Histological study of the healing of traumatic tympanic membrane perforation after basic fibroblast growth factor application

Multimodal additive manufacturing of biomimetic tympanic membrane replacements with near tissue-like acousto-mechanical and biological properties

The three additive manufacturing techniques fused deposition modeling, gel plotting and melt electrowriting were combined to develop a mimicry of the tympanic membrane (TM) to tackle large TM perforations caused by chronic otitis media. The mimicry of the collagen fiber orientation of the TM was accompanied by a study of multiple funnel-shaped mimics of the TM morphology, resulting in mechanical and acoustic properties similar to those of the eardrum. For the different 3D printing techniques used, the process parameters were optimized to allow reasonable microfiber arrangements within the melt electrowriting setup. Interestingly, the fiber pattern was less important for the acousto-mechanical properties than the overall morphology. Furthermore, the behavior of keratinocytes and fibroblasts is crucial for the repair of the TM, and an in vitro study showed a high biocompatibility of both primary cell types while mimicking the respective cell layers of the TM. A simulation of the in vivo ingrowth of both cell types resulted in a cell growth orientation similar to the original collagen fiber orientation of the TM. Overall, the combined approach showed all the necessary parameters to support the growth of a neo-epithelial layer with a similar structure and morphology to the original membrane. It therefore offers a suitable alternative to autologous materials for the treatment of chronic otitis media. STATEMENT OF SIGNIFICANCE: Millions of people worldwide suffer from chronic middle ear infections. Although the tympanic membrane (TM) can be reconstructed with autologous materials, the grafts used for this purpose require extensive manual preparation during surgery. This affects not only the hearing ability but also the stability of the reconstructed TM, especially in the case of full TM reconstruction. The synthetic alternative presented here mimicked not only the fibrous structure of the TM but also its morphology, resulting in similar acousto-mechanical properties. Furthermore, its high biocompatibility supported the migration of keratinocytes and fibroblasts to form a neo-epithelial layer. Overall, this completely new TM replacement was achieved by combining three different additive manufacturing processes.

Evaluation of Safety After Intracordal Basic Fibroblast Growth Factor Injection

OBJECTIVES

Although there are many reports of voice improvement with intracordal trafermin (a basic fibroblast growth factor) injections under local anesthesia, few papers have documented the safety of trafermin. Therefore, we aimed to investigate whether trafermin is safer than control drugs (triamcinolone acetonide) early after intracordal injection under local anesthesia.

METHODS

We conducted a retrospective review from the medical records of patients who underwent intracordal injection with trafermin and triamcinolone acetonide under local anesthesia at our institution. Early postinjective complications were defined as changes in vital signs and chief complaints early after intracordal injection.

RESULTS

A total of 699 and 297 patients underwent intracordal injection under local anesthesia with trafermin and triamcinolone acetonide, respectively. Of these, 227 and 130 patients had early postinjective complications with trafermin and triamcinolone acetonide, retrospectively. The most common complications occurring with trafermin was increased blood pressure in 39 cases (5.58%): 17 cases (2.43%) of blood pressure increase of ≥20 mm Hg. Other complications included pharyngeal discomfort in 37 (5.29%), lightheadedness in 33 (4.72%), and phlegm discharge in 29 (4.15%). Triamcinolone acetonide caused pharyngeal discomfort in 28 patients (9.43%), phlegm discharge in 17 patients (5.72%), lightheadedness in 12 patients (4.04%), sore throat in 11 patients (3.70%), increased blood pressure in 10 patients (3.37%): 7 cases (2.36%) of blood pressure increase of ≥20 mm Hg, and dizziness in seven patients (2.36%). Statistical analysis of the complications between trafermin and triamcinolone acetonide showed no significant differences.

CONCLUSIONS

The proportion of early postinjective complications from intracordal injection of trafermin is no significant difference in that of triamcinolone acetonide. The results suggest that the early postinjective complications are not due to the drug action of trafermin, but rather to complications from the intracordal injection procedures. Intracordal trafermin injection may be safe in the short term.

Thymosin beta-4 - A potential tool in healing middle ear lesions in adult mammals

Acute tympanic membrane perforations primarily occur due to injury or infection in humans. In acute cases, nearly 80-94 % of the perforations heal spontaneously. In chronic cases, non-surgical treatment becomes significantly limited, and the perforation can be restored only by myringoplasty. In addition to classical grafts such as the fascia or cartilage, promising results have been reported with various biological materials including silk or acellular collagen. However, despite of all the efforts, healing remains insufficient. Consequentially, a need for substances which actively promote tympanic cell migration and proliferation is deemed essential. In our study, we utilized Thymosin beta-4 (TB4), a 43aa peptide possessing many regenerative properties in various organ systems. Our aim was to reveal the impact of externally administered TB4 regarding impairments of the middle ear, particularly the tympanic membrane. We harvested tympanic membranes from adult mice and treated these with TB4 or PBS on both collagen gel matrixes and in the form of floating, ex vivo explants. Cell migration and proliferation was measured, while immunocytochemical analyses were performed to determine cell type and the nature of the targeted molecules. We discovered the peptide affects the behavior of epidermal and epithelial cells of the tympanic membrane in vitro. Moreover, as our initial results imply, it is not the differentiated, yet most likely the local epidermal progenitor cells which are the primary targets of the molecule. Our present results unveil a new, thus far undiscovered field regarding clinical utilization for TB4 in the future.

Changes in serum basic fibroblast growth factor concentration following intracordal injection

Objective

Although many studies have reported improvements in voice outcomes with intracordal trafermin injection, there is a lack of data documenting its changes in serum basic fibroblast growth factor (bFGF) blood concentration. This study examined whether serum bFGF concentrations change after intracordal trafermin injection.

Methods

This retrospective study was conducted at Tokyo Voice Center. We investigated serum bFGF concentrations before and after injection in 40 patients who underwent intracordal trafermin injection. There were 26 males and 14 females, with an age ranging from 13 to 88 years (average 53.25 years). They were diagnosed with paralysis (15 patients), atrophy (15 patients), sulcus (8 patients), and others (2 patients: scar and functional), presenting with severe hoarseness that interfered with daily life.

Results

The mean pre- and post-injective serum bFGF concentration of the 40 patients was 6.689 and 4.658 pg/mL, respectively. The difference in mean serum bFGF concentration between pre- and post-injective was -2.031 pg/mL. The Pearson correlation coefficient was calculated to evaluate the correlation between dosage of trafermin and post-injective serum bFGF concentration, and a moderate correlation was found at r = 0.52. Generalized linear model regression analysis was performed for the purpose of adjusting for confounding among variables. The only variable that showed a statistically predominant association with post-injective serum bFGF concentrations was the dosage of trafermin, with an estimated regression coefficient of 0.048.

Conclusion

In this study, the dosage of trafermin we injected and post-injective serum bFGF concentrations were dose-dependent but the amount of changes in the serum bFGF concentration was negligible within the physiological range. Therefore, as with subcutaneous and wound administration, intracordal trafermin injections may be safe.

Level of Evidence

Level IV.

Fine-mapping and association analysis of candidate genes for papilla number in sea cucumber, Apostichopus japonicus

The papilla number is one of the most economically important traits of sea cucumber in the China marketing trade. However, the genetic basis for papilla number diversity in holothurians is still scarce. In the present study, we conducted genome-wide association studies (GWAS) for the trait papilla number of sea cucumbers utilizing a set of 400,186 high-quality SNPs derived from 200 sea cucumbers. Two significant trait-associated SNPs that passed Bonferroni correction (P < 1.25E-7) were located in the intergenic region near PATS1 and the genic region of EIF4G, which were reported to play a pivotal role in cell growth and proliferation. The fine-mapping regions around the top two lead SNPs provided precise causative loci/genes related to papilla formation and cellular activity, including PPP2R3C, GBP1, and BCAS3. Potential SNPs with P < 1E-4 were acquired for the following GO and KEGG enrichment analysis. Moreover, the two lead SNPs were verified in another population of sea cucumber, and the expressive detection of three potential candidate genes PATS1, PPP2R3C, and EIF4G that near or cover the two lead SNPs was conducted in papilla tissue of TG (Top papilla number group) and BG (Bottom papilla number group) by qRT-PCR. We found the significantly higher expression profile of PATS1 (3.34-fold), PPP2R3C (4.90-fold), and EIF4G (4.23-fold) in TG, implying their potential function in papilla polymorphism. The present results provide valuable information to decipher the phenotype differences of the papilla trait and will provide a scientific basis for selective breeding in sea cucumbers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-022-00139-w.

3D printing for tissue engineering in otolaryngology

Airway and other head and neck disorders affect hundreds of thousands of patients each year and most require surgical intervention. Among these, congenital deformity that affects newborns is particularly serious and can be life-threatening. In these cases, reconstructive surgery is resolutive but bears significant limitations, including the donor site morbidity and limited available tissue. In this context, tissue engineering represents a promising alternative approach for the surgical treatment of otolaryngologic disorders. In particular, 3D printing coupled with advanced imaging technologies offers the unique opportunity to reproduce the complex anatomy of native ear, nose, and throat, with its import in terms of functionality as well as aesthetics and the associated patient well-being. In this review, we provide a general overview of the main ear, nose and throat disorders and focus on the most recent scientific literature on 3D printing and bioprinting for their treatment.

Effect of Basic Fibroblast Growth Factor on Perforated Chinchilla Tympanic Membranes

Basic fibroblast growth factor (bFGF) is a polypeptide mitogen which stimulates proliferation of epidermal and connective tissue cells. When applied to tympanic membrane perforations it has been reported to enhance healing and produce connective tissue hyperplasia. Previous work with animal models has shown that hyperplastic alterations of the tympanic membrane play an essential role in cholesteatoma development. This study was designed to further investigate the hyperplastic effects of bFGF and to determine if it might induce cholesteatoma formation during the healing process.

Ten chinchillas received bilateral tympanic membrane perforations. In each animal, three doses of bFGF (400 nanograms per dose) were applied to the perforated tympanic membrane on one side; the opposite (control) ear received saline alone. The animals were terminated at either two or four weeks and studied histologically.

Although the dosage and administration schedule used were consistent with previous studies utilizing other rodent species, there was little evidence that bFGF affected tympanic membrane healing in chinchillas. In both control and bFGF-treated ears, dense connective tissue occupied the lamina propria of the tympanic membrane, providing an effective barrier against ingrowth of skin toward the middle ear. No cholesteatomas developed in any animals included in the study.

The results of this work indicate that the risk of cholesteatoma formation following administration of bFGF is minimal when it is applied short-term to acute perforations.

A moist edge environment aids the regeneration of traumatic tympanic membrane perforations

OBJECTIVE

To review the history of moist therapy used to regenerate traumatic tympanic membrane perforations.

STUDY DESIGN

Literature review.

METHODS

The literature on topical agents used to treat traumatic tympanic membrane perforations was reviewed, and the advantages and disadvantages of moist therapy were analysed.

RESULTS

A total of 76 studies were included in the analysis. Topical applications of certain agents (e.g. growth factors, Ofloxacin Otic Solution, and insulin solutions) to the moist edges of traumatic tympanic membrane perforations shortened closure times and improved closure rates.

CONCLUSION

Dry tympanic membrane perforation edges may be associated with crust formation and centrifugal migration, delaying perforation closure. On the contrary, moist edges inhibit necrosis at the perforation margins, stimulate proliferation of granulation tissue and aid eardrum healing. Thus, moist perforation margins upon topical application of solutions of appropriate agents aid the regeneration of traumatic tympanic membrane perforations.

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.

Direct application of bFGF without edge trimming on human subacute tympanic membrane perforation

OBJECTIVE

To investigate the feasibility of direct application of basic fibroblast growth factor (bFGF) without edge trimming on human subacute traumatic tympanic membrane perforation (TMP).

METHODS

A total of 29 patients with traumatic TMPs beyond 1 month after trauma were enrolled. Patients were placed into two groups: an observation group (n=17) and a bFGF-treated group (n=12). The bFGF-treated group was treated by direct application of bFGF, in which the margin of the perforation was not trimmed. All patients were followed at least once per week until the perforation was completely closed or for up to 6 months. The closure rate and closure time were estimated.

RESULTS

At 6 months, 11/12 (91.7%) perforations achieved complete closure after bFGF treatment. The mean closure time was 18.1 ± 11.4 days (range=3-65 days). Purulent otorrhea was found after treatment in five patients, but resolved after oral amoxicillin and ofloxacin ear drops. Of these five patients, four achieved complete closure. However, only 9/17 (52.9%) perforations achieved complete spontaneous closure in the observation group. FGF-treated groups had significantly improved closure rates compared to the observation group (91.7% vs. 52.9%, respectively, P=0.03).

CONCLUSIONS

Although the margin of the perforation was not trimmed, direct application of bFGF on human subacute TMP was feasible, and it could significantly improve the closure rate of the subacute TMPs. The technique was simple and convenient. Thus, direct application of bFGF should be recommended pre-myringoplasty.

A pilot study investigating basic fibroblast growth factor for the repair of chronic tympanic membrane perforations in pediatric patients

OBJECTIVE

A pilot study to investigate the utility of basic Fibroblast Growth Factor (bFGF) in tympanic membrane perforation (TMP) closure in a small cohort of pediatric patients.

METHODS

Prospective cohort study. Suitability for inclusion in the study was confirmed by the application of defined inclusion and exclusion criteria, and informed parental consent obtained. The technique used was a modification of the bFGF-technique by Kanemaru et al. Response to treatment was monitored with serial otoscopy and audiometric outcomes were determined. Statistical analysis of the outcomes was carried out.

RESULTS

TMPs were successfully closed in 7/12 children at the first attempt (58%) and in 10/12 children overall (83%). Hearing improvement was observed in 8/10 successfully treated cases (80%). There were no complications or adverse outcomes.

CONCLUSIONS

The topical bFGF regeneration technique offers a promising, minimally invasive alternative to conventional myringoplasty in pediatric patients with comparable success and reduced morbidity and cost, especially considering the option of performing repeat applications. Patients with an active infection or inflammation are not suitable for the bFGF-mediated technique.

Impact of basic fibroblast growth factor on healing of tympanic membrane perforations due to direct penetrating trauma: a prospective non-blinded/controlled study

OBJECTIVE

To investigate the effect of direct application of basic fibroblast growth factor (bFGF) on healing of tympanic membrane perforations due to direct traumatic penetration through the external auditory canal.

DESIGN

A prospective non-blinded controlled study.

SETTING

University-affiliated teaching hospital.

PARTICIPANTS

In total, 104 patients with small [<25%] penetrating perforations were recruited. They were alternatively allocated to two groups: Control (spontaneous healing, n = 51) and FGF treatment (direct application of bFGF drops in the clinic and repeated daily by the patient, n = 53).

OUTCOMES

Perforation closure rate and time and hearing gain were recorded and compared between the two groups. Information on earache, dizziness and facial paralysis was also collected.

RESULTS

In total, 93 (89%) patients were finally analysed. The closure rate at 3 m of the perforations in the control spontaneous healing and bFGF treatment groups were 77% and 100%, respectively; the difference was statistically significant (P = 0.01). The average closure time was 43.1 ± 2.5 days (range, 17-57 days) for control patients, which was significantly longer (P < 0.01) than that for the bFGF-treated patients (12.6 ± 1.2 days; range, 3-21 days). The mean hearing improvement at 3 m was not significantly different between the FGF treatment and control groups (1.7 ± 2.4 dB vs 11.5 ± 1.9 dB, P > 0.05). No significant difference was observed in earache, dizziness and facial paralysis between two groups.

CONCLUSIONS

Direct application of bFGF may offer an effective topical management of penetrating traumatic tympanic membrane perforations, particularly for small-sized perforations.

Repair of tympanic membrane perforation using novel adjuvant therapies: a contemporary review of experimental and tissue engineering studies

OBJECTIVE

To perform a contemporary review of experimental studies to describe the effects of various novel adjuvant therapies in enhancing tympanic membrane (TM) perforation healing.

METHODS

A PubMed search for articles from January 2000 to June 2012 related to TM perforation, along with the references of those articles, was performed. Inclusion and exclusion criteria were applied to all experimental studies assessing adjuvant therapies to TM healing.

RESULTS

Many studies have assessed the efficacy of biomolecules or growth factors, such as epidermal growth factors and basic fibroblast growth factors, in TM regeneration with significant success. More recent strategies in TM tissue engineering have involved utilizing bioengineered scaffold materials, such as silk fibroin, chitosan, calcium alginate, and decellularized extracellular matrices. Most scaffold materials demonstrated biocompatibility and faster TM perforation healing rates.

CONCLUSION

Although several studies have demonstrated promising results, many questions still remain, such as the adequacy of animal models and long-term biocompatibility of adjuvant materials. As well, further studies comparing various adjuvant substances and bioscaffolds are required prior to clinical application.

The impact of platelet-derived growth factor on closure of chronic tympanic membrane perforations: a randomized, double-blind, placebo-controlled study

OBJECTIVE

Patients with tympanic membrane (TM) perforations often have infections, and repetitive topical treatment may be required. These infections can be prevented by permanent closure of the TM perforation. Different surgical treatment options have been described, but noninvasive techniques may be preferred as they carry less risk than surgery. One noninvasive approach is to induce wound healing by application of growth factors. The effect and clinical use of applying topical platelet-derived growth factor (PDGF) for decrease of size and closure of chronic TM perforations is evaluated.

STUDY DESIGN

Prospective, randomized, placebo-controlled, double-blind study.

SETTING

Tertiary referral center.

PATIENTS

Twenty patients with chronic suppurative otitis media without cholesteatoma for more than 3 months.

INTERVENTION

Topical treatment with PDGF or placebo applied weekly to the TM for 6 weeks.

MAIN OUTCOME MEASURES

Success rate, defined as a reduction of perforation size of 50% or more to determine relative changes of the perforation size; effect of initial size and location of TM perforation on success rate; and air and bone conduction thresholds to determine air-bone gap measured before treatment.

RESULTS

Randomization made matching pretreatment perforation size of the 2 study groups impossible, and the initial rate perforation/TM was significantly smaller in the PDGF group. No difference between the 2 groups was found for perforation/TM less than 10%. However, success rate did not differ significantly between the 2 groups (power = 0.8), and the effect of PDGF was found to be small (-2%; standard deviation, ±49%). Initial size and position of the TM perforation were not significant factors determining success. Mean air-bone gap for the frequencies of 0.5, 1, 2, and 4 kHz was 22.5 dB.

CONCLUSION

The topical application of PDGF as an office treatment for chronic otitis media is not a favorable alternative to surgery.

Tympanic membrane wound healing in rats assessed by transcriptome profiling

OBJECTIVES/HYPOTHESIS

The aim of this study is to elucidate transcriptional changes that occur in response to tympanic membrane (TM) perforation in rats and to infer key genes and molecular events in the healing process.

STUDY DESIGN

A prospective cohort study of 393 male Sprague-Dawley (Rattus norvegicus) rats.

METHODS

Sprague-Dawley rats were randomly allocated into either control or perforation groups spanning a 7-day time period. Perforation groups consisted of 12-hour, 24-hour, 36-hour, 2-day, 3-day, 4-day, 5-day, six-day, and 7-day time points. The left TMs of all perforation groups were perforated and the RNA extracted at the specified time point postperforation. Subsequent analysis was performed using Agilent's 4 × 44 k whole rat genome arrays (40 in total) to assess wound-healing gene expression over a 7-day time period.

RESULTS

Over a 7-day time course and at nine time points that encompassed the wounding and progression of healing, a total of 3,262 genes were differentially expressed. In this study the transcripts most upregulated occurred at 12 hours. These were Stefin A2 (344-fold), Stefin 2 (143-fold), and Natriuretic peptide precursor type B (222-fold). Those most downregulated also occurred at 12 hours. These were alcohol dehydrogenase 7 (13.1-fold) and gamma-butyrobetaine hydroxylase (10.4-fold). Results were validated by quantitative real-time polymerase chain reaction.

CONCLUSIONS

The findings of this study provide a baseline against which to identify disease-related molecular signatures, biomarkers, and to develop new treatments for TM conditions based on molecular evidence.

Keratinocyte growth factor 1, fibroblast growth factor 2 and 10 in the healing tympanic membrane following perforation in rats

The aim of this study was to provide a transcriptome profile of Keratinocyte Growth Factor (KGF)-1, Fibroblast Growth Factor (FGF) 2 and FGF10 (KGF2) in the healing rat tympanic membrane (TM) over 7 days and an immunohistochemical account over 14 days following perforation. KGF1, FGF2, and FGF10 play important roles in TM wound healing. The tympanic membranes of rats were perforated and sacrificed at time points over a 14-day period following perforation. The normalized signal intensities and immunohistochemical protein expression patterns at each time point for KGF1, FGF2, and FGF10 are presented. The primary role of both KGF1 and FGF2 appeared to be in the proliferation and migration of keratinocytes. Whereas the role of KGF1 appeared to be exclusively concerned with increased proliferation and migration at the perforation site, the continued expression of FGF2, beyond perforation closure, suggested it has an additional role to play. FGF10 (KGF2), whilst possessing the highest sequence homologous to KGF1, has a different role in TM wound healing. The effect of FGF10 on keratinocytes in wound healing appeared to emanate from the connective tissue layer.

[Tympanic membrane perforation and tympanoplasty]

OBJECTIVES

To report anatomic and physiologic characteristics of the tympanic membrane, to discuss the etiology and pathogenesis of tympanic perforation, and to discuss its management.

MATERIAL AND METHODS

After a review of the literature, different surgical techniques and the postoperative results were evaluated.

RESULTS

The rate of tympanic membrane closure is greater than 90% for the majority of authors. Age, mucosa inflammation, pathological contralateral ear (perforation, otitis media, cholesteatoma), and surgical experience influence this result.

DISCUSSION

Even if surgical results are good, abstention must always be proposed and all complications must be explained.

CONCLUSION

Palisade cartilage tympanoplasty is an effective technique for both tympanic membrane closures.

Delay of tympanic membrane wound healing in rats with topical application of a tyrosine kinase inhibitor

An animal model of chronic tympanic membrane (TM) perforation is needed for experiments on supporting wound healing of TM perforations. The epidermal growth factor receptor (EGFR) has been implicated in the regulation of wound healing. The object of this study was to investigate the efficacy of topical EGFR-inhibitor (erlotinib) to arrest wound healing of experimental TM perforation in rats. Bilateral instrumental myringotomies were performed in 13 male rats. A solution of erlotinib (10 mg/mL) was applied to one TM of each animal and vehicle only (control group) to the other side. The application procedure was repeated on both sides daily for 12 consecutive days. Thereafter, tympanic membranes were observed weekly for a total of 30 days. The mean healing period was found to be 12.1 days in the group with erlotinib and 6.4 days in the control group. The difference was significant. We observed differences in the histologic parameters between erlotinib group and control group. The inhibition of EGFR by topical application of erlotinib did delay the healing rate of myringotomies but seems not to be suitable to create a chronic TM perforation in rat.

[An improved animal model for chronic perforation of the tympanic membrane]

BACKGROUND

An inexpensive and valid animal model of chronic tympanic membrane perforation is needed.

METHOD

Twelve male rats were selected for different surgical procedures (subtotal tympanic membrane perforation with local microflaps, re-perforation without flaps, partial excision of the handle of malleus). The inhibition of spontaneous healing was accomplished by the application of prednisolon or mitomycin directly onto the tympanic membrane.

RESULTS

Only by additional partial excision of the handle of malleus followed by local application of mitomycin were we able to achieve a persistent tympanic membrane perforation.

CONCLUSION

Chronic tympanic membrane perforation using this procedure may be useful in further investigations of the medical impact of tympanic membrane healing.

Miringoplastia com a utilização de um novo material biossintético

A miringoplastia é uma cirurgia com a finalidade de controlar a infecção no ouvido médio, reconstruir o mecanismo de transmissão sonora para a janela oval e proteger a janela redonda. São descritos diversos materiais para reconstruir a membrana timpânica, destacando-se a fáscia do músculo temporal, pericôndrio do tragus, cartilagem, dura-máter, tecido placentário, entre outros. OBJETIVO: Este trabalho tem objetivo de demonstrar o efeito de um novo biomaterial, a membrana de látex natural com polilisina, desenvolvida no laboratório de Neuroquímica do Departamento de Bioquímica da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo - USP. FORMA DE ESTUDO: Coorte Longitudinal. MATERIAL E MÉTODO: O biomaterial utilizado é estimulante da neovascularização e crescimento tecidual organizado em diferentes órgãos e tecidos, sendo um material inócuo e não rejeitado pelo organismo. Foi usada a biomembrana de látex com polilisina como um implante transitório para o fechamento da perfuração da membrana timpânica. A membrana foi colocada na face externa dos bordos da membrana timpânica e a fáscia temporal na face interna da mesma. Foram estudadas 238 orelhas com perfuração de membrana timpânica por seqüela de otite média crônica, submetidas a miringoplastia com enxerto de fáscia de músculo temporal e a membrana de látex natural, com idades de 7 a 76 anos. Apresentavam uma ou mais miringoplastias anteriores sem sucesso 41 dos casos. RESULTADO: Como ressaltamos preliminarmente, verificamos pega do enxerto em 90,5% das orelhas (181), sendo fechamento de perfuração amplas, 96; médias, 73 e 12 pequenas. Verificamos intensa vascularização em 100% dos enxertos, o que não é habitual quando não se usa a membrana de látex natural. CONCLUSÃO: Conclue-se que o biomaterial usado merece nossa atenção quanto ao seu uso como implante transitório em miringoplastias, melhorando o processo de revascularização da membrana timpânica remanescente.

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.

Epidermal and fibroblast growth factors enhance fibrovascular integration of porous polyethylene implants

PURPOSE

Porous implants used in functional and aesthetic reconstruction of the orbit, face, and cranium are less likely to develop complications after they become biointegrated. We investigated whether the administration of exogenous growth factors could increase the rate of implant integration.

METHODS

High-density porous polyethylene cubes were placed in dorsal paraspinal muscles of rabbits, and daily transcutaneous injections of saline, epidermal growth factor, or basic fibroblast growth factor were administered directly over the cubes for 10 days. At serial time points up to 10 weeks, cubes were explanted and the fibroblasts present at the center of the cubes were counted.

RESULTS

Injections of epidermal growth factor and basic fibroblast growth factor increased the rate at which fibroblasts accumulated in porous polyethylene implants and decreased the time required to achieve a maximal rate of cellular accumulation within the cubes. At 4 weeks, when all cell populations had attained a linear rate of accumulation, cubes previously injected with saline, epidermal growth factor, or basic fibroblast growth factor contained an average of 10, 40, and 80 cells per 0.0156 mm2, at their centers, respectively.

CONCLUSIONS

Enhancement of the rate of biointegration of porous polyethylene cubes in rabbits is achievable by repeated, transcutaneous administration of exogenous growth factors.

Effects of platelet-derived growth factor-AA on the healing process of tympanic membrane perforation

PURPOSE

Platelet-derived growth factor basic 30-kD disulfide-bonded dimer of A and B chains (PDGF-AA, PDGF AB, PDGF-BB) and a cytokine, promoting wound healing by its mitogenicity for fibroblast and by stimulating the production of fibronectin and hyaluronic acid. This article investigates the effect of PDGF on the healing process of tympanic membrane (TM) perforation.

MATERIALS AND METHODS

The pars tensa of the posterior aspect of the TM of rats was excised and treated with 2 microg of PDGF-AA or placebo. The animals were killed at 3, 5, 7, 9, 11, 15, and 28 days after operation. The healing process of TM perforation was observed with a telescope and light microscope. The temporal bones were also immunohistochemically examined for PDGF-alpha receptor (PDGF-R(alpha)) and fibronectin.

RESULTS

All PDGF-AA-treated TM were completely closed by 5 days after surgery, whereas some of the placebo-treated TM were not closed at 15 postoperative days. PDGF-AA induced the most prominent proliferation of the connective tissue by 9 postoperative days, after which the growth of the connective tissue decreased. By the 4th postoperative week, the PDGF-treated TM were slightly thicker than normal TM. An intense expression of fibronectin was detected in the connective tissue layer of the TM that were treated with PDGF-AA. PDGF-R(alpha) was expressed in the epithelial layer of both the PDGF-treated and control TM.

CONCLUSION

These results show that PDGF-AA speeds up the healing process of TM defect, improves the rate of healing, and prevents atrophic changes in the healed TM by promoting the connective tissue growth. The use of PDGF-AA can be an effective alternative to surgery for managing TM perforations.

Modulation of tissue ingrowth into porous high-density polyethylene implants with basic fibroblast growth factor and autologous blood clot

OBJECTIVE

To investigate the effect of direct application of biologic materials normally present in wounds (basic fibroblast growth factor [bFGF] and autologous blood clot [ABC]) to accelerate the bony and soft tissue ingrowth into porous high-density polyethylene implants.

METHODS

We conducted a prospective, blinded animal histological study. Disks made of porous high-density polyethylene impregnated with bFGF or ABC were implanted into adult Sprague-Dawley rats in both subcutaneous and subperiosteal locations. Animals were killed and implants were harvested at 2, 4, and 10 weeks postimplantation and examined histologically for fibroblast invasion, collagen deposition, and inflammatory reaction.The results were compared with control (untreated) implants.

RESULTS

As a group, the histological results showed significantly more fibroblasts within the ABC-treated implants than control implants or bFGF-treated implants. This difference in the number of fibroblasts between ABC-treated implants and bFGF-treated and control implants was also statistically significant 2 weeks after implantation.

CONCLUSIONS

At the concentration of bFGF of 1 microg/10 microL, no acceleration of tissue ingrowth into porous high-density polyethylene implants was noted. However, when porous high-density polyethylene implants were treated with ABC, the implants were invaded to a greater degree by soft tissue, particularly in the early postoperative period (first 2 weeks). Bioactive substances associated with the coagulation and platelet cascades present in the ABC may be responsible for this accelerated incorporation of the porous implant and may have clinical implications. Arch Facial Plast Surg. 2000;2:27-33

Healing large tympanic membrane perforations using hyaluronic acid, basic fibroblast growth factor, and epidermal growth factor

Large tympanic membrane perforations usually require a surgical tympanoplasty for closure. Reducing surgical costs and risks has encouraged investigators to examine nonsurgical office procedures for healing these perforations. Growth accelerators are the most promising agents. We study here the closure of large acute perforations using weekly applications of 1 mg of 1% hyaluronic acid (HA), 0.4 microg basic fibroblast growth factor (bFGF), or 1.0 microg epidermal growth factor (EGF) directly to the tympanic membranes of the experimental ears. Control ears were treated with 0. 1 mL Vasocidin. Complete closure was obtained in 100% of the ears treated with HA and EGF and 85.7% of those treated with bFGF by day 21, compared with 63.6% of the controls by day 32. Moderate-to-severe ipsilateral and contralateral external canal hypertrophy was noted in 14.2% and 37.5% of the ears treated with bFGF and HA, respectively, but was not seen in ears treated with EGF or in the control group.

Overlay versus underlay tympanoplasty. Part I: historical review of the literature

The history of otology is the history of the successful treatment of infections of the middle ear and the eardrum. Otologists have sought to restore hearing lost to infections of the eardrum since the 1600s. The development of instruments, techniques, and materials to treat infection is fascinating because of the serendipitous nature of the discoveries and the insight of the discoverers. This historical review describes the history of the treatment of infections of the ear and the development of modern techniques of ear surgery. Two contemporary methods of tympanic membrane repair are then described.

Treatment of chronic postoperative otorrhea with cultured keratinocyte sheets

Cultured allogeneic ear keratinocyte sheets were used to treat 26 ears presenting with long-standing (average 37 months) chronic otorrhea, resistant to regular treatment, long after surgery for atresia (n = 8), cholesteatoma (n = 10), and chronic otitis media (n = 8). Complete epithelial healing and cessation of otorrhea were obtained in 18 cases (69%), following an average of 2.2 weekly applications. Temporary epithelial healing lasting at least 3 months was observed in 3 patients (12%) subsequently needing repeated applications. Lack of complete epithelialization was documented in 5 cases (19%). In 3 of those 5 cases, a reason could be determined. The authors speculate that the allocultured keratinocytes are able to promote migration and proliferation of resident cells at the wound edges, despite their short survival time, by release of keratinocyte-stimulating factors.

Repair of Chronic Tympanic Membrane Perforations with Fibroblast Growth Factor

A number of angiogenic growth factors have been shown to accelerate wound healing. Previous work has demonstrated that topical application of epidermal growth factor is effective in healing chronic tympanic membrane perforations in an animal model. Theoretically, fibroblast growth factor may result in a superior healed membrane through preferential stimulation of the fibroblasts within the middle layer of the tympanic membrane. To test this hypothesis, the effects of exogenously applied fibroblast growth factor on the chronically perforated tympanic membrane were evaluated. A buffered solution of fibroblast growth factor (25 μl of fibroblast growth factor, 0.2 mg/ml) was administered to a Gelfoam pledget placed over chronic tympanic membrane perforations in chinchillas. Control ears were treated with Gelfoam and the buffer solution only. Complete closure of the tympanic membrane perforation was observed in 81% (13 of 16) of the fibroblast growth factor-treated ears, but in only 41% (7 of 17) of the controls ( p = 0.05). Healing took place gradually, requiring an average of 4 weeks for the fibroblast growth factor-treated and 6.5 weeks for the control ears that healed. The relatively high healing rate for the control group does not imply that the pretreatment perforations were not chronic, rather there appears to be some efficacy to the control protocol of repeated applications of Gelfoam and buffer. A histologic analysis of the fibroblast growth factor-healed eardrums immediately after closure demonstrated hypertrophy of the squamous and fibrous layers of the tympanic membrane. Over time, the eardrum thinned to reach proportions similar to those of the normal tympanic membrane, including the presence of a substantial middle fibrous layer. A screening ototoxicity study revealed no structural damage to the organ of Corti after growth factor treatment. To assess the potential for systemic toxicity, blood and peripheral tissues were analyzed for radioactivity at time points during a 48-hour period after application of 25 μl of 125l-fibroblast growth factor to the perforated tympanic membrane. More than 78% of the radioactivity remained at the application site. Given the tiny original dosage, the small fraction absorbed systemically is minuscule and highly unlikely to induce adverse effects in light of published toxicity data. On the basis of these promising safety and efficacy data in the chinchilla model, clinical trials of fibroblast growth factor in repair of chronic tympanic membrane perforations in human beings are being initiated.

Lysates from cultured allogeneic keratinocytes stimulate wound healing after tympanoplasty

In the past, cultured keratinocyte allografts have been used with benefit in the treatment of burn wounds and leg ulcers. Since in burn wounds autologous and allogeneic fresh keratinocyte cultures were found to give similar favorable results as lysates of allogeneic cultured cells, the authors investigated whether this lysate mixed in an antibiotic suspension would also accelerate the epithelial healing after routine tympanoplasty. In a double blind setting the healing process in 50 consecutive tympanoplasty ears was studied: an acceleration of healing of 8 days was observed in the lysate-treated group (39.25 days) as compared with the control group (47.23 days). The percentage of ears which healed within 6 weeks (after 5 weekly applications of 200 microliters suspension in both groups) was significantly higher in the treated group (61%) than in the control population (36%). Although the therapeutical effect of the keratinocyte lysate in this study is believed to be due primarily to its mitogenic activity through growth factors or cytokines, at present it is still unclear which growth factors are involved and which combinations of these factors have to be present to modulate the different stages of the complex healing processes.

Epidermal growth factor and basic fibroblast growth factor are induced in guinea-pig tympanic membrane following traumatic perforation

Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF or FGF-2) have been shown to enhance the healing of traumatic tympanic membrane (TM) perforations. The action of EGF and bFGF in the TM repair process remains unknown. This study was designed to determine the expression of EGF and bFGF in normal and injured TM by immunohistochemistry. EGF was detected in normal TM mainly in the annulus tympani area. After a perforation in the TM posterior/superior quadrant, EGF was detected around the perforated area in polynuclear cells, in pericytes and in basal epithelial cells. EGF was also detected in the antero/superior quadrant in basal epithelial cells and pericytes. The peak of EGF detection was observed 3 days after the perforation. bFGF was not detected in normal TM, but it was expressed 3 days after a traumatic perforation mainly in the perforated area in pericytes and in polynuclear cells. This study suggests that EGF and bFGF are involved in the control of TM acute perforation repair. These findings help to explain the accelerated healing of TM perforations that are seen after application of FGF or EGF, and suggest that antibodies against these growth factors would retard the healing process.