Bing Mei Teh

A review on the use of hyaluronic acid in tympanic membrane wound healing

Introduction: Tympanic membrane perforation represents a significant morbidity, especially if it occurs during a childs speech and language development. Recently, there has been an increased interest in hyaluronic-acid-related research and products as a potential therapeutic option for tympanic membrane perforation repair. Areas covered: This review describes the physical and chemical properties of hyaluronic acid and examines the role of hyaluronic acid in wound healing, in particular on the tympanic membrane. It also reviews the safety and efficacy of hyaluronic acid and its derivatives in animal studies as well as in clinical trials. Finally, it considers the potential future clinical applications in tympanic membrane perforation repair. Expert opinion: Hyaluronic acid has been found to accelerate tympanic membrane perforation closure, shorten the period of healing, produce a better quality neo-membrane and improve hearing. More importantly, hyaluronic acid is biodegradable, safe and biocompatible in the ear. Recently, there has been a trend towards the use of modified hyaluronic acid. However, there is a lack of higher-level evidence to support the use of hyaluronic acid in tympanic membrane perforations in the clinical setting. More large-scale randomised control trials are warranted before these bio-devices will be used routinely.

Tympanic membrane repair using silk fibroin and acellular collagen scaffolds

To evaluate the efficacy of silk fibroin scaffolds (SFS) and acellular collagen scaffolds (ACS) for the repair of tympanic membrane (TM) in a guinea pig acute perforation model.

To Pack or Not to Pack? A Contemporary Review of Middle Ear Packing Agents

Middle ear packing agents are used in otologic surgery to provide support to the middle ear structures, maintain aeration of the middle ear, and promote hemostasis. However, there is currently a lack of standardization regarding the use of different types of packing agents. The choice of materials and how they are used remain controversial. In fact, some have recently advocated for no packing. In view of this, this review focuses on the types of materials available, a brief historical account of each material, characteristics of an ideal packing agent, and a discussion on the techniques of insertion to optimize surgical outcomes.

The biocompatibility of silk fibroin and acellular collagen scaffolds for tissue engineering in the ear

Recent experimental studies have shown the suitability of silk fibroin scaffold (SFS) and porcine-derived acellular collagen I/III scaffold (ACS) as onlay graft materials for tympanic membrane perforation repair. The aims of this study were to further characterize and evaluate the in vivo biocompatibility of SFS and ACS compared with commonly used materials such as Gelfoam and paper in a rat model. The scaffolds were implanted in subcutaneous (SC) tissue and middle ear (ME) cavity followed by histological and otoscopic evaluation for up to 26 weeks. Our results revealed that SFS and ACS were well tolerated and compatible in rat SC and ME tissues throughout the study. The tissue response adjacent to the implants evaluated by histology and otoscopy showed SFS and ACS to have a milder tissue response with minimal inflammation compared to that of paper. Gelfoam gave similar results to SFS and ACS after SC implantation, but it was found to be associated with pronounced fibrosis and osteoneogenesis after ME implantation. It is concluded that SFS and ACS both were biocompatible and could serve as potential alternative scaffolds for tissue engineering in the ear.

TGF-α/HA complex promotes tympanic membrane keratinocyte migration and proliferation via ErbB1 receptor

Tympanic membrane perforations are common and represent a management challenge to clinicians. Current treatments for chronic perforations involve a graft surgery and require general anaesthesia, including associated costs and morbidities. Bioactive molecules (e.g. growth factors, cytokines) play an important role in promoting TM wound healing following perforation and the use of growth factors as a topical treatment for tympanic membrane perforations has been suggested as an alternative to surgery. However, the choice of bioactive molecules best suited to promote wound healing has yet to be identified. We investigated the effects of hyaluronic acid, vitronectin, TGF-α, IL-24 and their combinations on migration, proliferation and adhesion of cultured human tympanic membrane-derived keratinocytes (hTM), in addition to their possible mechanisms of action. We found that TGF-α, TGF-α/HA and TGF-α/IL-24 promoted wound healing by significantly increasing both migration and proliferation. TGF-α and/or HA treated cells showed comparable cell-cell adhesion whilst maintaining an epithelial cell phenotype. With the use of receptor binding inhibitors for ErbB1 (AG1478) and CD44 (BRIC235), we revealed that the activation of ErbB1 is required for TGF-α/HA-mediated migration and proliferation. These results suggest factors that may be incorporated into a tissue-engineered membrane or directly as topical treatment for tympanic membrane perforations and hence reduce the need for a surgery.

Bone wax extrusion through postauricular wounds: A case series

Bone wax is an effective hemostatic agent that generally is considered safe. However, because it is nonabsorbable, significant complications can occur. We present the first two reported cases of delayed migration and extrusion of bone wax through postauricular wounds due to foreign body reaction and granuloma formation following mastoid surgery. We also present a literature review of complications associated with intraoperative bone wax use and discuss alternative hemostatic agents. Laryngoscope, 2017Bone wax is an effective hemostatic agent that generally is considered safe. However, because it is nonabsorbable, significant complications can occur. We present the first two reported cases of delayed migration and extrusion of bone wax through postauricular wounds due to foreign body reaction and granuloma formation following mastoid surgery. We also present a literature review of complications associated with intraoperative bone wax use and discuss alternative hemostatic agents. Laryngoscope, 128:369–372, 2018

Not all that wheezes is asthma

F a s p n 80-year-old woman presented with a history of orsening cough, dyspnoea and wheeze, and was ospitalised for an infective exacerbation of asthma. he reported a 17-year history of mild nonroductive cough. She was diagnosed with dult-onset asthma 8 years earlier, when her xacerbations responded to bronchodilator therapy nd corticosteroids and subsequent respiratory unction tests showed a 21% bronchodilator sponse. Serial chest x-rays and computed omography (CT) scans were normal except for table pulmonary nodules, which were under close urveillance by her respiratory physician. Relevant ast medical history included hypertension, paceaker for complete heart block, hay fever, excision f cutaneous melanoma and laparotomy for small owel obstruction. She had no known allergies, was lifelong non-smoker and lived at home with her usband and pet budgie.

In response to Tympanic membrane repair using silk fibroin and acellular collagen scaffolds: Letter to the Editor

We appreciate Dr. Lou’s comments on our successful repair of traumatic tympanic membrane (TM) perforations in guinea pigs with biomaterial scaffolds. In the letter, Dr. Lou compares other effective approaches to the treatment of traumatic TM perforations such as using growth factors (GF) alone or in combination with biomaterials. Indeed, recent advances in tissue engineering have provided numerous alternative therapies for TM regeneration. It is evident that some scaffolds and GFs interact to achieve TM repair with different mechanisms. Scaffolds offer structural support to guide regenerating tissue, whereas GFs enhance cellular proliferation and migration. Because not all GFs or scaffolds are effective adjuncts to healing, the efficacy for each needs to be established experimentally to optimize outcomes. Whether one single approach will provide the best outcome for the complex set of conditions seen clinically is not yet clear. In our study, silk and collagen patches not only shortened the closure time but also enhanced the quality of the neomembrane. This finding is similar to other previous studies, illustrating that a patching material is beneficial in guiding the regenerating epithelial growth. Moreover, Dr. Lou suggested that studies of patch materials should be performed on chronic TM perforations, to which we completely agree and had published this view in our article. The majority (up to 94%) of acute TM perforations heal spontaneously without any intervention, so there is limited benefit to accelerate healing of an acute or traumatic perforation. In this study, we utilized an acute animal model due to the lack of an appropriate chronic perforation animal model at that stage. Various attempts have been made to create a chronic perforation model in rodents; however, most only delayed healing rather than produced chronic wounds. Recently, our research group has developed a chronic perforation rat model using ventilation tube and mitomycin C/dexamethasone treatment, which we are now using to evaluate various treatments for chronic perforations. The future will tell whether studies of ventilation tube-related mechanisms may also provide insight to treatment of other mechanisms that produce chronic TM perforations.

In response to Tympanic membrane repair using silk fibroin and acellular collagen scaffolds.

We appreciate Dr. Lou’s comments on our successful repair of traumatic tympanic membrane (TM) perforations in guinea pigs with biomaterial scaffolds. In the letter, Dr. Lou compares other effective approaches to the treatment of traumatic TM perforations such as using growth factors (GF) alone or in combination with biomaterials. Indeed, recent advances in tissue engineering have provided numerous alternative therapies for TM regeneration. It is evident that some scaffolds and GFs interact to achieve TM repair with different mechanisms. Scaffolds offer structural support to guide regenerating tissue, whereas GFs enhance cellular proliferation and migration. Because not all GFs or scaffolds are effective adjuncts to healing, the efficacy for each needs to be established experimentally to optimize outcomes. Whether one single approach will provide the best outcome for the complex set of conditions seen clinically is not yet clear. In our study, silk and collagen patches not only shortened the closure time but also enhanced the quality of the neomembrane. This finding is similar to other previous studies, illustrating that a patching material is beneficial in guiding the regenerating epithelial growth. Moreover, Dr. Lou suggested that studies of patch materials should be performed on chronic TM perforations, to which we completely agree and had published this view in our article. The majority (up to 94%) of acute TM perforations heal spontaneously without any intervention, so there is limited benefit to accelerate healing of an acute or traumatic perforation. In this study, we utilized an acute animal model due to the lack of an appropriate chronic perforation animal model at that stage. Various attempts have been made to create a chronic perforation model in rodents; however, most only delayed healing rather than produced chronic wounds. Recently, our research group has developed a chronic perforation rat model using ventilation tube and mitomycin C/dexamethasone treatment, which we are now using to evaluate various treatments for chronic perforations. The future will tell whether studies of ventilation tube-related mechanisms may also provide insight to treatment of other mechanisms that produce chronic TM perforations.

Response to “Tympanic membrane repair using silk fibroin and acellular collagen scaffolds”

We appreciate Dr. Lou’s comments on our successful repair of traumatic tympanic membrane (TM) perforations in guinea pigs with biomaterial scaffolds. In the letter, Dr. Lou compares other effective approaches to the treatment of traumatic TM perforations such as using growth factors (GF) alone or in combination with biomaterials. Indeed, recent advances in tissue engineering have provided numerous alternative therapies for TM regeneration. It is evident that some scaffolds and GFs interact to achieve TM repair with different mechanisms. Scaffolds offer structural support to guide regenerating tissue, whereas GFs enhance cellular proliferation and migration. Because not all GFs or scaffolds are effective adjuncts to healing, the efficacy for each needs to be established experimentally to optimize outcomes. Whether one single approach will provide the best outcome for the complex set of conditions seen clinically is not yet clear. In our study, silk and collagen patches not only shortened the closure time but also enhanced the quality of the neomembrane. This finding is similar to other previous studies, illustrating that a patching material is beneficial in guiding the regenerating epithelial growth. Moreover, Dr. Lou suggested that studies of patch materials should be performed on chronic TM perforations, to which we completely agree and had published this view in our article. The majority (up to 94%) of acute TM perforations heal spontaneously without any intervention, so there is limited benefit to accelerate healing of an acute or traumatic perforation. In this study, we utilized an acute animal model due to the lack of an appropriate chronic perforation animal model at that stage. Various attempts have been made to create a chronic perforation model in rodents; however, most only delayed healing rather than produced chronic wounds. Recently, our research group has developed a chronic perforation rat model using ventilation tube and mitomycin C/dexamethasone treatment, which we are now using to evaluate various treatments for chronic perforations. The future will tell whether studies of ventilation tube-related mechanisms may also provide insight to treatment of other mechanisms that produce chronic TM perforations.