Rehabilitation of surgically traumatized paranasal sinus mucosa using retinoic acid

Compatibility of a Thermoresponsive and Controlled Release System for Promoting Sinonasal Cilia Regeneration

The current clinical goal for managing chronic rhinosinusitis (CRS), a heterogenous disease of the paranasal sinuses, is to control inflammation, yet adjunct therapies that promote mucosal regeneration can improve the long-term health of the upper airways. The small natural openings to the sinuses, however, limit the efficacy of traditional drug delivery methods (i.e., nasal sprays and irrigation). Accordingly, a conformable thermoresponsive and controlled release system ("TEMPS", Thermogel, Extended-release Microsphere-based delivery to the Paranasal Sinuses) is developed. The poly(lactic-co-glycolic acid) microsphere component enables the encapsulation of numerous therapeutics, such as retinoic acid (RA), an analog of vitamin A (VA). Studies in CRS patients and preclinical models have shown that aqueous RA or VA gels promoted the differentiation of ciliated cells and improved mucosal healing following repeat applications. In the present study, TEMPS is designed for the controlled release of RA such that a single dose of RA-TEMPS delivers bioactive drug for at least 30 days. Furthermore, as TEMPS will be in direct contact with sinonasal tissue, its compatibility with ciliated human nasal epithelium is explored. After ex vivo incubation in thermogel for 24 h, cilia motility is maintained, providing evidence that TEMPS can be compatible for application along the sinonasal epithelium.

Effects of Hangeshashinto on the nasal physiological function: An in vitro study

OBJECTIVE

Hangeshashinto is a Japanese Kampo medicine applied for the treatment of oral mucositis and gastroenteritis. Hangeshashinto exhibits broad-spectrum antibacterial activity and suppresses prostaglandin (PG)E2 production in the mucosa and has the ability to improve the inflammatory condition. In addition to these effects, because cAMP, a composition of Hangeshashinto, facilitates ciliary beat, Hangeshashinto could also improve the physiological function of the nasal mucosa, consist of ciliated epithelium, but details were unknown.

METHODS

This study was aimed to investigate the effects of Hangeshashinto on the nasal mucosa. Healthy nasal mucosal sections were collected from the nasal septum of ten Japanese white rabbits, placed in a collagen dish for tissue culture, and rinsed with two different concentrations of Hangeshashinto solution (1.0%, n = 10 and 2.5%, n = 10) and cAMP solution (50µM, n=10 and 100 µM, n=10) or saline (control, n = 10). Ciliary beat frequency (CBF) as a physiological function of the nasal mucosa was recorded at 1, 3 and 7 days after rinsing, and histological evaluation of epithelial damage was performed at 7 days after rinsing.

RESULTS

CBF in the 1.0% but not in the 2.5% Hangeshashinto group, increased at 3 and 7 days compared with that in the control group (p < 0.05). This trend was also observed in the CBF in the 100 µM cAMP group, significant difference was not observed between the CBF of the 1.0% Hangeshashinto group and the 100 µM cAMP group at 1, 3 and 7 days after rinsing (p > 0.05). Histological score only in the 2.5% Hangeshashinto group was lower than that in the control group (p < 0.05), while a significant decline was not observed in the other groups compared to that in the control group (p > 0.05).

CONCLUSION

Our results suggest that 1.0% Hangeshashinto solution facilitates the physiological function of the nasal mucosa by promoting ciliary functions without histological damage of cilia epithelium. When applied with the appropriate concentration, Hangeshashinto could have ability to improve the physiological functions of the nasal mucosal epithelium.

The effects of topical agents on paranasal sinus mucosa healing: a rabbit study

BACKGROUND

Numerous topical agents have been used intraoperatively to enhance postoperative mucosal healing or reduce scar formation. However, the histological effects of many of these treatments have not been well described. This study investigates the impact of topical mometasone furoate, acitretin, lactoferrin, and Silastic sheet (Medtronic) on sinus mucosal healing in a rabbit model.

METHODS

Forty-eight New Zealand white rabbits underwent defined, localized stripping of a bilateral region of maxillary sinus mucosa. One of 6 treatments was placed in 1 maxillary sinus, and the treatment carrier was applied contralaterally (0.1% mometasone furoate, 0.25% and 0.5% acitretin, lactoferrin, Silastic, and no treatment; n = 8 each group). Rabbits were euthanized after 2 weeks and histological sections were examined with light microscopy.

RESULTS

Treatment with acitretin 0.25% and 0.5% improved cilial recovery by 0.9 ± 0.5 (p = 0.003) and 0.5 ± 0.5 (p < 0.05), respectively. Acitretin 0.25% treatment also significantly reduced collagen in healing mucosa (5.1% ± 4.8%, p = 0.04). Conversely, rabbits treated with mometasone furoate 0.1% were more likely to have reduced cilial and goblet cell recovery. Intergroup comparisons demonstrated a significant improvement in cilial recovery scores with both acitretin doses compared with mometasone furoate (p < 0.05) and less collagen deposition in rabbits treated with placebo gel over Silastic (p < 0.05). Mucosa directly underlying a blood clot had a lower cilia score and impaired epithelial recovery (p < 0.001).

CONCLUSION

Intraoperatively applied agents have the potential to significantly affect wound healing. Acitretin improved cilial recovery and reduced collagen deposition.

Clinical efficacy of a spray containing hyaluronic Acid and dexpanthenol after surgery in the nasal cavity (septoplasty, simple ethmoid sinus surgery, and turbinate surgery)

Background. This prospective, controlled, parallel-group observational study investigated the efficacy of a spray containing hyaluronic acid and dexpanthenol to optimise regular treatment after nasal cavity surgery in 49 patients with chronic rhinosinusitis. Methods. The control group received standard therapy. Mucosal regeneration was determined using rhinoscopy sum score (RSS). Pre- and postoperative nasal patency was tested using anterior rhinomanometry. The participants were questioned about their symptoms. Results. Regarding all RSS parameters (dryness, dried nasal mucus, fibrin deposition, and obstruction), mucosal regeneration achieved good final results in both groups, tending to a better improvement through the spray application, without statistically significant differences during the whole assessment period, the mean values being 7.04, 5.00, 3.66, and 3.00 (intervention group) and 7.09, 5.14, 4.36, and 3.33 (control group). No statistically significant benefit was identified for nasal breathing, foreign body sensation, and average rhinomanometric volume flow, which improved by 12.31% (control group) and 11.24% (nasal spray group). Conclusion. The investigational product may have additional benefit on postoperative mucosal regeneration compared to standard cleaning procedures alone. However, no statistically significant advantage could be observed in this observational study. Double-blind, controlled studies with larger populations will be necessary to evaluate the efficacy of this treatment modality.

Nasal epithelial repair and remodeling in physical injury, infection, and inflammatory diseases

PURPOSE OF REVIEW

To summarize the current knowledge of cellular and molecular mechanisms of nasal epithelial repair and remodeling during physical and pathophysiological conditions.

RECENT FINDINGS

Nasal epithelial repair and remodeling is a highly organized and well coordinated process, involving inflammation, proliferation, differentiation, matrix deposition, and remodeling, and is regulated by a wide variety of growth factors and cytokines. From the in-vivo and in-vitro studies conducted in both human and animal models, undifferentiated basal cells (progenitors) are able to migrate from adjacent epithelium, spread over the denuded basement membrane, and proliferate in injured regions (self-renewal) in necessary (homeostasis) or excessive (hyperplasia) degree. Progenitor cells reorient to an apical-basal polarity, and progressively differentiate into ciliated and nonciliated columnar cells and goblet cells, reconstituting a functional respiratory epithelium after several weeks. This recovery process can be observed during various types and severity of injury, and also in common nasal diseases, including acute viral, allergic, and nonallergic rhinitis, as well as chronic rhinosinusitis with and without nasal polyps.

SUMMARY

Although nearly 10 000 articles about nasal epithelium have been published in the last decade, the mechanisms underlying the nasal epithelial repair are still understood at only a superficial descriptive level. In order to advance rhinology to the next level of a comprehensive knowledge of the orchestrated genetic and molecular processes acting during epithelial repair, combined clinical and experimental studies using sophisticated investigational plans to elucidate the functions of both the protein-coding and regulatory portions of the human genome are required.

Retinoic acid improves morphology of cultured peritoneal mesothelial cells from patients undergoing dialysis

Patients undergoing continuous ambulatory peritoneal dialysis are classified according to their peritoneal permeability as low transporter (low solute permeability) or High transporter (high solute permeability). Factors that determine the differences in permeability between them have not been fully disclosed. We investigated morphological features of cultured human peritoneal mesothelial cells from low or high transporter patients and its response to All trans retinoic Acid (ATRA, vitamin A active metabolite), as compared to non-uremic human peritoneal mesothelial cells. Control cells were isolated from human omentum. High or low transporter cells were obtained from dialysis effluents. Cells were cultured in media containing ATRA (0, 50, 100 or 200 nM). We studied length and distribution of microvilli and cilia (scanning electron microscopy), epithelial (cytokeratin, claudin-1, ZO-1 and occludin) and mesenchymal (vimentin and α-smooth muscle actin) transition markers by immunofluorescence and Western blot, and transforming growth factor β1 expression by Western blot. Low and high transporter exhibited hypertrophic cells, reduction in claudin-1, occludin and ZO-1 expression, cytokeratin and vimentin disorganization and positive α-smooth muscle actin label. Vimentin, α-smooth muscle actin and transforming growth factor- β1 were overexpressed in low transporter. Ciliated cells were diminished in low and high transporters. Microvilli number and length were severely reduced in high transporter. ATRA reduced hypertrophic cells number in low transporter. It also improved cytokeratin and vimentin organization, decreased vimentin and α-smooth muscle actin expression, and increased claudin 1, occludin and ZO-1 expression, in low and high transporter. In low transporter, ATRA reduced transforming growth factor-β1 expression. ATRA augmented percentage of ciliated cells in low and high transporter. It also augmented cilia length in high transporter. Alterations in structure, epithelial mesenchymal markers and transforming growth factor-β1expression were differential between low and high transporter. Beneficial effects of ATRA were improved human peritoneal mesothelial cells morphology tending to normalize structures.

Wound healing of nasal mucosa in a rat

BACKGROUND

Postoperative wound healing of the nasal mucosa is a highly organized process. However, this process still has not been fully understood. The present study aimed to establish a wound healing model in a rat and describe histomorphological changes of the nasal mucosa after mechanical injury.

METHODS

Unilateral wound in the nasal cavity was induced using the brushing technique in 4-week-old, Sprague-Dawley rats. Experimental rats were divided into five groups (n = 7 for each group). Animals were killed 1 hour and 2, 5, 14, and 28 days after injury. The histological sections were examined for inflammatory cell infiltration, goblet, and ciliated cell formation in hematoxylin and eosin staining. The subepithelial and epithelial thicknesses were measured and expressed as the subepithelial thickness index (STI) and epithelial thickness index (ETI). Fibrosis was evaluated by subepithelial fibrosis index (SFI) in Masson's trichrome-stained sections.

RESULTS

Respiratory epithelial discontinuity and hemorrhage were observed 1 hour after injury. On day 2, edematous subepithelium and infiltration of neutrophils could be found on the injured site. Day 5 was characterized by the infiltration of monocytes and granulation tissue. SFI and ETI values increased significantly at day 14. Goblet cells and ciliated cells began to regenerate from day 14 and restored to near normal at day 28.

CONCLUSION

Using mechanical injury, the wound healing model of the nasal mucosa was established in a rat. The regeneration of respiratory mucosa was completed on day 28 after injury.

The effects of retinoic acid on ciliary function of regenerated sinus mucosa

BACKGROUND

Retinoic acid (RA) has been shown to enhance ciliary ultrastructure in regenerated sinus mucosa compared with controls. However, the functional status of the regenerated cilia has not been studied. Our objective was to evaluate the ciliary beat frequency (CBF) of regenerated sinus mucosa treated with topical RA in a rabbit model.

METHODS

Twelve rabbits underwent bilateral surgical stripping of the maxillary sinuses, followed by treatment with RA gel in the right side and an inert gel control in the left side. The rabbits were then killed at either 2 or 4 weeks, and CBF analysis of the regenerated mucosa was performed. Three unoperated rabbits were used to establish normative CBF data.

RESULTS

Functional cilia were recovered from 11/12 RA-treated sinuses and 12/12 gel control sinuses. At 2 weeks postoperatively, the RA-treated sinuses showed an average CBF of 19.78 Hz, which was statistically comparable with the normal unoperated controls (p < 0.26). The inert gel-treated mucosa showed a CBF of 29.24 Hz, which was significantly elevated compared with normals (p < 0.05). At 4 weeks, ciliary activity persisted, but both RA-treated sinuses and gel controls showed elevated CBF compared with normals (p < 0.03).

CONCLUSION

Topical RA placed in a demucosalized maxillary sinus yields functional cilia. RA appears to have a normalizing effect on CBF early in the mucosal wound healing process compared with control. This effect appears to be mitigated in later stages of wound healing. RA may be beneficial in enhancing morphological and functional aspects of regenerating cilia.