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

Effect of basic-fibroblast growth factor on tympanic membrane perforation in a mouse model of blast injury

BACKGROUND

Tympanic membrane perforation (TMP) caused by blast injury result in poor TMP closure and pathological regeneration of the tympanic membrane (TM). TM regeneration therapy using basic fibroblast growth factor (bFGF) has demonstrated good outcomes for chronic otitis media.

AIMS/OBJECTIVES

To investigate the efficacy of bFGF treatment in the management of blast-induced TMP.

MATERIAL AND METHODS

Male CBA/J mice (10-12-week-old) were divided into the bFGF-treatment and no-treatment groups. Blast-tube systems were used to induce TMP. Auditory evaluation, TM observation, histological evaluation of the regenerated TM, and histological evaluation of the inner ear were conducted.

RESULTS

Auditory assessment revealed no difference between the groups, with persistent auditory threshold elevation being observed even 1 month post-injury. Similarly, histological evaluation of the inner ear hair cells revealed no significant differences between the groups; no hair cell death was evident. However, the regenerated TM in the bFGF-treated group was significantly thicker than that in the untreated group.

CONCLUSIONS AND SIGNIFICANCE

A good TMP closure rate was observed in the present study; however, bFGF treatment exacerbated thickening of the regenerated TM. Future studies must study the therapeutic effects of bFGF treatment using various animal models and timing and concentration of bFGF treatment.

Surgical Bioengineering of the Microvasculature and Challenges in Clinical Translation

Tissue and organ dysfunction are major causes of worldwide morbidity and mortality with all medical specialties being impacted. Tissue engineering is an interdisciplinary field relying on the combination of scaffolds, cells, and biologically active molecules to restore form and function. However, clinical translation is still largely hampered by limitations in vascularization. Consequently, a thorough understanding of the microvasculature is warranted. This review provides an overview of (1) angiogenesis, including sprouting angiogenesis, intussusceptive angiogenesis, vascular remodeling, vascular co-option, and inosculation; (2) strategies for vascularized engineered tissue fabrication such as scaffold modulation, prevascularization, growth factor utilization, and cell-based approaches; (3) guided microvascular development via scaffold modulation with electromechanical cues, 3D bioprinting, and electrospinning; (4) surgical approaches to bridge the micro- and macrovasculatures in order to hasten perfusion; and (5) building specific vasculature in the context of tissue repair and organ transplantation, including skin, adipose, bone, liver, kidney, and lung. Our goal is to provide the reader with a translational overview that spans developmental biology, tissue engineering, and clinical surgery.

Latent stem cell-stimulating radially aligned electrospun nanofibrous patches for chronic tympanic membrane perforation therapy

Chronic tympanic membrane (TM) perforation is a tubotympanic disease caused by either traumatic injury or inflammation. A recent study demonstrated significant progress in promoting the regeneration of chronic TM perforations through the application of nanofibers with radially aligned nanostructures and controlled release of growth factors. However, radially aligned nanostructures with stem cell-stimulating factors have never been used. In this study, insulin-like growth factor binding factor 2 (IGFBP2)-incorporated radially aligned nanofibrous patches (IRA-NFPs) were developed and applied to regenerate chronic TM perforations. The IRA-NFPs were prepared by electrospinning 8 wt% polycaprolactone in trifluoroethanol and acetic acid (9:1). Random nanofibers (RFs) and aligned nanofibers (AFs) were successfully fabricated using a flat plate and a custom-designed circular collector, respectively. The presence of IGFBP2 was confirmed via Fourier transform infrared spectroscopy and the release of IGFBP2 was sustained for up to 20 days. In vitro studies revealed enhanced cellular proliferation and migration on AFs compared to RFs, and the incorporation of IGFBP2 further promoted these effects. Quantitative real-time PCR revealed mRNA downregulation, correlating with accelerated migration and increased cell confluency. In vivo studies showed IGFBP2-loaded RF and AF patches increased regeneration success rates by 1.59-fold and 2.23-fold, respectively, while also reducing healing time by 2.5-fold compared to the control. Furthermore, IGFBP2-incorporated AFs demonstrated superior efficacy in healing larger perforations with enhanced histological similarity to native TMs. This study, combining stem cell stimulating factors and aligned nanostructures, proposes a novel approach potentially replacing conventional surgical methods for chronic TM perforation regeneration. STATEMENT OF SIGNIFICANCE: Chronic otitis media (COM) affects approximately 200 million people worldwide due to inflammation, inadequate blood supply, and lack of growth factors. Current surgical treatments have limitations like high costs and anesthetic risks. Recent research explored the use of nanofibers with radially aligned nanostructures and controlled release of growth factors to treat chronic tympanic membrane (TM) perforations. In this study, insulin-like growth factor binding protein 2 (IGFBP2)-incorporated radially aligned nanofibrous patches (IRA-NFPs) were developed and applied to regenerate chronic TM perforations. We assessed their properties and efficacy through in vitro and in vivo studies. IRA-NFPs showed promising healing capabilities with chronic TM perforation models. This innovative approach has the potential to improve COM management, reduce surgery costs, and enhance patient safety.

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

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

Fabrication and Evaluation of Hyaluronidase-Responsive Scaffolds by Electrospinning with Antibacterial Properties for Tympanic Membrane Repair

Tympanic membrane perforation (TMP) is prevalent in clinical settings. Patients with TMPs often suffer from infections caused by Staphylococcus aureus and Pseudomonas aeruginosa, leading to middle ear and external ear canal infections, which hinder eardrum healing. The objective of this study is to fabricate an enzyme-responsive antibacterial electrospun scaffold using poly(lactic-co-glycolic acid) and hyaluronic acid for the treatment of infected TMPs. The properties of the scaffold were characterized, including morphology, wettability, mechanical properties, degradation properties, antimicrobial properties, and biocompatibility. The results indicated that the fabricated scaffold had a core-shell structure and exhibited excellent mechanical properties, hydrophobicity, degradability, and cytocompatibility. Furthermore, in vitro bacterial tests and ex vivo investigations on eardrum infections suggested that this scaffold possesses hyaluronidase-responsive antibacterial properties. It may rapidly release antibiotics when exposed to the enzyme released by S. aureus and P. aeruginosa. These findings suggest that the scaffold has great potential for repairing TMPs with infections.

Ultrasound-Triggered Microbubbles: Novel Targeted Core-Shell for the Treatment of Myocardial Infarction Disease

Myocardial infarction (MI) is known as a main cardiovascular disease that leads to extensive cell death by destroying vasculature in the affected cardiac muscle. The development of ultrasound-mediated microbubble destruction has inspired extensive interest in myocardial infarction therapeutics, targeted delivery of drugs, and biomedical imaging. In this work, we describe a novel therapeutic ultrasound system for the targeted delivery of biocompatible microstructures containing basic fibroblast growth factor (bFGF) to the MI region. The microspheres were fabricated using poly(lactic-co-glycolic acid)-heparin-polyethylene glycol- cyclic arginine-glycine-aspartate-platelet (PLGA-HP-PEG-cRGD-platelet). The micrometer-sized core-shell particles consisting of a perfluorohexane (PFH)-core and a PLGA-HP-PEG-cRGD-platelet-shell were prepared using microfluidics. These particles responded adequately to ultrasound irradiation by triggering the vaporization and phase transition of PFH from liquid to gas in order to achieve microbubbles. Ultrasound imaging, encapsulation efficiency cytotoxicity, and cellular uptake of bFGF-MSs were evaluated using human umbilical vein endothelial cells (HUVECs) in vitro. In vivo imaging demonstrated effective accumulation of platelet- microspheres injected into the ischemic myocardium region. The results revealed the potential use of bFGF-loaded microbubbles as a noninvasive and effective carrier for MI therapy.

Controlled growth factor delivery via a degradable poly(lactic acid) hydrogel microcarrier synthesized using degassed micromolding lithography

Controlled and targeted delivery of growth factors to biological environments is important for tissue regeneration. Polylactic acid (PLA) hydrogel microparticles are attractive carriers for the delivery of therapeutic cargoes based on their superior biocompatibility and biodegradability, uniform encapsulation of cargoes, and non-requirement of organic solvents during particle synthesis. In this study, we newly present controlled growth factor delivery utilizing PLA-based hydrogel microcarriers synthesized via degassed micromolding lithography (DML). Based on the direct gelation procedure from the single-phase aqueous precursor in DML, bovine serum albumin, a model protein of growth factor, and fibroblast growth factor were encapsulated into microparticles with uniform distribution. In addition, by tuning the monomer concentration and adding a hydrolytically stable crosslinker, the release of encapsulated cargoes was efficiently controlled and extended to 2 weeks. Finally, we demonstrated the biological activity of encapsulated FGF-2 in PLA-based microparticles using a fibroblast proliferation assay.

Healing large Traumatic Tympanic Membrane Perforations Using Vaseline Gauze and Gelfoam Patching Alone

OBJECTIVE

The aim of this study was to evaluate the effect of vaseline gauze (VG) patching on the treatment of large traumatic perforation of tympanic membrane (TM).

MATERIAL AND METHODS

90 patients with traumatic perforation larger than 25% of the TM were randomly allocated into the control group of observation only, VG group, and Gelfoam patch alone group. The closure rate and closure time among the 3 groups were compared at 3 months.

RESULTS

In total, 82 large traumatic perforations were analyzed in this study. The closure rates in the control, VG, and gelfoam patch groups were 84.6%, 100.0%, and 89.3%, respectively (P = 0.637). Post-hoc multiple comparisons showed that the difference between the control and VG groups was significant (P = 0.047), but the difference wasn't significant between gelfoam alone and control groups (P = 0.699) or VG groups (P = 0.236). The mean closure times were 5.41 ± 1.47, 2.14 ± 0.93, and 3.00 ± 0.62 weeks for the control, VG, and gelfoam patch groups, respectively (P < 0.001). Post-hoc multiple comparisons showed that the difference was significant between the control and VG groups (P < 0.001) or gelfoam alone group (P < 0.001) or VG and gelfoam groups (P < 0.05).

CONCLUSIONS

VG improved the closure rate and shortened the closure time compared with observation only, which could be an effective patch material for repairing traumatic lager perforations in the outpatient setting, which is readily available and convenient.

3D printing technology and applied materials in eardrum regeneration

Tympanic membrane perforation is a common condition in clinical otolaryngology. Although some eardrum patients can self-heal, a long period of non-healing perforation leads to persistent otitis media, conductive deafness, and poor quality of life. Tympanic membrane repair with autologous materials requires a second incision, and the sampling site may get infected. It is challenging to repair tympanic membranes while maintaining high functionality, safety, affordability, and aesthetics. 3D bioprinting can be used to fabricate tissue patches with materials, factors, and cells in a design manner. This paper reviews 3D printing technology that is being used widely in recent years to construct eardrum stents and the utilized applied materials for tympanic membrane repair. The paper begins with an introduction of the physiological structure of the tympanic membrane, briefly reviews the current clinical method thereafter, highlights the recent 3D printing-related strategies in tympanic membrane repair, describes the materials and cells that might play an important role in 3D printing, and finally provides a perspective of this field.

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.

Butterfly Cartilage Tympanoplasty as an Alternative to Conventional Surgery for Tympanic Membrane Perforations: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare the effectiveness of butterfly cartilage tympanoplasty (BCT) with that of conventional surgical approaches in the treatment of tympanic membrane perforations.

METHODS

A systematic search was performed by screening the PubMed, Embase, and Cochrane Library databases up to October 31, 2020. Two coauthors independently identified studies in accordance with the selection criteria. Data were pooled and analyzed via Review Manager version 5.3 and Stata version 12.0 software. The postoperative outcomes were measured and expressed as odds ratios (ORs) and standardized mean differences (SMDs). Additionally, heterogeneity was assessed through the I² statistic.

RESULTS

A total of 15 articles were eligible for final inclusion. The OR values for the graft uptake rate, compared to conventional tympanoplasty, were 1.12 (95%CI: 0.56-2.22, I² = 52%, P = .75) and 1.22 (95%CI: 0.58-2.59, I² = 0%, P = .60), and the OR compared to fat plug myringoplasty was 3.02 (95%CI: 1.04-8.77, I² = 0%, P = .04). The qualitative analysis of the hearing results reflected significant postoperative auditory gains with no significant differences between the BCT and control groups, indicating satisfactory and similar postoperative hearing improvement. Moreover, the operation time was shortened (SMD = -2.19, 95%CI: -2.79 to -1.59, I² = 82%, P < .05), and the postoperative pain was less with the BCT approach.

CONCLUSION

Butterfly cartilage tympanoplasty has satisfactory efficacy in terms of anatomical and functional results in small to medium perforations. It reduces operation time and postoperative pain. However, the effectiveness on large perforation requires further assessment by well-designed studies.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effect of Growth Factor-Loaded Acellular Dermal Matrix/MSCs on Regeneration of Chronic Tympanic Membrane Perforations in Rats

The success rate of grafting using acellular dermal matrix (ADM) for chronic tympanic membrane was reported in previous studies to be lower than fascia or perichondrium. Combining mesenchymal stem cells (MSCs) and growth factor-loaded ADM for the regeneration of chronic TMP has not been reported so far. In this study, we hypothesized that combining growth factor-loaded ADM/MSCs could promote the recruitment of MSCs and assist in TMP regeneration. We evaluated the regeneration and compared the performance of four scaffolds in both in vitro and in vivo studies. MTT, qPCR, and immunoblotting were performed with MSCs. In vivo study was conducted in 4 groups (control; ADM only, ADM/MSC, ADM/MSC/bFGF, ADM/MSC/EGF) of rats and inferences were made by otoendoscopy and histological changes. Attachment of MSCs on ADM was observed by confocal microscopy. Proliferation rate increased with time in all treated cells. Regeneration-related gene expression in the treated groups was higher. Also, graft success rate was significantly higher in ADM/MSC/EGF group than other groups. Significant relationships were disclosed in neodrum thickness between each group. The results suggest, in future, combining EGF with ADM/MSCs could possibly be used as an outpatient treatment, without the need for surgery for eardrum regeneration.