Effects of fibroblast growth factor on the healing process of tympanic membrane perforations in an animal model

Audiologic and Otologic Clinical Manifestations of Loeys-Dietz Syndrome: A Heritable Connective Tissue Disorder

OBJECTIVE

Loeys-Dietz syndrome (LDS) is a rare genetic connective tissue disorder resulting from TGF-ß signaling pathway defects and characterized by a wide spectrum of aortic aneurysm, arterial tortuosity, and various extravascular abnormalities. This study describes the audiologic, otologic, and craniofacial manifestations of LDS.

STUDY DESIGN

Consecutive cross-sectional study.

SETTING

Tertiary medical research institute.

METHODS

Audiologic and clinical evaluations were conducted among 36 patients (mean ± SD age, 24 ± 17 years; 54% female) with genetically confirmed LDS. Cases were categorized into genetically based LDS types 1 to 4 (TGFBR1, TGFBR2, SMAD3, TGFB2, respectively). Audiometric characteristics included degree and type of hearing loss: subclinical, conductive, mixed, and sensorineural.

RESULTS

LDS types 1 to 4 included 11, 13, 5, and 7 patients, respectively. In LDS-1, 27% had bilateral conductive hearing loss; 9%, unilateral mixed; and 36%, subclinical. In LDS-2, 38% had conductive hearing loss and 38% subclinical. In LDS-3 and LDS-4, 40% and 43% had bilateral sensorineural hearing loss, respectively. Degree of hearing loss ranged from mild to moderate. Bifid uvula was observed only in LDS-1 (55%) and LDS-2 (62%). Submucosal/hard cleft palates were primarily in LDS-1 and LDS-2. Posttympanostomy tympanic membrane perforations occurred in 45% (10/22 ears) of LDS-1 and LDS-2. There were 4 cases of cholesteatoma: 3 middle ear (LDS-1 and LDS-2) and 1 external ear canal (LDS-3).

CONCLUSION

Conductive hearing loss, bifid uvula/cleft palate, and posttympanostomy tympanic membrane perforation are more common in LDS-1 and LDS-2 than LDS-3 and LDS-4, while sensorineural hearing loss was present only in LDS-3 and LDS-4. These LDS-associated key clinical presentations may facilitate an early diagnosis of LDS and thus prompt intervention to prevent related detrimental outcomes.

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.

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.

Pretreatment factors affecting traumatic tympanic membrane regeneration therapy using epidermal growth factor

OBJECTIVE

The use of epidermal growth factor (EGF) to achieve closure of human traumatic tympanic membrane perforations (TMPs) was recently reported. However, pretreatment factors affecting healing outcomes have seldom been discussed. This study was performed to evaluate pretreatment factors contributing to the success or failure of TMP healing using EGF.

DESIGN AND PARTICIPANTS

This was a retrospective cohort study of 95 TMPs who were observed for at least 6 months after EGF treatment. Eleven factors considered likely to affect healing outcome were evaluated by univariate and multivariate logistic regression analyses.

INTERVENTIONS

Each traumatic TMP was treated by daily topical application of EGF. The main outcome measures were complete closure versus failure to close and mean closure time.

RESULTS

A total of 95 patients were included in the analyses. The total closure rate was 92.6% at 6 months, and the mean closure time was 10.5 ± 4.8 days. The closure rate was not significantly different according to the duration of perforation ≤3 days and >3 days (P = 0.816). However, the mean closure time was significantly different according to the duration of perforation (P < 0.001). The perforation size did not affect the closure rate (P = 0.442). The mean closure time in the low-dose EGF group was significantly shorter than that in the high-dose EGF group (P = 0.001). Logistic regression analyses showed that perforations with preexisting myringosclerosis were more likely to fail to close compared to those without preexisting myringosclerosis (P = 0.001). Multivariate logistic regression analyses showed that the duration of perforation (P = 0.011), size of perforation (P < 0.001), and involvement of the malleus in perforation (P = 0.005) were factors independently correlated with closure time.

CONCLUSIONS

Daily application of EGF can be used to treat all traumatic TMPs. The size of the perforation and inverted edges did not affect the closure rate, and the most beneficial dosage was sufficient to keep the eardrum moist. Multivariate logistic regression analyses revealed a significant correlation between preexisting myringosclerosis and failure to heal. Nevertheless, the size of perforation, starting time of application, and malleus injury were independent prognostic factors for prolonged healing time.

Regeneration of the tympanic membrane using fibroblast growth factor-2

OBJECTIVE

A systematic review was conducted to investigate the effectiveness of fibroblast growth factor-2 on the regeneration of tympanic membrane perforation.

METHODS

The PubMed database was searched for relevant studies. Experimental studies, human randomised controlled trials, prospective single-arm studies and retrospective studies reporting acute and chronic tympanic membrane perforations in relation to two healing outcomes (success rate and closure time), were selected.

RESULTS

All 11 clinical studies investigating the effect of fibroblast growth factor-2 on traumatic tympanic membrane perforations in humans reported a success rate of 89.3-100 per cent, with a closure time of around 2 weeks. Three studies of fibroblast growth factor-2 combined with Gelfoam showed that the success rate of chronic tympanic membrane perforation was 83-98.1 per cent in the fibroblast growth factor-2 group, but 10 per cent in the gelatine sponge groups.

CONCLUSION

Fibroblast growth factor-2 with or without biological material patching promotes regeneration in cases of acute and chronic tympanic membrane perforation, and is safe and efficient. However, the best dosage, application time and administration pathway of fibroblast growth factor-2 are still to be elucidated.

Novel transparent collagen film patch derived from duck's feet for tympanic membrane perforation

To increase healing rate of tympanic membrane (TM) perforations, patching procedure has been commonly conducted. Biocompatible, biodegradable patching materials which is not limited across cultures is needed. The authors evaluated the effectiveness of novel transparent duck's feet collagen film (DCF) patch in acute traumatic TM perforation. This procedure was compared with spontaneous healing and paper patching. Cell proliferation features were observed in paper and DCF patches. Forty-eight TMs of 24 rats were used for animal experiment, perforations were made on each TMs, and divided into three groups according to treatment modality. Sixteen were spontaneously healed, 16 were paper patched and 16 were DCF patched. The gross and histological healing results were analyzed. Both paper and DCF patch showed no cytotoxicity, but cell proliferations were more active in DCF than paper in early stage. In animal study, the healing of TM perforations were completed within 14 days in all three groups, but found to be faster in DCF patch group than paper patch or spontaneous healing group. The DCF patches were transparent and size of DCF patches were gradually decreased, so there were no need to remove the DCF patches to check the wound status or after the completion of healing. According to this result, authors concluded that DCF patch is transparent, biocompatible and biodegradable material, and can induce fast healing in acute traumatic TM perforations.

A comparative study to evaluate the efficacy of EGF, FGF-2, and 0.3% (w/v) ofloxacin drops on eardrum regeneration

BACKGROUND

Traumatic tympanic membrane perforations (TMPs) tend to spontaneous healing, however, large TMPs usually fail to healing. Clinical and experimental studies had demonstrated that growth factors accelerated the healing of large TMPs. The aim of this study was to compare the effects of growth factors and 0.3% (w/v) ofloxacin drops n the healing of human large TMPs.

METHODS

A total of 184 human large traumatic TMPs were randomly assigned to receive epidermal growth factor (EGF) treatment, fibroblast growth factor-2 (FGF-2) treatment, 0.3% (w/v) ofloxacin drops treatment, and conservative observation (only).

RESULTS

A total of 180 patients were analyzed in this study at the 6-month follow-up. The closure rates of the perforations in the EGF, FGF-2, 0.3% (w/v) ofloxacin drops, and conservative observation groups were 91.11%, 93.18%, 95.65%, and 82.22%, respectively, the closure rates did not significantly differ among the groups (P = .165). Similarly, pairwise comparisons did not reveal any significant between-group differences (P > .0083). However, the difference of the mean closure time was significant among the 4 groups (P < .001), pairwise comparisons showed that closure time was significantly longer in the observational group than in the other 3 groups (P < .001). Nevertheless, no significant difference in mean closure time was evident between any 2 treated groups (P > .0083). The mean hearing gain after 6 months was 11.49 ± 5.88 dB for the EGF group, 10.89 ± 5.16 dB for the FGF-2 group, 10.54 ± 5.56 dB for the ofloxacin group, and 9.29 ± 5.36 dB for the observation group. Differences in hearing improvement rates among the 4 groups were not statistically significant (P = .283).

CONCLUSION

Epidermal growth factor, FGF-2, and 0.3% (w/v) ofloxacin drops accelerated the closure of large TMPs compared with conservative treatment. Surprisingly, neither the closure rate nor closure time differed significantly among the 3 treated groups. Further experimental studies to demonstrate whether 0.3% (w/v) ofloxacin per se accelerates the healing of TMPs will be interesting in the future.

Rat model of chronic tympanic membrane perforation: A longitudinal histological evaluation of underlying mechanisms

OBJECTIVE

To evaluate histologically the progressive development and underlying mechanisms of chronic tympanic membrane perforation (TMP) in a rat model using a two-weeks ventilation tube (VT) treatment combined with topical application of mitomycin C/dexamethasone (VT-M/D), compared with normal tympanic membrane and acute TMPs.

METHODS

Fifty male Sprague-Dawley rats were divided into three experimental groups: a normal control group (n = 5), an acute TMP group (n = 5) (i.e. 3 days post-myringotomy) and a VT-M/D group (n = 40). The TMs were regularly assessed by otoscopy. The normal control animals were sacrificed on day 0 and the acute TMP group was sacrificed 3 days post-myringotomy for histological and immunohistochemical evaluations. The VT-M/D group was sacrificed at various time points - 14 and 17 days, 3, 4, 6, 8 and 10 weeks.

RESULTS

On longitudinal histological examination, compared with normal TM and acute TMP, the perforation edges at the later time points illustrated thickened stratified squamous epithelium rimming around the edges, significant increase in keratin and collagen deposition, increased macrophage infiltration as well as reduced cellular proliferation. Three phases of TMP healing process were identified - the acute healing phase (3-17 days), the transition phase (3-4 weeks) and the chronic phase (6-10 weeks).

CONCLUSION

Based on the histological results of this study, the progressive development of chronic TMPs appeared to be associated with increased epidermal thickening, collagen and keratin deposition, macrophage infiltration and reduced cellular proliferation. After the 3-4 weeks of transition phase, the TMPs seemed to have transformed into a non-healing chronic TMP between 6 and 10 weeks.

Rat model of chronic tympanic membrane perforation: Ventilation tube with mitomycin C and dexamethasone

OBJECTIVE

Chronic tympanic membrane perforation (TMP) in a clinical setting may attract surgical intervention. With the advent of modern biomaterials, new options are available for myringoplasty but safety and efficacy need evaluation in a chronic TMP animal model. The aim of this study was to evaluate the efficacy of ventilation tube (VT) insertion in conjunction with topical application of mitomycin C/dexamethasone (M/D) for the creation of chronic TMP in rats.

METHODS

Thirty male Sprague-Dawley rats underwent myringotomy of the right tympanic membrane (TM) and were divided into three experimental groups: spontaneous healing (myringotomy control), VT insertion for 2 weeks and VT insertion for 2 weeks in conjunction with topical application of M/D (VT-M/D). All TMs were regularly assessed by otoscopy for 10 weeks and then animals were sacrificed for histological evaluation.

RESULTS

In the VT-M/D group, seven out of ten (70%) perforations were patent at 10 weeks (mean patency, 57.9 days; P<0.01). The VT group had two out of ten (20%) perforations patent at 10 weeks (mean patency, 26.5 days; P<0.01), while all TMPs from the myringotomy control group were closed by day 9 (mean patency, 7.2 days). Histologically, the TMPs patent at week 10 had a stratified squamous epithelialized rim, keratinocyte layer thickening around the perforation edge as well as increased collagen deposition and macrophage infiltration.

CONCLUSION

Chronic TMP in a rat model was successfully created by VT insertion and the efficacy was increased in combination with topical application of M/D.

Utility of basic fibroblast growth factor in the repair of blast-induced total or near-total tympanic membrane perforations: A pilot study

OBJECTIVE

A pilot study was performed to investigate the utility of basic fibroblast growth factor (bFGF) in the repair of blast-induced total or near-total tympanic membrane perforations (TMPs).

STUDY DESIGN

Prospective clinical study.

SETTING

Tertiary university hospital.

SUBJECTS AND METHODS

Patients who fulfilled the inclusion criteria were treated with 0.10-0.15 mL of bFGF solution applied directly to total or near-total TMPs once daily until the perforations closed or for a maximum of 6 months. The treatment response was monitored via serial otoendoscopy, and audiometric outcomes were evaluated.

RESULTS

Complete TMP closure was achieved in 16 of 17 patients with a blast-induced total or near-total TMP. The mean closure time was 28.4 ± 10.9 days. The improvement in hearing from pre- to post-treatment was statistically significant. There were no complications or adverse outcomes.

CONCLUSIONS

The direct application of bFGF to blast-induced total or near-total TMPs is a promising, minimally invasive alternative to conventional tympanoplasty, with a comparable success rate. As reported in the literature, the closure rate was higher than achieved with spontaneous healing. There was no effect of the inverted edge on healing outcome. The use of bFGF in this setting has immediate therapeutic applications for military personnel with blast-induced TMPs who are stationed in isolated, remote environments.

Searching for a rat model of chronic tympanic membrane perforation: Healing delayed by mitomycin C/dexamethasone but not paper implantation or iterative myringotomy

OBJECTIVES

Surgical intervention such as myringoplasty or tympanoplasty is an option in the current clinical management of chronic tympanic membrane perforation (TMP). Animal models of chronic TMP are needed for pre-clinical testing of new materials and to improve existing techniques. We evaluated several reported animal model techniques from the literature for the creation of chronic TMPs. The aim of this study was to evaluate production of chronic TMPs in a rat model using topical mitomycin C/dexamethasone, paper insertion into middle ear cavity (MEC) or re-myringotomy.

METHODS

Forty male Sprague-Dawley rats underwent myringotomy of the right tympanic membrane (TM) and were randomly divided into 3 experimental groups: application of topical mitomycin C/dexamethasone, paper insertion into middle ear cavity, or re-myringotomy. Control perforations were allowed to close spontaneously. TMs were assessed regularly with otoscopy for 8 weeks. At the end of 8 weeks, animals were sacrificed for histology.

RESULTS

The closure of TMPs was significantly delayed by mitomycin C/dexamethasone (mean patency, 18.9 days; P≤0.01) compared with the control (mean patency, 7 days), but was not significantly delayed in the paper insertion group (mean patency, 9.4 days; P=0.74). Repeated myringotomy of closed perforations (mean number of myringotomies, 8.9 per ear) stimulated acceleration of closure rather than delay. Histologically, the mitomycin C/dexamethasone group had almost normal TM morphology, while the paper insertion group revealed inflammatory and granulomatous responses. The re-myringotomy group had a thickened TM fibrous layer with collagen deposition.

CONCLUSIONS

Mitomycin C/dexamethasone delayed TMP closure in rats but the effect was not sufficiently long-lasting to be defined as a chronic TMP. Neither paper insertion into middle ear cavity nor re-myringotomy created chronic TMP in rats.

Evaluation of the optimum time for direct application of fibroblast growth factor to human traumatic tympanic membrane perforations

OBJECTIVE

The aim of this study was to determine the optimum time for direct application of basic fibroblast growth factor (bFGF) on large traumatic tympanic membrane perforations (TMPs).

STUDY DESIGN

Prospective clinical study.

SETTING

Tertiary University Hospital.

METHODS

Ninety-three patients, with traumatic TMPs greater in extent than 25% of the entire tympanic membrane, were randomized into observation and bFGF-treated groups (~0.2-0.25 mL of bFGF solution was applied directly onto the TM once daily and continued until the perforation closed). Initial visit times were subcategorized into perforation durations of ≤3 and >3 days, thereby rendering two subgroups, as follows: A and B in the observation group; and C and D in the bFGF-treated group. The closure rate and mean closure time were evaluated after 6 months.

RESULTS

Eighty-six patients were finally analyzed. After 6 months, the bFGF-treated group exhibited a significantly higher total closure rate (97.8 versus 82.5%, p < 0.05) and a shorter mean closure time (12.5 ± 3.4 versus 34.0 ± 5.9 days, p < 0.05) compared with the spontaneous healing group. In addition, in the observation group, visiting time was not associated with differences in closure rate (p > 0.05) and mean closure time (p > 0.05), between the A and B subgroups. Similarly, in the bFGF-treated group, visiting time was not associated with differences in closure rate (p > 0.05) between the C and D subgroups. However, the D subgroup was characterized by significantly shortened mean closure time compared with the C subgroup (p < 0.05).

CONCLUSIONS

This study shows the beneficial effect of bFGF on human traumatic large TMPs when applied after the 3rd day post-injury had passed (i.e. during the proliferative stage of wound healing). The procedure can not only significantly shorten closure time but can also reduce both the clinical administration duration and occurrence of side-effects associated with bFGF.

Risk factors affecting human traumatic tympanic membrane perforation regeneration therapy using fibroblast growth factor-2

OBJECTIVE

The use of growth factors to achieve closure of human traumatic tympanic membrane perforations (TMPs) has recently been demonstrated. However, pretreatment factors affecting healing outcomes have seldom been discussed. The objective of this study was to evaluate pretreatment factors contributing to the success or failure of healing of TMPs using fibroblast growth factor-2 (FGF-2).

DESIGN AND PARTICIPANTS

A retrospective cohort study of 99 patients (43 males, 56 females) with traumatic TMPs who were observed for at least 6 months after FGF-2 treatment between March 2011 and December 2012. Eleven factors considered likely to affect the outcome of perforation closure were evaluated statistically using univariate and multivariate logistic regression analysis.

INTERVENTIONS

Each traumatic TMP was treated by direct application of FGF-2.

MAIN OUTCOME MEASURES

Complete closure versus failure to close.

RESULTS

In total, 99 patients were analyzed. The total closure rate was 92/99 (92.9%) at 6 months; the mean closure time was 10.59 ±  6.81 days. The closure rate did not significantly differ between perforations with or without inverted edges (100.0% vs. 91.4%, p = 0.087), among different size groups (p = 0.768), or among different periods of exposure to injury (p = 0.051). However, the closure rate was significantly different between the high- and low-dose FGF-2 groups (85.0% vs. 98.3%, p = 0.010) and between perforations where the umbo or malleus was or was not involved in perforation (85.4% vs. 98.3%, p = 0.012). Additionally, univariate logistic regression analysis tests showed that it was difficult to achieve healing of these perforations with a history of chronic otitis media or residual TM calcification (p = 0.006), the umbo or malleus was involved in perforation (p = 0.038), and with a high dose of FGF-2 (p = 0.035) compared with control groups. Multivariate logistic regression analysis showed that only a history of chronic otitis media and residual TM calcification and perforation close to the umbo or malleus were associated with non-healing of the TM perforation (p = 0.03 and p = 0.017, respectively) with relative risk factors.

CONCLUSIONS

Direct application of FGF-2 can be used in all traumatic TMPs, the size of the perforation and inverted edges did not affect the closure rate, and the most beneficial dose was sufficient to keep the residual eardrum environment moist, but without adding liquid. Additionally, multivariate logistic regression analysis revealed that a large perforation was not a major risk factor for nonhealing of TM perforations. However, a history of chronic otitis media, residual TM calcification and involvement of the umbo or malleus in perforation were significant risk factors.

Animal models of chronic tympanic membrane perforation: a 'time-out' to review evidence and standardize design

OBJECTIVE

To review the literature on techniques for creation of chronic tympanic membrane perforations (TMP) in animal models. Establishing such models in a laboratory setting will have value if they replicate many of the properties of the human clinical condition and can thus be used for investigation of novel grafting materials or other interventions.

METHODS

A literature search of the PubMed database (1950-August 2014) was performed. The search included all English-language literature published attempts on chronic or delayed TMP in animal models. Studies of non English-language or acute TMP were excluded.

RESULTS

Thirty-seven studies were identified. Various methods to create TMP in animals have been used including infolding technique, thermal injury, re-myringotomy, and topical agents including chemicals and growth factor receptor inhibitors. The most common type of animal utilized was chinchilla, followed by rat and guinea pig. Twenty three of the 37 studies reported success in achieving chronic TMP animal model while 14 studies solely delayed the healing of TMP. Numerous experimental limitations were identified including TMP patency duration of <8 weeks, lack of documentation of total number of animals attempted and absence of proof for chronicity with otoscopic and histologic evidence.

CONCLUSION

The existing literature demonstrates the need for an ideal chronic TMP animal model to allow the development of new treatments and evaluate the risk of their clinical application. Various identified techniques seem promising, however, a need was identified for standardization of experimental design and evidence to address multiple limitations.

Effects of basic fibroblast growth factor dose on traumatic tympanic membrane perforation

OBJECTIVE

To compare the healing outcomes of higher and lower doses of basic fibroblast growth factor (bFGF) on human traumatic tympanic membrane perforation (TMP).

STUDY DESIGN

Prospective clinical study.

METHODS

All patients with traumatic TMP were treated by direct application of bFGF, and were sequentially allocated into one of two groups: lower-dose group (2-3 drops of bFGF solution daily, approximately 0.1-0.15 mL) and higher-dose group (5-6 drops of bFGF solution daily, approximately 0.25-0.3 mL). The results of closure rate, closure time, and rate of otorrhea between the higher- and lower-dose groups were compared at 3 months.

RESULTS

In total, 126 patients were included in this study. The higher-dose group showed significantly improved purulent otorrhea rate compared with the lower-dose group (p < 0.01) for perforations of the same size, although the closure rate of the middle-sized perforations did not differ significantly between higher- and lower-dose groups (p > 0.05). However, the lower-dose group had a significantly shorter closure time of 5 d compared with the higher-dose group (p < 0.05). In addition, although the lower-dose group showed shorter healing times (about 3 d) compared to the higher-dose group for large-sized perforations, the dosage of bFGF did not significantly affect the large-sized perforation closure rate (p > 0.05) or closure time (p > 0.05). Nine large-sized perforations with secondary purulent otorrhea achieved complete closure, with closure times of 7-25 (14.2 ± 5.8) d.

CONCLUSION

This study suggested that continued daily application of a lower dose of bFGF not only shortens the closure time of human traumatic TMP but also avoids secondary purulent otorrhea.

A new patch material for tympanic membrane perforation by trauma: the membrane of a hen egg shell

CONCLUSION

The egg shell membrane (ESM) patch may promote tympanic membrane (TM) healing in acute traumatic TM perforation.

OBJECTIVE

To evaluate the use of ESM for treating acute traumatic TM perforation.

METHODS

We reviewed charts of patients with traumatic TM injury from 2008 to 2011. Treatments were an ESM patch or a perforation edge approximation. We divided patients into two groups according to the treatment used. Each patient was matched by treatment onset and perforation size. We compared healing ratio, healing time, and frequency of otorrhea between the perforation edge approximation group and the ESM patch group. Matched t tests were used for analysis.

RESULTS

The healing ratio of the TM showed no significant difference between the two groups, but the time to heal was significantly shorter in the ESM patch group than in the perforation edge approximation group.

Tissue engineering of the tympanic membrane

Tympanic membrane (TM) perforations are common, with current treatments for chronic perforations involving surgery, using various graft materials, from autologous cartilage or fascia through to paper patch. Recent research developments in this field have begun applying the principles of tissue engineering, with appropriate scaffolds, cells, and bioactive molecules (BMs). This has revolutionized the therapeutic approach due to the availability of a wide range of materials with appropriate compatibility and mechanical properties to regenerate the membrane acoustics and may also represent a paradigm shift in the management of TM perforations in an outpatient setting without surgery. However, many factors need to be considered in the fabrication of a bioengineered TM. This review discusses the issues associated with current treatment and examines TM wound healing relevant to the construction of a bioengineered TM. It also describes the tissue-engineering approach to TM regeneration by summarizing currently used scaffolds, BMs, and cells in TM wound healing. Finally, it considers the design of scaffolds, delivery of BMs, and cell engraftment toward potential clinical application.

The importance of vascular endothelial growth factor in the healing of acute tympanic membrane perforation

PURPOSE

The purpose of this study was to determine the more important growth factor expression between basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in the healing of acute tympanic membrane (TM) perforation.

MATERIALS AND METHODS

Bilateral perforations of the TM were created in 12 rats. The TM perforations in the right ears were treated with dexamethasone, and left ears were designated as the control group. The TM was examined for the growth factor expression immunohistochemically in the epithelial and fibrous layers according to the rate of TM perforation healing.

RESULTS

The mean spontaneous healing time of the TM perforations was 11.0 +/- 2.0 days. However, dexamethasone-treated group showed no evidence of closure. The bFGF and VEGF expression were significantly correlated with the rate of healing of acute TM perforations. The VEGF expression was decreased both in the epithelial and fibrous layers, but bFGF expression was decreased only in the epithelial layer in the dexamethasone-treated group. The VEGF was expressed to a lesser degree than bFGF in the dexamethasone-treated group.

CONCLUSION

Vascular endothelial growth factor is the more specific and important growth factor than bFGF in the healing of acute TM perforation.

Chronic tympanic membrane perforation: a better animal model is needed

Developments in the treatment of chronic tympanic membrane perforation have been hindered by the lack of an ideal animal model. It is not appropriate to test such treatments on acute perforations as the majority of these heal spontaneously. An ideal animal model would be one that most closely resembles the human clinical situation. It should be inexpensive, readily available, and easy to create. There have been a number of attempts to create a chronic tympanic membrane perforation model with limited success. All published attempts at chronic tympanic membrane perforations have been reviewed and the limitations of each model are discussed. A number of areas for research exist for further developing a chronic tympanic membrane perforation model. These areas include a perforation model in the presence of bacteria and eustachian tube dysfunction. Understanding the molecular and genetic mechanisms of chronic otitis media and potential treatments will also be useful.

A new method for closing tympanic membrane perforations using basic fibroblast growth factor

OBJECTIVE

To present a new method for closing tympanic membrane perforations using basic fibroblast growth factor (bFGF) combined with an atelocollagen/silicone bilayer membrane as a patch material.

STUDY DESIGN

Closure of tympanic membrane perforations was attempted using bFGF, which is thought to facilitate the growth of fibroblasts and collagen fibers at the margin of the perforation.

METHODS

Under an operating microscope, the margin of the perforation was trimmed, and a piece of an atelocollagen/silicone bilayer membrane infiltrated with 0.2 mL Trafermin (0.1% solution) (bFGF group) or saline (control group) was then placed in the perforation with the silicon layer facing outward. Nine patients were treated with bFGF, and five were treated with saline. Data obtained from patient records included patient age, perforation size, and duration of treatment, with a focus on hearing improvement and complete tympanic membrane closure.

RESULTS

The mean perforation size before treatment was 16.5% in the bFGF group and 9.6% in the control group. Closure of the tympanic membrane perforation was achieved in all cases in the bFGF group, whereas it was achieved in only two of five cases in the control group. With bFGF treatment, the tympanic membrane perforations closed completely within 3.7 weeks, and hearing improved by 13.3 dB in the bFGF group.

CONCLUSION

The study demonstrated that bFGF combined with an atelocollagen/silicone bilayer membrane is effective for the conservative treatment of tympanic membrane perforation.

Topical treatment with growth factors for tympanic membrane perforations: progress towards clinical application

Basic scientific research has demonstrated that epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor-AA (PDGF-AA) and transforming growth factor-alpha (TGF-alpha) are induced by acute tympanic membrane (TM) perforation. The expression of these growth factors peaks during the inflammatory phase and then declines, suggesting their involvement in the healing process of the TM. Expression of EGF receptor, bFGF receptor, PDGF receptor and keratinocyte growth factor (KGF) receptor in the TM has also been reported. Identification of these receptors indicates that the target cells in the TM may be stimulated during the process of healing by the corresponding exogenous growth factor in vivo. Some reports from animal studies showed encouraging effects of EGF, bFGF and PDGF-AA in terms of accelerated or enhanced healing of acute and chronic TM perforations without significant adverse effects. Two reports of clinical trials of topical application of EGF or bFGF for TM perforations revealed mixed results. In this article special considerations for future directions of research into growth factors are discussed and related articles on healing of skin wounds and other lesions are reviewed. Further experimental and clinical studies on the mechanism of action of growth factors, timing of application, selection (either singly or in combination), delivery mode, dose and safety aspects, as well as more clinical trials, are warranted, and will pave the way for clinical application.