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

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.

Bioprinted collagen-based cell-laden scaffold with growth factors for tympanic membrane regeneration in chronic perforation model

With the recent development of bioprinting technology, various attempts have been made to replace bioprinting technologies and regenerative medicine are more directed towards transplantation/reconstructive surgeries only with the implantation of scaffolds. The purpose of this study is to determine whether the growth factors, human umbilical cord serum (hUCS) and bFGF (basic fibroblast growth factor), have a synergistic effect on eardrum regeneration, when used with a cell-printed scaffold in a chronic tympanic membrane perforation (TMP) model. In this study, in vitro cellular activities for bioprinted cell-laden collagen scaffolds using human adipose stem cells (hASCs) and supplemented with 10 μg/mL hUCS and 10 ng/mL bFGF were performed. The mixture of the growth factors in the cell-laden structures effectively affects various in vitro cellular responses including the proliferation of hASCs and the migration of keratinocytes due to the synergistic effect of the growth factors and hASCs. For the in vivo evaluation, a rat TMP model was used, and the TMP regeneration was assessed by otoscopic examination, hearing threshold measurement, and histologic examination. Although the cell-laden structure containing hUCS was more enhancing effect compared to the structure with bFGF, more synergistic effect in the structure using hUCS/bFGF was observed. Based on the results, we believe that the cell-laden structure incorporating hUCS and bFGF can induce significant regeneration of chronic tympanic membrane perforation.

Acellular Collagen Scaffold With Basic Fibroblast Growth Factor for Repair of Traumatic Tympanic Membrane Perforation in a Rat Model

OBJECTIVE

To evaluate the efficacy of acellular collagen scaffold (ACS) in combination with basic fibroblast growth factor (bFGF) for the repair of traumatic tympanic membrane (TM) perforation in a rat model.

STUDY DESIGN

A prospective controlled animal study in a rat model of traumatic TM perforation.

SETTING

Tertiary medical center.

SUBJECTS AND METHODS

Sprague-Dawley rats (N = 84) with unilateral traumatic perforation of the right TMs were randomized to receive ACS, bFGF, ACS in combination with bFGF (ACS/bFGF), or nothing (spontaneous healing without any interventions as a control group). The healing outcomes were evaluated by otoscopy, optical coherence tomography, histology, and transmission electron microscopy at 1, 2, and 4 weeks postoperatively. The hearing outcomes were assessed with auditory brainstem response testing.

RESULTS

ACS/bFGF resulted in higher perforation closure rates at an earlier stage than spontaneous healing, ACS, and bFGF. Based on histology, optical coherence tomography, and transmission electron microscopy, a trilaminar structure and uniform thickness with mature, densely packed collagen fibers were seen in the ACS/bFGF group. Auditory brainstem response evaluation also showed that ACS/bFGF treatment promoted faster functional hearing recovery as compared with the control group.

CONCLUSIONS

ACS is an effective TM scaffold and a carrier for bFGF. ACS/bFGF improves the TM closure rate, results in better-reconstructed TMs, and improves hearing. ACS/bFGF serves as a potential substitute for TM perforations in clinical settings.

Comparative efficacy of platelet-rich plasma applied in myringoplasty: A systematic review and meta-analysis

BACKGROUND

Tympanic membrane (TM) perforation is quite common in the clinical setting. Chronic TM perforations require surgical treatments such as myringoplasty. Currently, platelet-rich plasma (PRP) is a novel, effective substance that is increasingly utilized for TM perforation repair. This study aims to evaluate the effectiveness of PRP in the application of TM perforation repair.

METHODS

A systematic search was conducted to screen the Medline, Embase, Cochrane, Scopus and Web of Science databases up to July 2020. Studies were identified in accordance with the selection criteria by two coauthors independently. Data regarding the healing and hearing outcomes were pooled and analyzed via Review Manager version 5.3 and STATA version 12.0 software. Odds ratio (OR) was utilized to compare the closure rate. Furthermore, the results of hearing improvements and incidence of complications were also compared to evaluate the effectiveness of PRP.

RESULTS

A total of eight studies with 455 participants were eligible according to the selection criteria. Compared to conventional surgery, the OR of closure was 2.70 (95% CI: 1.27 to 5.76, P = 0.01, I2 = 0%) in randomized controlled trial (RCT) subgroup and 6.18 (95% CI: 2.22 to 17.25, P = 0.0005, I2 = 0) in non-RCT subgroup. The overall OR of closure was 3.69 (95% CI: 2.02 to 6.74, P<0.0001, I2 = 0%), suggesting a significant effect on the healing of TM perforation. Between preoperative and postoperative hearing results, there is no statistical difference between the PRP and the control groups. Additionally, the use of PRP resulted in a lower incidence of complication than the use of conventional approaches.

CONCLUSION

The application of PRP during the TM surgeries can enhance the closure rate, provide similar hearing improvements and decrease the incidence of postoperative complications. Given these advantages, PRP can be considered an effective treatment for TM regeneration.

Acceleration of Healing of Traumatic Tympanic Membrane Perforation in Rats by Implanted Collagen Membrane Integrated with Collagen-Binding Basic Fibroblast Growth Factor

Traumatic tympanic membrane (TM) perforation is very common in clinical practice. Several biomaterials have been reported to play a role in TM reparation, whereas their functional recovery is limited when used alone. Meanwhile, the administration of biofactors could promote functional recovery, but rapid distribution and short half-time obstruct their application. To study the effect of traumatic TM regeneration, we prepared collagen membrane (CM) integrated with collagen-binding basic fibroblast growth factor (CBD-bFGF) and implanted into the injury site of perforated TM in Sprague-Dawley rats. The study on CBD-bFGF in vitro showed that CBD-bFGF accelerated the proliferation of human fibroblast cell HS-865 biologically and was released from CM gradually. In vivo study, through the gross anatomy, auditory brainstem responses assay, histological staining, and transmission electron microscopy observation at d7, d14, and d28 after the acute TM perforation, we found that CBD-bFGF-integrated CM promoted the healing rate at an early stage (∼7 days), reduced the healing time of perforated TM, and notably retrieved the structure and hearing of TM. These findings suggest that CM modified with CBD-bFGF could be therapeutically appropriate for the treatment of TM perforation.

No systemic exposure of transtympanic heparin-binding epidermal growth factor like growth factor

CONTEXT

Heparin-binding epidermal growth factor like growth factor (HB-EGF) is an emerging therapeutic for the regeneration of the tympanic membrane (TM).

OBJECTIVE

Our aim was to determine whether the doses of HB-EGF delivered in a sustained release hydrogel into a middle ear mouse model, would be measurable in the systemic circulation. We also aimed to observe, in the scenario that the intended dose was absorbed directly into the circulation, whether these levels could be measured above the background levels of HB-EGF in the circulation.

METHODS

A total of 12 mice had transtympanic injections of 5 μg/ml of HB-EGF contained within a previously described novel hydrogel vehicle, while another 12 mice had intravenous delivery of 10 μg/kg of HB-EGF. Intravenous blood samples were collected at 0-, 3-, 24-, 168-, 288- and 720-h post-injection. A double-antibody sandwich one-step process enzyme-linked immunosorbent assay (ELISA) was used to determine the level of HB-EGF in the serum.

RESULTS

No mice in the transtympanic administration group and no mice in the intravenous administration group were found to have blood level measured above that in the controls.

DISCUSSION

The inability of the positive control to measure levels above background, suggest the total dose used in our studies, even if 100% absorbed into the system circulation is insignificant.

CONCLUSIONS

HB-EGF at the doses and delivery method proposed for treatment of chronic TM perforation in a mouse model are likely to have no measurable systemic effect.

Acupuncture-Induced Analgesia: The Role of Microglial Inhibition

The last three decades have documented preclinical and clinical data supporting the use of acupuncture in relieving symptoms of many diseases, including allergies, infections, and neurological disorders. The advent of electroacupuncture has not only modernized the practice of acupuncture, but also has improved its efficacy, especially for producing analgesic-like effects. Although the mechanism of action of acupuncture-induced analgesia remains largely unknown, several lines of investigation have implicated modulation of pain processes via brain opioid signaling and neuroimmunoregulatory pathways. Here, we review key findings demonstrating the efficacy and underlying mechanisms of acupuncture-induced analgesia. In particular, we discuss potent analgesic effects of acupuncture via neural pain processes through inhibition of microglial activation. The safe and effective use of acupuncture stands as a nonpharmacological alternative for induction of analgesia, which has direct clinical applications, especially for pain-related diseases.

Enhanced expression of hepatocyte growth factor in the healing of experimental acute tympanic membrane perforation

OBJECTIVES

The present study was performed to investigate the expression of hepatocyte (HGF), epidermal (EGF) and vascular endothelial (VEGF) growth factors in the course of healing of experimental tympanic membrane (TM) perforations in rats. The goal was to explain the role of these growth factors in the healing process of TM and to assess the possibility of their future application as healing promoters.

METHODS

Seventy rats were used, of which 10 served as controls and the others had their TM perforated. The experimental animals were divided into six subgroups on the basis of time points (01, 03, 05, 07, 09, 15 day after injury). Videootoscopy and histology were employed to assess the morphology of the healing process. The expressions of HGF, EGF and VEGF were evaluated using Western blot analysis. Tissue localization of HGF was determined by the immunofluorescence method.

RESULTS

HGF was hardly detectable in normal TM; however, a significant increase was noted in its expression starting from the third day after injury throughout the follow-up period, with the highest level on day 05. The analysis of HGF tissue localization with immunofluorescence revealed diffuse staining in the cytoplasm of proliferating epithelial cells. The expression of EGF was elevated on the first day after injury, not reaching statistical significance, and then returned to the level observed in the control TM. No significant differences were noted in the expression of VEGF.

CONCLUSION

High expression of HGF during the healing process of acute TM perforations makes it a promising candidate for further studies oriented towards its possible use in augmentation of TM healing.

Use of ambulatory anesthesia with manually assisted ventilation for tympanic membrane regeneration therapy in children

PURPOSE

To present the utility of ambulatory anesthesia using manually assisted ventilation via a facemask for tympanic membrane (TM) regeneration therapy in children.

MATERIAL AND METHODS

The study included 10 children (age 4-11years) in whom the duration of perforation before treatment exceeded 6months and who were followed for at least 1year after treatment between December 2009 and December 2012. Under ambulatory anesthesia using manually assisted ventilation via a facemask, TM regenerative therapy with atelocollagen combined with basic fibroblast growth factor was performed in children who could not tolerate the procedure under local anesthesia alone.

RESULTS

All of the children completed the TM regenerative therapy under ambulatory anesthesia in less than 5min. Complete closure was achieved in nine (81.8%) ears after 1year of postoperative follow-up.

CONCLUSION

TM regenerative therapy can be performed under local anesthesia in less than 5min without a skin incision. However, local anesthesia is often insufficient in small children undergoing this procedure. Therefore, ambulatory anesthesia using manually assisted ventilation via a facemask is appropriate to complete this procedure safely in small children.

Efficiency of cryotherapy in avoiding myringotomy closure in rats

Myringotomy and ventilation tube placement is an office-based procedure and represents the treatment of choice for middle ear effusions and for transtympanic drug administration. The aim of our study was to study the efficiency of low-pressure spray cryotherapy on protraction of patency time of myringotomies in rats. Bilateral myringotomies were performed with cold instruments. Afterward, one ear in each rat was randomly assigned for liquid nitrogen treatment of the perforated eardrum. Myringotomy patency was recorded daily and histological analysis of the eardrums was performed. In the myringotomy group patency time was 4.75 ± 2.93 days, while in the cryotherapy group was 11.01 ± 4.87 days. The difference is statistically significant: Student t test, p < 0.00001, 95 % CI (-8.82; -3.67). Moreover, according to Kaplan-Meier method, myringotomy survival is significantly longer in the cryotherapy group. The healing processes of the cryotreated eardrums last longer and the patency of myringotomy was longer as compared to untreated myringotomies.

Gelatin hydrogel with basic fibroblast growth factor for tympanic membrane regeneration

HYPOTHESIS

In this developmental research study that aimed to develop tympanic membrane regeneration therapy, we devised a method of sustained bFGF formulation release using gelatin hydrogel in a guinea pig eardrum perforation model.

BACKGROUND

Basic fibroblast growth factor (bFGF) can promote perforation closure. In addition, several studies of bFGF formulations have used gelatin hydrogel-bFGF coupled electrostatically to a gelatin polymer. BFGF is released gradually as a result of degradation of the gelatin polymer, and studies have shown that the long-term pharmacologic effects of bFGF can be maintained.

METHODS

Using a CO(2) laser, total tympanic membrane perforations were created in 24 guinea pig ears and divided into 3 groups: the bFGF-gelatin hydrogel group(n = 8), the saline-gelatin hydrogel group (n = 8), and the control group (n = 8). Either a bFGF formulation or saline was impregnated into gelatin hydrogen and implanted into the perforated tympanic membrane.

RESULTS

All ear drums of the control group showed large perforations at even the 30th postoperative day. The perforation persisted in 3 of 8 ears in the saline-gelatin hydrogel group, and the tympanic membranes that had achieved closure were thinned, whereas all ears in the bFGF-gelatin hydrogel group achieved closure of the perforation. In the ears in which a normal tympanic membrane had regenerated, histologic observation with hematoxylin and eosin staining revealed that, although mucosal and epithelial layer regeneration had occurred in the saline-gelatin hydrogel group, the bFGF-gelatin hydrogel group showed regeneration of the fibrous layer in addition to the other 2 layers.

CONCLUSION

These data suggest that hydrogel impregnated with bFGF induces regeneration of the tympanic membrane and can conservatively treat tympanic membrane perforation.

Plasminogen initiates and potentiates the healing of acute and chronic tympanic membrane perforations in mice

BACKGROUND

Most tympanic membrane (TM) perforations heal spontaneously, but approximately 10-20% remain open as chronic TM perforations. Chronic perforations can lead to an impaired hearing ability and recurrent middle ear infections. Traditionally, these perforations must be surgically closed, which is costly and time consuming. Therefore, there is a need for simpler therapeutic strategies. Previous studies by us have shown that plasminogen (plg) is a potent pro-inflammatory regulator that accelerates cutaneous wound healing in mice. We have also shown that the healing of TM perforations is completely arrested in plg-deficient (plg(-/-)) mice and that these mice develop chronic TM perforations. In the present study, we investigated the therapeutic potential of local plg injection in acute and chronic TM perforation mice models.

METHODS

Plg(-/-) mice and wild-type mice were subjected to standardized TM perforations followed by local injection of plg into the soft tissue surrounding the TM. TM perforations with chronic characteristics were induced by leaving TM perforations in plg(-/-) mice untreated for 9 days before treatment. The healing process was observed through otomicroscope and finally confirmed by immunostaining. The quality of TM healing was evaluated based on the morphology of the TM.

RESULT

Daily local injections of plg into the soft tissue surrounding the TM restored the ability to heal TM perforations in plg-/- mice in a dose-dependent manner, and potentiated the healing rate and quality in wild-type mice. A single local injection of plg initiated the healing of the chronic-like TM perforations in these mice, resulting in a closed TM with a continuous but rather thick outer keratinocyte layer. However, three plg injections led to a completely healed TM with a thin keratinizing squamous epithelium covering a connective tissue layer.

CONCLUSION

Our data suggests that plg is a promising drug candidate for the treatment of chronic TM perforations in humans.

Mice deficient in urokinase-type plasminogen activator have delayed healing of tympanic membrane perforations

Mice deficient in plasminogen, the precursor of plasmin, show completely arrested healing of tympanic membrane (TM) perforations, indicating that plasmin plays an essential role in TM healing. The activation of plasminogen to plasmin is performed by two plasminogen activators (PAs), urokinase-type PA (uPA) and tissue-type PA (tPA). To elucidate the functional roles of PAs in the healing of TM perforations, we investigated the phenotypes of single gene-deficient mice lacking uPA (uPA(-/-)) or tPA (tPA(-/-)) after TM perforation. Delayed healing of TM perforations was observed in uPA(-/-) mice but not tPA(-/-) mice. The migration of keratinocytes was clearly delayed and seemed to be misoriented in uPA(-/-) mice. Furthermore, fibrin deposition and the inflammatory response were persistent in these mice. Our findings demonstrate that uPA plays a role in the healing of TM perforations. The observed phenotypes in uPA(-/-) mice are most likely due to the reduced generation of plasmin.

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.

Healing of laser-induced tympanic membrane perforations in rats: no contribution of granulocyte colony-stimulating factor or Gelfoam

OBJECTIVES

To study whether granulocyte colony-stimulating factor together with Gelfoam (absorbable gelatin sponge, USP) could enhance the healing of freshly perforated tympanic membranes. The frequency and occurrence of different immunocompetent cells and collagen types was noted.

METHODS

Laser perforations were made in the tympanic membrane of rats that were sacrificed at different time intervals post-myringotomy: Day 1, 3, 6, and 12. Tympanic membrane specimens were embedded and sections were stained with hematoxylin/eosin and an immunohistochemical technique was used, with antibodies against macrophages, B-cells, T-cells, and type I-IV collagens. Semi-quantification was performed after counting positive cells, mean values were calculated and analyzed statistically.

RESULTS

All perforations, except one, had closed by Day 12 and no difference was observed between experimental and control ears at the other time points. Gelfoam was still present in a high amount at Day 12. The sections were initially stained positive for type I and II collagen, but after Day 6, the regenerating tissue stained positive for mainly type III and IV collagens. Results showed that the recruitment of macrophages, B-cells, and T-cells could not be mapped with a statistical significance.

CONCLUSIONS

This study showed that at 6-12 days post-laser myringotomy, type III and IV collagen has replaced the collagen type II that normally constitutes the healthy tympanic membrane. There is a concern for excessive scarring involving adjacent structures. It was also seen that the combination of Gelfoam and granulocyte colony-stimulating factor or saline did not affect the healing times in perforated tympanic membranes. No significant results regarding the inflammatory cell recruitment could be obtained on the studied time points or between experimental and control ears, except for in the Gelfoam matrix.

Analysis of the effectiveness of basic fibroblast growth factor treatment on traumatic perforation of the tympanic membrane at different time points

OBJECTIVE

The aim of this study was to evaluate the effectiveness of basic fibroblast growth factor (bFGF) treatment on traumatic perforation of the tympanic membrane at different time points.

RESEARCH DESIGN

This is a prospective clinical study.

METHODS

Patients with traumatic perforations of the tympanic membrane were given a treatment of gelatin sponge + bFGF at different time intervals of 3 days, 4 to 7 days, 8 to 15 days, and more than 4 weeks after the injury. Healing rate and time of perforation were also observed after 1 month.

RESULTS

In 147 ears, 144 (98.0%) were healed. The perforation healing rates were 98.6%, 97.6%, 96.3%, and 100%, respectively, at the following time intervals: within 3 days, 4 to 7 days, 8 to 14 days, and 2 to 4 weeks since the injury. This was quite true without any significant difference (P > .05). Meanwhile, in the small perforation healing of 120 ears, the average healing times from admission to perforation within 3 days, 4 to 7 days, and 8 to 14 days after the injury were 7.95 ± 2.07, 6.75 ± 2.67, and 4.18 ± 0.91 days, respectively. No significant difference was found among the 3 groups (P(1) < .01).

CONCLUSION

Treating traumatic perforation of the tympanic membrane using the bFGF technique at different times of admissions is quite effective.

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.

Effect of treatment at different time intervals for traumatic tympanic membrane perforation on the closure

CONCLUSION

Treatment of traumatic tympanic membrane (TM) perforation with everted or involute edge flaps at different time intervals within 1 week after the injury did not affect the perforation closure rate and mean closure time.

OBJECTIVE

To retrospectively analyze the effect of treatment at different time intervals for traumatic tympanic membrane perforation with gelatin sponge patch and edge approximation plus gelfoam patching.

METHODS

Patients with traumatic TM perforation visited at different days since the injury for medical treatment (1, 2, 3, 4, and 5-7 days post trauma). These patients were treated with the following prominent methods of treatment: gelatin sponge patch treatment and edge approximation plus gelfoam patching. Measurement indicators were perforation closure rate and mean closure time at 3 months.

RESULTS

In the group treated with the gelatin sponge patch technique, the patients sought medical treatment at different time intervals since the injury. Accordingly, the outcome of the treatment varied in terms of the perforation closure rates achieved in different patients in this group. The respective perforation closure rates were 100%, 100%, 96%, 94%, and 89% in accordance with the time interval at which the patients were treated since the injury. The results were not significantly different when compared by statistical analysis (p > 0.05); the mean closure times in each of the different sets of cases in this group were calculated and the following values were reported: 7.1 ± 2.3, 8.2 ± 1.6, 8.7 ± 1.2, 9.2 ± 3.1, and 10.7 ± 3.9 days. On the other hand, in the edge approximation plus gelfoam patching group, the perforation closure rates were 100%, 97%, 96%, 97%, and 94%, respectively. This was in accordance with the time elapsed since the injury for the patients who visited the hospital on different days. Statistical analysis confirmed that the perforation closure rates for the different cases of this group did not have any significant difference (p > 0.05); the mean closure times were 7.6 ± 1.9, 7.9 ± 2.2, 9.2 ± 2.8, 8.5 ± 3.6, and 11.2 ± 4.1 days, respectively, indicating that differences were not significant even in terms of mean closure rates for the different cases of this group (p > 0.05).

Outcome of children with edge-everted traumatic tympanic membrane perforations following spontaneous healing versus fibroblast growth factor-containing gelfoam patching with or without edge repair

OBJECTIVES

To retrospectively analyze the outcome of children with edge-everted tympanic membrane (TM) perforations following spontaneous healing and fibroblast growth factor-containing gelfoam patching with or without repair of the edge flaps.

METHODS

Medical records of children with TM perforations who underwent spontaneous healing (n = 69) or received fibroblast growth factor (FGF)-containing gelfoam patching treatment (n = 67) were retrieved from the Records Department of the Wenzhou Medical College-Affiliated Yiwu Hospital in China. The demographic data and outcome measures were analyzed and compared between these two groups of patients.

RESULTS

Patching with FGF-containing gelfoams significantly improved the healing rate (P < 0.01) and the average perforation closure time (P<0.01), as compared with spontaneous healing. Repair of the perforation edge flaps did not significantly affect the outcome of gelfoam patching (P>0.05), despite a slightly reduced healing rate (96.4% versus 100%) and a slightly shorter closure time (10.2 ± 2.6 d versus 10.9 ± 3.3 d) observed as compared with no edge repair. The everted perforation edge flaps formed scabs during the process of spontaneous healing whereas they underwent retraction and eventually dissolved during the process of gelfoam patching-facilitated healing.

CONCLUSIONS

As compared with spontaneous healing, FGF-containing gelfoam patching had an improved outcome in children with edge-everted traumatic eardrum perforation. Repair of everted edge flaps did not affect the healing outcome. Our results suggest that growth factor-containing gelfoam patching without eardrum flap repair would offer a feasible option to manage traumatic tympanic membrane perforations in children.

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.

The role of epidermal growth factor in the healing tympanic membrane following perforation in rats

Epidermal Growth Factor (EGF) has been identified as playing a critical role in the wound healing process. The objective of this study is to investigate the role that EGF plays in rat tympanic membrane (TM) wound healing using two techniques, microarray and immunohistochemistry. The tympanic membranes of rats were perforated using a sterile needle and sacrificed at time points during 2 weeks following perforation. The normalized signal intensities at the time points for EGF and associated genes are presented. The rat EGF mRNA did not change significantly between time points. Five associated proteins, including heparin-binding EGF-like growth factor were found to be differentially expressed above a two fold threshold at 12 h following perforation. EGF staining was found at low levels in the uninjured TM. Levels of EGF staining increased at 24 h in the basal keratinocyte layer, became diffusely elevated in the specimen at 36 h, before a second peak in staining of the keratinocyte layer at Day 4. The staining of EGF corresponds to its multiple roles in TM wound healing.

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.

Basic fibroblast growth factor combined with atelocollagen for closing chronic tympanic membrane perforations in 87 patients

OBJECTIVE

To present the clinical results of closing chronic tympanic membrane (TM) perforations using basic fibroblast growth factor (bFGF) combined with an atelocollagen/silicone bilayer membrane patch.

STUDY DESIGN

Closure of TM perforations in 87 patients was attempted using bFGF, which is thought to promote the regeneration of TM tissues by facilitating the growth of fibroblasts and collagen fibers.

METHODS

Under an operating microscope, the margin of the perforation was trimmed, and a piece of an atelocollagen/silicone bilayer membrane was placed in the perforation with the silicon layer facing outward and then infiltrated with 0.1 ml of trafermin. Data obtained from patient records included patient age, perforation size, and duration of treatment, with a focus on hearing improvement and complete TM closure.

RESULTS

The mean perforation size before treatment was 14.4%. Complete closure of the TM perforation was achieved in 80 patients (92.0%), whereas pinholes remained in 5 patients (8.7%), and small perforations were observed in 2 patients (2.3%). In the patients with complete closure, the TM perforations closed after an average 1.8 treatments, and hearing improved by 13.6 dB.

CONCLUSION

This study demonstrated that bFGF combined with atelocollagen is effective for the conservative treatment of TM perforation.

Acute tympanic membrane perforations and the early immunological response in rats

CONCLUSIONS

This study showed that macrophages, B cells, and T cells occurred at different frequencies, localizations, and times after acute laser tympanic membrane perforation. Immunological cells were most prevalent in the proliferative mass adjacent to the annulus region. The cellular immunological response in freshly perforated eardrums was unexpectedly aggressive.

OBJECTIVES

To study the occurrence of immunocompetent cells during the healing process of fresh perforated tympanic membranes. The information could be used to develop alternative outpatient procedures in the cure of chronic perforations, replacing conventional surgery.

MATERIALS AND METHODS

A laser myringotomy was carried out in Sprague-Dawley rats, which were sacrificed at 3 and 6 days after the myringotomy. Tympanic membrane sections were stained immunohistochemically according to the avidin-biotin method, targeting macrophages, B cells, and T cells. Semi-quantification was performed; positive cells were counted and mean values were calculated.

RESULTS

Macrophages and B cells were most frequent at day 6 and T cells at day 3 after laser myringotomy. B cells were the most prevalent studied cell type. T cells peaked at day 3, after which they decreased in number. Most immunocompetent cells were observed in the proliferative mass at the edge of the perforation.

Platelet-rich plasma improves healing of tympanic membrane perforations: experimental study

Objective:

The aim of this study was to investigate the effect of local application of platelet-rich plasma to perforated rat tympanic membranes, in terms of healing time and histopathological outcome.

Methods:

Eighty-eight tympanic membranes of 44 rats were given a standard 3 mm perforation, and platelet-rich plasma was applied to the right tympanic membrane perforations. The left tympanic membranes were left to heal spontaneously, as controls. The 44 rats were divided into two groups. In group one, comprising 20 rats, daily otomicroscopic examination of the tympanic membrane perforations was performed. The 24 rats in group two were subdivided into four subgroups of six rats each; these subgroups were sacrificed sequentially on days three, seven, 14 and 28 for histopathological examination, regardless of tympanic membrane healing stage.

Results:

In group one, the mean tympanic membrane healing times for tympanic membrane perforations receiving platelet-rich plasma and controls were respectively 10.2 ± 2.1 and 13.0 ± 2.9 days (mean ± standard deviation). This difference was statistically significant (p < 0.001). In group two, histopathological evaluation of tympanic membrane perforation healing at days three, seven, 14 and 28 did not reveal any statistically significant difference, individually or within the four groups as a whole.

Conclusion:

These findings suggest that earlier healing of tympanic membrane perforations occurred in the platelet-rich plasma group compared with the control group. These findings suggest that platelet-rich plasma is effective in accelerating tympanic membrane perforation healing, and that it may be effective in human subjects, particularly as it is an autologous material.

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.

Stem cells and enhanced healing of chronic tympanic membrane perforation

CONCLUSIONS

Important information about the basic reparative process of tympanic membrane (TM) healing is shown, which can be incorporated for further clinical understanding. This provides a basis for the exploration of stem cell treatment for TM perforations and holds promise for future improvements.

OBJECTIVES

This study aimed to analyse the healing of TM perforation by using stem cells and the stiffness of the membrane was tested in an acute and long-term study.

MATERIALS AND METHODS

Sprague-Dawley rats were used in a model of TM perforation. The perforation was performed with a laser system. Stem cells were applied and the healing time and morphological analysis were performed with light and transmission electron microscope. Stiffness was examined by moiré interferometry.

RESULTS

The stiffness of the perforated and healed TM was restored after just 2 weeks. In the chronic perforation model, mesenchymal stem cells enhanced the healing.

Healing time, long-term result and effects of stem cell treatment in acute tympanic membrane perforation

OBJECTIVE

The incidence of otitis media in children between the age of 2 and 6 years is well documented. Repeated attacks may cause acute and chronic perforations. The surgical treatment for repairing chronic perforation is quite uncomfortable for the patients of this age group because of the invasiveness of this treatment. The aim of this study was to determine the long-term influence of embryonic stem cells on acute perforations and the effect of gelatin as a vehicle for applied stem cells. The possibility of teratogenic effects of the stem cells was also observed.

METHODS

Bilateral laser myringotomy was performed in 17 adult Sprague-Dawley rats, divided into two groups. Gelatin, a substance suitable as vehicle for bioactive material was used bilaterally around the perforation in group A, to serve as a scaffold for repairing tissue. The stem cells were used in the right tympanic membrane perforation leaving the left tympanic membrane as a control. The animals in group B received the same treatment except for the use of gelatin and in addition received an immuno-suppressive agent. After half a year of observation the mechanical stiffness of the tympanic membrane was measured by moiré interferometry for group B and the morphological study was performed by light microscopy for both groups A and B and electron microscopy for group A.

RESULTS

Stem cell treated ears did not show any enhanced healing of the perforation although a marked thickening of the lamina propria was observed compared with control group. After half a year the strength and the stiffness of the tympanic membrane was almost the same for both treated and untreated ears. No evidence of teratoma was found after half a year.

CONCLUSION

This study suggests that the stem cells stimulate the proliferation of connective tissue and fibers in the lamina propria, possibly mediated by secreted substances, although the stiffness properties do not seem to be altered. The use of gelatin does not seem to enhance the healing process of the tympanic membrane perforation.

Topical thyroid hormone accelerates wound healing in mice

Although the physiologic role of thyroid hormone in skin is not well understood, mounting evidence suggests that T3 plays an important role in epidermal proliferation. The goal of this project was to evaluate whether the topical application of supraphysiologic doses of T3 could accelerate wound healing. We evaluated mice treated with topical T3 vs. the same mice receiving vehicle alone (Novasome A). Ten-millimeter diameter (79 mm2) dorsal skin wounds were established in all animals, and wounds were remeasured 4 d after injury. All animals were evaluated twice: once with the T3 treatment and once with the vehicle alone. Daily topical application of 150 ng T3 resulted in 58% greater wound closure relative to wounds on the same animals receiving vehicle alone (P < 0.001). Furthermore, we determined that wound healing-associated keratin 6 protein expression in hair follicle keratinocytes increased in a dose-dependent manner in vivo during topical T3 treatment. The data support our previous hypothesis that T3 is necessary for optimal wound healing. Now, we further suggest that topical thyroid hormone may be an inexpensive agent to hasten healing of certain wounds.

Epidermal Growth Factor Expression in Middle Ear Cholesteatoma

Middle ear cholesteatoma is destructive to auditory ossicles and temporal bone, and treatment usually requires surgical removal of all epithelial content. Epidermal growth factor (EGF) can stimulate the growth and differentiation of a variety of mammalian cells, including epithelial cells. Our study used the avidin-biotin complex technique to evaluate the expression of EGF in 40 cases of middle ear cholesteatoma (active cholesteatoma, 31 cases; inactive cholesteatoma, 9 cases) and 34 normal postauricular skin samples. In middle ear cholesteatoma, EGF was expressed in squamous epithelium in 21 cases (53%), fibroblasts in two cases (5%), and cholesteatoma endothelium in two cases (5%). In normal postauricular skin, EGF was expressed in squamous epithelium in 14 samples (41%), fibroblasts in one sample (3%), and endothelium in none. No statistical difference in EGF expression was found between cholesteatoma and normal postauricular skin samples. These results show that the distribution of EGF in middle ear cholesteatoma is not deranged and that the progression of cholesteatoma might be induced by the release of factors from the cholesteatoma matrix via autocrine stimulation, or by inflammatory cells of the subepithelial tissue through paracrine stimulation, or in both of these ways.

A photo-crosslinked poly(vinyl alcohol) hydrogel growth factor release vehicle for wound healing applications

The objective of this study was to develop and evaluate a hydrogel vehicle for sustained release of growth factors for wound healing applications. Hydrogels were fabricated using ultraviolet photo-crosslinking of acrylamide-functionalized nondegradable poly(vinyl alcohol) (PVA). Protein permeability was initially assessed using trypsin inhibitor (TI), a 21 000 MW model protein drug. TI permeability was altered by changing the solids content of the gel and by adding hydrophilic PVA fillers. As the PVA content increased from 10% to 20%, protein flux decreased, with no TI permeating through 20% PVA hydrogels. Further increase in model drug release was achieved by incorporating hydrophilic PVA fillers into the hydrogel. As filler molecular weight increased, TI flux increased. The mechanism for this is most likely an alteration in protein/gel interactions and transient variations in water content. The percent protein released was also altered by varying protein loading concentration. Release studies conducted using growth factor in vehicles with hydrophilic filler showed sustained release of platelet-derived growth factor (PDGF-beta,beta) for up to 3 days compared with less than 24 hours in the controls. In vitro bioactivity was demonstrated by doubling of normal human dermal fibroblast numbers when exposed to growth factor-loaded vehicle compared to control. The release vehicle developed in this study uses a rapid and simple fabrication method, and protein release can be tailored by modifying solid content, incorporating biocompatible hydrophilic fillers, and varying protein loading concentration.