Treatment Of Vocal Fold Scarring Research Articles

Biocompatibility and efficacy of collagen/gelatin sponge scaffold with sustained release of basic fibroblast growth factor on vocal fold fibroblasts in 3-dimensional culture.

Treatment of vocal fold scarring remains challenging. We have previously reported the therapeutic effects of local injection of basic fibroblast growth factor (bFGF) in animal models and humans. A novel collagen/gelatin sponge (CGS) is capable of sustained release of bFGF, which compensates for its quick absorption in vivo, avoiding multiple injections. This study aimed to evaluate the biocompatibility and efficacy of the CGS in rat vocal fold fibroblasts prior to human trials. Fibroblasts extracted from Sprague-Dawley rat vocal folds were seeded onto a CGS and then cultivated with bFGF at concentrations of 0, 10, and 100 ng/mL. Vocal fold fibroblast morphology, adhesion, proliferation, and gene expression were measured under these 3-dimensional conditions. Cells adhered to the CGS from day 1. Although no significant differences in cell morphology were detected, cell proliferation was accelerated by bFGF administration. Expression of endogenous bFGF and hepatocyte growth factor was significantly up-regulated at 10 ng/mL bFGF. The expression of procollagen I and procollagen III was significantly suppressed, whereas HAS-1 and HAS-2 were up-regulated at 10 and 100 ng/mL bFGF. The collagen/gelatin sponge is biocompatible with vocal fold fibroblasts and may be useful as a bFGF drug delivery system for the treatment of scarred vocal folds.

Voice Outcomes following the Gray Minithyrotomy

Most practitioners have limited treatment options for vocal fold scar and sulcus vocalis. The Gray minithyrotomy (GMT) is a surgical procedure for the treatment of these conditions, although limited objective data exist regarding voice outcomes. This study compares the quantified subjective and visual perceptual outcomes following GMT for the treatment of vocal fold scar and sulcus vocalis. We performed a retrospective review of patients who underwent GMT in a single institution. Patient-reported satisfaction, Voice Handicap Index-10 scores, results of video perceptual analysis, and complications were recorded. Sixteen patients underwent GMT for phonotraumatic or postoperative scar (11), radiation-induced scar (3), or sulcus vocalis (2). Seven underwent bilateral operations. Follow-up data were available for 12 patients. Eight patients had 2 or more failed surgical interventions before GMT. Seven of the 13 procedures resulted in a self-reported improvement. Although the mean preoperative Voice Handicap Index-10 score (30.6) across all patients did not decrease after the operation, 6 of the 13 GMT procedures resulted in improvement (mean decrease, 7.5). Complications, encountered in 5 patients, included ecchymosis, neck abscess, tongue numbness, wound dehiscence, and aspiration pneumonia. The GMT is a viable treatment for severe vocal fold scar and sulcus vocalis. Our results show improvement in half of a cohort that was marked by previous failures at improving voice. These results point to the recalcitrant nature of voice difficulties in treating vocal fold scar and sulcus, and may properly guide clinicians and patients in their expectations following this infrequently used technique.

Therapeutic potential of gel-based injectables for vocal fold regeneration

Vocal folds are anatomically and biomechanically unique, thus complicating the design and implementation of tissue engineering strategies for repair and regeneration. Integration of an enhanced understanding of tissue biomechanics, wound healing dynamics and innovative gel-based therapeutics has generated enthusiasm for the notion that an efficacious treatment for vocal fold scarring could be clinically attainable within several years. Fibroblast phenotype and gene expression are mediated by the three-dimensional mechanical and chemical microenvironment at an injury site. Thus, therapeutic approaches need to coordinate spatial and temporal aspects of the wound healing response in an injured vocal tissue to achieve an optimal clinical outcome. Successful gel-based injectables for vocal fold scarring will require a keen understanding of how the native inflammatory response sets into motion the later extracellular matrix remodeling, which in turn will determine the ultimate biomechanical properties of the tissue. We present an overview of the challenges associated with this translation as well as the proposed gel-based injectable solutions.

Implantation of an Atelocollagen Sponge with Autologous Bone Marrow—Derived Mesenchymal Stromal Cells for Treatment of Vocal Fold Scarring in a Canine Model

Vocal fold scarring remains a therapeutic challenge. A new regenerative approach is needed to restore disorganized extracellular matrix. Tissue regeneration requires appropriate cells and a scaffold. Bone marrow-derived mesenchymal stromal cells (BMSCs) are multipotent and secrete many kinds of growth factors to regenerate tissues. Atelocollagen sponges have many large pores that permit cell entry. The present study was performed to evaluate whether implantation of an atelocollagen sponge plus BMSCs is effective for the treatment of vocal fold scarring. Twelve beagles underwent implantation of an atelocollagen sponge or of an atelocollagen sponge with autologous BMSCs (1.0 x 10(6) cells) in the subepithelial pockets of scarred vocal folds. Six months after the operation, vibratory examinations and histologic examinations were performed. Mucosal vibrations improved significantly for the atelocollagen sponge-implanted vocal folds. Histologic analyses revealed favorable restoration of the extracellular matrix in the lamina propria. Increased distribution of hyaluronic acid and decreased dense collagen deposition were also noted. These improvements were enhanced by implantation of BMSCs. Implantation of atelocollagen sponges with autologous BMSCs into scarred vocal folds significantly increased hyaluronic acid distribution and decreased dense collagen deposition in the lamina propria, leading to better mucosal vibration.

Prospective multi‐arm evaluation of surgical treatments for vocal fold scar and pathologic sulcus vocalis

The purpose of this study was to compare the clinical effectiveness of type I thyroplasty, injection laryngoplasty, and graft implantation for the treatment of vocal fold scar and pathologic sulcus vocalis. Prospective, multi-arm, quasi-experimental research design. Twenty-eight patients with newly diagnosed vocal fold scar and/or pathologic sulcus vocalis were assigned to one of three treatment modalities: type I thyroplasty (n = 9), injection laryngoplasty (n = 9), and graft implantation (n = 10). Psychosocial, auditory-perceptual, acoustic, aerodynamic, and videostroboscopic data were collected pretreatment and at 1, 6, 12, and 18 months posttreatment. Type I thyroplasty and graft implantation both resulted in reduced voice handicap with no concomitant improvement in auditory-perceptual, acoustic, aerodynamic, or vocal fold physiologic performance. Injection laryngoplasty resulted in no improvement on any vocal function index. Patients who underwent graft implantation exhibited the slowest improvement trajectory across the 18-month follow-up period. A persistent challenge in this area is that no single treatment modality is successful for the majority of patients, and there is no evidence-based decision algorithm for matching a given treatment to a given patient. Progress therefore requires the identification and categorization of predictive clinical features that can drive evidence-based treatment assignment.

Hyaluronic acid for the treatment of vocal fold scars

In vocal fold scars the lamina propria layer is lost or deficient. Lamina propria replacement therapy remains a clinical challenge because this layer has a highly specialized three-dimensional organization of extracellular matrix molecules and unique viscoelastic properties. Use of a polymer such as hyaluronic acid appears most promising for replacement therapy because it has the optimal viscoelasticity and also plays a role in the maturation and maintenance of vocal fold lamina propria. A variety of cross-linked hyaluronic acid formulations and growth factor therapies targeted to increase hyaluronic acid production have been used in the treatment of both acute and established vocal fold scars. Therapeutic strategies have focused on prevention of scar at the time of initial injury, and rejuvenation of lamina propria layer in established scars. Both strategies show improved histologic, viscoelastic, acoustic, and aerodynamic measures. Cross-linked hyaluronic acid formulations appear useful in the treatment of vocal fold scarring. Their use at the time of acute injury especially appears to lessen the degree of long-term scar formation and appears promising. While animal studies have demonstrated the safety profile of many hyaluronic acid formulations, further improvement in these materials and well designed and controlled human trials are needed to further establish the safety and efficacy of these materials and therapeutic approaches.

Characterization of vocal fold scar formation, prophylaxis, and treatment using animal models

To review recent literature on animal models used to study the pathogenesis, detection, prevention, and treatment of vocal fold scarring. Animal work is critical to studying vocal fold scarring because it is the only way to conduct systematic research on the biomechanical properties of the layered structure of the vocal fold lamina propria, and therefore develop reliable prevention and treatment strategies for this complex clinical problem. During the period of review, critical anatomic, physiologic, and wound healing characteristics, which may serve as the bases for selection of a certain species to help answer a specific question, have been described in mouse, rat, rabbit, ferret, and canine models. A number of different strategies for prophylaxis and chronic scar treatment in animals show promise for clinical application. The pathways of scar formation and methods for quantifying treatment-induced change have become better defined. Recent animal vocal fold scarring studies have enriched and confirmed earlier work indicating that restoring pliability to the scarred vocal fold mucosa is challenging but achievable. Differences between animal models and differences in outcome measurements across studies necessitate considering each study individually to obtain guidance for future research. With increased standardization of measurement techniques it may be possible to make more inter-study comparisons.

Implantation of atelocollagen sheet for vocal fold scar

This article reviews recent advances in scaffold-based interventions for the treatment of vocal fold scarring, with a particular emphasis on atelocollagen sheet implantation in the vocal fold lamina propria. Scaffold-based therapies have demonstrated therapeutic promise in both preclinical and early clinical studies. Recent research has begun to shed light on the interactions between scaffold material properties, encapsulated and infiltrating cells, stimulatory molecules such as growth factors, and external regulatory variables such as stress, strain, and vibration. The atelocollagen sheet, a cross-linked collagen material with abundant micropores, has an established clinical track record as a scaffold for dermal and epidermal repair and exhibited potential therapeutic benefit in a recent study of patients with vocal fold scarring and sulcus vocalis. Scaffolding is one of the useful tools in tissue engineering and atelocollagen sheet implantation has been shown to be effective in vocal fold regeneration. However, many of the scaffold materials under investigation still await clinical translation and those that have been investigated in human patients (such as the atelocollagen sheet) require additional research in appropriately powered placebo-controlled studies.

Pulse dye and other laser treatments for vocal scar

Vocal fold scar is a challenging clinical problem, resulting in a spectrum of voice-related complaints. While there are a variety of treatment options available, it is rare to obtain outcomes similar to the perfectly normal voice. The pulsed dye and other lasers are an emerging treatment option for cutaneous scar and have shown promise for the treatment of vocal fold scarring. The purpose of this review is to summarize the theory, and describe clinical outcomes from both cutaneous and vocal fold scarring treated with lasers. There are a growing number of papers in the literature substantiating the use of pulsed dye and other lasers used to treat cutaneous scars. Some experimental models describe potential mechanisms of laser effect, which include the development of a sub-basement membrane cleavage plane, as well as up-regulation of proteins which may actively modulate continued fibrosis. One prospective pilot study of 11 patients with vocal fold scarring treated with the pulsed dye laser has also shown statistically significant improvement in subjective and objective voice measures, as well as laryngeal stroboscopy findings after treatment. The pulsed dye and other lasers have shown effectiveness and potential in treating cutaneous and vocal scarring.

Tissue engineering for treatment of vocal fold scar

Creating a neovocal fold or lamina propria by tissue engineering is a potential scheme for treating severe vocal fold scar. Although still investigational, multiple approaches have recently been described in tissue culture or animal models. Proposed cell types for vocal fold application have been native vocal fold fibroblasts, autologous fibroblasts from nonlaryngeal tissues, and adult-derived stem cells. Scaffolds of interest include decellularized matrix, biological polymers, and synthetic or chemically modified biopolymers. Chemical, mechanical, and spatial signals have been applied, such as hepatocyte growth factor, cyclic stretch, and air interface. Cells, matrix, and signals are combined in an effort to replicate normal vocal fold tissue as closely as possible. Each of these components of vocal fold tissue engineering is discussed here. Multiple tissue engineering approaches hold promise for reproducing functional vocal fold tissue. Scar prevention techniques have been the most successful. Modifying existing scar is more difficult and may necessitate complete scar excision and replacement with a three-dimensional neotissue. Functional assessment in vivo is essential to the ongoing evaluation of techniques.

Atelocollagen Sponge as a Stem Cell Implantation Scaffold for the Treatment of Scarred Vocal Folds

Objectives: Treatment of vocal fold scarring remains a therapeutic challenge. Our group previously reported the efficacy of treating injured vocal folds by implantation of bone marrow—derived stromal cells containing mesenchymal stem cells. Appropriate scaffolding is necessary for the stem cell implant to achieve optimal results. Terudermis is an atelocollagen sponge derived from calf dermis. It has large pores that permit cellular entry and is degraded in vivo. These characteristics suggest that this material may be a good candidate for use as scaffolding for implantation of cells. The present in vitro study investigated the feasibility of using Terudermis as such a scaffold. Methods: Bone marrow—derived stromal cells were obtained from GFP (green fluorescent protein) mouse femurs. The cells were seeded into Terudermis and incubated for 5 days. Their survival, proliferation, and expression of extracellular matrix were examined. Results: Bone marrow—derived stromal cells adhered to Terudermis and underwent significant proliferation. Immunohistochemical examination demonstrated that adherent cells were positive for expression of vimentin, desmin, fibronectin, and fsp1 and negative for beta III tubulin. These findings indicate that these cells were mesodermal cells and attached to the atelocollagen fibers biologically. Conclusions: The data suggest that Terudermis may have potential as stem cell implantation scaffolding for the treatment of scarred vocal folds.

Effects of Basic Fibroblast Growth Factor on Rat Vocal Fold Fibroblasts

The overarching goal of this line of research is to translate basic fibroblast growth factor (bFGF) treatment for vocal fold scarring into practical clinical use. In a previous canine investigation, we demonstrated that bFGF improves phonation threshold pressure, mucosal wave amplitude, and histologic measures in vocal folds treated after injury. In the present study, we studied the effects of bFGF on gene expression of the extracellular matrix and growth factors in rat vocal fold fibroblasts. Fibroblasts harvested from the vocal folds of 5 rats were treated with 3 concentrations of bFGF (0, 10, and 100 ng/mL). The fibroblasts were collected at 24 hours and 72 hours after bFGF administration. Quantitative polymerase chain reaction was then used to investigate the gene expression of the investigated growth factors and extracellular matrices. The results revealed significantly down-regulated expression of procollagen I and significantly up-regulated expression of hyaluronic acid synthase (HAS) 2 and fibronectin in fibroblasts treated with bFGF. The administration of bFGF also resulted in the up-regulation of bFGF and hepatocyte growth factor (HGF). No changes in the expression of HAS-1, tropoelastin, or procollagen III were observed between the treatment and control conditions. Treatment with bFGF induces the down-regulation of procollagen I and the up-regulation of HAS-2 in vocal fold fibroblast cell cultures. These gene expression alterations to key mediators of the wound healing process may translate into potential benefits in the remediation of vocal fold injury. The up-regulation of HGF, an antifibrotic effector molecule, may demonstrate additional benefits by optimizing the wound healing environment and by accelerating the wound repair cascade. These findings may provide fuel for additional discoveries into the development of growth factor therapy for the treatment of vocal fold scar.

Treatment of vocal fold scar by carbon dioxide laser and collagen injection: retrospective study on 12 patients

Vocal fold scars are the result of injury to the vocal fold lamina propria. This condition leads to an impaired vibration and usually to poor voice quality. The purpose of our study was to compare the pre- and posttreatment voice assessment scores in patients treated by CO(2) laser-assisted freeing of the scar followed by collagen injection. A group of 12 patients (10 women and 2 men) with vocal fold scars was studied retrospectively. Voice assessment was based on stroboscopy and on perceptual scores using the Grade (G) of the GRABS scale, subjective evaluation by the use of the Voice Handicap Index (VHI), aerodynamic measurements [maximum phonation time (MPT) and phonation quotient (PQ)], and acoustical measurements (frequency range and low intensity). Stroboscopy showed an improvement on the mucosal vocal fold wave and on the glottic competence. The mean VHI was improved from 63.16 to 45.5; G from 2 to 1.41; MPT from 7.05 to 8.62 s; and PQ from 463.02 to 358.54 ml/s. CO(2) laser freeing of vocal fold scars followed by collagen injection, combined with speech therapy, improved significantly the aerodynamic parameters (efficiency of voice), but not the acoustical scores.

Atelocollagen Sponge as a Stem Cell Implantation Scaffold for the Treatment of Scarred Vocal Folds

Treatment of vocal fold scarring remains a therapeutic challenge. Our group previously reported the efficacy of treating injured vocal folds by implantation of bone marrow-derived stromal cells containing mesenchymal stem cells. Appropriate scaffolding is necessary for the stem cell implant to achieve optimal results. Terudermis is an atelocollagen sponge derived from calf dermis. It has large pores that permit cellular entry and is degraded in vivo. These characteristics suggest that this material may be a good candidate for use as scaffolding for implantation of cells. The present in vitro study investigated the feasibility of using Terudermis as such a scaffold. Bone marrow-derived stromal cells were obtained from GFP (green fluorescent protein) mouse femurs. The cells were seeded into Terudermis and incubated for 5 days. Their survival, proliferation, and expression of extracellular matrix were examined. Bone marrow-derived stromal cells adhered to Terudermis and underwent significant proliferation. Immunohistochemical examination demonstrated that adherent cells were positive for expression of vimentin, desmin, fibronectin, and fspl and negative for beta III tubulin. These findings indicate that these cells were mesodermal cells and attached to the atelocollagen fibers biologically. The data suggest that Terudermis may have potential as stem cell implantation scaffolding for the treatment of scarred vocal folds.

Implantation of an Atelocollagen Sheet for the Treatment of Vocal Fold Scarring and Sulcus Vocalis

The management of vocal fold scarring and sulcus vocalis is challenging. These disorders are thought to be fibroplastic anomalies in the cover portion of the vocal fold that cause deterioration of the vibratory properties of the vocal fold mucosa. Histologic studies have revealed disorganization of extracellular matrix that needs to be addressed in the treatment of scarred vocal folds. Replacement of scar tissues with an appropriate implant may lead to regeneration of the vocal fold mucosa and its tissue properties. This retrospective case study examined the feasibility of using an atelocollagen sheet as a regenerative implant. Six patients with a post-cordectomy scar or sulcus vocalis underwent implantation of an atelocollagen sheet into the lamina propria of the vocal folds. The procedure consisted of elevation of a microflap, dissection and removal of scar tissue, implantation of the material, and wound closure. Vocal function was evaluated before and after surgery by stroboscopic examination and by aerodynamic and acoustic analyses. The postoperative changes of aerodynamic and acoustic parameters varied among patients; however, gradual improvement was seen in most cases over a year. Stroboscopic findings also revealed gradual improvement of vibratory properties in most cases. Implantation of an atelocollagen sheet may have restorative effects on vocal fold scarring and sulcus vocalis in terms of tissue properties and function of the mucosa.

Effect of Exogenous Hepatocyte Growth Factor on Vocal Fold Fibroblasts

We have previously demonstrated the therapeutic potential of hepatocyte growth factor (HGF) in the treatment of vocal fold scarring, although how exogenous HGF affects gene expression of endogenous HGF or extracellular matrix components in the vocal fold fibroblasts remains unclear. In this in vitro study, we aimed to clarify this aspect in order to better understand the effects of HGF on the vocal folds. Fibroblasts were obtained from the lamina propria of the vocal folds of 5 Sprague-Dawley rats and were cultured with HGF at concentrations of 100, 10, 1, and 0 ng/mL. The cells were collected on days 1, 3, and 7, and the expression of endogenous HGF, its receptor c-Met, transforming growth factor-beta1 (TGF-beta1), procollagen types I and III, and hyaluronic acid synthase (HAS)-1 and HAS-2 messenger RNAs (mRNAs) was examined by real-time reverse transcription-polymerase chain reaction. The expression of endogenous HGF and HAS-1 mRNAs increased significantly when exogenous HGF was administered at a concentration of 1 ng/mL. On day 1, the expression of TGF-beta1 and HAS-2 mRNAs increased significantly in response to 1 ng/mL HGF. Exogenous HGF triggered the up-regulation of endogenous HGF, TGF-beta1, HAS-1, and HAS-2 mRNAs in vocal fold fibroblasts.

Office‐based treatment of vocal fold scarring with transcutaneous chordal steroid injections

Vocal fold scarring still remains a therapeutic challenge, with the most problematic issue being the histologic changes that are primarily responsible for altering the viscoelasticity of the vocal fold mucosa. Optimal treatment for vocal fold scarring has not yet been established. Local administrations of steroid directly into the larynx have been reported. Corticosteroid is one of the most potent inhibitors of inflammation in addition to promoting wound repair. Office-based steroid injections of the vocal folds are not popular as a result of the perception that technically it is difficult with questionable benefit. The aim of this study was to analyze the effects of office-based steroid injections for vocal fold scarring.

The Use of the Pulse Dye Laser in the Treatment of Vocal Fold Scar: A Preliminary Study

Dysphonia due to vocal fold scarring is a challenging problem to the laryngologist. Vocal fold scarring after radiation, phonosurgery, and laser cordectomy causes moderate to severe dysphonia. Surgical attempts at scar removal and voice restoration have limited success. Pulsed dye laser (PDL) treatment has been shown to be effective in softening scarred skin by serial office treatments. The objective of this preliminary study was to evaluate the use of the PDL in the management of patients with established vocal fold scar. This is an Institutional Review Board-approved prospective study involving 11 patients. The causes of scarring were phonosurgery (n = 7), radiation (n = 2), and partial laryngectomy (n = 2). The subjects were evaluated pre- and postprocedure using the voice handicap index (VHI), laryngeal stroboscopy rating, voice recordings with acoustic and aerodynamic analysis, and self-evaluation. The PDL was applied with the fiberoptic delivery system by three treatments at 1-month intervals in the office setting. Each treatment endpoint was blanching of the treatment site. : There were three women and eight men in our study group. Ten of 11 patients subjectively improved by self-rating. No patients were worse. VHI improved from 48.44 pretreatment to 35.55 at 6 months posttreatment (P < .05). The jitter at 6 months improved from 2.230% to 1.654% (P = NS) and shimmer improved from 3.679% to 3.196% (P = NS). The noise to harmonic ration improved from 0.1428 to 0.1316 (P = NS). The mean phonotory flow went from 0.177 to 0.254 L/S (P < .05). Three raters blinded to treatment sequence rated the posttreatment stroboscopy findings as better than pretreatment in a forced choice comparison, kappa score 0.903. PDL is a safe and potentially promising treatment for established vocal fold scar. Subjectively, no patients were worse and 10 of 11 patients reported improved voice. There was improvement in the VHI, acoustic measures of shimmer and jitter, and stroboscopy findings. Further study using this approach in a larger cohort seems to be warranted.

Expression of extracellular matrix proteins in the vocal folds and bone marrow derived stromal cells of rats

Vocal fold scarring remains a therapeutic challenge. Our research group has indicated that bone marrow-derived stromal cells (BSCs) may have therapeutic potential in restoration of injured vocal folds. However, it is still unclear how BSCs restore the viscoelasticity of vocal fold mucosa. Since a feature of vocal fold scarring is the disorganization of the extracellular matrix (ECM), it is important to understand how BSCs produce ECM. The present study aimed to clarify ECM gene expression in BSCs, and also examined the effects of hepatocyte growth factor (HGF) on this expression. BSCs obtained from the femurs of four Sprague-Dawley rats were cultured with or without HGF. The mRNA expression of ECM components (type I procollagen, decorin, Has2, CD44, MMP-1, and GAPDH) were examined in cultured BSCs and the vocal fold mucosa by the reverse transcription-polymerase chain reaction (RT-PCR). The mRNA expression of Has2 and MMP-1 was significantly stronger in BSCs than in the vocal folds (P < 0.05). Expression of Has2 in BSCs was significantly increased by the administration of HGF (P < 0.05). There was no significant difference in the gene expression of other ECM molecules between BSCs and vocal fold mucosa. Increased expression of Has2 and MMP-1 genes from BSCs may have a positive potential in the treatment of vocal fold scarring.

Drug Delivery System of Hepatocyte Growth Factor for the Treatment of Vocal Fold Scarring in a Canine Model

Vocal fold scarring remains a therapeutic challenge. Previous studies have indicated that hepatocyte growth factor (HGF), a strong antifibrotic element, has therapeutic potential for restoring scarred vocal folds. To enhance the effect of HGF in vivo, we developed a novel drug delivery system (DDS) in which HGF is embedded in gelatin hydrogel and continuously released over a period of 2 weeks. In the present study we investigated the therapeutic efficacy of the HGF DDS on vocal fold scarring by using a canine model. The vocal folds of 8 beagles were unilaterally scarred by stripping the entire layer of the lamina propria. The contralateral vocal folds were kept intact as normal controls. One month after the procedure, hydrogels (0.5 mL) containing 1 microg of HGF were injected into the scarred vocal folds of 4 dogs (HGF-treated group), whereas hydrogels containing saline solution were injected in the other 4 dogs (sham group). Histologic and vibratory examinations were completed for each group 6 months after the initial surgery. The excised larynx experiments showed significantly better vibration in terms of mucosal wave amplitude and glottal closure in the HGF-treated group compared to the sham group. Histologic evaluation of the vocal folds indicated remarkable reduction in collagen deposition and tissue contraction, with favorable restoration of hyaluronic acid and elastin in the HGF-treated group. The present findings suggest that the novel HGF DDS may provide favorable effects in restoring the vibratory properties of scarred vocal folds.