Topical fibroblast growth factor-2 for treatment of chronic tympanic membrane perforations

Evidence Showing Three Layers of Reconstructed Tympanic Membrane After Second Regenerative Treatment

OBJECTIVE

To describe the case of a patient who twice underwent recently developed regenerative treatment for tympanic membrane perforation (RT-TMP), achieving successful regeneration of the TM consisting of three layers (epidermis, lamina propria, and mucosa) on pathological analyses of the regenerated part.

STUDY DESIGN

Clinical capsule report.

PATIENT

A 48-year-old woman with right chronic otitis media, showing a large TMP covering 80% of the total TM.

INTERVENTIONS

After the initial RT-TMP, the patient had a residual posterior TMP affecting 25% of the TM. At the second procedure, a portion of the previously regenerated TM was harvested for pathological analysis.

RESULTS

Pathological analysis of the surgical specimen showed that the regenerated TM tissue coandnsisted of three parts: outer epidermal, intermediate, and mucosal layers.

CONCLUSION

By applying a recently developed RT-TMP, this report describes the first human study confirming the regeneration of the TM consisting of three layers (epidermis, lamina propria, and mucosa) on pathological analyses of the regenerated part at the second RT-TMP. This is a major step toward the goal of TM regeneration that recapitulates the structural properties of the native TM.

Efficacy of Concentrated Growth Factors in Treating Tympanic Membrane Perforation in Guinea Pigs

Background: Less invasive and cost-effective alternatives are needed to manage tympanic membrane perforation (TMP). Therefore, the effectiveness of concentrated growth factors (CGF) in promoting tympanic membrane regeneration in guinea pig models of eardrum perforation was invetigeted. Methods: Large TMPs were created in 34 guinea pig ears using a CO2 laser and divided into 3 groups: CGF-gelatin sponge (with-CGF group), saline-gelatin sponge (without-CGF group), and untreated group. In the with-CGF group, CGF and gelatin sponges were implanted into the perforations, while the without-CGF group received gelatin sponges impregnated with saline. Eardrums were observed under a light microscope on days 14 and 28, and tympanic membranes were examined histologically with hematoxylin and eosin staining. Results: On day 14, 8 of 14 (57.1%) ears in the with-CGF group achieved perforation closure, while no closures were observed in the withoutCGF or untreated groups. The closure rate was significantly higher in the with-CGF group compared to both without-CGF and untreated groups (P < .001). By day 28, 12 of 14 (85.7%) ears in the with-CGF group and 8 of 14 (57.1%) ears in the without-CGF group had closure. No closures were noted in the untreatedgroup. Although the closure rates between the with-CGF and without-CGF groups were similar (P=.07), the withCGF group showed a significantly higher rate than the untreated group (P < .001). Histological analysis revealed that the regenerated tympanic membrane was thicker in the with-CGF group compared to the without-CGF group. Conclusion: Concentrated growth factor effectively promotes tympanic membrane regeneration and provides a promising, minimally invasive treatment option for TMP.

Tough and self-adhesive zwitterionic hydrogels with mechano-responsive release of bFGF for tympanic membrane repair

The tympanic membrane (TM) is constantly in a state of vibrating. However, there is currently a lack of drug-delivery scaffolds suitable for the dynamic environment of TM perforation. In this study, a mechano-responsive tough hydrogel was developed. It consists of basic fibroblast growth factor (bFGF)-loaded sodium alginate (SA) microspheres, polysulfobetaine methacrylate (polySBMA), and gelatin methacrylate (GelMA). This hydrogel was designed to serve as a TM scaffold to promote perforation healing under dynamic conditions. bFGF was encapsulated in SA microspheres, which were then incorporated into polySBMA-GelMA hydrogels through photo-initiated free radical polymerization. The mechanical properties, tissue adhesiveness, swelling properties, and degradation of the hydrogels were evaluated before and after microsphere incorporation. It was observed that incorporating bFGF-loaded SA microspheres did not significantly impact the adhesion and degradation mechanisms of the hydrogel. The compressive strength and tensile strength of the microsphere-incorporated hydrogel were up to 6.6 MPa and 64.1 kPa, respectively, suitable for a TM scaffold. The release behavior of bFGF from the hydrogel could be controlled by vibration stimulation without significantly affecting the hydrogel's mechanical properties, indicating a mechano-responsive nature of the hydrogel. The in vitro cytotoxicity assay demonstrated that the hydrogels showed no cytotoxic effects. Moreover, cell culture assays demonstrated that vibration stimulation could enhance the release of bFGF, significantly promoting cell proliferation and migration. The results demonstrate the significant potential of the mechano-responsive hydrogel as a scaffold for repairing TM perforations.

Searching for a Better Animal Model for Chronic Tympanic Membrane Perforation

Chronic tympanic membrane perforation represents a prevalent otological condition, necessitating a reliable animal model for the validation and safety assessment of surgical techniques and materials employed in myringoplasty. This prospective study involved the establishment of chronic tympanic membrane perforation animal models in 16 chinchillas. A thermic myringotomy was conducted on the right ear (study group), followed by cold instrument myringotomy, coupled with the topical application of mitomycin C and dexamethasone solution on the left ear (control group). Results revealed that tympanic membrane perforations in the study group persisted for a minimum of 4 weeks in 93.7% of cases and extended to 12 weeks in 62.5% of the cases. In contrast, all tympanic membrane perforations in the control group were present at 4 weeks, with only 37.5% persisting after 12 weeks, although statistical tests did not find significant differences between the two groups (chi-square: p-value = 0.157, Kruskal-Wallis: p-value = 0.093, Mann-Whitney: p-value = 0.121). The thermic myringotomy employed to induce chronic tympanic membrane perforation in animals demonstrated efficiency and sustainability. This model, characterized by stability and reproducibility, holds promise for future experimental applications in the field.

In Vitro Assessment of Wound-Healing Efficacy of Stabilized Basic Fibroblast Growth Factor (FGF-2) Solutions

Chronic tympanic membrane perforations (TMP) pose a significant clinical challenge, but basic fibroblast growth factor (FGF-2) shows promise for their treatment, despite its instability in aqueous solutions which hampers the sustained delivery crucial for the healing process. Addressing this, our research focused on the development of stabilized FGF-2 formulations, F5 and F6, incorporating dual, generally regarded as safe (GRAS) excipients to enhance stability and therapeutic efficacy. F5 combined FGF-2 (1600 ng/mL) with 0.05% w/v methylcellulose (MC) and 20 mM alanine, while F6 used FGF-2 with 0.05% w/v MC and 1 mg/mL human serum albumin (HSA). Our findings demonstrate that these novel formulations not only significantly improve the cytoproliferation of human dermal fibroblasts but also exhibit the most potent chemoattractant effects, leading to the highest fibroblast monolayer closure rates (92.5% for F5 and 94.1% for F6 within 24 h) compared to other FGF-2 solutions tested. The comparable performance of F5 and F6 underscores their potential as innovative, less invasive, and cost-effective options for developing otic medicinal products aimed at the effective treatment of chronic TMP.

Overcoming barriers: a review on innovations in drug delivery to the middle and inner ear

Despite significant advances in the development of therapeutics for hearing loss, drug delivery to the middle and inner ear remains a challenge. As conventional oral or intravascular administration are ineffective due to poor bioavailability and impermeability of the blood-labyrinth-barrier, localized delivery is becoming a preferable approach for certain drugs. Even then, localized delivery to the ear precludes continual drug delivery due to the invasive and potentially traumatic procedures required to access the middle and inner ear. To address this, the preclinical development of controlled release therapeutics and drug delivery devices have greatly advanced, with some now showing promise clinically. This review will discuss the existing challenges in drug development for treating the most prevalent and damaging hearing disorders, in particular otitis media, perforation of the tympanic membrane, cholesteatoma and sensorineural hearing loss. We will then address novel developments in drug delivery that address these including novel controlled release therapeutics such as hydrogel and nanotechnology and finally, novel device delivery approaches such as microfluidic systems and cochlear prosthesis-mediated delivery. The aim of this review is to investigate how drugs can reach the middle and inner ear more efficiently and how recent innovations could be applied in aiding drug delivery in certain pathologic contexts.

Molecular and Clinical Significance of Fibroblast Growth Factor 2 in Development and Regeneration of the Auditory System

The fibroblast growth factor 2 (FGF2) is a member of the FGF family which is involved in key biological processes including development, cellular proliferation, wound healing, and angiogenesis. Although the utility of the FGF family as therapeutic agents has attracted attention, and FGF2 has been studied in several clinical contexts, there remains an incomplete understanding of the molecular and clinical function of FGF2 in the auditory system. In this review, we highlight the role of FGF2 in inner ear development and hearing protection and present relevant clinical studies for tympanic membrane (TM) repair. We conclude by discussing the future implications of FGF2 as a potential therapeutic agent.

FGF2 and EGF for the Regeneration of Tympanic Membrane: A Systematic Review

Objective

A systematic review was conducted to compare the effectiveness and safety of fibroblast growth factor-2 (FGF2) and epidermal growth factor (EGF) for regeneration of the tympanic membrane (TM).

Methods

The PubMed database was searched for relevant studies. Experimental and clinical studies reporting acute and chronic TM perforations in relation to two healing outcomes (success rate and closure time) and complications were selected.

Results

A total of 47 studies were included. Five experimental studies showed closure rates of 55%-100% with FGF2 compared with 10%-62.5% in controls for acute perforations. Five experimental studies showed closure rates of 30.3%-100% with EGF and 3.6%-41% in controls for chronic perforations. Two experimental studies showed closure rates of 31.6% or 85.7% with FGF2 and 15.8% or 100% with EGF. Nine clinical studies of acute large perforations showed closure rates of 91.4%-100% with FGF2 or EGF. Two clinical studies showed similar closure rates between groups treated with FGF2 and EGF. Seven clinical studies showed closure rates of 88.9%-100% within 3 months and 58%-66% within 12 months using FGF2 in repair of chronic perforations, but only one study showed a significantly higher closure rate in the saline group compared with the FGF2 group (71.4% vs. 57.5%, respectively, P = 0.547). In addition, three experimental studies showed no ototoxicity associated with FGF2 or EGF. No middle ear cholesteatoma or epithelial pearls were reported, except in one experimental study and one clinical study, respectively.

Conclusions

FGF2 and EGF showed good effects and reliable safety for the regeneration of TM. In addition, EGF was better for the regeneration of acute perforations, while FGF2 combined with biological scaffolds was superior to EGF for chronic perforations, but was associated with high rates of reperforation over time. Further studies are required to determine whether EGF or FGF2 is better for TM regeneration.

The effectiveness and safety of growth factors in the treatment of tympanic membrane perforations: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

To determine the clinical efficacy and safety of growth factors in the treatment of tympanic membrane (TM) perforations from randomized controlled trials (RCTs).

METHODS

Databases, including PubMed, EMBASE, Cochrane library, Ebsco, Ovid, Scopus, and Web of Science, were searched for articles in any language about studies on the treatment of TM perforations with growth factors. Inclusion criteria were: (1) randomized controlled trials (RCTs); (2) only patients with TM perforations included; and (3) any kinds of growth factors or related products were used as an intervention. Exclusion criteria were: (1) study was not reported as a full paper, only as an abstract; (2) review studies and case reports; and (3) an inability to extract valid data. Outcomes of interest included perforation closure rate, closure time, hearing improvement, and complications.

RESULTS

Nineteen RCTs with a total of 1335 participants were included. Growth factors effectively increased the rate of perforation closure [risk ratio (RR): 1.21 95% confidence interval (1.12, 1.30), p < 0.01] and shortened closure time [mean difference (MD): - 16.71 (- 22.74, - 10.15), p < 0.01]. There was no significant difference in hearing improvement [MD: 0.10 (- 0.50, 0.70), p = 0.74] or complications [RR: 1.49 (0.96, 2.32), p = 0.07] between the growth factor intervention group and the control group.

CONCLUSION

Growth factors are effective and safe in the treatment of TM perforations. However, better designed clinical trials should be carried out in the future to obtain more robust findings about the effectiveness of growth factors in the treatment of TM perforations.

Topical Application of bFGF Alone for the Regeneration of Chronic Tympanic Membrane Perforations: A Preliminary Case Series

Results

A total of 29 patients consisting 13 in the bFGF alone group and 16 in the myringoplasty group were finally included in the analysis. Of the 13 patients in the bFGF alone group, the perforations were small in 6 and medium in 7; the etiology was secondary to COM in 11 and to trauma in 2. One patient with an unhealed perforation continued bFGF treatment until 6 months, while the others stopped at 3 months. Of the seven medium-sized perforations, none of the five COM perforations closed, while the two traumatic perforations achieved complete closure within 2 and 4 weeks, respectively. The successful closure rate was 28.6% (2/7). Successful closure was achieved in 66.7% (4/6) of the six small perforations with COM, with a mean closure time of 4.75 weeks. Of the 16 patients in the myringoplasty group, all perforations were medium-sized and were secondary to COM in 15 cases and traumatic in 1 case; all achieved complete closure.

Conclusions

bFGF alone facilitated the repair of chronic traumatic perforations and small perforations with COM, but not medium-sized perforations with COM. These observations indicated that the regenerative conditions of traumatic perforations are better than those of COM perforations when using bFGF alone, and that graft materials could play a critical role in the regeneration of larger-sized chronic perforations with COM.