Healing of the nasal septal mucosa in an experimental rabbit model of mucosal injury

Nasal Packing Materials and Placement Duration on Wound Healing in Nasal Mucosa: An Animal Study

OBJECTIVE

The histological findings of wound healing depending on different nasal packing materials and replacement periods were lacking.

METHODS

Mucosal defects were created in the nasal septum of rabbits and covered with Spongel®, Algoderm®, or Nasopore®, which were cleaned on Day 14. To investigate the effect of replacement durations, Spongel® was removed on Days 3 and 7. All nasal septal specimens were collected on Day 28. Samples without packing material were prepared as controls. Depending on residual packing materials in the regenerated tissue, specimens were classified into the remnant and non-remnant groups, and morphology was compared using epithelium grade score and subepithelial thickness.

RESULTS

The epithelium grade score in the Spongel-14d group was lower than that in the other groups (p < 0.05). Subepithelial thickness was higher in the Algoderm-14d and Spongel-14d groups (p < 0.05). Epithelium grade scores were higher and subepithelial thicknesses were lower in the Spongel-3d and -7d groups than in the Spongel-14d group. Epithelium grade score was lower and subepithelial thickness was higher in the remnant group (n = 10) than in the non-remnant group (n = 15; p < 0.05).

CONCLUSIONS

Differences in packing materials and placement durations affected wound healing of nasal mucosa. The selection of appropriate packing materials and replacement duration was considered essential for ideal wound healing.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:562-568, 2024.

Topical Intranasal Insulin Enhances Healing of Nasal Mucosa: An Experimental Animal Study

OBJECTIVE

Aim of this study was to evaluate the effect of topical intranasal insulin on healing of nasal mucosa in a rat model.

METHODS

Forty-eight Wistar rats, weighing between 250 and 300 g and aged 10-12 weeks were used and randomized into two equal groups. 1.9 mm curette was introduced through the left nostril and 1.9 mm mucosa from the left nasal septum was curetted. Postoperatively, animals in the control group received 1 mL of physiologic saline, 3 times a day in a nasal irrigation fashion. Animals in the experimental group received 1 mL of 5 IU/mL regular insulin in saline solution. Subjects were sacrificed after 5, 10, and 15 days and macroscopic and histomorphometric evaluations were performed.

RESULTS

There were no mucosal synechiae and septal perforation macroscopically. Histological examination revealed that the defect size reduction was 21% in the saline group versus 56% in the insulin group on the fifth day (p = 0.006). There was 62% defect reduction in the saline group versus 79% in the insulin group on the 10th day (p = 0.034). On the 15th day, only 67% of saline group animals had complete defect closure, whereas 100% of animals treated with insulin had complete closure (92% vs 100% mucosal defect reduction, p = 0.036). Both edema and inflammation were less in the insulin group on 15th day (p = 0.006; p = 0.023, respectively).

CONCLUSION

The results from this study support the safety and efficacy of topical insulin on wound healing in the literature. This study could guide further experimental studies that examine human sinonasal wound healing.

The Impact of Adhesions on Nasal Airflow: A Quantitative Analysis Using Computational Fluid Dynamics

Background

Nasal adhesions (NAs) are a known complication of nasal airway surgery. Even minor NAs can lead to significant postoperative nasal airway obstruction (NAO). Division of such NAs often provides much greater relief than anticipated.

Objective

We examine the impact of NAs at various anatomical sites on nasal airflow and mucosal cooling using computational fluid dynamics (CFD) and multiple test subjects.

Methods

CT scans of healthy adult subjects were used to construct three-dimensional nasal airway computational models. A single virtual 2.5 mm diameter NA was placed at one of five sites commonly seen following NAO surgery within each nasal cavity bilaterally, resulting in 10 NA models and 1 NA-free control for each subject. CFD analysis was performed on each NA model and compared with the subject's NA-free control model.

Results

4 subjects were recruited to create 44 computational models. The NAs caused the airflow streamlines to separate, leading to a statistically significant increase in mucosal temperature immediately downstream to the NAs (wake region). Changes in the mucosal temperature in the wake region of the NAs were most prominent in anteriorly located NAs with a mean increase of 1.62 °C for the anterior inferior turbinate NAs ( P < .001) and 0.63 °C for the internal valve NAs ( P < .001).

Conclusion

NAs result in marked disruption to airflow patterns and reduced mucosal cooling on critical surfaces, particularly in the wake region. Reduced wake region mucosal cooling may be a contributing factor to the exaggerated perception of nasal obstruction experienced by patients with NAs.

Squamous and Respiratory Metaplasia After Olfactory Mucosal Resection

Resection of the olfactory mucosa (OM) is sometimes unavoidable during surgery; however, it is not known whether the OM can completely recover thereafter. The aim of this study was to uncover whether the OM fully recovers after mucosal resection and describe the process of OM regeneration. 8-week-old male Sprague–Dawley rats (n = 18) were subjected to OM resection at the nasal septum; six rats were euthanized for histological examination 0, 30, and 90 days after surgery. Immunohistochemistry was performed to identify olfactory receptor neuron (ORN) lineage cells [mature and immature ORNs and ORN progenitors, and olfactory ensheathing cells (OECs)], as well as dividing and apoptotic cells. Squamous and respiratory metaplasia and inflammatory cell infiltration were also assessed. On day 30 after resection, the mucosa had regenerated, and mainly contained thin nerve bundles, basal cells, and immature ORNs, with a few mature ORNs and OECs. On day 90, the repaired nasal mucosa had degenerated into stratified squamous or ciliated pseudostratified columnar epithelia, with reducing ORNs. The lamina propria contained numerous macrophages. Partial regeneration was observed within 1 month after OM resection, whereas subsequent degeneration into squamous and respiratory epithelia occurred within 3 months. Given the poor persistence of ORNs and OECs, OM resection is likely to result in olfactory impairment. Overall, surgeons should be cautious not to injure the OM during surgery.

The impact of nasal adhesions on airflow and mucosal cooling - A computational fluid dynamics analysis

Nasal adhesions are a known postoperative complication following surgical procedures for nasal airway obstruction (NAO); and are a common cause of surgical failure, with patients often reporting significant NAO, despite relatively minor adhesion size. Division of such nasal adhesions often provides much greater relief than anticipated, based on the minimal reduction in cross-sectional area associated with the adhesion. The available literature regarding nasal adhesions provides little evidence examining their quantitative and qualitative effects on nasal airflow using objective measures. This study examined the impact of nasal adhesions at various anatomical sites on nasal airflow and mucosal cooling using computational fluid dynamics (CFD). A high-resolution CT scan of the paranasal sinuses of a 25-year-old, healthy female patient was segmented to create a three-dimensional nasal airway model. Virtual nasal adhesions of 2.5 mm diameter were added to various locations within the nasal cavity, representing common sites seen following NAO surgery. A series of models with single adhesions were created. CFD analysis was performed on each model and compared with a baseline no-adhesion model, comparing airflow and heat and mass transfer. The nasal adhesions resulted in no significant change in bulk airflow patterns through the nasal cavity. However, significant changes were observed in local airflow and mucosal cooling around and immediately downstream to the nasal adhesions. These were most evident with anterior nasal adhesions at the internal valve and anterior inferior turbinate. Postoperative nasal adhesions create local airflow disruption, resulting in reduced local mucosal cooling on critical surfaces, explaining the exaggerated perception of nasal obstruction. In particular, anteriorly located adhesions created greater disruption to local airflow and mucosal cooling, explaining their associated greater subjective sensation of obstruction.

Current and Alternative Therapies for Nasal Mucosa Injury: A Review

Nasal mucosa injury can be caused by trauma, radiotherapy, chronic infection such as sinusitis, and post sinus surgery. The rate of healing and its treatment are important in the recovery of patients especially in post sinus surgery, which introduces new injuries. In this review, the current knowledge in terms of the mechanism underlying nasal wound healing was initially discussed. The currently available treatment options for enhancement of wound healing following sinus surgery were discussed and these had included intravenous antibiotics or steroids, various nasal sprays, and nasal packing. In addition, emerging alternative therapies in nasal mucosa wound healing such as herbal medicine and the advancement of regenerative medicine therapies such as stem cells and their byproducts were also discussed. Despite the various available treatment options for wound healing in nasal mucosa, rigorous strong evidence of their efficacy is gravely warranted in order to recommend them as part of the treatment modality.

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.

Effects of oral ısotretinoin on normal and wounded nasal mucosa: an experimental study

BACKGROUND

We aimed to investigate the effect of systemic isotretinoin therapy on normal and wounded nasal septal mucosa histopathologically in an experimental rabbit model.

METHODS

Circular mucosal defect with a 7 mm diameter was made in the left septum of 12 New Zealand white rabbits. The rabbits were divided into two groups (six rabbits in each group) oral isotretinoin was given with olive oil at the operation day to the first group. The control group was only oil given group. The harvested septum mucosas were divided into four groups (1-wounded-drug given side, 2-unwounded and drug-given side, 3-wounded-control and 4-unwounded-control side). The diameter of the defect, mucosal thickness, epithelial thickness, ciliated cell level, goblet cell level and inflammation were evaluated every week for 4 weeks.

RESULTS

At both wounded and normal side, thinning of normal respiratory ciliated epithelium was observed in the postoperative period. In study group at the wounded side; mean mucosal thickness was measured 139.66 µ (± 26.24), and in the control group, mean mucosal thickness was 238.33 µ (± 39.7) at the wounded side. (p < 0.001). The difference between the groups in thickness of normal septal mucosa was also statistically significant (p = 0.016) [190 µ (± 14.6) and 256.66 µ (± 44.66)]. The average cilia level was observed 1.16 in the wounded study group, while the average level was 2.33 in the wounded control group (p = 0.012). Average score measurements of the regenerated mucosa suggested that isotretinoin-given wounded animals have reduced goblet cell recovery, compared to the control both on the regenerated and unwounded mucosas (p = 0.007, p = 0.002, respectively). Inflammation was significantly higher in the wounded isotretinoin group (p = 0.018).

CONCLUSION

Oral isotretinoin has negative effects on epithelial and ciliary regeneration, significantly reduces mucosal thickness and goblet cell counts of the normal and regenerated mucosa, causes severe inflammation and significant reactive changes.