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.

Comparative Analysis of the Healing Effects of the Transplanted Cell Sheets to the Experimentally Injured Maxillary Sinuses

BACKGROUND

In our study, the authors aimed to obtain a live and functional sinus epithelium with mesenchymal stem cells and nasal mucosa epithelial cells from rabbits which are cultured in temperature-responsive culture plates to get a single-layer.

METHODOLOGY/PRINCIPAL

Twenty-two female New Zealand rabbits were included in the study. Two of them were used to obtain mesenchymal stem cells. A total of 40 maxillary sinuses were randomly divided into 5 groups: 1) control group which is used to investigate normal rabbit maxillary mucosa, 2) secondary healing group, 3) mesenchymal stem cell graft group, 4) differentiated mesenchymal stem cell group, and 5) nasal mucosal graft group. The animals were sacrificed at the 28th day after the surgery.Scanning electron microscopy, transmission electron microscopy, and immunohistochemical investigations were performed.

RESULTS

With these investigations, it was shown that; all graft groups were histologically better than secondary healing group and when the authors compared the graft groups, differentiated mesenchymal stem cell group were the best.

CONCLUSION

Our study results showed that endoscopic sinus surgery and treatment with cell sheets, which were generated in temperature-responsive culture dishes, had more functional respiratory epithelium.

Effects of Topically Applied Biomaterials on Paranasal Sinus Mucosal Healing

Background

Recently, nasal packing made of absorbable biomaterial has become increasingly popular. Although absorbable packs are effective for hemostasis, their impact on healing mucosa is unknown. Some have felt that a biocompatible sinus dressing actually may enhance healing, particularly in areas where the mucosa has been stripped. The aim of this study was to determine the effect of topical MeroGel and FloSeal on paranasal sinus mucosal healing in a rabbit model.

Methods

Bilateral maxillary sinuses of 12 New Zealand white rabbits were surgically opened and stripped of mucosa. The left maxillary sinus of six rabbits had sterile saline-soaked MeroGel placed in the antrum, and the other six rabbits received FloSeal. The right maxillary sinuses of all 12 animals were stripped and otherwise untreated to serve as stripped controls. The animals were killed at 2 weeks and specimens were examined by light microscopy.

Results

MeroGel-treated mucosa showed extensive fibrosis of the basal lamina and lamina propria, complete loss of surface epithelium, and loss of the mucociliary blanket. There was minimal resorption of the MeroGel, and MeroGel fibers were frankly incorporated into the regenerated epithelium, associated with an exuberant lymphocytic infiltrate. FloSealtreated mucosa showed similar fibrosis of the basal lamina and lamina propria with loss of the mucociliary blanket, although to a lesser degree than the MeroGel- treated group. FloSeal showed similar incorporation into the healed mucosa with lymphocytosis. Controls showed expected submucosal gland reduction, lamina propria fibrosis, and loss of cilia, but the lamina propria fibrosis seen in the MeroGel and FloSeal groups was markedly more prominent.

Conclusion

In a rabbit model, MeroGel and FloSeal appear to increase reactionary fibrosis of healing mucosa. These agents also appear to be incompletely resorbed and grossly incorporated into healing tissue. Mucosal healing may be impaired by the application of these agents.

Effect of a combination of mometasone furoate, levofloxacin, and retinyl palmitate with an in situ gel-forming nasal delivery system on nasal mucosa damage repair in an experimental rabbit model

BACKGROUND

In this study a combination of Mometasone Furoate (MF)+Levofloxacin hemihydrate (LH)+Retinyl palmitate (RP) with an in situ gel-forming delivery system was evaluated at different stages of nasal mucosal damage repair in a rabbit maxillary sinus model.

METHODS

In this study, 28 rabbits were included and assigned randomly to four groups. In all rabbits, a standard ostium was opened in the medial wall of the maxillary sinus by using a drill. Two different subsequently prepared gels with an in situ gel-forming delivery system were used. Of these 14 nasal cavities, combination 1 (active combination) was applied daily to 5, combination 2 (placebo) to 5, while 4 did not receive any pharmaceutical treatment. The diameter of the ostium was measured. Histopathological assessment was performed.

RESULTS

After 2, 3 and 4 weeks, the ostium diameter was significantly wider in the group where gel 1 had been applied compared to both the placebo group and control group. In the group treated with gel 1, after 2, 3 and 4 weeks the presence of superficial cilia was significantly greater, surface epithelium significantly less. In the 4th week, histologic scores for fibroblastic proliferation and vascular proliferation in the group treated with gel 1 were better than in either the control group or the placebo group. With gel 1, chronic inflammation parameters were also significantly lower than in the other groups.

CONCLUSION

The MF+LH+RP mixture with an in situ gel-forming nasal delivery system applied for wound healing after FESS prevents the formation of stenosis and is favorable for proper wound healing.

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.

Evaluation of domestic and Yucatan swine nasal sinus anatomy as models for future sinonasal research of medications delivered by standard instruments used in functional endoscopic sinus surgery

BACKGROUND

There is a need to find an animal model to study new medications to improve mucosal wound healing after functional endoscopic sinus surgery (FESS). Current literature suggests swine as a potential candidate. The lack of information correlating swine computer tomography (CT) and endoscopic sinonasal anatomy prompted us to investigate them in the domestic and Yucatan swine to determine their feasibility as models to test new medications and drug-embedded stents applied using FESS techniques.

METHODS

Two domestic pig heads and 2 Yucatan pig heads were imaged using helical thin slice (1 mm) CT. Two rhinologists analyzed the images and performed endoscopy on the swine. Particular attention was given to accessing the frontal sinus and suturing stents to the nasal septum using standard endoscopic instruments.

RESULTS

CT confirmed that swine sinonasal anatomy is largely similar to human, with all major sinuses present. The middle and inferior turbinates of swine arise from a single uniturbinate. The superior turbinates contain large concha bullosa. Unlike human, swine nasal septum is bone anteriorly and cartilage posteriorly. The frontal sinus ostia, regardless of head size, were consistently around 10 cm from the nasal aperture. On endoscopy, domestic swine frontal sinus ostia were easily accessible for topical medication deposition. Silastic splints can be sutured to the domestic swine septum through the posterior cartilaginous portion, allowing for studies involving medication-eluting material. The narrower nasal cavity of Yucatan pigs prohibited endoscopic maneuvers.

CONCLUSION

Domestic swine, but not Yucatan, are a feasible model for future sinonasal research using standard FESS instruments.

Innate immunity

Innate immunity is an exciting area of research in rhinology because emerging evidence suggests that abnormal local immune responses, rather than pathogen-specific adaptive immunity, may play a more important role in the pathogenesis of chronic rhinosinusitis (CRS). This article reviews important recent research regarding the innate immune system and CRS, with particular focus on the role of pattern recognition receptors, antimicrobial peptides and biofilms, epithelial ciliary function, cystic fibrosis, and cigarette smoking, and on areas for future research and therapy.

Advances in absorbable biomaterials and nasal packing

Absorbable biomaterials are commonly used after endoscopic sinus surgery, both for hemostatic and wound healing considerations. Although removable nasal packing is the traditional method of controlling ongoing bleeding and modulating wound healing, it is uncomfortable for patients and associated with several complications. Currently available absorbable agents frequently incite an inflammatory reaction and have been shown in animal and human trials to adversely affect the wound healing process. Newer agents offer distinct advantages because of their unique composition and rapid clearance profiles. The selection of packing material used in any given sinus procedure should be based on surgeon preference and the details of the specific case.

Regression of Polypoid Nasal Mucosa after Systemic Corticosteroid Therapy: A Proteomics Study

Background

Nasal polyposis (NP) treatment and pathophysiology have always been challenging for otolaryngologists. Among the medical treatments for NP, glucocorticoids (GCs) have been always one of the mainstays but the mechanisms of their action are not well defined. Identifying and comparing the protein profile of chronic rhinosinusitis (CRS) with NP before and after treatment with GCs can help to clarify NP pathogenesis and mechanisms of corticosteroid effects on NP.

Methods

Samples of nasal polyps were taken from selected NP patients in workup for endoscopic sinus surgery. None of the patients used local or systemic GCs within 30 days before the sampling. The patients were given prednisone, 30 mg/day, for 4 days before the surgery to shrink the NP tissue. Nasal polyp samples were collected during surgery. Proteins from samples were extracted and separated by immobilized pH gradient–based two-dimensional difference gel electrophoresis (2D DIGE). Resulting 2D-gel images were statistically analyzed using Delta2D software and differently expressed protein spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Results

A reference map of 1963 proteins could be established. Expression of 20 proteins changed significantly (twofold, p < 0.05) after treatment of NP with GCs. Heat shock proteins and retinoic acid were induced by GCs. Ingenuity pathway analysis of all identified proteins indicated that apoptosis pathway is triggered in NP after GC administration.

Conclusion

Identifying the changes of NP proteome due to GCs and the biological functions of proteins can lead to new ways of treatment and open new fields in NP research.

Activation of vocal fold healing with topical vitamin A in rabbits

CONCLUSION

The results suggest that vitamin A can prevent scar formation in the vocal fold after surgery.

OBJECTIVES

This study aimed to evaluate the effects of topically applied vitamin A on healing after vocal fold trauma.

MATERIALS AND METHODS

Vocal folds of 20 adult rabbits were traumatized unilaterally. Ten of them were treated with topical application of vitamin A and the others served as controls. All animals were sacrificed after 10 days. Vocal folds were resected for analysis by light microscopy.

RESULTS

The untreated vocal folds showed extensive deposition of collagen and fibroblast on light microscopy and vocal folds treated with vitamin A showed less deposition. There was a significant difference between the two groups according to the percentage of collagen and fibroblasts in the lamina propria (p<0.01).

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.

Rehabilitation of surgically traumatized paranasal sinus mucosa using retinoic acid

BACKGROUND

Paranasal sinus mucosa that regenerates after surgical stripping is characterized by sparse, dysmorphic cilia. Although such dysfunctional mucosal changes are thought to be irreversible, the potential rehabilitation of deciliated mucosa by topical therapies has not been explored. This study evaluated the effect of topical retinoic acid (RA) in rehabilitating deciliated sinus mucosa that has regenerated after surgical stripping.

METHODS

Twelve New Zealand rabbits underwent bilateral maxillary sinus mucosal stripping and were allowed to remucosalize for 10 days. In the first treatment arm (n = 6), 0.01% RA was applied to the regenerated mucosa of the left maxillary sinus and an aqueous control was placed contralaterally. In the second treatment arm, the regenerated mucosa was surgically restripped bilaterally before applying RA and control. After 14 additional days, mucosa was harvested and examined by scanning electron microscopy for ciliary density, orientation, and morphology.

RESULTS

In the first treatment arm, no significant differences in ciliary density, orientation, or morphology were noted between RA-treated sinuses and controls. In the second arm, RA-treated sinuses showed improved ciliary density, morphology, and orientation compared with controls.

CONCLUSION

RA does not appear to significantly enhance ciliogenesis when applied after mucosal regeneration has occurred. However, if deciliated mucosa is restripped and allowed to regenerate in the presence of RA, ciliary ultrastructural features may be enhanced. RA may have therapeutic value in rehabilitating deciliated sinus mucosa when applied before mucociliary differentiation of regenerating mucosa.

Bone changes after maxillary sinus surgery: an experimental scanning electron microscopy study

AIMS

The purpose of this study was to explore the pathogenic role of bone in sinus surgery, and to determine whether mucosal disease after sinus surgery may be induced by underlying disease within the bone.

MATERIAL AND METHODS

Twenty-five rabbits were divided into five groups. In group one, wide surgical removal of the maxillary sinus mucosa and creation of a nasoantral window were undertaken. In group two, only nasoantral window creation was undertaken. In group three, the mucosa of the anterior maxillary sinus was removed. In group four, a strip of mucosa around the ostium was removed. Group five was used as a control.

RESULTS

After three months, in the groups which had undergone wide surgical removal, the medial sinus walls were observed to be retracted and the inner curtain of the bone disturbed, with alteration of the haversian canal system and osteoclastic bone resorption.

CONCLUSIONS

After radical sinus surgery, electron microscopic changes were observed in the bony walls, similar to those changes seen in osteomyelitis.

Perioperative care for advanced rhinology procedures

Successful outcomes in rhinologic surgery require careful endoscopic interventions, not only in the operating room, but also in the perioperative setting. In particular, meticulous postoperative care is essential to successful outcomes. This article reviews aspects of wound healing and perioperative care that can optimize surgical patency and clinical outcome.

Retinoic acid improves ciliogenesis after surgery of the maxillary sinus in rabbits

OBJECTIVES/HYPOTHESIS

Retinoids have been shown to be important cofactors in regulating the differentiation and proliferation of ciliated epithelial cells of the respiratory tract. In particular, retinoic acid has been shown to enhance the regeneration of paranasal sinus mucosa. The objective of this study is to use scanning electron microscopy techniques to evaluate the effect of topical retinoic acid on mucosal wound healing in a rabbit model of maxillary sinus surgery. It is hypothesized that the application of topical retinoic acid will enhance ciliogenesis and improve the morphology of regenerated cilia compared with controls.

STUDY DESIGN

Prospective multi-arm controlled animal trial.

METHODS

Eighteen New Zealand white rabbits underwent surgical opening of the maxillary sinuses through a midline incision. The rabbits were divided among four experimental groups: 1) mucosal stripping alone (stripped control), 2) stripping followed by topical application of an inert aqueous gel, 3) stripping followed by application of 0.01% retinoic acid in aqueous gel, and 4) no mucosal stripping and no topical treatment (nonstripped control). After 14 days, the medial wall of the maxillary sinus was harvested and examined by scanning electron microscopy at x2,000 and x5,000 magnification. The micrographs were then rated by a blinded review panel for ciliary density, orientation, and morphology.

RESULTS

Mean scores for ciliary density, orientation, and morphology were all significantly higher for the retinoic acid treatment group compared with both the inert aqueous gel treatment group and the stripped control group (P=.004-.03 for all comparisons, Student's t test). Mean scores for the retinoic acid treatment group were numerically lower than the nonstripped control group but did not approach statistical significance for any parameter (P=.23-.31).

CONCLUSIONS

In a rabbit model of maxillary sinus surgery, topically delivered retinoic acid enhances ciliogenesis. Qualitative assessment of ciliary density, orientation, and morphology shows improved healing in retinoic acid treated sinuses compared with both untreated control sinuses and aqueous gel treated sinuses.