glottic web formation

CONCLUSION

The rabbit model of anterior glottic web (AGW) formation using the laryngofissure technique resulted in reproducible and stable AGW formation that may facilitate research into this area.

OBJECTIVE

To introduce and validate a novel experimental animal model of AGW formation using the rabbit.

METHODS

The inner larynges of eight New Zealand white rabbits were exposed through the laryngofissure technique. The mucosa of the bilateral true vocal fold was stripped off using the bevel of a needle tip. On the basis of the laryngoscopic findings at 8 weeks postoperatively, the extent of AGW was measured, and the success of this procedure was validated. Laryngeal specimens were sampled at 8 weeks for high-speed recording and histological analysis.

RESULTS

In seven (87.5%) rabbits, laryngoscopic examination revealed the formation of a scar band involving the anterior commissure. The mean extent of AGW ratio on the left and right sides was 0.58 ± 0.073 and 0.55 ± 0.075, respectively. The symmetric formation of AGW (p = 0.655, p = 0.128) and stability of the AGW procedure (p = 0.491, left; p = 0.501, right) were statistically validated. On high-speed recording, the vocal mucosal wave was hindered by AGW formation. Histologically, fibro-connective tissue, especially collagen fiber, was observed in the anterior commissure.

Is there any synergic effect for coadministration of mitomycin C and halofuginone on the skin wound healing?

OBJECTIVE

This study compared the potencies of the antifibrotic agents mitomycin C (MMC) and halofuginone (HFN) and investigated whether coadministration of these agents produces synergic effects in an animal skin wound model.

SUBJECTS AND METHODS

Twenty male Sprague-Dawley rats were used for this study. After a full-thickness excisional wound was made on the dorsum of each rat, each rat was treated with topical mitomycin, intraperitoneal HFN, or both. Wound surface areas were measured over time, and histologic analysis was performed after wounds healed completely.

RESULTS

The groups treated with MMC alone, HFN alone, and a combination of the two all exhibited delayed wound healing compared with the untreated group. Histologically, fibrosis and matrix metalloproteinase-2 expression were significantly inhibited in the treated groups. However, there were no gross or histologic differences between the MMC-treated group, the HFN-treated group, and the combination-treatment group.

CONCLUSIONS

Both MMC and HFN inhibited excessive fibrosis. However, there was no significant difference in the antifibrotic effects of MMC and HFN on surgically induced skin wounds. Moreover, combination treatment with both MMC and HFN failed to confer an additional antifibrotic effect on skin wounds when compared with treatment with MMC or HFN alone.

The butterfly procedure: a new technique and review of the literature for treating anterior laryngeal webs

Congenital laryngeal webs, subglottic stenosis, and laryngeal atresia result from various degrees of failure of airway recanalization as a spectrum. The symptoms also range from asymptomatic to dysphonia and severe airway obstruction. There are a number of methods for management of symptomatic patients. In this article, we discuss a new procedure that was used in the management of two anterior laryngeal web patients with relatively acceptable results.